THE EFFECT OF WATER TEMPERATURE ON IMMOBILITY IN THE FORCED SWIMMING TEST IN RATS

In the Porsolt swimming test intact rats acquire and retain the immobi le response indistinguishably at 25 and 30 degrees C; at both temperat ures retention is abolished by administration of the glucocorticoid an tagonist RU38486 and the kappa-selective opiate receptor antagonist MR 2266 when given together, but not when either is given alone. At 20 de grees C, however, the animals do not acquire the response, and have le vels of retention significantly lower than at the higher temperature. This deficit is not restored by administration of glucocorticoids, kap pa-opioid receptor-selective agonists, thyroid hormone or glucose.