HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Innis, S. M. Articles by Dyer, R. A. Search for Related Content PubMed PubMed Citation Articles by Innis, S. M. Articles by Dyer, R. A. Social Bookmarking                      What's this?

Journal of Lipid Research, Vol. 43, 1529-1536, September 2002
Copyright © 2002 by Lipid Research, Inc.

Brain astrocyte synthesis of docosahexaenoic acid from n-3 fatty acids is limited at the elongation of docosapentaenoic acid

Sheila M. Innis¹ and Roger A. Dyer

Department of Paediatrics, University of British Columbia, Vancouver, BC, Canada, V5Z 4H4

DOI 10.1194/jlr.M200120-JLR200

¹ To whom correspondence should be addressed. e-mail: sinnis{at}nutrition.ubc.ca

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
The phospholipids, particularly phosphatidylethanolamine, of brain gray matter are enriched with docosahexaenoic acid (22:6n-3). The importance of uptake of preformed 22:6n-3 from plasma compared with synthesis from the -linolenic acid (18:3n-3) precursor in brain is not known. Deficiency of 18:3n-3 results in a compensatory increase in the n-6 docosapentaenoic acid (22:5n-6) in brain, which could be formed from the precursor linoleic acid (18:2n-6) in liver or brain. We studied n-3 and n-6 fatty acid incorporation in brain astrocytes cultured in chemically defined medium using delipidated serum supplemented with specific fatty acids. High performance liquid chromatography with evaporative light scattering detection and gas liquid chromatography were used to separate and quantify cell and media lipids and fatty acids. Although astrocytes are able to form 22:6n-3, incubation with 18:3n-3 or eicosapentaenoic acid (20:5n-3) resulted in a time and concentration dependent accumulation of 22:5n-3 and decrease in 22:6n-3 g/g cell fatty acids. Astrocytes cultured with 18:2n-6 failed to accumulate 22:5n-6.

Astrocytes secreted cholesterol esters (CE) and phosphatidylethanolamine containing saturated and monounsaturated fatty acids, and arachidonic acid (20:4n-6) and 22:6n-3. These studies suggest conversion of 22:5n-3 limits 22:6n-3 synthesis, and show astrocytes release fatty acids in CE.

Abbreviations: CE, cholesterol ester; dbc-AMP, dibutyryl cyclic AMP; ELSD, evaporative light scattering detection; FCS, fetal calf serum; GFAP, glial fibrillary acidic protein; GLC, gas liquid chromatography; HPLC, high performance liquid chromatography; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PI, phosphatidylinositol; PS, phosphatidylserine; TG, triglyceride

Supplementary key words astrocyte • docosahexaenoic acid • docosapentaenoic acid • alpha linolenic acid • desaturation • elongation • cholesterol ester • phosphatidylethanolamine

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Brain gray matter is highly enriched in the long chain polyunsaturated fatty acids docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) (1). Docosahexaenoic acid is formed from 18:3n-3 by 6 and 5 desaturation and elongation which gives rise to 20:5n-3 and 22:5n-3 in endoplasmic reticulum; 22:5n-3 is then elongated to 24:5n-3 and undergoes a second 6 desaturation to 24:6n-3 and is translocated to the peroxisomes where it undergoes one cycle of ß-oxidation to form 22:6n-3 (Fig. 1) (2–4). Whether the 6 desaturase responsible for the desaturation of 18:3n-3 and 24:5n-3 are the same or different enzymes, and the steps involved in the intracellular movement of 24:6n-3 are not completely understood (5, 6). Synthesis of 20:4n-6 from 18:2n-6 is believed to involve the same 6 and 5 desaturases involved in the metabolism of 18:3n-3. Further metabolism of 20:4n-6 leads to formation of 22:5n-6 in an analogous pathway to that used for formation of 22:6n-3 (6). Dietary deficiency of 18:3n-3 results in a characteristic increase in 22:5n-6 in brain phospholipids, such that the total amount of carbon chain n-6 plus n-3 fatty acids is maintained (7–10). Despite this, decreased 22:6n-3 in the developing brain and retina results in decreased visual and neural function, and altered monoaminergic neurotransmitter metabolism (9–13). Uptake and conversion of ¹⁴C-labeled 18:3n-3 to n-3 products by brain and isolated brain cells has been shown (14–16). However, developing brain is also able to take up 22:6n-3 and 20:4n-6 from plasma (12, 17, 18). The importance of uptake of 22:6n-3 from plasma compared with synthesis of 22:6n-3 in the brain following uptake of n-3 fatty acid precursors is not known (5). However, studies with preterm infants have shown that the dietary intake and blood lipid level of 22:6n-3 is positively related to visual and neural development (19–22).

View larger version (24K): [in this window] [in a new window]   Fig. 1. Schematic of the desaturation and elongation of 18:2n-6 and 18:3n-3.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Materials
Fatty acids were purchased from Sigma Chemical Co. (St. Louis, MO, USA) and Nuchek Prep (Elysion, MN). Rat glial fibrillary acidic protein (GFAP) and its conjugate, rabbit anti-rat IgG, was from DAKO (Santa Barbara, CA). Dibutyryl cAMP and fatty acid free BSA were from Sigma (St Louis, MO). Fetal calf serum (FCS), DMEM/F12, trypsin, streptomycin, penicillin, and Versene were from Canadian Life Technologies (Burlington, Canada).

Cell culture
Primary cultures were prepared from forebrain gray matter of 1-day-old rat pups after dissecting away meningeal tissues using the procedures of McCarthy and de Vellis (23). The resulting mixed glial culture enriched in astrocytes, but containing oligodendrocytes and neurons was seeded at a density of 1 x 10⁶ in 75 cm² tissue culture flasks and maintained in DMEM/F12 supplemented with 10% FCS, 50 µg/ml streptomycin, and 50 U/ml penicillin. The media was changed 24 h after seeding, and thereafter every 48 h. Neurons fail to survive the initial phase of these culture conditions and were eliminated by the third day of culture. Contaminating oligodendrocytes, which form a top layer of process bearing cells, were removed between days 8 and 10 by dissociation (23). The astrocytes formed a confluent monolayer within about 4 days and were 95% astrocytes when characterized by GFAP staining and light microscopy as described by Bock et al. (24). Astrocytes from neonatal rat brain, termed type-A astrocytes, undergo morphological and histochemical changes similar to in vivo differentiation when treated with dibutyryl cAMP (25). Within 3 to 4 h of addition of dibutyryl cAMP to the culture, astrocytes transform from a polygonal morphology to a process bearing morphology similar to that found in 10-day-old rat pup astrocytes (25). Whether these morphological and histochemical changes include changes in n-6 and n-3 fatty acid uptake is not known. In initial studies, we therefore compared n-3 and n-6 fatty acid uptake and incorporation in neonatal type A astrocytes and in astrocytes transformed with dibutyryl cAMP. Time and substrate concentration studies with 18:3n-3 supplemented media found no differences in the accumulation of n-3 fatty acids between neonatal astrocytes and astrocytes transformed with dibutyryl cAMP. We note, however, that transformed cell lines of neural origin are known to lose their ability to desaturate and elongate fatty acids (26, 27), and dibutyryl cAMP may not induce biochemical development analogous to that in vivo. Only results for neonatal astrocytes without treatment with dibutyryl cAMP are presented.

Experimental procedures
The uptake and incorporation of n-3 and n-6 fatty acids into astrocyte lipids was studied in 6-well tissue culture plates. The cells were maintained at 37°C in a 5% CO₂ incubator during all experiments, in 2.5 ml DMEM/F12 with 5% delipidated FCS, with media changed every 24 h. Delipidated FCS was prepared according to the method of Rothblat et al. (28), and the absence of n-6 and n-3 fatty acid checked by gas liquid chromatography (GLC) (21, 29). Fatty acids, 0–50 µm, as their sodium salts, were complexed with fatty acid free bovine serum albumen at a molar ratio of 2:1. For each experiment, a minimum of three parallel cell cultures were established.

Lipid analysis
Total lipids were extracted from the cells and media (30), the organic phase evaporated under nitrogen, and the lipids solubilized in chloroform-methanol-acetone-hexane (2.0:3.0:0.5:0.5, v/v/v/v). Separation of polar and non-polar lipids, including individual classes, was achieved using a HPLC (Waters 2690 Alliance HPLC, (Milford MA), equipped with an auto-sampler and column heater. The sample chamber was kept at 18°C and the column heater at 35°C. The column was a Waters YMC-Pack Diol 120NP, 25 cm x 4.6 mm id, 5 µm particle size and 12 nm pore size. We used a quaternary solvent system of hexane-petroleum ether, 97:3 (v,v); methanol-triethylamine-acetic acid, 765:15:13 (v/v/v); acetone-triethylamine-acetic acid, 765:15:13 (v/v/v); isopropanol-acetic acid, 800:40 (v/v) in a linear gradient with a flow rate of 2 ml/min. The column eluant was split 10:90 to an ELSD (Alltech, model 2000; Mandel Scientific, Guelph, Canada) and a fraction collector (Gilson FC204, Mandel Scientific). ELSD detection and quantitation of the separated lipid classes was performed with a nitrogen flow rate of 1.8 ml/min, a drift tube temperature of 60°C, and the impactor OFF. Calibration curves to determine the linear range of the analysis were established using authentic standards for each lipid class, and samples were quantified using the external standard method. The identification of cholesterol ester recovered in the media was confirmed by GCL-mass spectrometry (Varian Saturn II; Varian Canada, Mississagua, Canada). Fatty acids were quantified as their respective methyl esters using heptadecanoic acid (17:0) as the internal standard, with a Varian 3400 GLC equipped with a flame ionization detector, Varian Star data system and a 30 m x 0.25 mm id glass capillary SP 2330 columns (21, 29).

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Although brain astrocytes as well as neurons are enriched in 22:6n-3 (31), this fatty acid must be obtained either by uptake and further desaturation and elongation of 18:3n-3 or other intermediary metabolites or by uptake of 22:6n-3 itself from plasma. Astrocytes cultured in defined media with delipidated serum with and without 18:3n-3 had similar concentrations of 22:6n-3 in individual phospholipids and triglycerides (Fig. 2) . As is characteristic of brain gray matter (1), 22:6n-3 was enriched in cultured neonatal astrocyte phosphatidylethanolamine. Neural cells typically contain very low 22:5n-3. Supplementation with 18:3n-3, however, resulted in accumulation of 22:5n-3 in all lipid classes, such that 22:5n-3 became the major n-3 fatty acid in triglycerides, phosphatidylserine, and phosphatidylcholine. The major product of 18:3n-3 incorporated into the cell lipids of astrocytes cultured with 18:3n-3 was 22:5n-3 (Fig. 3) . Increasing concentrations of the 18:3n-3 substrate resulted in increased incorporation of 22:5n-3. No accumulation of 24 carbon chain n-3 fatty acids was found (<0.01% total cell fatty acids).

View larger version (23K): [in this window] [in a new window]   Fig. 2. Concentrations of 22:6n-3 and 22:5n-3 in neonatal astrocytes cultured with delipidated serum with 30 µM 18:3n-3 for 72 h. The cell lipids, triglycerides (TG), phophatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), and phosphatidylcholine (PC) were separated by HPLC and detected and quantified by ELSD, fractionated, and the fatty acids determined as their methyl esters using GLC as described in Materials and Methods. The data are means and standard error from a minimum of three separate cultures. Small standard errors do not signify in the plot.

View larger version (41K): [in this window] [in a new window]   Fig. 3. Concentrations of n-3 fatty acids in cell lipids of neonatal astrocytes cultured with delipidated serum with 0, 10, 30 or 50 µM 18:3n-3 for 24, 48, 72 or 96 h. The cell lipids were extracted and analyzed by capillary GLC as described in Materials and Methods. The data are means and standard error from a minimum of three separate cultures. Small standard errors do not signify in the plot.

View larger version (33K): [in this window] [in a new window]   Fig. 4. Concentrations of n-3 fatty acids in cell lipids of neonatal astrocytes cultured in delipidated serum supplemented with 50 µM 20:5n-3 or 22:6n-3 for 72 h. The cell lipids were extracted and analyzed by capillary GLC as described in Materials and Methods. The data are means and standard error from a minimum of three separate cultures. Small standard errors do not signify in the plot.

View larger version (27K): [in this window] [in a new window]   Fig. 5. Concentrations of n-3 fatty acids in cell lipids of freshly isolated neonatal astrocytes and astrocytes cultured with delipidated serum without or with 50 µM 18:2n-6 and no n-3 fatty acids. The cell lipids were extracted and analyzed by capillary GLC as described in Materials and Methods. The data are means and standard error from a minimum of three separate cultures. Small standard errors do not signify in the plot.

View larger version (24K): [in this window] [in a new window]   Fig. 6. Concentrations of individual lipids in neonatal brain astrocytes and media following culture for 12 h with lipid-free serum. TG, free cholesterol (FC), esterified cholesterol (CE), unesterified fatty acids (FFA), PE, PC, sphingomyelin (SpH), PS, PI, and lysophophatidylcholine (LPC) were separated by HPLC, then detected and quantified by ELSD as described in Materials and Methods. The data are means and standard error from a minimum of three separate cultures. Small standard errors do not signify in the plot. The concentrations of TG, PE, PI and PS in the culture media were <1 µg/ml media/mg cell protein.

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

Previous studies have provided evidence of 22:6n-3 synthesis in brain and brain astrocytes based on the recovery of ¹⁴C from [1-¹⁴C]18:3n-3 in 22:6n-3 (14–16, 33). Consistent with our results, others have shown the most abundant radio-labeled product in astrocytes cultured with [1-¹⁴C]18:3n-3 is 22:5n-3, not 22:6n-3 (33), although this does not exclude the capacity for 22:6n-3 synthesis (15, 16). We suggest the current evidence indicates astrocyte synthesis of 22:6n-3 from n-3 precursors, or of 22:5n-6 from 18:2n-6 under conditions of n-3 fatty acid deficiency, is not the major route through which developing brain accumulates high concentrations of 22:6n-3 or 22:5n-6. However, it is possible that primary cultures of neonatal brain astrocytes loose a capacity for further metabolism of 22:4n-6 and 22:5n-3, which is expressed in vivo.

Rapoport et al. (17) have estimated that 2–8% of rat brain phospholipid 22:6n-3 is replaced daily with 22:6n-3 from the plasma unesterified fatty acid pool. Turnover of 22:6n-3 involves de-esterification and re-esterification, and appears to be related to phospholipase-A₂ activity and receptor-dependent signal transduction involving GTP proteins (34–37). These pathways are also critical to the functional roles of 22:6n-3 in neural tissues. Efficient recycling and reacylation is likely to conserve a large proportion of 22:6n-3 released during phospholipid deacylation (37) consistent with the ability of the adult brain to retain 22:6n-3 even during severe dietary n-3 fatty acid deficiency (38). Net accumulation of 22:6n-3, however, is essential to support the rapid structural lipid growth that occurs during brain development (9), and failure to do so is accompanied by reduced visual and neural function (9–13). Consequently, an understanding of the importance of the plasma supply of 22:6n-3 in maintaining optimal neural concentrations of 22:6n-3 is important in resolving the significance of low plasma 22:6n-3 in infants fed formulas without this fatty acid (19–22), and in some psychiatric diseases (39). It is clear that the liver is able to desaturate 18:3n-3 to 22:6n-3 (3) and many studies have provided evidence that plasma 22:6n-3, which could be derived from synthesis in liver or from the diet, is taken up and esterified into brain lipids (12, 17, 18, 40). It is also clear that the ability of the brain (12, 18) and astrocytes in culture to take up 22:6n-3 (Fig. 3) (33) far exceeds the efficiency with which 18:3n-3 can be converted into 22:6n-3 and incorporated into membrane lipids. The capacity for chain shortening and retro-conversion of 22:6n-3 to 22:5n-3 and 20:5n-3 in astrocytes cultured with 22:6n-3 suggests that the ability for peroxisomal ß-oxidation is not likely to limit 22:6n-3 synthesis. The cumulative evidence thus supports the view that the main source of brain 22:6n-3 is the plasma, being derived from the liver or diet.

Neonatal brain astrocytes cultured in the presence of lipid-free serum preferentially secreted CE, and small amounts of lysophosphosphatidylcholine, phosphatidylcholine, sphingomyelin, and unesterfied fatty acids. This is significant because cholesterol and non-essential saturated and monounsaturated fatty acids are preferentially synthesized de novo in the developing brain (41, 42), probably from acetyl-CoA in astrocytes. Oxidation of 18:3n-3 may contribute acetyl-CoA for de novo fatty acid and cholesterol synthesis in the brain (41, 43–45). Synthesis of specific lipoproteins in brain (46) and of apolipoproteins by astrocytes (47, 48) has been reported. Further, astrocytes play an important role in supplying 22:6n-3 to neurons and cerebromicrovascular cells (15, 16, 49). Our results suggest CE and other lipids, potentially secreted with apolipoproteins could be important in the intracellular trafficking of cholesterol and non-essential and essential n-6 and n-3 fatty acids from astrocytes to other neural cells.

	ACKNOWLEDGMENTS

 
This work was supported by a grant from the Canadian Institute for Health Research.

Manuscript received March 13, 2002 and in revised form May 28, 2002.

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

1. Sastry, P. S. 1985. Lipids of nervous tissue: composition and metabolism. Prog. Lipid Res. 24: 169–176.

2. Luthria, D. L., B. S. Mohammed, and H. Sprecher. 1996. Regulation of the biosynthesis of 4,7,10,13,16,19-docosahexaenoic acid. J. Biol. Chem. 271: 16020–16025.[Abstract/Free Full Text]

3. Sprecher, H., D. L. Luthria, B. S. Mohammed, and S. P. Baykousheva. 1995. Reevaluation of the pathways for biosynthesis of polyunsaturated fatty acids. J. Lipid Res. 36: 2471–2477.[Abstract]

4. Voss, A., M. Reinhard, S. Sankarappa, and H. Sprecher. 1991. The metabolism of 7,10,13,16,19-docosapentaenoic acid to 4,7,10,13, 16,19-docosahexaenoic acid in rat liver is independent of a 4-desaturase. J. Biol. Chem. 266: 19995–20000.[Abstract/Free Full Text]

5. Innis, S. M., H. Sprecher, D. Hachey, R. Anderson, and J. Edmond. 1999. Neonatal polyunsaturated fatty acid metabolism. Lipids. 34: 139–149.[CrossRef][Medline]

6. Sprecher, H., Q. Chen, and F. Q. Yin. 1999. Regulation of the biosynthesis of 22:5n-6 and 22:6n-3: a complex intracellular process. Lipids. 34: S153–S156.

7. Galli, C., H. I. Trzeciak, and R. Paoletti. 1971. Effects of dietary fatty acids on the fatty acid composition of brain ethanolamine phosphoglyceride: reciprocal replacement of n-6 and n-3 polyunsaturated fatty acids. Biochem. Biophys. Acta. 248: 449–454.

8. Hrboticky, N., M. J. MacKinnon, and S. M. Innis. 1990. Effect of a vegetable oil formula rich in linioleic acid on tissue fatty acid accretion in the brain, liver, plasma, and erythrocytes of infant piglets. Am. J. Clin. Nutr. 51: 173–182.[Abstract/Free Full Text]

9. Innis, S. M. 1991. Essential fatty acids in growth and development. Prog. J. Lipid Res. 30: 39–103.[Abstract]

10. Neuringer, M., W. E. Connor, D. S. Lin, L. Barstad, and S. Luck. 1986. Biochemical and functional effects of prenatal and postnatal -3 deficiency on retina and brain in rhesus monkeys. Proc. Natl. Acad. Sci. USA. 83: 4021–4025.[Abstract/Free Full Text]

11. Bourre, J. M., M. Francois, A. Youyou, O. Dumont, M. Piciotti, G. Pascal, and G. Durand. 1989. The effects of dietary -linolenic acid on the composition of nerve membranes, enzymatic activity, amplitude of electrophysiological parameters, resistance to poisons and performance of learning tasks in rats. J. Nutr. 119: 1880–1892.

12. De la Presa Owens, S., and S. M. Innis. 1999. Docosahexaenoic and arachidonic acid reverse changes in dopaminergic and sertoninergic neurotransmitters in piglet frontal cortex caused by a linoleic and alpha linolenic acid deficient diet. J. Nutr. 129: 2088–2093.[Abstract/Free Full Text]

13. Delion, S., S. Chalon, J. Herault, D. Guilloteau, J. C. Besnard, and G. Durand. 1994. Chronic dietary -linoleic acid deficiency alters dopaminergic and serotinergic neurotransmitters in rats. J. Nutr. 124: 2466–2476.

14. Dhopesharkar, G. A., and C. Subramanian. 1976. Biosynthesis of polyunsaturated fatty acids in the developing brain: I. Metabolic transformation of intracranially administered 1–14C linolenic acid. Lipids. 11: 67–71.[CrossRef][Medline]

15. Moore, S. A., E. Yoder, S. Murphy, G. R. Dutton, and A. A. Spector. 1991. Astrocytes, not neurons, produce docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6). J. Neurochem. 56: 518–524.[Medline]

16. Bernoud, N., L. Fenart, C. Benistant, J. F. Pageaux, M. P. Dehouck, P. Moliere, M. Lagarde, R. Cecchelli, and J. Lecerf. 1998. Astrocytes are mainly responsible for the polyunsaturated fatty acid enrichment in blood-brain barrier endothelial cells in vitro. J. Lipid Res. 39: 1816–1824.[Abstract/Free Full Text]

17. Rapoport, S. I., M. C. J. Chang, and A. A. Spector. 2001. Delivery and turnover of plasma-derived essential PUFAs in mammalian brain. J. Lipid Res. 42: 678–685.[Abstract/Free Full Text]

18. Su, H. M., L. Bernardo, M. Mirmiran, X. H. Ma, T. N. Corso, P. W. Nathanielsz, and J. T. Brenna. 1999. Bioequivalence of dietary -linolenate and docosahexaenoate acids as possible sources of docosahexaenoate accretion in brain and associated organs of neonatal baboons. Ped. Res. 45: 87–93.[Medline]

19. Birch, E. E., D. R. Hoffman, R. Uauy, D. G. Birch, and C. Prestidge. 1998. Visual acuity and the essentility of docosahexaenoic acid and arachidonic acid in the diet of term infants. Pediatr Res. 44: 201–209.[Medline]

20. Carlson, S. E., S. H. Werkman, P. G. Rhodes, and E. A. Tolley. 1993. Visual-acuity development in healthy preterm infants: effect of marine-oil supplementation. Am. J. Clin. Nutr. 58: 35–42.[Abstract/Free Full Text]

21. Innis, S. M., J. Gilley, and J. Werker . 2001. Are human-milk long-chain polyunsaturated fatty acids related to visual and neural development in breast-fed infants ? Pediatrics. 139: 532–538.

22. O'Connor, D. L., N. Auestad, and J. Jacobs. 2001. Growth and development in preterm infants fed long-chain polyunsaturated fatty acids: a prospective randomized controlled trial. Pediatrics. 108: 359–372.[Abstract/Free Full Text]

23. McCarthy, K. D., and J. de Vellis. 1980. Preparation of separate astroglial and oligodendroglial cell cultures from rat cerebral tissue. J. Cell Biol. 85: 890–902.[Abstract/Free Full Text]

24. Bock, E., O. S. Jorgensen, L. Driftmann, and L. F. Eng. 1975. Determination of brain specific antigens in short term cultured rat astroglial cells and in rat synaptosomes. J. Neurochem. 25: 867–870.[CrossRef][Medline]

25. Federoff, S., R. White, L. Subrahmanyan, and V. I. Kalnins. 1981. Properties of putative astrocytes in colony cultures of mouse neopallium. Prog. Clin. Biol. Res. 59: 1–19.

26. Cook, H. W., and M. W. Spence. 1987. Studies of the modulation of essential fatty acid metabolism by fatty acids in cultured neuroblastoma and glioma cells. Biochim. Biophys. Acta. 918: 212–229.

27. Yavin, E., Z. Menkes, and J. H. Menkes. 1975. Polyunsaturated fatty acid metabolism in neuroblastoma cells in culture. J. Neurochem. 24: 71–77.[CrossRef][Medline]

28. Rothblat, G. H., L. Y. Arbogast, L. Ouellette, and B. V. Howard. 1976. Preparation of delipidized serum protein for use in cell culture systems. In Vitro. 12: 554–557.[Medline]

29. Elias, S. L., and S. M. Innis. 2000. Newborn infant plasma trans, conjugated linoleic, n-6 and n-3 fatty acids are related to maternal plasma fatty acids, length of gestation and birth weight and length. Am. J. Clin. Nutr. 73: 807–814.[Abstract/Free Full Text]

30. Folch, J., M. Less, and G. H. S. Sloane-Stanley. 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226: 497–509.[Free Full Text]

31. Bourre, J. M., A. Faivre, O. Dumont, A. Nouvelot, C. Loudes, J. Puymirat, and A. Tixier-Vidal. 1983. Effect of polyunsaturated fatty acids on fetal mouse brain cells in culture in a chemically defined medium. J. Neurochem. 41: 1234–1242.[CrossRef][Medline]

32. Sinclair, A. J., and M. A. Crawford. 1972. The accumulation of arachidonate and docosahexaenoate in the developing rat brain. J. Neurochem. 19: 1753–1758.[Medline]

33. Williard, D. E., S. D. Harmon, T. L. Kaduce, M. Preuss, S. A. Moore, M. E. C. Robbins, and A. A. Spector. 2001. Docosahexaenoic acid synthesis from n-3 polyunsaturated fatty acids in differentiated rat brain astrocytes. J. Lipid Res. 42: 1368–1376.[Abstract/Free Full Text]

34. Axelrod, J. 1995. Phospholipase A2 and G proteins. Trends Neurosci. 18: 64–65.[CrossRef][Medline]

35. Jones, C. R., T. Arai, and I. Rapoport. 1997. Evidence for the involvement of docosahexaenoic acid in cholinergic stimulated signal transduction at the synapse. Neurochem. Res. 22: 663–670.[CrossRef][Medline]

36. Litman, B. J., S. L. Niu, A. Polozova, and D. C. Mitchell. 2001. The role of docosahexaenoic acid containing phospholipids in modulating G protein-coupled signaling pathways: visual transduction. J. Mol. Neurosci. 16: 237–242.[CrossRef][Medline]

37. Gordon, W. C., E. B. Rodriguez de Turco, and N. G. Bazan. 1992. Retinal pigment epithelial cells play a central role in the conservation of docosahexaenoic acid by photoreceptor cells after shedding and phagocyctosis. Curr. Eye Res. 11: 73–83.[Medline]

38. Tinoco, J. 1982. Dietary requirements and function of alpha linolenic acid in animals. Prog. Lipid Res. 21: 1–45.[CrossRef][Medline]

39. Locke, C. A., and A. L. Stoll. 2001. Omega-3 acids in major depression. World Rev. Nutr. Diet. 89: 173–185.[Medline]

40. Scott, B. L., and N. G. Bazan. 1989. Membrane docosahexaenoate is supplied to the developing brain and retina by the liver. Proc. Natl. Acad. Sci. USA. 86: 2903–2907.[Abstract/Free Full Text]

41. Edmond, J., R. A. Korsak, J. W. Morrow, G. Torok-Both, and D. Catlin. 1991. Dietary cholesterol and the origin of cholesterol in brain of developing rats. J. Nutr. 121: 1323–1330.

42. Edmond, J., T. A. Higa, R. A. Korsak, E. A. Bergna, and W. N. Lee. 1998. Fatty acid transport and utilization for the developing brain. J. Neurochem. 70: 1227–1234.[Medline]

43. Marbois, B. N., H. O. Ajie, R. A. Korsak, D. K. Sensharma, and J. Edmond. 1992. The origin of palmitic acid in brain of the developing rat. Lipids. 27: 587–592.[CrossRef][Medline]

44. Cunnane, S. C., C. R. Menard, S. S. Lokhodi, J. T. Brenna, and M. A. Crawford. 1999. Carbon recycling into de novo lipogenesis is a major pathway in neonatal metabolism of linoleate and -linolenate. Prostaglandins Leukot. Essent. Fatty Acids. 60: 387–392.[CrossRef][Medline]

45. Sheaff Greiner, R. C., Q. Zhang, K. J. Goodman, D. A. Giussani, P. W. Nathanielsz, and J. T. Brenna. 1996. Linoleate, -linolenate, and docosahexaenoate recycling into saturated and mono unsaturated fatty acids is a major pathway in pregnant or lactating adults and fetal or infant rhesus monkeys. J. Lipid Res. 37: 2675–2686.[Abstract]

46. Pitas, R. E., J. K. Boyles, S. H. Lee, D. Hui, and K. H. Weisgraber. 1987. Lipoproteins and their receptors in the central nervous system. Characterization of the lipoproteins in cerebrospinal fluid and identification of apolipoprotein B,E (LDL) receptors in the brain. J. Biol. Chem. 262: 14352–14360.[Abstract/Free Full Text]

47. Pitas, R. E., J. K. Boyles, S. H. Lee, D. Foss, and R. W. Mahley. 1987. Astrocytes synthesize apolipoprotein E and metabolize apolipoprotein E-containing lipoproteins in the central nervous system. Biochim. Biophys. Acta. 917: 148–161.[Medline]

48. Oropeza, R. L., H. Werkerle, and Z. Werb. 1987. Expression of apolipoprotein E by mouse brain astrocytes and its modulation by interferon gamma. Brain Res. 410: 45–51.[CrossRef][Medline]

49. Moore, S. A. 2001. Polyunsaturated fatty acid synthesis and release by brain-derived cells in vitro. J. Mol. Neurosci. 16: 195–200.[CrossRef][Medline]

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				M. S. Kim, F. Wang, P. Puthanveetil, G. Kewalramani, E. Hosseini-Beheshti, N. Ng, Y. Wang, U. Kumar, S. Innis, C. G. Proud, et al. Protein Kinase D Is a Key Regulator of Cardiomyocyte Lipoprotein Lipase Secretion After Diabetes Circ. Res., August 1, 2008; 103(3): 252 - 260. [Abstract] [Full Text] [PDF]

				A. M. Devlin, R. Singh, R. E. Wade, S. M. Innis, T. Bottiglieri, and S. R. Lentz Hypermethylation of Fads2 and Altered Hepatic Fatty Acid and Phospholipid Metabolism in Mice with Hyperhomocysteinemia J. Biol. Chem., December 21, 2007; 282(51): 37082 - 37090. [Abstract] [Full Text] [PDF]

				S. Ghosh, E. M. Novak, and S. M. Innis Cardiac proinflammatory pathways are altered with different dietary n-6 linoleic to n-3 {alpha}-linolenic acid ratios in normal, fat-fed pigs Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H2919 - H2927. [Abstract] [Full Text] [PDF]

				J. L. Pongrac, P. J. Slack, and S. M. Innis Dietary Polyunsaturated Fat that Is Low in (n-3) and High in (n-6) Fatty Acids Alters the SNARE Protein Complex and Nitrosylation in Rat Hippocampus J. Nutr., August 1, 2007; 137(8): 1852 - 1856. [Abstract] [Full Text] [PDF]

				S. M Innis, A G. F Davidson, S. Melynk, and S J. James Choline-related supplements improve abnormal plasma methionine-homocysteine metabolites and glutathione status in children with cystic fibrosis Am. J. Clinical Nutrition, March 1, 2007; 85(3): 702 - 708. [Abstract] [Full Text] [PDF]

				G. Qiu, A. C. Ho, W. Yu, and J. S. Hill Suppression of endothelial or lipoprotein lipase in THP-1 macrophages attenuates proinflammatory cytokine secretion J. Lipid Res., February 1, 2007; 48(2): 385 - 394. [Abstract] [Full Text] [PDF]

				B. T. Kao, K. A. Lewis, E. J. DePeters, and A. L. Van Eenennaam Endogenous production and elevated levels of long-chain n-3 fatty acids in the milk of transgenic mice. J Dairy Sci, August 1, 2006; 89(8): 3195 - 3201. [Abstract] [Full Text] [PDF]

				J. E. Bauer, K. M. Heinemann, G. E. Lees, and M. K. Waldron Retinal Functions of Young Dogs Are Improved and Maternal Plasma Phospholipids Are Altered with Diets Containing Long-Chain n-3 Polyunsaturated Fatty Acids during Gestation, Lactation, and after Weaning J. Nutr., July 1, 2006; 136(7): 1991S - 1994S. [Full Text] [PDF]

				P. Coti Bertrand, J. R. O'Kusky, and S. M. Innis Maternal Dietary (n-3) Fatty Acid Deficiency Alters Neurogenesis in the Embryonic Rat Brain J. Nutr., June 1, 2006; 136(6): 1570 - 1575. [Abstract] [Full Text] [PDF]

				R. Friesen and S. M. Innis Maternal dietary fat alters amniotic fluid and fetal intestinal membrane essential n-6 and n-3 fatty acids in the rat Am J Physiol Gastrointest Liver Physiol, March 1, 2006; 290(3): G505 - G510. [Abstract] [Full Text] [PDF]

				K. Jacobson, H. Mundra, and S. M. Innis Intestinal responsiveness to experimental colitis in young rats is altered by maternal diet Am J Physiol Gastrointest Liver Physiol, July 1, 2005; 289(1): G13 - G20. [Abstract] [Full Text] [PDF]

				S. Ghosh, D. Qi, D. An, T. Pulinilkunnil, A. Abrahani, K.-H. Kuo, R. B. Wambolt, M. Allard, S. M. Innis, and B. Rodrigues Brief episode of STZ-induced hyperglycemia produces cardiac abnormalities in rats fed a diet rich in n-6 PUFA Am J Physiol Heart Circ Physiol, December 1, 2004; 287(6): H2518 - H2527. [Abstract] [Full Text] [PDF]

				K.-F. Ng and S. M. Innis Behavioral Responses Are Altered in Piglets with Decreased Frontal Cortex Docosahexaenoic Acid J. Nutr., October 1, 2003; 133(10): 3222 - 3227. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Innis, S. M. Articles by Dyer, R. A. Search for Related Content PubMed PubMed Citation Articles by Innis, S. M. Articles by Dyer, R. A. Social Bookmarking                      What's this?