The behavioural effects induced in male Wistar rats by SND 919, a new drug reputed to have selective agonistic activity at D-2 dopamine (DA) receptors, were studied. The following aspects of behaviour were considered: motor activity, stretching-yawning (SY), penile erection (PE) and stereotyped behaviour (SB). Intraperitoneal injection (IP) of the drug (0.01-20 mg/kg) induced an SY syndrome in the form of a bell-shaped dose-response curve, the effect being maximal at the dose of 0.1 mg/kg and disappearing completely at 10 mg/kg. SND 919 also potently elicited PE; this latter effect, however, was not coincident with SY induction, being maximal at 1 mg/kg and persisting at 10 and 20 mg/kg. SND 919-induced SY was potently antagonized by pretreatment not only with the D-2 antagonist, L-sulpiride (20 mg/kg), but also with the alpha(2) antagonist, yohimbine (1, 3 mg/kg), and the more selective alpha(2) antagonist, idazoxan (1, 2 and 5 mg/kg). While sulpiride also decreased SND 919-induced PE, idazoxan at all doses and yohimbine at 1 mg/kg did not affect this behaviour. Inhibition of motor activity was induced by the D-2 agonist at low doses (0.05, 0.1 mg/kg), while at high doses (1, 10 and 20 mg/kg), it was actually replaced by a form of SB characterized by downward sniffing and licking. When, for comparison, the D-2 agonist, RU 24213 (0.1-20 mg/kg IF), was tested for PE, SY, motor activity and SB, it displayed a behavioural pattern very similar to that obtained with SND 919. Idazoxan (2 mg/kg), administered before RU 24213 (10 mg/kg), significantly antagonized the drug-induced SY, but not PE. The discussion centres on the specific neurochemical mechanisms presumably underlying the various forms of SND 919-induced behaviour and, in particular, PE and SY, which seem to differ, at least with respect to alpha(2) involvement.
BEHAVIORAL EVIDENCE THAT DIFFERENT NEUROCHEMICAL MECHANISMS UNDERLY STRETCHING-YAWNING AND PENILE ERECTION INDUCED IN MALE-RATS BY SND-919, A NEW SELECTIVE D-2 DOPAMINE-RECEPTOR AGONIST / F., Ferrari; F., Pelloni; Giuliani, Daniela. - In: PSYCHOPHARMACOLOGY. - ISSN 0033-3158. - STAMPA. - 113:(1993), pp. 172-176.
BEHAVIORAL EVIDENCE THAT DIFFERENT NEUROCHEMICAL MECHANISMS UNDERLY STRETCHING-YAWNING AND PENILE ERECTION INDUCED IN MALE-RATS BY SND-919, A NEW SELECTIVE D-2 DOPAMINE-RECEPTOR AGONIST
GIULIANI, Daniela
1993
Abstract
The behavioural effects induced in male Wistar rats by SND 919, a new drug reputed to have selective agonistic activity at D-2 dopamine (DA) receptors, were studied. The following aspects of behaviour were considered: motor activity, stretching-yawning (SY), penile erection (PE) and stereotyped behaviour (SB). Intraperitoneal injection (IP) of the drug (0.01-20 mg/kg) induced an SY syndrome in the form of a bell-shaped dose-response curve, the effect being maximal at the dose of 0.1 mg/kg and disappearing completely at 10 mg/kg. SND 919 also potently elicited PE; this latter effect, however, was not coincident with SY induction, being maximal at 1 mg/kg and persisting at 10 and 20 mg/kg. SND 919-induced SY was potently antagonized by pretreatment not only with the D-2 antagonist, L-sulpiride (20 mg/kg), but also with the alpha(2) antagonist, yohimbine (1, 3 mg/kg), and the more selective alpha(2) antagonist, idazoxan (1, 2 and 5 mg/kg). While sulpiride also decreased SND 919-induced PE, idazoxan at all doses and yohimbine at 1 mg/kg did not affect this behaviour. Inhibition of motor activity was induced by the D-2 agonist at low doses (0.05, 0.1 mg/kg), while at high doses (1, 10 and 20 mg/kg), it was actually replaced by a form of SB characterized by downward sniffing and licking. When, for comparison, the D-2 agonist, RU 24213 (0.1-20 mg/kg IF), was tested for PE, SY, motor activity and SB, it displayed a behavioural pattern very similar to that obtained with SND 919. Idazoxan (2 mg/kg), administered before RU 24213 (10 mg/kg), significantly antagonized the drug-induced SY, but not PE. The discussion centres on the specific neurochemical mechanisms presumably underlying the various forms of SND 919-induced behaviour and, in particular, PE and SY, which seem to differ, at least with respect to alpha(2) involvement.Pubblicazioni consigliate
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