Portal de Periódicos da CAPES

Effects of putative dopamine D3 receptor agonists, 7-OH-DPAT, and quinpirole, on yawning, stereotypy, and body temperature in rats

1995; Elsevier BV; Volume: 52; Issue: 3 Linguagem: Inglês

10.1016/0091-3057(95)00103-4

1873-5177

Motoko Kurashima, Katsushi Yamada, Mariko Nagashima, K Shirakawa, Tatsuo Furukawa,

Regulation of Appetite and Obesity

7-OH-DPAT ((±)-2-(dipropylamino)-7-hydroxy-1,2,3,4-tetrahydro-naphthalene) was recently identified as a dopamine receptor agonist having a > 100-, 1,000- and > 10,000-fold higher affinity for dopamine D3 than for D2, D4 and D1 receptors, respectively. Quinpirole (LY 171555) has also been reported to have a 113-fold greater affinity for dopamine D3 receptors than for D2 receptors. Therefore, we investigated the effects of these putative dopamine D3 receptor agonists on yawning, Stereotypy and rectal temperature in rats (N = 424). 7-OH-DPAT and quinpirole administered subcutaneously (SC) at respective low doses of 10–250 μg/kg and 25–500 μg/kg elicited yawning behavior. The yawning induced by these agents was blocked by spiperone (0.5 mg/kg, SC) and scopolamine (0.5 mg/kg, SC) but was increased by intraperitoneal (IP) administration of pindolol (20 mg/kg). The yawning was also potentiated after treatment with reserpine. 7-OH-DPAT and quinpirole at respective high doses of 0.25 mg/kg (SC) and 0.5 mg/kg (SC) evoked slight Stereotypy such as sniffing and licking, and this effect was enhanced by a selective dopamine D1 receptor agonist, SK&F 38393 (1-phenyl-2,3,4,5,-tetrahydro-(1H)-3-benzazepine-7,8-diol). 7-OH-DPAT (0.5 mg/kg, SC) and quinpirole (0.5 mg/kg, SC) decreased, but SK&F 38393 (10 mg/kg, SC) increased body temperature. However, the hyperthermia induced by SK&F 38393 was interestingly enhanced by 7-OH-DPAT and quinpirole. The present results demonstrate that 7-OH-DPAT and quinpirole evoke yawning at low doses and Stereotypy at high doses, and that these agents reduce body temperature but enhance the hyperthermia induced by the dopamine D1 receptor agonist SK&F 38393.