Agonist-induced homologous and heterologous sensitization to D-1- and D-2-dependent contraversive turning.
A low dose of the D-1 receptor agonist SKF 38393 (2.0 mg/kg s.c.) 14 days post-lesion failed to induce contraversive turning in male Sprague-Dawley rats lesioned unilaterally in the medial forebrain bundle with 6-hydroxydopamine (6OHDA). Priming with a single administration of the specific D-2 agonist LY 171555 (0.2 mg/kg s.c. 3 days before), which itself elicited contraversive turning, made SKF 38393 (2.0 mg/kg s.c.) very active to produce contraversive turning. Priming with LY 171555 (0.2 mg/kg s.c. 3 days before) potentiated the contraversive turning in response to a low dose of LY 171555 (0.05 mg/kg s.c.). In naive 6OHDA-lesioned rats a rather high dose of SKF 38393 (10 mg/kg s.c.) was needed to induce a low intensity contraversive turning. Priming with a single administration of SKF 38393 (10 mg/kg s.c. 3 days before) made an otherwise ineffective dose of SKF 38393 (2.0 mg/kg s.c.) very effective to produce contraversive turning. The results indicate that the sensitization to the behavioural expression of supersensitivity for a given DA-receptor type follows not only priming with agonists for the same DA-receptor type (homologous sensitization) but also priming with agonists for a different DA-receptor type (heterologous sensitization).
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000818:Animals; D001067:Appetite Depressants / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D004873:Ergolines / Q000494:pharmacology; D006892:Hydroxydopamines / Q000494:pharmacology; D008297:Male; D016627:Oxidopamine; D019257:Quinpirole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D013239:Stereotyped Behavior / Q000187:drug effects*
D001067:Appetite Depressants; D001552:Benzazepines; D004873:Ergolines; D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D019257:Quinpirole; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D016627:Oxidopamine