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Biomedical subjects

P Jenner

Publications and source records attributed to P Jenner.

At least 19 recordsLinked to original sources
PubMed1979

Tardive dyskinesias.

Explore the source record for details and available documents.

Antipsychotic Agents↗
PubMed1979

Changes in dopamine-mediated behaviour during one year's neuroleptic administration.

Trifluoperazine (2.5--3.5 mg/kg/day) or thioridazine (30--40 mg/kg/day) were given in the drinking water to male Wistar rats for 12 months. Initial catalepsy and inhibition of spontaneous locomotion disappeared by 3 months and thereafter. Initial inhibition of stereotypy induced by s.c. apomorphine also disappeared by 3 months to be replaced by an enhanc-d stereotypy response after 6 and 12 months' drug intake. Drug-treated animals exhibited a greatly increased incidence of spontaneous mouth movements after 12 months' intake compared with control animals. Lower doses of both drugs (trifluoperazine 0.7--0.9 mg/kg/day; thioridazine 6--8 mg/kg/day) also initially suppressed behavioural responses but by 1 month and thereafter these animals were indistinguishable from controls. At 12 months, however, these animals also exhibited an increased incidence of spontaneous mouth movements. The data demonstrate a reversal of the initial dopamine receptor-blocking properties of trifluoperazine or thioridazine to be replaced by an enhanced response of cerebral dopamine systems while animals were still continuously receiving the drug.

Animals↗
PubMed1979

Dopamine-mediated circling behaviour does not involve the nigro-tectal pathway.

Extensive unilateral or bilateral electrolytic ablation of the rat superior colliculus failed to reduce apomorphine- or amphetamine-induced rotation in animals with a unilateral 6-hydroxydopamine lesion of one nigro-striatal dopaminergic pathway. These findings suggest that a nigro-tectal pathway does not play a crucial role in mediating the circling response caused by striatal dopamine receptor stimulation. However, electrolytic lesions of the dorsal tegmental decussation reduced apomorphine- but not amphetamine-induced rotation in such animals, perhaps by sectioning some commissural pathway between the two nigro-striatal systems.

Animals↗
PubMed1979

Turning behaviour induced by injection of muscimol or picrotoxin into the substantia nigra demonstrates dual GABA components.

Injection of the GABA agonist muscimol into rat caudal substantia nigra caused contralateral turning, whereas injection into the rostral substantia nigra caused ipsilateral turning. The GABA antagonist picrotoxin had the opposite effect. These findings support the hypothesis that GABA has dual actions in the substantia nigra. Ipsilateral turning induced by injection of muscimol into rostral nigra was abolished by haloperidol pretreatment, indicating the involvement of dopaminergic mechanisms. Haloperidol pre-treatment did not prevent turning induced by muscimol injected into the caudal nigra, supporting the existence of a non-dopaminergic nigral output system.

Animals↗
PubMed1979

beta-Adrenoreceptor antagonists in essential tremor.

Three different beta-adrenoreceptor antagonists--propranolol, sotalol, and atenolol--were compared in a double-blind study with placebo in nine patients with essential tremor. All three drugs produced an equal reduction in standing pulse rate but atenolol was less effective in reducing tremor than propranolol and sotalol. These results suggest that the reduction in tremor produced by beta-adrenoreceptor antagonists is mediated by an effect on peripheral beta 2-adrenoreceptors.

Adult↗
PubMed1979

Relationship between plasma propranolol concentration and relief of essential tremor.

The relationship between plasma propranolol concentration and relief of essential tremor was examined in 11 patients during treatment with oral racemic propranolol in doses of 30 to 640 mg/day. Although propranolol decreased tremor in all 11 patients, the degree of improvement varied widely in individuals (mean 51%, range 25--90%), and was not related directly occurred at plasma propranolol concentrations below 20 ng/ml (0.077 mumol/l) and, in three others, below 40 ng/ml (0.154 mumol/l). It is concluded that the optimum response of essential tremor to propranolol is achieved at relatively low plasma propranolol levels, levels which are obtained by daily propranolol doses of 120--240 mg.

Adult↗