Ontogenic homologous supersensitization of quinpirole-induced yawning in rats.
Yawning in male rats is a behavior that may be induced by a group of dopamine receptors when low doses of dopamine-receptor agonists are administered. To determine whether agonist treatments during postnatal development could produce a long-lived supersensitization of these dopamine receptors, rats were treated daily for the first 28 days from birth with quinpirole HCl (3.0 mg/kg/day, IP), an agonist that acts at D2 and D3 receptors. At 8 to 10 weeks from birth the dose-effect curve for quinpirole-induced yawning demonstrated that a supersensitization of dopamine receptors for yawning behavior had occurred. Yawning at the optimal dose of quinpirole HCl (100 microgram/kg, IP) was increased 2-fold. The Bmax and Kd for D2 receptor binding in rat striatum were unaltered in this group of rats. These findings indicate that dopamine receptors can be ontogenically "primed" or supersensitized, and that the phenomenon apparently is not related to changes in striatal D2 receptor binding characteristics.
Department of Pharmacology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614.
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D000375:Aging / Q000523:psychology*; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D015259:Dopamine Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004873:Ergolines / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D008297:Male; D011247:Pregnancy; D019257:Quinpirole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects; D017448:Receptors, Dopamine D2; D015000:Yawning / Q000187:drug effects*
D015259:Dopamine Agents; D004873:Ergolines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D019257:Quinpirole