Glucose tolerance, serum insulin, insulin receptors in epididymal fat tissue, circulating total cholesterol and triglyceride concentrations as well as serum prolactin were studied in obese and lean spontaneously hypertensive rats (SHR) of both sexes. Obese animals displayed insulin resistance and elevated insulin and triglyceride concentrations. Moreover, in obese rats the increased mass of epididymal fat tissue was accompanied with decreased capacity of high affinity binding sites of insulin receptors in the tissue plasma membranes. Terguride treatment lowered prolactin serum levels which was accompanied by ameliorated insulin sensitivity in obese animals of both sexes. In addition, terguride treatment decreased serum insulin and triglyceride concentrations in obese females and at the same time enhanced the affinity of high affinity insulin binding sites. Our results show that obesity in SHR is associated with a decreased capacity of insulin receptors and that prolactin may play a role in obesity-induced insulin resistance, particularly in female rats.

Institute of Experimental Neurosurgery Hradec Králové Czech Republic