Activity of cat cerebellar neurons in penicillin epilepsy and amphetamine treatment.

The discharge pattern of cerebellar Purkinje cells and fastigial neurons was studied after acute amphetamine treatment in immobilized cats, as well as during generalized penicillin-induced epilepsy. There was a marked reversible decrease in spontaneous firing rate of Purkinje cells and an increase in spontaneous firing rate of fastigial neurons after acute d-1 amphetamine administration (5 mg/kg, s.c.). The discharge pattern of Purkinje cells showed tendency towards inhibition, while the fastigial neurons showed less clear tendency towards disinhibition in the course of epilepsy induced by parenteral administration of penicillin (400.000-500.000 I.U./kg, i.m.). Moreover, acute amphetamine treatment (5 mg/kg, s.c.) performed after the development of penicillin-induced epileptic episodes elicited a prominent suppression of Purkinje cell discharges associated with a parallel increase in discharges of fastigial neurons. These results suggest that the changes in discharge rate of cerebellar corticonuclear neurons induced by amphetamine contribute to suppression of seizural activity in the feline model of generalized epilepsy.

Effect of calcium ionophore A23187 on the sensitivity of early sea urchin embryos to cytotoxic neuropharmacological drugs.

The ability of cytotoxic neurochemicals (indole and amphetamine derivatives) to block first cleavage division in the embryos of the sea urchin Arbacia lixula abruptly increases when the embryos are incubated in calcium-free seawater and decreases when the external Ca concentration is raised up to 46.4 mM. Sensitivity of the embryos to these drugs decreases also in the presence of the Ca-ionophore A23187. It is suggested that Ca ions are involved in the realization of physiological effects of "prenervous" neurotransmitters whose presence in early sea urchin embryos was shown by us earlier.