In experiments on five awake cats, we studied the effects of bemitil, a drug possessing psychostimulatory, antidepressive, and actoprotector properties (peroral introduction, 50 mg/kg), on the activity of neurons of the aminergic cerebral systems. Eleven noradrenergic (NA-ergic) neurons of the locus coeruleus (LC) and 11 serotonergic (ST-ergic) neurons of the nuclei raphe (NR) were examined. A control experimental series was carried out on 8 NA-ergic neurons of the LC and 8 ST-ergic neurons of the NR. Bemitil was found to exert opposite effects on the impulse activity of NA-ergic and ST-ergic brainstem neurons; it suppressed impulsation of LC neurons and increased the spiking frequency of NR neurons within certain time intervals after its introduction. Analysis of EEG showed that bemitil decreased the spectral power of the delta and theta activities, which was accompanied by behavioral relaxation.

No abstract

No abstract

No abstract

Using intracellular recording, we studied electrical activity of unidentified neurons of the Helix visceral ganglion under conditions of application of Viagra (sildenafil citrate). Neurotropic effects of Viagra were clearly pronounced at concentrations of 10 -5 and 10 -4 M; they were excitatory and reversible. In the case where the concentration was 10 -3 M, the effect of Viagra was converted into an inhibitory one; some hyperpolarization of the neuronal membrane, a decrease in the amplitude of action potentials (APs), and reduction of their first derivatives reflecting the rates of rise of integral inward and outward currents were observed. In the concentration of 0.5×10 -2 М (5.0 mM), Viagra evoked hyperpolarization of the neuronal membrane by 8 to 10 mV. Against the background of such hyperpolarization, APs were rather rapidly reduced and disappeared; after washing out from the preparation tested, the initial values did not recover. The obtained data allow us to believe that the uncontrolled and excessive use of Viagra can be rather dangerous since it can lead to noticeable functional disturbances in the nervous system.

Under conditions of chronic experiments on awake cats, we studied changes in the impulse activity generated by brainstem monoaminergic neurons and also in the background field electrical activity of the neocortex induced by peroral administration of 150 mg/kg bemitil. In supposedly serotonergic neurons of the n. raphe, upon the action of this agent, the frequency of spike generation underwent two-phase modifications. Five to 20 min after administration of bemitil, a decrease (insignificant) in the frequency was followed by an increase (on the 35th min, the frequency began to significantly exceed the initial values, P < 0.05). Beginning from the 5th min of the exposure, discharges of noradrenergic neurons of the locus coeruleus were unidirectionally and significantly (P < 0.05) suppressed. With parallel EEG recording, we observed changes in the spectral powers (SPs) of separate rhythms; the SPs of alpha and delta oscillations increased, while the power of the theta rhythm dropped. We compared the effects of bemitil administered in different doses (50, 100, and 150 mg/kg). Possible mechanisms underlying the effect of bemitil on the functioning of cerebral mechanisms are discussed.

No abstract