Bromocriptine-induced dissociation of hyperglycemia and prolactin responseto restraint

The present study investigated the effects of immobilization (restraint str ess) on rat chronically treated with a D-2 receptor agonist (bromocriptine, 0.4 mg/100 g body weight, injected daily intraperitoneally (ip) for 2 week s) on plasma glucose, prolactin, and insulin levels. During restraint, the plasma prolactin of vehicle-treated (VEH) rats increased rapidly, reaching a peak at 10 min (57.9 +/- 8.1 ng/ml, P<.01). In contrast, restraint failed to induce any significant change in the plasma prolactin levels of bromocr iptine-treated (BR) rats. The hyperglycemic response to immobilization was 97% higher (P<.05) in BR rats than in VEH rats. Our data demonstrate that p rolactin secretion and hyperglycemia in response to restraint can be dissoc iated by chronic treatment with BR, which also increased the hyperglycemic response to immobilization probably due to central D-2 dopaminergic activit y. (C) 2001 Elsevier Science Inc. All rights reserved.