The heat shock protein 70 kDa (Hsp70) is known as the molecular chaperone taking a part in the protein folding and regulation of cell functions. Also it was shown that Hsp70 can regulate physiological functions at whole organism level (Pastukhov et al. 2004). The central microinjections of Hsp70 could increase the total time of non-rapid-eye-movement sleep (non-REMS) and decrease the brain temperature. It is unclear what effect can Hsp70 exert on sleep and thermoregulatory characteristics during the recovery after sleep deprivation (SD) in pigeons. The total SD was evoked by a tactile and sound stimulation during 5 hours. Exogenous Hsp70 (purified from contamination and consisting of constitutive and inducible isoforms) was injected into the 3rd brain ventricle in dose of 1.5 mg/ml in the end of SD. In control conditions pigeons were injected with vehicle in the same volume. Recording of polysomnogram and thermoregulatory characteristics during 24 h was carried out by computer system. The procedure of SD was characterized by an increase in brain temperature and contractile muscular activity. During the first hour after the end of SD wakefulness prevailed and the level of contractile muscular activity remained high. The rebound effect of non-REMS was observed only in the second hour. The injection of Hsp70 after the end of SD evoked the non-REMS rebound, which occurred during the first hour. During the next 5 hours the amount of non-REMS was also increased. Hsp70 also induced a decrease in brain temperature and contractile muscular activity which occurred immediately after the end of SD. Thus we suppose that early appearance of non-REMS and decrease in brain temperature and contractile muscular activity can be an evidence of stress-limiting effect of Hsp70.

References: 

1.Pastuchov Yu.F., Ekimova I.V., Hudik K.A. & Guzhova I.V. 2004. Dokl.Acad.Sci 402, 275–278