Dopamine denervation of frontal cortex or nucleus accumbens does not affect ACTH-induced grooming behaviour.
Studies with dopamine (DA) receptor antagonists have implicated brain DA systems in the increased grooming behaviour elicited by intracerebroventricular (i.c.v.) administration of ACTH or exposure to a novel environment. To evaluate the potential contributions of DA terminals innervating frontal cortex and nucleus accumbens, stereotaxically guided injections of 6-hydroxydopamine (6-OHDA) were made into these regions of rat brain following peripheral administration of desmethylimipramine and pargyline. Despite an 88% mean reduction of DA, and 68% mean reduction of noradrenaline in frontal cortex, the amount of grooming behaviour observed either in a novel cage, or after i.c.v. injection of ACTH1-24 was not detectably altered. The lesions also did not affect locomotor activity measured during the scoring of grooming, in an open field, in photocell cages, or in a running wheel, even in the animals most severely depleted of DA. Following nucleus accumbens 6-OHDA infusions, depletions of DA as great as 99% were obtained. Animals with accumbens depletions greater than 90% showed the expected attenuation of amphetamine-stimulated locomotor activity. Nevertheless, they exhibited normal grooming scores in a novel cage, and in response to i.c.v. ACTH1-24. It is concluded that dopaminergic terminals in nucleus accumbens and probably those in frontal cortex are not necessary for the expression of novelty- or ACTH-induced grooming.
D000324:Adrenocorticotropic Hormone / Q000031:analogs & derivatives*; D000818:Animals; D001143:Arousal / Q000187:drug effects; D003366:Cosyntropin / Q000494:pharmacology*; D003714:Denervation; D004298:Dopamine / Q000378:metabolism*; D005625:Frontal Lobe / Q000187:drug effects* / Q000378:metabolism; D006120:Grooming / Q000187:drug effects*; D006892:Hydroxydopamines / Q000633:toxicity*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D012686:Septal Nuclei / Q000187:drug effects*
D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D003366:Cosyntropin; D016627:Oxidopamine; D000324:Adrenocorticotropic Hormone; D004298:Dopamine; D009638:Norepinephrine