Induction of grooming in resting rats by intracerebroventricular oxytocin but not by adrenocorticotropic hormone-(1-24) and alpha-melanocyte-stimulating hormone.
Adrenocorticotropic hormone (ACTH) and alpha-melanocyte-stimulating hormone (alpha-MSH) injected i.c.v. induce so called 'excessive grooming'. Whether these peptides play a role in the initiation of grooming is not clear, since rats will groom even as a consequence of a particular environmental stimulation, such as handling and/or a novel environment. In most studies, therefore, the first 15 min after i.c.v. injection are not examined. Here we report on the effects of slow i.c.v. infusions of ACTH-(1-24), alpha-MSH and oxytocin in resting rats in their home cages. Interestingly, i.c.v. infusions of oxytocin did initiate grooming in a dose-related way. In contrast, i.c.v. infusions of both ACTH-(1-24) and alpha-MSH in resting rats were without effect on grooming. Oxytocin is apparently involved in the initiation of self-grooming in rats, whereas ACTH and alpha-MSH prolonged grooming initiated by other means, e.g. handling procedures and/or a novel environment. We conclude that the effects of alpha-MSH and ACTH on grooming are conditional, depending on the behavioural state (active or resting) of the animal.
Ethopharmacology Group, Medical Faculty, Sylvius Laboratory, Leiden, Netherlands.
A M
AM
Van Erp
M R
MR
Kruk
E R
ER
De Kloet
D000818:Animals; D003366:Cosyntropin / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006120:Grooming / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D000521:alpha-MSH / Q000008:administration & dosage / Q000494:pharmacology*
D003366:Cosyntropin; D010121:Oxytocin; D000521:alpha-MSH