BLOOD-GLUCOSE AND PROLACTIN IN HYPERPROLACTINEMIC RATS EXPOSED TO RESTRAINT AND SURGICAL STRESS

The effects of chronic hyperprolactinemia on plasma prolactin (PRL) an d glucose were investigated in male rats submitted to two different ty pes of stress: restraint (60 min in a plastic tube) or surgery (laparo tomy under ether anesthesia). Hyperprolactinemia was induced by grafti ng one homologous pituitary gland under the kidney capsule. Restraint stress induced a marked increase of plasma PRL of control rats with a peak at 15 min (increase of 403%), but did not change the PRL levels o f hyperprolactinemic rats. Plasma glucose levels of both groups were e levated by restraint stress at 5 min (control, 26%; grafted, 63%), and remained above basal levels during the whole experimental period. How ever, at 15 min the hyperglycemic response of the grafted rats was hig her than that of control rats (p<0.05). Surgical stress induced a 204% increase of plasma PRL at 5 min in the control group, but failed to i nduce alteration of PRL in the hyperprolactinemic group. Plasma glucos e was remarkably elevated at 15 min both in control (138%) and grafted (124%) rats after surgery, producing a hyperglycemic response much mo re intense than that induced by restraint. Grafted rats presented hype rglycemia during all the experimental period, whereas control rats sho wed glycemia similar to basal levels by the end of the experiment. In conclusion, different responses are induced depending on the type of s tress: more intense PRL secretion is induced by restraint and higher h yperglycemia by surgery. Chronic hyperprolactinemia induced a higher ( restraint) or longer lasting (surgery) hyperglycemic response in the r at, adding new evidence for a diabetogenic effect of PRL.