Neurohypophyseal hormones and excessive grooming behaviour.

The pattern of excessive grooming displayed by rats treated with vasopressin and oxytocin was investigated by calculating the frequencies and contribution of the behavioural elements head washing, body grooming, anogenital grooming, paw licking and scratching. In addition, the suppressive effect on peptide-induced grooming of the dopamine D1 receptor antagonist SCH 23390, of neurotensin and of the opiate receptor antagonists naloxone and naloxone-methobromide was studied. The pattern of excessive grooming induced by vasopressin and by oxytocin was characterized by the contribution of most behavioural elements to the total grooming scores. Oxytocin-induced excessive grooming was characterized by a marked increase in the frequency of anogenital grooming. SCH 23390, neurotensin and naloxone, but not naloxone-methobromide, suppressed excessive grooming induced by vasopressin and oxytocin. It is suggested that dopamine D1 receptors as well as opiate receptors located within the blood-brain barrier are involved in the excessive grooming induced by neurhypophyseal hormones.