Behavioural responses to stereotactically controlled injections of monoamine neurotransmitters into the accumbens and caudate-putamen nuclei

Abstract

Bilateral stereotactically-controlled injections of dopamine (5–50 μg of the hydrochloride salt) into the nucleus accumbens of nialamide-pretreated rats induced a marked stimulation of exploratory and locomotor activity, accompanied by intense sniffing and rearing. Conversely, bilateral injection of dopamine (12.5–50 μg of the hydrochloride salt) into the caudate-putamen induced intense stereotyped activity which was dose-related. Both responses were blocked by IP haloperidol. Bilateral injection of noradrenaline (50 μg of the hydrochloride salt) into the accumbens nuclei did not produce any particular behavioural changes. The same injection into the caudate-putamen led to a moderate stimulation of stereotyped activity. Bilateral injection of 5-HT (50 μg of the bimaleinate salt) into the accumbens nuclei induced a moderate locomotor activity with some hole-dipping activity and sniffing; these behaviours were incoordinated and indecisive. The same injections into the caudateputamen led to a moderate stimulation of locomotor activity and hole-dipping which was predominantly “stereotyped” in character; on visual observation no other striking abnormalities were noted.