RESUMEN

Cholinergic mechanisms in the medial preoptic area of the hypothalamus were found to be involved in controlling the time characteristics of the states of sleep and waking, as well as measures of thermoregulation, in pigeons. Muscarinic and nicotinic cholinergic receptors were involved in the mechanisms maintaining waking. Activation of muscarinic cholinoreceptors in the medial preoptic area was accompanied by increases in brain temperature due to increases in peripheral vasoconstriction and decreases in the level of muscle contractile activity. Activation of nicotinic cholinoreceptors in this area led to decreases in brain temperature and increases in the level of contractile muscle activity. Comparative analysis of the results of experiments and previous studies showed that changes in brain temperature in pigeons occurring on activation of cholinoreceptors depend on the type of cholinoreceptor activated but are independent of their location in the preoptic area of the hypothalamus.

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RESUMEN

The data obtained show that cholinergic mechanisms of the medial preoptic area of hypothalamus participate in control of wakefulness-sleep states and thermoregulation parameters in pigeons. Muscarinic and nicotinic cholinergic receptors are established to be involved in the wakefulness maintenance. The muscarinic cholinergic receptor activation of the medial preoptic area is accompanied by an elevation of the brain temperature, by development of peripheral vasoconstriction, and by an in increase in level of the muscle contractile activity. During the nicotinic cholinergic receptor activation of the area, a decrease in the brain temperature and an increase in level of the muscle contractile activity are found. A comparative analysis of experiments and early investigation suggests that during the cholinergic receptors activation changes in the brain temperature of pigeons depend on type of the cholinergic receptors but not on their localization in the preoptic area of hypothalamus.

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RESUMEN

Maintenance of waking in pigeons was found to be linked with the mechanisms of activation of muscarinic (M-) cholinergic receptors of the ventrolateral preoptic area of the hypothalamus. "Muscarinic" waking was characterized by an increase in the power of the EEG spectrum at 0.75-12 Hz and an increase in brain temperature. Activation of nicotinic (N-) cholinergic receptors in this area was associated with an increase in the duration of slow sleep, a decrease in the spectral EEG power at 0.75-7 Hz, and a decrease in brain temperature in this state; hyperactivation of these receptors led to the development of waking, where waking episodes were associated with significant decreases in brain temperature. Blockade of M-and N-cholinergic receptors resulted in changes in the sleep-waking cycle and thermoregulation which were oppose to those seen on receptor activation. It is suggested that M-and N-cholinergic receptors of the ventrolateral preoptic area of the pigeon hypothalamus are involved in regulating sleep and waking, their effects being associated with influences on the GABAergic system of this area.

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RESUMEN

By using electrophysiological methods, it has been established that muscarinic (M-) cholinergic mechanisms of the ventrolateral preoptic area (VLPA) of pigeon hypothalamus participate in maintenance of wakefulness, whereas nicotinic (N-) mechanisms--in maintenance of the slow-wave sleep. Activation of the VLPA M-cholinergic receptors has been found to be accompanied by an elevation of the brain temperature, by development of peripheral vasoconstriction, and by an increase in the muscle contractive activity. Activation of N-cholinoreceptors leads to a decrease in the brain temperature and development of peripheral vasoconstriction. It is suggested that the VLPA M- and N-cholinergic receptors are involved in different mechanisms of regulation of wakefulness and sleep states and brain temperature in pigeons.

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RESUMEN

Maintenance of wakefulness is established to accomplish muscarinic (M-) cholinergic receptor activation in the ventrolateral preoptic area of the hypothalamus. The "muscarinic" wakefulness is characterized by enhancement of electroencephalogram (EEG) power spectra in the 0.75-12 Hz band and by increase in brain temperature. Activation of nicotinic (N-) cholinergic receptors of the area produces an increase in the duration of slow wave sleep, EEG power spectra reduction in the 0.75-7 Hz band, a decrease in brain temperature. And its hyperactivation leads to wakefulness, during its episodes the brain temperature decreases. During M- and N-cholinergic receptor blockade, the sleep-wakefulness and thermoregulation changes opposite to their activation were found. It is suggested that M- and N-cholinergic receptors of the ventrolateral preoptic area in pigeons participate in the sleep-wakefulness regulation and this effect is related to influence of this area on GABA-ergic system.

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