Involvement of the substantia innominata/ventral pallidum complex in transmitting forelimb muscular rigidity evoked from the nucleus accumbens in rats.
In the present study it was investigated whether muscular rigidity elicited from the nucleus accumbens could be transmitted via the substantia innominata/ventral pallidum (SI/VP) complex. For this purpose rats were equipped with cannulae aimed at the nucleus accumbens and/or the SI/VP, and with electrodes in the triceps muscle of the forelimb. In the first set of experiments it was found that the GABA agonist muscimol (10-25 ng/0.5 microliters) dose-dependently increased tonic EMG activity upon injection into the SI/VP region. The GABA antagonist bicuculline (50 ng/0.5 microliters) antagonized the effects of muscimol (25 ng/0.5 microliters). In the second set of experiments it appeared that the increase in tonic EMG activity induced by haloperidol (1000 ng/0.5 microliters) injected into the nucleus accumbens was antagonized by subsequent injection of bicuculline (25 ng/0.5 microliters) into the SI/VP complex. These data suggest that the SI/VP complex may be one station through which the muscular rigidity elicited from the nucleus accumbens is transmitted to lower brain structures.
van den Bos
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Psychoneuropharmacological Research Unit, Catholic University Nijmegen, The Netherlands.
Cools
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D000818:Animals; D001479:Basal Ganglia / Q000502:physiology*; D001640:Bicuculline / Q000494:pharmacology; D004566:Electrodes; D004576:Electromyography; D005552:Forelimb; D006220:Haloperidol / Q000494:pharmacology; D007267:Injections; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009127:Muscle Rigidity / Q000209:etiology*; D009714:Nucleus Accumbens / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012686:Septal Nuclei / Q000502:physiology*; D013377:Substantia Innominata / Q000502:physiology*
D009118:Muscimol; D006220:Haloperidol; D001640:Bicuculline