Under conditions of the open-field test, we demonstrated that bemitil and benzimidazole injected intraperitoneally into rats in doses of 50 to 150 mg/kg suppress horizontal and vertical (motor and research) activities, as well as decrease the frequencies of episodes of grooming, defecation, and urination. Possible mechanisms underlying modifications of behavioral phenomena triggered by the above agents are discussed.
We showed that applications of cobalt and zinc salicylates lead to restoration of the impulse activity of a PPa1 neuron of the snail, Helix pomatia, under conditions of the blockade of synaptic transmission by cadmium ions. In the case where a PPa1 neuron demonstrated no background activity and/or under conditions of total isolation of this cell, the above-mentioned salicylates initiate generation of action potentials, as well as exert an excitatory effect on "silent" non-identified cells of the parietal and visceral ganglia. Based on the data obtained, we conclude that the activating effect of cobalt and zinc salicylates on the PPa1 cell is similar to that of the so-called initiating factor (IF), which initiates generation of the burst activity. These effects are independent of the inward calcium current. Using an activator of cAMP phosphodiesterase, imidazole, we showed that the effects of the above salicylates (similar to the effect of IF) are related to the influence of these agents on the system of cyclic nucleotides.
The impulse activity of 227 neurons of field 5 was investigated in cats trained to complete a movement of the forepaw in response to a stimulus. The discharges of each of them were collected relative to three markers: the presentation of the conditional signal, the raising of the paw from a support, and pressing on a pedal. The reactions associated with the performance of the reflex were recorded in 224 neurons. The majority of the cells reacting to the stimulus generated a pronounced excitatory response even at the beginning of the movement, but were inhibited at the moment of the touching of the pedal. Sixty-seven percent of the neurons whose discharges were collected relative to the raising of the paw reacted prior to the appearance of the EMG response. The parietofrontal neurons were identified on the basis of the presence of an antidromic response to the stimulation of the motor cortex. The changes in the discharge frequency which were associated with the movement significantly more often anticipated the EMG response in the parietofrontal neurons as compared with non-parietofrontal cells (79.0 and 63.3%, respectively). The parietofrontal neurons reacted more actively to the conditional signal, light flashes, acoustic tone, and tactile stimulation as well. Their role in the triggering and unfolding of the program of a voluntary movement is discussed.
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.
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