Muscimol and related GABA receptor agonists: the potency of GABAergic drugs in vivo determined after intranigral injection.

Contralateral turning behaviour following unilateral intranigral injection of a large series of GABA analogues was investigated. The results indicated that the turning behaviour was induced stereospecifically and was selectively antagonized by the GABA antagonist bicuculline methochloride. The comparative potencies of a series of GABA agonists related to muscimol in general corresponded well to the affinity for 3H-GABA receptor sites and to the depressant action on single neurons using microelectrophoretic administration. However, the GABA agonists trans-aminocrotonic acid and 3-aminopropanesulphonic acid were much weaker than expected from in vitro studies. The GABA-uptake inhibitors nipecotic acid and guvacine showed only weak and short-lasting effects. The GABA-transaminase inhibitor gamma-acetylenic GABA showed delayed effects compared with the agonists which acted immediately. It is proposed that this behavioural effect may be a sensitive and quantitative method for evaluation of GABA agonists in vivo.     

The effect of sodium valproate on serum cortisol levels in healthy subjects and depressed patients

In nine healthy subjects the i.v. injection of 800 mg of the GABA-transaminase inhibitor sodium valproate (SV) was able to suppress serum cortisol significantly when compared to saline. Three and a half hours after the administration of SV, serum cortisol was reduced to less than 50% of the basal value in each of the subjects. Among 17 depressed patients serum cortisol was reduced to less than 50% of basal value 3 1/2 h after SV in only two patients. No difference was found between nine patients with endogenous depression and eight with non-endogenous depression. The dexamethasone suppression test was abnormal in four out of 17 patients. These four patients had endogenous depression, and also an abnormal response to SV. A positive correlation was found between the effect of SV on serum cortisol, and age (r = 0.55), but not between the percentual decrease of serum cortisol and the severity of depression. The effect of SV on serum cortisol was significantly less pronounced in depressed patients than in controls but no difference was found between patients with endogenous and non-endogenous depression.     

High dosage haloperidol therapy in chronic schizophrenic patients: A double-blind study of clinical response,side effects,serum haloperidol,and serum prolactin

In a 12-weeks double-blind study high dosage versus standard dosage haloperidol therapy was evaluated in 23 male, chronic schizophrenic inpatients. The patients were relatively treatment-resistant and, in spite of traditional neuroleptic medication, were characterized by a moderate to severe degree of illness. At the end of the trial the dose of haloperidol in the standard dosage group was 12–36 mg/day (mean 15), in the high dosage group 10–240 mg/day (mean 103). No significant difference in therapeutic effect was found between the two groups as measured by the Brief Psychiatric Rating Scale and global assessment. About half the patients in both groups improved during the trial. A greater incidence of side effects was noticed in the high dosage group than in the standard group, especially in the form of sedation (5 of 12 patients), aggressive episodes (three patients), muscular weakness and tendency to fall (two patients), and epileptic attacks (one patient). The incidence of extrapyramidal phenomena showed fewer differences between the two groups. In addition, the high dosage group showed a temporary rise in serum alkaline phosphatase and serum aspartate-aminotransferase. There was a positive correlation between the dose of haloperidol and serum haloperidol, and between the haloperidol dose of up to 80 mg/day and serum prolactin. At higher doses prolactin response leveled off. Neither serum haloperidol nor serum prolactin showed any correlation to clinical response. It is concluded (1) that very high doses of haloperidol in only a few cases show any therapeutic advantage over haloperidol in standard doses; (2) that high dosage treatment has a higher incidence of side effects; and (3) that the serum concentrations of a given neuroleptic and of prolactin are of very limited value in the monitoring of neuroleptic treatment.     

The St. Hans Rating Scale for extrapyramidal syndromes: reliability and validity

The St. Hans Rating Scale (SHRS) is a multidimensional rating scale for the evaluation of neuroleptic-induced hyperkinesia, parkinsonism, akathisia and dystonia. This scale and the Abnormal Involuntary Movement Scale (AIMS) were tested by 7 raters (2 experienced, 2 less experienced and 3 totally inexperienced) in 30 psychiatric patients with tardive dyskinesia (TD). The test was performed 3 times in the same patients: 1) live evaluation during a video recording, 2) evaluation 2 weeks later from the videotape, and 3) evaluation after another 2 weeks from the same videotape. The intrarater reliability was high in the experienced group (0.91–0.96 for SHRS hyperkinesia scale, 0.80–0.84 for AIMS, and 0.82–0.97 for SHRS total parkinsonism). No significant changes occurred from live to video evaluation. The interrater reliability coefficient for the experienced group was also high: 0.89–0.95 for the SHRS hyperkinesia scale, 0.76–0.85 for the AIMS scale and 0.95–0.98 for the SHRS parkinsonism scale. The less experienced and the inexperienced raters had coefficients for intra- and interrater reliability that were 0.10 and 0.20 lower, respectively. The SHRS parkinsonism scale had a high construct validity, as determined by the homogeneity coefficients of Cronbach (0.82) and Loevinger (0.43). The corresponding coefficients for the hyperkinesia scales were low, in agreement with the individual distribution of TD (only about 50% present extremity dyskinesia and less than 25% facial, head and trunk dyskinesia, independent of the severity of the syndrome). Finally, convergent validity was found between the SHRS hyperkinesia scale and AIMS and divergent validity between all of the other scales. It is concluded that the SHRS represents an easily completed, reliable, valid and sensitive rating scale for extrapyramidal symptoms that can be used with and without videotapes.     

Neuroleptic-potentiating effect of alpha-methyl-p-tyrosine compared with haloperidol and placebo in a double-blind cross-over trial.

The hypothesis that schizophrenia results from overactive dopaminergic influences suggests that reducing dopamine synthesis may increase the clinical effects of dopamine receptor blocking neuroleptic drugs. The neuroleptic potentiating role of alpha-methyl-paratyrosine (AMPT), a tyrosine hydroxylase inhibitor, was compared with haloperidol and placebo in a double-blind cross-over trial. Both AMPT and haloperidol increased the anti-schizophrenic effect of neuroleptic treatment in reduced dose compared with placebo (P less than 0.05), though two patients relapsed during the AMPT period. Both drugs slightly increased extrapyramidal symptoms, but the effect was greater with haloperidol. The limited antipsychotic effect and the potential for aggravating neurological symptoms suggest that the combination of AMPT and neuroleptics does not offer a superior advantage to treating schizophrenia. AMPT, however, may still be used as a research tool in elucidating pathogenetic mechanisms.