Repeated intraventricular injections of ACTH 1–24: The effects of home or novel environments on excessive grooming

Rats implanted with cannulas in the intraventricular foramen were tested after repeated daily injections of ACTH 1–24 or saline. Animals were either observed in their home cages or transported to an experimental room and observed in a “novel” Plexiglas chamber. Animals treated with the ACTH peptide evidenced an excessive, natural-type grooming which did not differ in the two experimental situations. No sign of adaptation of the ACTH-induced grooming was found over 10 consecutive days of testing. Saline-treated animals evidenced more grooming in the novel experimental chambers than when observed in their home cages. Some suggestion of adaptation of the grooming response was found in the saline-treated animals tested in the novel chambers. The results suggest that ACTH 1–24 induces a specific grooming response that is not dependent on being tested in a novel environment.