PERINATAL DIETARY OMEGA-3 FATTY ACID MANIPULATION AFFECTS NEURAL CONTROL OF SODIUM HOMEOSTASIS IN ADULTHOOD

Nora Chen, Michael L. Mathai, Andrew J. Sinclair, Richard S. Weisinger, Harrison S. Weisinger, Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Vic.

Polyunsaturated omega-3 fatty acids are the most abundant fatty acid found in the central nervous system and are essential, as mammals are unable to synthesise them de novo and therefore must rely on dietary supplementation to acquire them. This study aimed to determine whether dietary manipulation of omega-3 fatty acid levels during the perinatal period would lead to alterations in the central control of sodium homeostasis. Pregnant rat dams were fed either an omega-3 sufficient (CON) or deficient (DEF) diet. All pups were initially fed the same diet as their mothers, with pups born to dams fed the deficient diet divided into two groups: those continued on DEF (DEF-DEF) and those switched to the CON diet at weaning (DEF-CON3). A rapid salt-appetite was induced by intraperitoneal injection of furosemide (20mg/kg) followed by a low-dose injection of captopril (20µg/kg) after an hour's delay. Animals were deprived access to NaCl for 2 hours prior to injection. No significant differences were found between groups for baseline salt (0.5M NaCl) intakes, nor salt intake after sodium depletion. All animals had significantly increased stimulated sodium appetite following return of NaCl access, which returned to baseline the day after injection in CON-CON animals. The DEF-CON3 group required an extra day to return to baseline, while the increased salt intake of DEF-DEF rats persisted for 5 days. These results suggest that a deficiency of essential omega-3 fatty acids during the perinatal period can lead to dysregulation of central sodium homeostatic mechanisms. These findings are consistent with the reported effects of perinatal omega-3 fatty acid supply on blood pressure.