Participation of vertebrate forebrain activating systems in organization of the wakefulness-sleep cycle

The article considers mechanisms of diencephalic-telencephalic interactions in regulation of the wakefulness-sleep cycle in various classes of vertebrates. In such interactions a special role is played by the dopaminergic systems that perform neurosecretory function at the level of diencephalon and neurotransmitter function at the level of telencephalon. Concepts of A.I. Karamyan and A.L. Polenov about the stage pattern of development of CNS and neurosecretory systems are presented, as well as the interconnection of dopaminergic and glutamatergic neurotransmitter systems in the mammalian neostriatum in the wakefulness-sleep cycle is considered. Comparison of dynamics of expression of the dopamine metabotropic receptors and of the glutamate ionotropic receptors in neostriatum showed unidirectional changes of D₁ and AMPA on the background of the 6-h sleep deprivation as well as of D₂ and NMDA on the background of postdeprivative sleep. The corticofugal direction of glutamate impulsation and its relatively fast actions allow admitting its triggering action on generation of the sleep-inducing processes in the underlying brain parts.     

Dissolution of the wakefulness-sleep cycle in patients with catatonic form of schizophrenia

Polysomnograms of two patients with catatonic form of schizophrenia of different duration of the disease were recorded and analyzed. Pronounced disturbances of the wakefulness-sleep cycle (WSC) were revealed. Apart from differences connected with duration of the disease and treatment with corresponding medications, there were detected the general features indicating dissolution of the central nervous system and the very wakefulness-sleep cycle. A certain similarity of the found WSC disturbances with the earlier shown WSC disturbances in rats with predisposition to catalepsy was noted. The conclusion is made about domination of diencephalic influences over the telencephalic one in the studied patients.     

Effect of photostimulation on the wakefulness-sleep cycle in the common frog Rana temporaria

Effect of daily 30-min photostimulation in the 10 s light: 10 s pause regime (the total of 5 days) on the time structure of the wakefulness-protosleep cycle (WPC) was studied in the common frog Rana temporaria. Changes of EEG wave components were analyzed in three immobility forms of the types of catalepsy (P-1), catatonia (P-2), and cataplexy (P-3) that form protosleep. The first three photostimulations promoted a gradual increase of the P-1 state to 84.16 ± 11.6% (the initial value (IV) 22.9 ± 9.1%) and a decrease of representation of wakefulness to 4.86 ± 2.1% (IV 13.8 ± 7.8 %), of P-2 to 11.1 ± 5.3 (IV 53.3 ± 13.3 %), and of P-3 to 2.21 ± 1.0% (IV 11.1 ± 5.6%). After 4–5 photostimulations and especially after their complete cessation the percentage of P1 in the WPC was restored to initial values, whereas the percentage of the frog WPC P-3 considered to be a precursor of the homoiothermal sleep rose to 20 ± 8.3% after 5 photostimulations and to 38.5 ± 6.7% the next day. Changes in the frog EEG spectra appeared only after one photostimulation and were characterized by a brief increase of power of α-like waves and by inhibition of slow δ-waves. In P-2 the power of the slow δ-waves gradually rose. In P-3 the EEG parameters did not change. In all experimental animals a decrease of the relative thymus and adrenal masses was revealed, which indicates the stress nature of the photostimulation regime used in the work. The obtained data allow thinking that a certain neurohormonal response to stress has already been formed at the amphibian level and that an important role in this response realization is played by a coordinated interaction of the hypothalamic sleep-regulating system providing protosleep manifestations and of the hypothalamic neurosecretory system triggering hormonal cascade of the stress-reaction.     

Effect of photostimulation on the wakefulness-sleep cycle in the common frog Rana temporaria

Effect of daily 30-min photostimulation in the 10 s light: 10 s pause (the total of 5 days) on the time structure of the wakefulness--protosleep cycle (WPC) was studied in the common frog Rana temporaria. Changes were analyzed of EEG wave components in three immobility forms of the type of catalepsy (P-1), catatonia (P-2), and cataplexy (P-3) that form protosleep. The first three photostimulations promoted a gradual increase of the P-1 state to 84.16 +/- 11.6% [the initial value (IV) 22.9 +/- 9.1%] and a decrease of representation of wakefulness to 4.86 +/- 2/1% (IV 13.8 +/- 7.8%), of P-2 to 11.1 +/- 5.3 (IV 53.3 +/- 13.3%), and of P-3 to 2.21 +/- 1.0% (IV 11.1 +/- 5.6%). After 4-5 photostimulations and especially after their complete cessation the percentage of P-1 in the WPC was restored to initial values, whereas the percentage of the frog WPC P-3 considered to be a precursor of the homoiothermal sleep rose to 20 +/- 8.3% after 5 photostimulations and to 38.5 +/- 6.7% the next day. Changes in the frog EEG spectra appeared only after one photostimulation and were characterized by a brief increase of power of alpha-like waves and by inhibition of slow 6-waves. In P-2 the power of the slow delta-waves gradually rose. In P-3 the EEG parameters did not change. In all experimental animals a decrease of the relative thymus and adrenal masses was revealed, which indicates the photostimulation regime used in the work induces stress. The obtained data allow thinking that a certain neurohormonal response to stress has already been formed at the amphibian level and that an important role in this response realization is played by a coordinated interaction of the hypothalamic sleep-regulating system providing protosleep manifestations and of the hypothalamic neurosecretory system triggering the stress-reaction hormonal cascade.     

The wakefulness-sleep cycle in rats with a genetic predisposition to catalepsy

Neurophysiological studies on wakefulness-sleep cycle have been made in rats selected for hereditary inclination to catalepsy. It was shown that in these animals, the stage of delta-sleep is significantly reduced, whereas the duration of a superficial slow-wave sleep is increased. In a sleeping phase of the cycle, large amount of spindles in the range of alpha- and beta 1-oscillations was observed, especially significant in electrograms of n. caudatum and sensorimotor cortex. This activity is considered as a pathological manifestation of a transient hypnotic phase which includes the increase in immobilization of a cataleptic type.     

Electroencephalographic analysis of manifestations of latent forms of paroxysmal syndrome in the wakefulness-sleep cycle in rats

An electroencephalographic study of the brain activity in the wakefulness-sleep cycle was carried out on rats of Krushinskii-Molodkina line (KM) with hereditary predisposition to audiogenic convulsions and on Wistar rats that were insensitive to the convulsiogenic sound effect, but with epileptiform manifestations appearing on the background of cadmium intoxication and administration of kainic acid into the caudate nucleus head. There were revealed several EEG patterns whose presence was an indicator of formation of disorders of the CNS activity of the paroxysmal character in the animals. It has been established that in the phase of the rat rapid-wave sleep, a high representation of episodes with predominance of a-diapason EEG oscillations can be considered a specific non-paroxysmal abnormality due to the presence of convulsive syndrome in these animals. It was shown the long steady decrease of sensitivity of KM rats to the convulsiogenic sound effect, which appeared after multiple audiogenic generalized tonicoclonic convulsive attacks, correlated with a decrease of the degree of theta-diapason oscillations and with an increase of representation of alpha-diapason waves on EEG in the state of the animal quiet consciousness. A role of disintegration in activity of the ascending activating brain systems in the animal and human paroxysmal syndromes is discussed.     

Electroencephalographic analysis of manifestations of hidden forms of paroxysmal syndrome in the wakefulness-sleep cycle in rats

An electroencephalographic study of the brain activity in the wakefulness-sleep cycle was carried out on rats of Krushinskii-Molodkina line (KM) with hereditary predisposition to audiogenic convulsions and on Wistar rats that were insensitive to the convulsiogenic sound effect, but with epileptiform manifestations appearing on the background of cadmium intoxication and administration of kainic acid into the caudate nucleus head. There were revealed several EEG patterns whose presence was an indicator of formation of disorders of the CNS activity of the paroxysmal character in the animals. It has been established that in the phase of the rat rapid-wave sleep, a high representation of episodes with predominance of α-diapason EEG oscillations can be considered a specific non-paroxysmal abnormality due to the presence of convulsive syndrome in these animals. There was shown a long steady decrease of sensitivity of KM rats to the convulsiogenic sound effect, which appeared after multiple audiogenic generalized tonicoclonic convulsive attacks, correlated with a decrease of the degree of ?-diapason oscillations and with an increase of representation of α-diapason waves on EEG in the state of the animal quiet wakefulness. The role of disintegration in activity of the ascending activating brain systems in the animal and human paroxysmal syndromes is discussed.     

Reactivity of the somesthesic cortex (S1) during the wakefulness-sleep cycle in the rat]

The changes in amplitude of the activities evoked in the S1 cortex by stimulation of the specific radiations have been studied during the sleep-waking cycle. The recovery mode of these activities after a short or long delay has been tested by the paired stimuli method. Results are in general agreement with those described in the cat.     

Participation of peptide hydra morphogen in the regulation of proliferation processes in different tissues of white rats]

The PMH influence on proliferation processes in some tissues of white rats was studied. PMH injections in doses 10.0 mkg/kg and 100.0 mkg/kg stimulated the processes of DNA--synthesis after 24 hours in corneal and tongue epithelium. The direct dose-dependent effect was revealed. PMH in dose 10.0 mkg/kg activated the proliferative processes in the stomach epithelium and thymus cortex. after 24 hours too. The given dose of PMH caused trustworthy decreasing of proliferative activity in thymus after 4 hours. The stimulation of DNA-synthesis and acceleration of mitosis were found after 5-times application on white rat's corneal with 100 nM PMH solution.     

The phenomenon of the functional dissolution of the wakefulness-sleep cycle in white rats under the influence of immobilization]

Studies have been made on functional dissolution of the sleep cycle in albino rats due to immobilization of various duration. It was shown that 1-day immobilization increases microactivational representation in the EEG, facilitates rhythmic movements of the lower jaw, affects relative duration of the diurnal and nocturnal sleep, increases sleep fragmentation, and in some of the animals decreases the EEG amplitude. It is suggested that strong stress results in the return of sleep mechanisms to a more ancient level.     

Pregnancy-induced hyperphagia is associated with increased gene expression of hypothalamic agouti-related peptide in rats

Pregnancy is characterized by an increase in food intake that, in turn, produce a positive energy balance in order to face the considerable metabolic demands associated with the challenge of reproduction. Since hypothalamus is a key brain region involved in many peripheral signals and neuronal pathways that control energy homeostasis and food intake, we investigated if during pregnancy the increase in food intake is mediated by stimulating orexigenic and/or inhibiting anorexigenic neural pathways. We examined hypothalamic gene expressions of Ob-Rb, NPY, AgRP, POMC, MC4-R, and preproorexins in pregnant Wistar rats at day 19 of gestation. Food intake and body weight were increased progressively during the pregnancy. Visceral fat mass depots and serum leptin levels were also increased when compared with virgin animals. No differences were found in mRNA expression of Ob-Rb, POMC, MC4-R, NPY or preproorexin between virgin and pregnant animals. However, pregnancy produced a selective increase in AgRP mRNA levels. These results indicate that the positive energy balance that occurred during pregnancy can hardly be explained by changes in Ob-Rb despite hyperleptinemia associated with pregnancy. The enhanced expression of AgRP suggests the involvement of this neuropeptide in mediating pregnancy-associated hyperphagia.