Zh Vyssh Nerv Deyat+
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Zh Vyssh Nerv Deyat+ · Nov 2003
[Sensory responses of neurons in the medial septal area to modulation of the theta-activity by alpha2-adrenergic receptor agonist clonidine].
It was shown by us earlier that bilateral intracerebroventricular injection of alpha2-adrenoreceptor agonist clonidine produced a dose-dependent effect on theta oscillations in the septohippocampal system of awake rabbits. A relatively low dose of clonidine (0.5 microgram) attenuated and a high dose (5 micrograms) significantly enhanced the rhythmic activity. It was suggested that the effect of the low dose of clonidine is mediated by presynaptic alpha2-adrenoreceptors were as postsynaptic alpha2-adrenoreceptors. ⋯ Persisted excitatory and inhibitory responses became less distinct than the initial ones except single excitatory reactions. The results suggest that alpha2-adrenoreceptors are involved in the control of the sensory reactivity of MS neurons. A sharp decrease in neuronal reactivity during stable rhythmical oscillations developing under the influence of high dose of clonidine confirm the role of the theta rhythm in the septohippocampal system as an active filter in information selection and registration.