Effects of acute central infusion of different doses of insulin on food intake of male and Female Wistar rats

• Grant number: 15/26156-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2016
• End date: July 31, 2019
• Field of knowledge: Health Sciences - Nutrition
• Principal Investigator: Ana Carolina Inhasz Kiss
• Grantee: Giovana Pereira de Oliveira
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Research in animals showed that intracerebroventricular (ICV) administration of insulin decreases food intake. However most of these studies were conducted on males and it is well established that food intake on females varies according to estrous cycle phase. Plus the results vary according to the dose employed. Therefore, the experiments proposed in the present study were designed to investigate the effects of acute central infusion of different doses of insulin on food intake of male and female wistar rats. Rats will be assigned to the experimental groups based on sex, saline or insulin treatment, and the dose of insulin employed. Female rats will be divided into groups of "ovriectomized", "intact" and "ovariectomized with hormonal replacement" rats. Around PND 75 female rats from "ovariectomized" and "ovariectomized with hormonal replacement" groups will be ovariectomized. Esrous cycle from "intact" female rats will be followed. After ovariectomy, "ovariectomized with hormonal replacement" female rats will receive estradiol replacement. On PND 90 a cannula will be placed on the lateral ventricle of all animals. Animals will receive an acute injection of saline, 10 or 100 mU of insulin 7 days after cannula placement surgery. Food intake and body weight will be recorded 24 and 48 hours after the infusion. We hypothesized that both doses of acute ICV insulin infusion will reduce food intake on males and only the higher dose will have an effect on females. Preliminaries results from our lab showed that, unlike males, females did not present reduced food intake in response to ICV chronicle insulin infusion, reinforcing our hypothesis. The present study adds up to the demand to balance the use of males and females in research, with our preliminary result reinforcing the need to compare male and female results regarding food intake control in a more detailed study, as suggested on the present proposal.