INTRACEREBRAL SUBSTRATES OF SLEEP-WAKE REGULATION IN BIRDS

Pastukhov Yuri F.
Sechenov Institute of Evolutionary Physiology
and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia

The characteristics of sleep and mechanisms of its regulation in birds have been studied to a considerably lesser degree than in mammals. The lecture presents data on the features of temporal, temperature, and somato-visceral characteristics of NREM (NS) and REM (RS) sleep and quantitative contribution of NS, RS and wakefulness to "cooling" and "heating" of the brain during circadian cycle in euthermia, hypothermia and hyperthermia in birds in comparison with mammals. Analysis of the involvement in sleep-wake regulation of the main inhibitory system, GABA-ergic, and interacting with it, cholin- and glutamatergic mechanisms of the midbrain (substantia grisea centralis (SGC), nucleus reticularis pontis oralis (NRPO) and other areas) and of the ventrolateral and medial preoptic region/anterior hypothalamus also revealed certain differences in their structural and functional organization in birds as compared with mammals. An increase in NS and potentiation of its thermoregulatory function in birds protect them from overheating and energy, emotional and intoxication stress (during food and sleep deprivation, inhibition of catalase, application of endotoxin) and also serve for acceleration of post-stress rehabilitation. GABA(A)-ergic inactivation of the SGC transmitter mechanisms leads to a longer NS and an attenuated energy stress during fasting. First evidence is obtained for the involvement of the major stress protein, heat-shock protein 70 kD (HSP70) in sleep-wake regulation. Intracerebral microinjections of natural HSP70 were accompanied by a longer NS in intact pigeons; the effect enhanced in a period after sleep deprivation. Combined microinjections of HSP70 and the acetylcholine agonist carbachol to NRPO resulted in diminished differences between temporal, temperatute, and somato-visceral components of "cholinergic" and natural RS. It is suggested that HSP70 can affect synaptic events in the brain structures and potentiate the protein biogenesis during post-stress rehabilitation.

The study was suppoted by RFRF (grants 01-04-49628; 03-03-33024) and RAS Presidium ("Basic sciences to medicine" Program).