Biomedical subjects

F Tempia

Publications and source records attributed to F Tempia.

22 records · Page 2Linked to original sources

PubMed1988

Antagonist action of imidazobenzodiazepine Ro 15-4513 on ethanol-induced alterations of saccadic eye movements in the pigmented rat.

Following an intraperitoneal injection of ethanol (1 g/kg), spontaneous saccades performed by pigmented rats showed a backward post-saccadic drift which was still present 45 min after the administration. When 5 mg/kg of Ro 15-4513 were injected, 15 min after ethanol, there was an immediate remarkable reduction in post-saccadic drift amplitude, with a full recovery in about 30 min after Ro 15-4513 administration. This drug is thus able to reverse the effect of ethanol and to restore effectively a mechanism of motor integration.

Animals↗

PubMed1985

On the Purkinje cell activity increase induced by suppression of inferior olive activity.

Previous experiments performed in rats under barbiturate anaesthesia have shown a remarkable increase of simple spike firing rate in cerebellar Purkinje cells following inferior olive lesion or inactivation. The increase is due, at least in part, to the withdrawal of the tonic background activity of corticocerebellar interneurones, which have GABA as a chemical transmitter. Since barbiturates potentiate GABAergic inhibition, it is possible that the effect is due to the presence of this type of anaesthesia. In absence of general anaesthesia, we have compared the simple spike firing rate of the Purkinje cells in rats with intact inferior olive and 3-5 days after inferior olive lesion by 3-acetylpyridine. In the latter condition, the firing rate is significantly higher. In other rats, under urethane anaesthesia, which is not known to interfere with GABAergic transmission, the inferior olive has been reversibly inactivated by applying a cooling probe to the ventral surface of the medulla. Following cooling of the inferior olive on one side, a remarkable increase of simple spike activity, parallel to the disappearance of complex spike activity, has been observed in the Purkinje cells of the contralateral side. These results show that the presence of the simple spike firing increase, which follows the removal of the climbing fibre activity, does not depend on an anaesthetic which potentiates GABAergic transmission, although its amplitude is affected by the same anaesthetic. They suggest, therefore, that the tonic inhibition exerted by the olivocerebellar pathway on the Purkinje cells operates also in physiological conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗

PubMed1983

Inferior olive inactivation decreases the excitability of the intracerebellar and lateral vestibular nuclei in the rat.

In rats under sodium pentobarbitone anaesthesia the inferior olive region has been reversibly inactivated by applying a cooling probe to the ventral surface of the medulla. Unitary activity has been recorded from the fastigial, interpositus and Deiters nuclei. Identification of units was based on the presence of a dye spot, left by the recording micropipette. In the Deiters nucleus, an additional criterion of identification was the antidromic activation from spinal cord stimulation. Following cooling of the inferior olive of one side, we have observed suppression of the activity of all the fourteen Deiters neurones and of seventeen out of twenty neurones recorded from the intracerebellar nuclei. In two out of seven Deiters neurones tested the antidromic invasion elicited by spinal cord stimulation was suppressed. In rats, whose inferior olive was previously destroyed, cooling of the inferior olive region was not followed by the powerful depression of spike activity seen in the vestibular and cerebellar nuclei cells in the intact rats. These results indicate that the olivocerebellar system is very important in regulating the level of excitability of the subcerebellar structures and therefore in controlling both postural mechanisms and the processing of information relating to sensorimotor integration.

Animals↗

PubMedDate not supplied

Magnesium deficiency affects the pentylenetetrazol-induced convulsions in magnesium-deprived rats.

A group of 11 young albino rats was fed with a Mg2+ free diet. After a few days, the animals showed typical signs of Mg2+ deficiency, consisting in skin vasodilation, red conjunctiva and hair loss. Pentylenetetrazol (50 mg/kg i.p.) injected in these rats, 6 and 12 days after the beginning of the diet, elicited a more severe convulsive activity compared with that shown by a control group of 12 rats. These results suggest that a Mg2+ deficiency, though not necessarily responsible for the convulsive activity, may contribute to facilitate an epileptic episode or may lead to more severe convulsions. The possibility of a more powerful activation of the NMDA receptors in Mg2+ deficiency is discussed.

Animals↗