Portal de Periódicos da CAPES

Effects of Selective Serotonin and Dopamine Agonists on Plasma Levels of Glucose, Insulin and Glucagon in the Rat

1996; Karger Publishers; Volume: 63; Issue: 3 Linguagem: Inglês

10.1159/000126970

1423-0194

Kerstin Uvnäs-Moberg, Sven Ahlénius, Pawel Alster, Viveka Hillegaart,

Receptor Mechanisms and Signaling

Male Sprague-Dawley rats were given one of the 5-HT receptor agonists 8-OH-DPAT (0.5–2.0 mg kg–1), TFMPP (0.125–2.0 mg kg–1), DOI (0.125–2.0 mg kg–1), and m-CPBG (1.25–20.0 mg kg–1), selective for 5-HT1A, 5-HT1B, 5-HT2 and the 5-HT3 receptors, respectively, or one of the DA receptor agonists broraocriptine (2.0–32.0 mg kg–1), quinpirole (0.5–8.0 mg kg–1) and 7-OH-DPAT (0.2–3.2 mg kg–1), selective for DA D2, DA D2/D3 and DA D3 receptors, respectively. An additional group of animals was given buspirone (2.0-8.0 mg kg-1) a 5-HTιA receptor agonist and DA D2 receptor antagonist. Separate groups of rats were given both the 5-HT1A receptor antagonist pindolol and 8-OH-DPAT or both the DA D2/D3 receptor antagonist raclopride and 7-OH-DPAT. Blood samples were collected 30 min (in some cases 120 min) after drug administration and assayed for insulin, glucagon and glucose levels. The 5-HTIA receptor agonist 8-OH-DPAT produced a statistically significant decrease in plasma insulin levels and an increase in glucose, whereas glucagon levels were unaffected. The only effect observed after buspirone treatment was a small increase in plasma glucose levels. No significant effects on plasma insulin, glucagon or glucose were seen after treatment with the 5-HTIB, 5-HT2 or 5-HT3 agonists. The DA D3 receptor agonist 7-OH-DPAT produced a decrease in plasma insulin (3.2 mg kg-1, 120 min) and an increase in glucose levels. Administration of the DA D2/D3 receptor agonist quinpirole resulted only in increased plasma glucose, whereas the DA D2 receptor agonist bromocriptine had no effect. In support of a separate mediation of glucose secretion by 5-HT1A and DA D3 receptors, the effects of 8-OH-DPAT on glucose levels were antagonized by (-)pindolol pretreatment, and the 7-OH-DPAT-induced effects on glucose levels were antagonized by raclopride pretreatment. It is concluded that plasma glucose levels are under separate serotonergic and dopaminergic control, exerted via 5-HTιA and DA D3 receptors, respectively.