Differential effects of chronic antidepressants in behavioural tests of beta-adrenergic and GABAB receptor function.

The effects of chronic administration of anti-depressant drugs (28 days SC via Alzet 2ML4 osmotic minipumps) on the functional sensitivity of beta-adrenergic and GABA receptors have been assessed. Phenelzine (10 mg/kg), tranylcypromine (1 mg/kg), imipramine (30 mg/kg) and desmethylimipramine (10 mg/kg) attenuated the motor-suppressant effects of salbutamol (3 mg/kg) observed at 21-22 days of drug administration. No changes in the motor-suppressant effects of the GABA prodrug progabide (50 mg/kg) or the GABAB agonist (+/-)-baclofen (5 mg/kg) were induced by these antidepressants. These findings extend and confirm previous reports of functional changes in beta-adrenergic receptors but not of GABAB receptors following chronic antidepressant treatment.