EFFECT OF HEAT-SHOCK PROTEIN 70 ON "CHOLINERGIC" REM SLEEP IN PIGEONS

Guselnikova E.A., Ekimova I.V., Pastukhov Yu.F.
Sechenov Institute of Evolutionary Physiology and Biochemistr
Russian Academy of Sciences, St. Petersburg, Russia

The role of heat shock protein 70 kD (HSP70), present in pre- and postsynaptic elements [Bechtold et al., 2000] in the regulation of the neurotransmitter release [Ohtsuka, Suzuki, 2000] and protection of the synaptic function from heat stress [Kelty et al., 2002] has been discussed in the last years. Evidence for the effect of exogenous HSP70 on the parameters of sleep and wakefulness upon activation of the brain transmitter systems in vivo is not available. Earlier we found dose-dependent biphasic changes ( an increase followed by a decrease) in the wakefulness total time (TT) and somato-visceral indices after microinjections of HSP70, purified from a bovine muscles, to the mesencephalic region of Nucleus Reticularis Pontis Oralis (NRPO) in pigeons [Pastukhov et al., 2003]. NRPO is critical region for triggering REM sleep (RS) ) in rats and cats [review: Siegel, 2000]. Microinjections of the acetylcholine agonist carbachol to NRPO in pigeons induced a considerable increase in the number of RS episodes (by 12-15 times) [Guselnicova et al., 2002]. Along with typical characters (EEG-desynchronization, muscular atony, accelerated heart beat), "cholinergic" RS was found to differ from natural one. Most RS episodes appeared after drowsiness episodes (due to a drastic decrease in TT of NREM sleep), RS episodes were more frequently interrupted by transient motor components, and brain temperature decelerated to grow and decreased in RS episodes. In the present study, 3 series of bilateral microinjections to NRPO in pigeons were performed: 1) carbachol (0.2*g/0.2*l); 2) HSP70 (0.4 *g/0.4 *l); 3) carbachol (0.2 *g/0.2 *l) in an hour after HSP70 (0.4 *g/0.2 *l). The results of the first two series confirmed the above date. The 3rd series showed that at the background of HSP70 carbachol induced a less significant rise in the number of RS episodes and TT, as well as diminished differences in the temperature and somato-visceral characters between "cholinergic" and natural RS. It is suggested that HSP70 can modulate the cholinergic transmission in the CNS.

The study was supported by RFRF (grant 03-03-33024).