A role of central GABA(A)-ergic mechanisms in realization of somnogenic and thermoregulatory effects of exogenous HSP70

I.V. Ekimova

Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St. Petersburg, Russia

e-mail: pastukh@iephb.ru

 

Роль центральных ГАМК(А)-ергических механизмов в реализации сомногенных и терморегуляторных эффектов БТШ70

И.В. Екимова

Институт эволюционной физиологии и биохимии им. И.М.Сеченова, РАН,

Санкт-Петербург, Россия

 

 

Earlier, we elicited that microinjections of heat shock protein 70 kDa (HSP 70) contaminant free into the 3-d brain ventricle (b.v.) induce a dose-dependant increase in slow sleep (SS), a decrease in wakefulness, brain temperature and level of contractile muscle activity in rats and pigeons [Pastukhov et al., 2004-2005]. Recent studies indicate that the preoptic areas of hypothalamus of rats and pigeons contain heterogenic neuron populations discriminated in the functions and distributions of receptor types, which participate in the control of sleep and thermoregulation [Alam et al., 1995; Gallopin et al., 2000; Lu et al., 2000; Ekimova et al., 2004; 2005]. The ventrolateral preoptic area (VLPO cluster) is necessary for generation of slow sleep (SS) and the onset of SS is associated with an increase in the activity of inhibitory GABA-ergic mechanisms of the VLPO [Sherin et al., 1996, 1998; Lu et al., 2000; Ekimova et al., 2005]. The following working hypotheses have been proposed: 1. Somnogenic and thermoregulatory effects of HSP 70 are associated with activation of a sleep-positive and thermo-positive neurons in the preoptic area of hypothalamus; 2. Central GABA(A)-ergic mechanisms participate in realization of effects of HSP 70.

In order to find out a role of central GABA(A)- receptors in the realization mechanisms of somnogenic and thermoregulatory effects of HSP 70, microinjections of GABA(A)- receptor antagonist bicuculline were made into the 3-d b.v. (6 mkg/1 mkl) and the VLPO (1.0 mkg/0.2 mk/l) of hypothalamus 15 min before the intraventricular HSP 70 injections in rats and pigeons. The intraventricular injections of bicuculline were found to block somnogenic (since the 3-d h) and thermoregulatory (since the 1-t h) effects of HSP 70. It has been found that microinjections of bicuculline into the VLPO of the hypothalamus more greatly and earlier to block somnogenic effects of HSP 70 compared to the intraventricular injections; the total time of SS, the number of SS episodes and their average duration significantly decreased during 1-5 h since the moment of microinjection. GABA(A)-ergic receptors of the periventricular structures of the preoptic area of hypothalamus are presumed to participate in realization of thermoregulatory effects of HSP 70, whereas GABA(A)-ergic mechanisms of the VLPO are responsible mainly for realization of somnogenic effects of HSP 70.

This work was supported by the RFFR (grant 05-04-49356)

 

Сведение об авторе

Екимова Ирина Васильевна

Институт эволюционной физиологии и биохимии им. И.М. Сеченова, РАН

Ученая степень: к.б.н.

Звание: вед.н.с.

Адрес – Санкт-Петербург, пр. Мориса Тореза, 44

Тел. Сл. 552-30-24 тел. Дом. 538-29-06

e-mail – pastukh@iephb.ru