Bromocriptine-induced dissociation of hyperglycemia and prolactin response to restraint.
The present study investigated the effects of immobilization (restraint stress) on rat chronically treated with a D(2) receptor agonist (bromocriptine, 0.4 mg/100 g body weight, injected daily intraperitoneally (ip) for 2 weeks) 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 bromocriptine-treated (BR) rats. The hyperglycemic response to immobilization was 97% higher (P < .05) in BR rats than in VEH rats. Our data demonstrate that prolactin secretion and hyperglycemia in response to restraint can be dissociated by chronic treatment with BR, which also increased the hyperglycemic response to immobilization probably due to central D(2) dopaminergic activity.
Department of Internal Medicine, School of Medicine, Federal University of Minas Gerais, Avenida Antonio Carlos 6627, 31270-901, MG, Belo Horizonte, Brazil.
A
A
Ribeiro-de-Oliveira
R M
RM
Guerra
R B
RB
Fóscolo
U
U
Marubayashi
A M
AM
Reis
C C
CC
Coimbra
D000818:Animals; D001786:Blood Glucose / Q000187:drug effects* / Q000378:metabolism; D001971:Bromocriptine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology*; D006943:Hyperglycemia / Q000097:blood; D007328:Insulin / Q000097:blood*; D008297:Male; D011388:Prolactin / Q000097:blood / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000097:blood*
D001786:Blood Glucose; D018491:Dopamine Agonists; D007328:Insulin; D001971:Bromocriptine; D011388:Prolactin