Correction of Mitochondrial Enzyme Activities in the Skeletal Muscles of Old Rats in Response to Addition of Olive Oil to the Ration.

Activities of mitochondrial electron transport chain enzymes NADH-CoQ oxidoreductase (complex I), cytochrome C-oxidase (complex IV), and citrate synthase were measured by spectrophotometry in m. quadriceps femoris homogenate from old rats receiving olive oil with the ration. Reduced activities of complexes I and IV in old animals were restored to the level of young animals after 6-week consumption of olive oil. Activity of citrate synthase did not change with age. Positive effect of olive oil on fatty-acid composition of the muscle tissue in old animals was demonstrated. The content of summary monounsaturated fatty acids, reduced with aging, and of summary polyunsaturated ones, increasing with age, were restored in old rats to the levels virtually not differing from the levels of young animals.

[Endogenous hypometabolic-hypothermic factors and their possible application to life in the cold].

Hibernation is a natural model of Tolerance of hypometabolism, hypothermia, hypoxia, bradycardia, and longterm hypophagia. Here, we review recent advances in the isolation and identification of some natural endogenous regulators from hibernating and cold-adapted animals: proteins, peptides, and nonpeptide substances. We also discuss the employment of molecular, biochemical, and physiological bases of natural hypobiosis in ecology, cryomedicine, and the cryopreservation of genetic material from rare and endangered species. We suppose that our approaches can be extensively used (i) in medicine, when there is a need to slow down or suspend life processes for a short time; (ii) for the adaptation of humans to cold; and (iii) in long-term space flights.

The modulatory effects of mu and kappa opioid agonists on 5-HT release from hippocampal and hypothalamic slices of euthermic and hibernating ground squirrels.

To elucidate the role of opioids in regulating hibernation, the modulatory effects of different opioids on 35 mM K(+)-stimulated [3H]-5-HT release from brain slices were examined in the Richardson's ground squirrels. DAGO ([D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin), a specific mu agonist, evoked a significant dose-dependent (10(-7)-10(-5) M) inhibition of K(+)-stimulated 5-HT release from hippocampal slices of the non-hibernating squirrels. The inhibitory effect of DAGO was attenuated by either the opioid antagonist naloxone (10(-6) M) or the voltage dependent sodium channel blocker tetrodotoxin (TTX, 10(-6) M). The inhibitory effect of DAGO persisted in the hibernating squirrels; however, a ten fold higher concentration of DAGO (10(-6)-10(-5) M) was required to elicit a significant inhibition. In contrast, kappa agonist U50488 (10(-5) M) exerted a significant enhancement of K(+)-stimulated 5-HT release from hippocampal slices of the non-hibernating squirrels. This enhancement was blocked by either the specific kappa antagonist nor-binaltorphimine (10(-6) M) or TTX (10(-6) M). However, in the hibernating squirrels, the stimulatory effect of U50488 (10(-5) M) on 5-HT release was absent. DAGO and U50488 had no modulatory effects on K(+)-stimulated 5-HT release from the hypothalamic slices of either the non-hibernating or hibernating squirrels. These results demonstrate that the modulatory effects of opioids on 5-HT release are receptor-specific and state-dependent, indicating the complex nature of the roles of different opioids in regulating hibernation.

State-dependent variation in the inhibitory effect of [D-Ala2, D-Leu5]-enkephalin on hippocampal serotonin release in ground squirrels.

Accumulated evidence has suggested that increased endogenous opioid activities may facilitate the onset of hibernation either directly or possibly through modulation of other neurotransmitter systems. The seasonal change of [D-Ala2, D-Leu5]-enkephalin (DADLE), a delta receptor agonist, in modulating K+ (35 mM)-induced [3H]-5-hydroxytryptamine (5-HT) release from the hippocampal and hypothalamic slices of euthermic and hibernating Richardsons' ground squirrels was therefore investigated. DADLE (0.1-10 microM) had no effect on 5-HT release in the hypothalamic slices but elicited a dose-related inhibition on [3H]-5-HT release from the hippocampal slices of the euthermic ground squirrel. The inhibitory effect of DADLE was completely reversed by naloxone (10 microM), but not by tetrodotoxin (1 microM). In contrast, DADLE failed to alter the K(+)-induced 5-HT release from the hippocampal slices of the hibernating ground squirrel. This state-dependent reduction in responsiveness to an opioid is consistent with the hypothesis that enhanced endogenous opioid activity in the hibernating phase could lead to down regulation of the opioid receptors and minimize its inhibition on hippocampal serotonergic activity. A high 5-HT activity would inhibit midbrain reticular activating system indirectly through non-serotonergic fibers, which in turn facilitate the onset or maintenance of hibernation.

Anti-lymphoproliferative activity of brown adipose tissue of hibernating ground squirrels is mainly caused by AMP.

A fraction with mol wt < 1 kDa was obtained from the brown fat of hibernating ground squirrels (Citellus undulatus) by means of delipidization, acid extraction, ultracentrifugation and ultrafiltration. This fraction suppressed the proliferation of mouse lymph node cells under standard mitogenic stimuli for T lymphocytes. In contrast, the fraction with mol wt < 1 kDa obtained from the brown fat of active ground squirrels in spring did not display such activity. Further HPLC purification of the biologically active fraction and chemical and structural analysis of its most potent antilymphoproliferative component revealed that this is adenosine 5'-monophosphate (AMP). These data lend support to the notion that in hibernating mammals AMP originating, at least partly, from the brown fat down-regulates the seasonally-dependent proliferation of the thymus.

[Hypothermic effect on mice of a 1-10 kD fraction of the small intestine of the hibernating suslik Citellus undulatus during hypoxia and hypercapnia]. / Gipotermicheskoe vliianie na myshei fraktsii 1-10 kD tonkoi kishki giberniruiushchego suslika Citellus undulatus v usloviiakh gipoksii i giperkapnii.

Studies have been made on a possibility of inducing a prolonged hypothermia by injections to albino mice of a fraction with a molecular mass 1-10 KD isolated from the small intestine of hibernating ground squirrels. Specific conditions for the onset of hibernation (hypoxia, hypercapnia, temperature) were simulated. Exposure of mice to hypoxia and hypercapnia for 2 hours in combination with injection of the mentioned fraction extended hypothermic condition in animals up to 24-36 hours as compared to 2-3 hours after sole injection of the fraction. After the injection of 5-OT under the same conditions, the prolonged hypothermia was less stable.

[The cardiotropic, hypometabolic and hypothermic activity of peptide fractions from the tissues of hibernating cold-adapted animals]. / Kardiotropnaia, gipometabolicheskaia i gipotermicheskaia aktivnost' peptidnykh fraktsii iz tkanei zimospiashchikh kholodoadaptirovannykh zhivotnykh.

From tissues of hibernating and active long-tailed ground squirrels and from the brain of cold-adapted Yakut horses, low molecular peptide fractions were obtained which, after injection to albino mice, decreased oxygen consumption and rectal temperature in them. The same fractions exhibited negative chrono- and inotropic effects on isolated hearts of ectothermic and endothermic animals. Fractions from the brain of ground squirrels and the brain of horse exhibited similar pattern of the activity. The activity of fractions was subjected to seasonal changes and depended on the degree of their purification. Provisional intracellular microelectrophysiological analysis of the effect of these fractions on the frequency and strength of contractions in isolated heart was made.

Kyotorphin suppresses proliferation and Ca2+ signaling in brown preadipocytes.

A positive correlation was revealed between stimulation of protein and DNA synthesis in preadipocytes by norepinephrine or neokyotorphin and intracellular Ca2+ concentration in these cells. Kyotorphin abolished the stimulatory effect of norepinephrine on proliferation of cultured cells and cold-induced [3H]-thymidine incorporation into DNA of mouse brown adipose tissue in vivo. These changes correlated with peptide-induced suppression of slow calcium signaling in preadipocytes.

Content of DSIP, enkephalins and ACTH in some tissues of active and hibernating ground squirrels (Citellus suslicus).

Seasonal changes in the amount of DSIP-like material have been measured in extracts from the brain of Citellus suslicus. 2. Analysis of extracts from the brain of deeply sleeping ground squirrels shows that the level of enkephalin-like material reliably increases while that of ACTH-like material decreases. 3. It is concluded that the opiate brain activation system is among the factors participating in the induction of hibernation in ground squirrels.

Electrolyte and water transport in the newt renal tubule due to the action of low-molecular fractions isolated from the intestine of the hibernating ground squirrel.

The micropuncture technique and X-ray microanalyses were used to evaluate Na, K, Ca, Mg, Cl and fluid transport in the early distal tubule mediated by low-molecular fractions isolated from the intestine of the hibernating ground squirrel (HSI). Perfusion of intertubular capillaries with a solution containing HSI with a molecular weight of 1-10 kD (0.1 mg.ml-1) decreased the relative reabsorption of fluid, Ca and Mg. The other low-molecular fraction 1-10 kD of m.v. (0.1 mg.ml-1) isolated from the intestine of alert ground squirrels (ASI 1-10) caused no significant changes of the ionic concentration and inulin concentration index in the distal tubule. Fraction 1 with molecular weight 1.2-4.5 kD (0.1 mg.ml-1) obtained by further division of HSI 1-10, decreased the reabsorption of fluid and ions under study. Fractions 2 (m.w. 0.98 kD) and 3 (m.w. 0.89 kD) had no effect on the ion and fluid transport in the same tubule. The addition of naloxone (0.4 mg.ml-1) blocked the action mediated by HSI 1-10 or fraction 1. Thus, the substance(s) capable of regulating Ca, Mg, and fluid transport in the distal tubule likely to be mediated by the opiate-dependent process has a molecular weight of 1.2-4.5 kD.

Cold adaptation modulates Ca2+ signaling in brown preadipocytes.

One-week cold exposure of mice led to a 2-fold increase in the density of alpha1-adrenoceptors in brown adipose tissue. The density of alpha1-adrenoceptors returned to normal after adaptation to cold for 2 weeks. The reduced Ca2+ signaling in stem cells of brown fat activated via beta-adrenoceptors and cAMP was transformed into the Ca2+-system induced by alpha1-adrenoceptors and similar to that in mature brown adipocytes.

Hypometabolic and hypothermic factors from small intestine of hibernating ground squirrels (Citellus undulatus).

Low molecular mass components of the acetic acid extract from the small intestine of hibernating ground squirrels (Citellus undulatus) produced a decrease in oxygen consumption and body temperature of white mice and a dose-dependent delay in embryonic development of sea urchin (Strongylocentrotus intermedius). Equivalent doses of low molecular mass components obtained by the same method from active (summer) animals did not have such an effect.