n‐3 Fatty Acids Modulate T‐Cell Calcium Signaling in Obese Macrosomic Rats

Objective: We investigated the effects of a diet containing EPAX‐7010, rich in PUFAs such as eicosapentaenoic acid [20:5(n‐3)] and docosahexaenoic acid [22:6(n‐3)], i.e., a PUFA/EPAX regimen, on T‐cell activation in diabetic pregnant rats and their obese pups. Research Methods and Procedures: Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on Day 5 of gestation. T‐cell blastogenesis was assayed by using 3H‐thymidine, whereas intracellular free calcium concentrations ([Ca2+]i) were measured by using Fura‐2 in diabetic pregnant rats and their obese offspring. Results: Concavalin‐A‐stimulated T‐cell proliferation was decreased in both pregnant diabetic rats and their obese pups as compared with control animals. Feeding the PUFA/EPAX diet restored T‐cell proliferation in both groups of animals. We also employed ionomycin, which at 50 nM opens calcium channels, and thapsigargin (TG), which recruits [Ca2+]i from endoplasmic reticulum pool. We observed that ionomycin‐induced increases in [Ca2+]i in T‐cells of diabetic mothers and obese offspring were greater than in those of control rats. Furthermore, feeding PUFA/EPAX diet diminished significantly the ionomycin‐evoked rise in [Ca2+]i in diabetic and obese animals. TG‐induced increases in [Ca2+]i in T‐cells of diabetic pregnant rats and their obese offspring were greater than in those of control rats. The feeding of the experimental diet significantly curtailed the TG‐evoked increases in [Ca2+]i in both diabetic and obese rats. Discussion: Together, these observations provide evidence that T‐cell activation and T‐cell calcium signaling are altered during gestational diabetes and macrosomia. Hence, dietary fish oils, particularly eicosapentaenoic acid and docosahexaenoic acid, may restore these T‐cell abnormalities.