Inhibitory effects of propranolol and oxprenolol on excitation induced by a MAO inhibitor and reserpine in the mouse

The use of sodium valproate, carbamazepine and oxcarbazepine in patients with affective disorders

During recent years alternatives to lithium prophylaxis have been developed using primary dipropylacetamide and, later on, sodium valproate, as a mono-therapy as well as in combination with low-dosage lithium treatment. It has been shown in a placebo-controlled ABA design that sodium valproate exerts an acute antimanic effect and a prophylactic action of sodium valproate has also been established. Carbamazepine represents another important contribution to the arsenal of drugs to be used as alternatives for the prophylactic treatment in patients not responding to lithium and/or experiencing too many side effects. The keto-derivative of carbamazepine, oxcarbazepine, has been shown to exert acute antimanic effects in a similar way to carbamazepine itself.

Effect of sodium valproate on mania. The GABA-hypothesis of affective disorders

A possible antimanic property of the GABA-ergic anticonvulsant valproate was examined by use of a double-blind placebo-controlled ABA design in 5 acutely ill manic patients. In 4 cases a marked improvement was observed after valproate medication whereas one patient showed no response. Seven further patients with frequently recurrent episodes of a manic or maniform schizoaffective psychosis, irresponsive to lithium prophylaxis, were chronically treated with valproate in combination with low doses of lithium (one case only with valproate). Over an observation period of 1 1/2-3 years none of the patients exhibited a relapse. It is proposed that, in general, GABA-ergic anticonvulsants possess antimanic properties and that the specific antimanic effect of lithium is due to a GABA-ergic mode of action. The possible role of GABA-systems in affective disorders and in organic types of psychoses (e.g.,porphyria-psychosis, delirium tremens) is discussed on the basis of pharmacopsychiatric considerations.

Beta-adrenoceptor antagonists: studies on behaviour (delayed differentiation) in the monkey (Macaca mulatta)

1 Activity of six beta-adrenoceptor antagonists was studied on behavioural activity (delayed differentiation) in the monkey (Macaca mulatta). The drugs, three relatively lipophilic antagonists (propranolol, oxprenolol and metoprolol), and three relatively hydrophilic antagonists (acebutolol, atenolol and sotalol), were given by intraperitoneal injection (5 to 30 mg/kg).2 With atenolol (25 to 30 mg/kg), total response time was increased, but there was no effect on the number of correct responses. With acebutolol (25 to 30 mg/kg), the number of correct responses was reduced, but there was no effect on total response time. With metoprolol (25 to 30 mg/kg), there was an increase in total response time and a decrease in the number of correct responses, and correct responses were decreased 4 h after injection over the whole dose range (5 to 30 mg/kg).3 Some animals failed to respond or complete the task with 30 mg/kg oxprenolol, 25 mg/kg sotalol and 20 mg/kg propranolol. With 25 mg/kg oxprenolol, the total response time was increased and the number of correct responses was decreased. With 5-20 mg/kg sotalol, total response time was increased, but there was no effect on the number of correct responses. With 15 mg/kg of (+/-)-propranolol and its isomers, there were increases in total response time and decreases in correct responses.4 The studies suggest that lipophilic antagonists, such as propranolol, oxprenolol and metoprolol, are likely to have, at least, effects on the central nervous system, while hydrophilic antagonists may modify the peripheral nervous system. In the dose-ranges studied, propranolol had the greatest, and atenolol and acebutolol had the least effects. Atenolol and acebutolol may prove to be particularly useful in man when disturbances of the nervous system are to be avoided.

Action of d-propranolol in manic psychoses

Six manic patients were treated with high doses of d-propranolol or d- and dl-propranolol in a double-blind, placebo controlled study. The following variables were measured: propranolol dosage, propranolol serum concentration, pulse frequency, blood pressure, and psychotic behavior. In all cases an improvement was noticed. High dosages were necessary to obtain sufficient effect. The antimanic property of d-propranolol was approximately 50% smaller than the antimanic property of dl-propranolol. We conclude that at least some part of the antimanic action of beta-blockers is independent from the beta-blocking property.

Differential effects of d- and l-propranolol on dopamine turnover stimulated by oxotremorine in striatal and mesolimbic areas of rat brain

The effects of l-propranolol, d-propranolol and clonidine on homovanillic acid (HVA) concentrations in the corpus striatum and nucleus accumbens of rats were studied under normal conditions and after treatment with oxotremorine or haloperidol. Thile propranolol and clonidine given alone had no significant effect on HVA levels in either area, l-propranolol (1--10 mg/kg) and clonidine (0.1 mg/kg), both significantly inhibited the elevation of striatal HVA, found 60 min after oxotremorine administration. Both l- and d-propranolol (2.5 mg/kg), reduced the effect of oxotremorine in the nucleus accumbens. Neither l-propranolol no clonidine affected the rise in HVA in either brain area seen after haloperidol. Our results suggest that propranolol may reduce cholinergic activation of dopaminergic pathways by two different mechanisms. One is stereospecific for the l-isomer and operates in the striatum and another, which is shared by both isomers, occurs in the nucleus accumbens.

Long-term haloperidol-treatment of mice: a change in beta-adrenergic receptor responsiveness

Mice administered haloperidol 3 mg/kg/day in their drinking water for 21 days were tested for their locomotor responsiveness to saline or acid vehicle, dl-, l- or d-propranolol, metoprolol, butoxamine or practolol. Haloperidol-treated animals administered saline or acid-vehicle were, in five of six experiments, more active than animals withdrawn from vehicle-treatment. Haloperidol- and vehicle-treated animals responded differently to the non-selective beta-adrenoreceptor antagonists (dl-propranolol and l-propranolol) and selective beta1-adrenoreceptor antagonists (practolol and metoprolol), but not to a selective beta2-adrenoreceptor antagonist (butoxamine). With dl-propranolol (4 mg/kg) the locomotor activity of haloperidol-treated animals was significantly (0.01 less than P less than 0.02) greater than that of the vehicle-treated animals. Similar effects in the same direction were seen with l-propranolol (1 mg/kg, 0.005 less than P less than 0.01), practolol (10 and 100 mg/kg, 0.025 less than P less than 0.05 and 0.01 less than P less than 0.025 respectively) and metoprolol 8 mg/kg, 0.005 less than P less than 0.01). The d-isomer of propranolol which is about 50 times less active as a beta-adrenoreceptor antagonist than the l-isomer, although having equal membrane stabilizing effects, did not differentially affect haloperidol- or vehicle-treated groups. The results suggest that there has been a change in beta 1-adrenoreceptor responsiveness in animals withdrawn from long-term haloperidol treatment.