Action of neuroleptics and antidepressants on the hypothermia produced by dopaminomimetics apomorphine and piribedil in mice

Abstract

Neuroleptics, antidepressants and anticholinergics were compared in their action on the hypothermia produced by apomorphine (AP, 5.0 mg/kg i.p.) or piribedil (PRB, 100 mg/kg i.p.) in mice. Anticholinergics atropine, scopolamine and benactizine did not affect either hypothermia in contrast to neuroleptics and imipramine-like antidepressants which antagonized both hypothermias. Among neuroleptics studied the minimal effective doses (MED) antagonizing AP hypothermia (APH) ranged from 0.006 (trifluperidol) to 0.5 mg/kg (chlorpromazine), while MED antagonizing PRB hypothermia (PRBH) ranged from 0.05 (trifluperidol and perphenazine) to 2.0 mg/kg (haloperidol). Amongst antidepressants the MED ranged from 0.2 (desipramine) to 5.0 mg/kg (amitriptyline) in the case of APH, and ranged from 0.025 (desipramine) to 0.5 mg/kg (amitriptyline) in the case of PRBH, the potency correlated directly with the adrenopositive activity. The higher activity of neuroleptics in the case of APH, and the discrepancy between the order of their effectiveness in tests of APH and PRBH are discussed. The data confirm that the stimulation of the dopamine receptors results in hypothermia and are in accord with the postulated importance of the adrenergic link in the hypothermia produced by dopaminomimetics.