Terguride Treatment Attenuated Prolactin Release and Enhanced Insulin Receptor Affinity and GLUT 4 Content in Obese Spontaneously Hypertensive Female, but Not Male Rats

: Glucose tolerance, serum insulin, insulin receptors in epididymal fat tissue, and GLUT 4 content in muscle, as well as serum prolactin, were studied in obese and lean spontaneously hypertensive rats (SHRs) of both sexes. Obese animals displayed insulin resistance and decreased capacity of high-affinity binding sites of insulin receptors in fat tissue plasma membranes. GLUT 4 content in musculus quadriceps was diminished only in obese females. Terguride treatment lowered prolactin serum levels, which was concomitant with ameliorated insulin sensitivity in obese animals of both sexes. Similarly, only in obese females, terguride significantly increased the affinity of high-affinity insulin-binding sites and normalized GLUT 4 content. Our results document downregulation of insulin receptors and GLUT 4 in obesity and suggest a role for prolactin in obesity-induced insulin resistance, particularly in female rats.