An adequate ingestion of essential fatty acids is required for optimal development of the central nervous system and visual acuity in infants. For breast feeding mothers, it is important that a diet containing an adequate balance of essential fatty acids of the n-6 and n-3 series be consumed as this is reflected in breast milk. The objective of this investigation was to determine the essential fatty acid status of breast feeding women and their infants in Havana, Cuba, with particular focus on the n-3 series. The group of 56 Cuban mothers and infants under investigation did not show biochemical or functional signs of poor essential fatty acid status. Based on the biochemical and functional data collected, it is conceivable to conclude that n-3 fatty acid deficiencies must be exceedingly rare, if they exist at all, in the population of breast feeding women and their infants residing in Havana, Cuba. (Abstract shortened by UMI.)

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Essential fatty acids nutrition and its effects on immune responses of the juvenile grouper, Epinephelus malabaricus Feng-Cheng Wu (Advisor: Dr. Houng-Yung Chen) Institute of Marine Biology, National Sun Yat-sen University Kaohsiung 804 Taiwan. A series of three experiments was conducted to study the essential fatty acids nutrition and its effects on immune responses (IR) of the juvenile grouper, Epinephelus malabaricus. All experimental diet contained 10 g/100 g diet supplemental lipids from various sources. A reference diet was used in all experiments and contained natural oil mixture of cod liver oil, linseed oil, and safflower oil at a rate of 2:1:1 (wt/wt/wt). In experiment 1, juvenile grouper (11.8 ¡Ó 0.7 g) were fed for 12 wks on one of the seven experimental diets, control diet and the reference diet to investigate dietary requirement for docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and effects on IR of grouper. Seven experimental diets contained 1 g/100 g diet of DHA and EPA in various combinations and 9 g/100 g diet of tristearin. The control diet contained 1 g/100 g diet of trilinolenin and trilinolein (3:1, wt/wt). The results indicate that there was a significant difference among dietary treatments in growth, phagocytosis and leucocytes proliferation, when stimulated by Con A and PHA-P but not by LPS. However there was no difference in survival rate and relative liver weight. Enhanced growth was observed when the dietary DHA/EPA was greater than 1, indicating that DHA was superior to EPA in promoting fish growth. DHA is the only member in the family of (n-3) highly unsaturated fatty acid (HUFA) that stimulates phagocytic functions of leucocytes and T cell proliferation of the juvenile grouper. In experiment 2, juvenile grouper (11.3 ¡Ó 0.6 g) were fed for 12 wks on one of the eight experimental diets or the reference diet to investigate dietary requirement for linolenic acid (LNA) and linoleic acid (LA), as well as effects on nonspecific IR of grouper. The test diets were supplemented with LNA or LA at a rate of 1 or 2 g LNA or LA/100 g diet or 2 g/100 g diet of LNA and LA in various ratios (3, 1.4, 0.7 and 0.4). Tristearin was used to fill the lipid supplemental level to 10 g/100 g diet. The results show that enhanced growth and optimal non-specific cellular IR were observed when the grouper were fed on the diet having the highest LNA/LA ratio (3:1) or on the diets supplemented with LNA. But the enhancement was not different (P>0.05) from that of the reference diet group. Thus, incorporating 2 g/100 g LNA/LA (3:1, wt/wt) in diet ensures adequacy of the grouper for essential fatty acid. In experiment 3, juvenile grouper (13.2 ¡Ó 0.9 g) were fed on one of the six experimental diets in the 2 ¡Ñ 3 factorial design or on the reference diet for 12 wks to investigate dietary requirement for (n-3)HUFAs and arachidonic acid (AA), as well as effects on IR of grouper. Two levels of (n-3)HUFAs (1 or 2 g/100 g ) in combination with 3 levels of AA (0, 1 or 2 g/100 g) were tested. The results show an enhanced growth when optimal concentrations of AA and (n-3)HUFA were incorporated to the diets. Liver (n-6)HUFAs concentration reflects IR of the juvenile grouper. Interaction of AA and (n-3)HUFAs in affecting fish growth and IR was insignificant (P>0.05), and concentrations of dietary (n-3)HUFAs or AA did not significantly affect fish survival rate. The results of the 3 experiments show that the grouper will benefit most in growth and IR when their diets contain 1 g/100 g diet of (n-3)HUFA and 1 g/100 g diet of AA, when (n-3)HUFA is a mixture of DHA and EPA at a ratio of 3:1 (wt/wt).

Dietary N-3 PUFA plays a key role in brain maturation, development, stress response and cognitive abilities (Weiser et al., 2016; Devarshi et al., 2019). As adolescent’s prefrontal cortex is maturating, the period becomes sensitive to external factors such as environment, nutrition, and stress (Petrovich et al., 2001; Calabro et al., 2020). In this thesis, we aim to expand our knowledge of the influence of external factors, such as dietary omega-3 supplementation and enriched environment, during this critical maturation period. By designing four distinct studies, we tested the hypothesis that visible sex-specific alterations would arise from adolescence targeted diet n-3 PUFA supplementation and enriched environment, which would act to modify physiological and stress responses, as well as socio-emotional and cognitive performance. Our first study characterized the impact n-3 PUFA and n-6 PUFA regimen on corticosterone secretion and behavioural responses in adolescent male rodents. Additionally, it assessed the effects of delivery method (gavage versus restricted feeding) during this sensitive maturation period to ensure using a method with limited stress-mediated outcomes. This study highlighted gavage to induce reduced effects on corticosterone (CORT) secretion, regardless of the provided supplementation. On the last day of feeding, CORT secretion was diminished in fish oil (FO) fed rats exposed to restricted feeding, suggesting FO diet to promote physiological adjustments. Data also demonstrated that FO and soybean (CSO) rich diets were able to reduce anxiety-like behaviour compared to a high-fat diet intake (Hydrogenated Vegetal Fat - HVF), highlighting the role of n-3 PUFA dietary supplementation during adolescence on stress regulation. Our second study assessed sex-specific impact of adolescence targeted dietary supplementation on brain Docosahexaenoic Acid (DHA), Arachidonic Acid (AA) and Linolenic acid (LA) concentrations immediately following supplementation and during adulthood. Our findings demonstrated overall elevated DHA, AA and LA brain tissue concentrations in female compared to male rats, regardless of dietary supplementation. Benefit of supplementation were most apparent in adolescent males, where FO led to higher DHA concentrations compared to soybean oil supplementation, supporting a positive influence of FO dietary supplementation in males during intensive hormonal fluctuation and brain maturation. However, adolescent male rats showed reduced ability to extract nutrient essential fatty acids compared to female counterparts. Our third study characterized sex-specific coping strategies, socioemotional responses, and glucocorticoid regulation following an n-3 PUFA rich diet and enriched environment (EE) during the adolescent period. While basal CORT secretions were not significantly altered by supplementation in males, a gradual increase in CORT was observed during supplementation, peaking at DAY21. Passive coping strategies was preferred in the FST in RC (Regular Cage)- housed females exposed to FO while RC-housed CSO-fed males opted for an active climbing coping strategy. Increase locomotion and anxiolytic behaviour were observed in CSO-supplemented males (exposed to EE), while CSO by itself promoted social recognition in males. In contrast, sociability was improved in FO EE exposed females, indicating possible synergic effects. Adulthood hippocampal GR-ir expression was reduced at the hippocampal CA3 region in FO/RC and CSO/EE rat groups, which could have influenced memory consolidation and stress resilience. Overall, results from this study provided insights on positive effects associated with short-term adolescent n-3 PUFA supplementation in females, while male appeared to most benefited from soybean diet supplementation. Our fourth and last study assessed age- and sex-dependent influences of dietary supplementation on cognitive performance in the Barnes Maze Test. Our results showcase a gradual decrease in latencies to the escape box, as well as progressive decrease in working memory errors (WME) in adult compared to adolescent rats. Over the testing period, the FO females and CSO males showed improved performance through reduction of WMEs on specific days, which could subtend sex-related effects of dietary supplementations. However, while discrete effects of n-3 PUFA were more apparent in female rats, short-term supplementation appeared insufficient to promote consistent enhancement of visuospatial performance or cognitive flexibility that could be observed throughout the testing period. In conclusion, our findings support the importance of studying single and combined factors to understand overall impact. We were able to consistently demonstrate beneficial effects on coping strategies, stress reactivity, sociability, and cognitive performance of adolescence-targeted fish oil supplementation, especially in female rodents.