Proceedings of The Physiological Society

Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCB195

Poster Communications

Oxytocin influences food intake and body weight in estrogen-treated rats

D. Sloan1, K. Curtis1

1. Pharmacology and Physiology, Oklahoma State University - Center for Health Sciences, Tulsa, Oklahoma, United States.

A wealth of data shows that estrogen decreases food intake and body weight in ovariectomized (OVX) rats, but the mechanism(s) by which these effects occur is not fully understand. One possibility involves the neuropeptide neurotransmitter, oxytocin (OT), which also has been shown to reduce food intake. The OT promoter region contains an estrogen response element (ERE), and when estrogen binds its receptor, this complex translocates to the ERE located within the promoter region of the OT gene. We hypothesized that estrogen acts to decrease food intake by interacting with the OT system. Accordingly, the goal for this study was to investigate interactions between estrogen and OT on food intake and body weight. Female Sprague-Dawley rats (n = 34) were OVX, and an intracerebroventricular cannula was implanted in the lateral ventricle (coordinates from bregma = AP -1.2, ML -1.7). These procedures were performed under 2.5% isoflurane anesthesia (flow rate = 2L/min). Rats were allowed to recover for one week and then treated with 10 µg estradiol benzoate (EB) or oil vehicle (Oil) on days 1 and 2 of a 4 day protocol. On day 4, rats were injected with 0, 0.25, or 0.5ug of OT into the lateral cerebral ventricle. Food intake and body weight was monitored throughout the experiment. Results show that 0.5 µg of OT caused the greatest reduction in food intake and body weight, especially in EB-treated rats. These data show that the combined effects of estrogen and oxytocin decrease food intake and body weight, supporting the idea that estrogen-modulated oxytocin expression may be one pathway by which estrogen is involved in the regulation of food intake and body weight. Further studies will be necessary to determine whether oxytocin mRNA expression and protein production is influenced by EB, as well as whether blockade of OT receptors reverse the inhibitory effects of EB on food intake. All animal protocols were approved by the Oklahoma State University - Center for Health Sciences Institutional Animal Care and Use Committee.

Where applicable, experiments conform with Society ethical requirements