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At least 1,225 records · Page 68Linked to original sources
PubMed1987

Relationship between body and testis temperatures in the European hedgehog, Erinaceus europaeus, during hibernation and sexual reactivation.

Simultaneous telemetry of the body and testis temperatures of 8 hedgehogs was carried out during hibernation and during sexual reactivation in spring. Between October and January, when the testes were involuted, the body/testis temperature differential was variable, with mean daily testis temperatures up to 1 degrees C warmer than body temperatures. From mid-February onwards, when plasma testosterone approached maximal concentrations, mean testicular temperatures stabilized 1.4 +/- 0.2 degrees C below body temperatures. During spermatogenesis testicular temperature of hedgehogs was significantly lower than body temperature. Over the euthermic body temperature range of 34.7-36.2 degrees C, testicular temperatures varied from 34.0 to 34.9 degrees C. Only at body temperatures over 36.2 degrees C did testicular temperature reach 35 degrees C. During spermatogenesis hedgehog testis temperatures are similar to those of many scrotal mammals.

Animals↗
PubMed1993

Stability of the sperm plasma membrane of hibernating bats (Myotis velifer) compared with other mammals.

Previous experiments have established that the long-lived spermatozoa of hibernating bats are resistant to the acrosome reaction and fertilization in vitro conventional techniques. We tested the hypothesis that the membranes of these spermatozoa are more resistant to perturbation than those of other mammals. We exposed them to non-specific bilayer destabilizing agents and abrupt changes in incubation temperature and tested their response by observing their status (motility and viability) after a time interval compared with other mammals (golden hamster, rabbit, human). The results did not support the hypothesis. The inherent longevity of bat spermatozoa may thus be a function of some component other than unique resilience of their plasma membrane.

Animals↗
PubMed2003

Endocrine control of the reproductive activity in hibernating bats.

Bats, Chiroptera, constitute the second largest order of the class Mammalia and vary greatly in habitats, available foods and mating systems. The timing, duration and patterns of reproduction in bats vary considerably among species and different localities. Though much is known about the reproductive phenomena and associated endocrine characteristics of various species, the central mechanism regulating the peculiar delay and asynchrony in reproductive activity remains to be elucidated. The current understanding on the endocrine characteristics and possible mechanism of regulation of the hypothalamo-adenohypophysial-gonadal axis of bats will be reviewed, based mainly on our own studies in hibernating rhinolophid bats.

Animals↗
PubMed2001

Sulfurtransferase activity and sulfur compound content in Rana temporaria brain following hibernation.

The activity of rhodanese, 3-mercaptopyruvate sulfurtransferase and gamma-cystathionase and the content of glutathione and sulfane sulfur compounds were determined in Rana temporaria brain in April. The high sulfane sulfur level observed in the spring seems to be associated with protection against cellular oxidative stress after the period of hibernation with its minimal oxidative metabolism.

Animals↗
PubMed1991

Weights and hematology of wild black bears during hibernation.

We compared weights and hematological profiles of adult (greater than 3-yr-old) female black bears (Ursus americanus) during hibernation (after 8 January). We handled 28 bears one to four times (total of 47) over 4 yr of varying mast and berry production. Mean weight of lactating bears was greater (P less than 0.0001) than that of non-lactating females. White blood cells (P less than 0.05) and mean corpuscular volume (P = 0.005) also differed between lactating and non-lactating bears. Hemoglobin (P = 0.006) and mean corpuscular hemoglobin concentration (P = 0.02) varied among years; values were lowest during 1975, following decreased precipitation and the occurrence of a second year of mast and berry crop shortages in a three-year period. Significant (P less than 0.05) interaction between reproductive status (lactating versus non-lactating) and study year for hemoglobin, red blood cells, and packed cell volume, and increased mean corpuscular volume, suggested a greater nutritional challenge for lactating females compared to non-lactating females during the 1975 denning season. Our data suggest that hematological characteristics of denning bears may be more sensitive than weights as indicators of annual changes in nutritional status; however, other influential factors, in addition to mast and berry crop production, remain to be examined.

Age Factors↗
PubMed1996

[The fine structure of the gustatory cells of the circumvallate, foliate and fungiform papillae in hibernating bats].

The cells of vallate, foliate and fungiform papillae were studied in insectivore hibernating bats (Pipistrellus pipistrellus and Rhinolophus ferrumequinum) in the various epochs of the year in order to show cell types the seasonal changes. On the basis of the ultrastructural aspects and the relationships with nerve endings, besides the few basal cells, three types of sensorial cells can be identified: dark type I cells, light type II cells and light type III cells. All gustatory cells, long and narrow shaped, extend from the epithelial basal lamina to the gustatory canal, where they send long microvillous expansions of the apical cytoplasm. These expansions, except those of the fungiform papillae which never extend beyond the lower two thirds, usually reach the external opening of the taste pore, always completely void of dense substance. Dark type I cells are characterized by a developed RER and large granules. Light type III cells show peculiar dense core light vesicles, labelled protein A-gold particles immunoreactive to 5-HT. These cells only in the foliate and fungiform papillae also have bundles of microtubules whose function is still unknown. After comparative evaluation and discussion of topographical and ultrastructural aspects with those of other mammals and humans, the Authors states that bats are provided with a valid gustatory system and that all cell types are involved in taste transduction.

Animals↗
PubMed1979

[Ribosomal crystallization and hibernation in a viviparous lizard].

Part of the ribosomes crystallize in the ovarian follicles during hibernation. The association between ribosomes crystals and endoplasmic reticulum membranes depends on the cell types of the follicle. The cytoplasm of oocytes with a nucleolus shows ribosome crystals. In larger oocytes, without nucleolus, there is no ribosome crystallization. The ribosomes which crystallize would be newly synthesized.

Animals↗
PubMed1975

The hypothalamo-hypophysial system in the ground squirrels, Citellus erythrogenys Brandt and Citellus undulatus Pallas. I. Microanatomy and cytomorphology of the gomori-positive neurosecretory system with special reference to its state during hibernation.

Microanatomy of the peptidergic hypothalamo-hypophysial neurosecretory system in the ground squirrels, C. erythrogenys and C. undulatus, is similar to that of other rodents, but differs in details. Bundles of neurosecretory fibres with single neurosecretory cells along their course connect the hypothalamic neurosecretory centers into the one system. The dorso-caudal portions of the NPV reach the level of the columna fornix. The NPO is a special indepedent formation and appears to have some specific functions in the HHNS. The infundibular recess penetrates deeply ihto the hypophysial stem, but does not reach the posterior pituitary. The glandular epithelium of the tuberal portions of the adenohypophysis surrounds the median eminence and a considerable part of the lateral surface of the tuber cinereum. Different functional types of neurosecretory cells reflect certain phases of their secretory cycle. Correlations between their size, structure and the content of NSM are found. A low activity of the HHNS is observed in both C. erythrogenys and C. undulatus during December-January. A higher activity of the HHNS in torpid C. undulatus than in C. erythrogenys is established. This correlates with a difference in deepness of torpor in C. erythrogenys and C. undulatus. An important role of the HHNS in hibernation, i.e. in realization of adaption of species in ontogenesis is suggested.

Adaptation, Physiological↗
PubMedDate not supplied

[Phosphorylation of sarcomeric cytoskeletal proteins--an adaptive factor for inhibiting the contractile activity of muscle during hibernation].

The influence of phosphorylation in vitro of the sarcomere cytoskeletal proteins titin and X-protein of skeletal muscles as well as C-protein of cardiac muscle of ground squirrel Citellus undulatus on the actin-activated ATPase activity of myosin and its Ca2+ sensitivity was studied. It was shown that phosphorylation lowers the activating effect of titin and C-protein and increases the inhibitory effect of X-protein on the enzymatic properties of actomyosin. The phosphorylation of the proteins has the most pronounced influence on Ca2+ sensitivity of actomyosin: it drops to a greater extent in the presence of phosphorylated C-protein and titin and is completely inhibited by phosphorylated X-protein. The inhibitory influence of phosphorylation in vitro of sarcomere cytoskeletal proteins on the above functional properties of the actomyosin system as well as the increase in the extent of phosphorylation of titin in vivo upon hibernation allow one to conclude that this posttranslation modification contributes to adaptive mechanisms of suppression of the contractile ability of muscles in this period.

Animals↗
PubMedDate not supplied

Comparative anatomical and ultrastructural features of the sensory papillae in the tongue of hibernating bats.

The papillae of the tongue dorsal surface of the insectivorous, hibernating bats (Vespertilionidae and Rhinolophidae), whose function is mainly sensorial, consist of two circumvallate papillae, two foliate papillae, located at the side edges at the glossopalatine arch, and numerous fungiform papillae. The circumvallate and foliate papillae are characterized not only by their position, but also by presence of several taste buds which open through the external orifice of the gustatory canal into the cavity of the vallum, or furrow, which divides the two folds of the lingual mucosa. The fungiform papillae (extremely numerous on the whole dorsal surface) are characterized by an unusual arrangement (along 3 oblique lines on the anterior two-thirds and predominantly on the middle line of the tongue body) and by the presence of only one to three taste buds which open on the heavily keratinized dorsal epithelial surface. The taste buds are made up of sensory cells with a light or dark matrix; their apical cytoplasmic expansions are not found beyond the middle part of the gustatory canal, in contrast with the circumvallate and foliate papillae which protrude from the orifice of the gustatory pore. Comparisons with the papillae of other types of bats and Insectivora and evaluations of the morphological characteristics and their functional values (unusual areas of distribution of the papillae, apical cytoplasmic expansions and behaviour of microfolds observed under SEM) have been made in different environmental conditions and nutritional habits, with attention to the mechanical events in the course of feeding.

Animals↗
PubMed1975

[Plasma Ca, Na, and K levels during the hibernation of hedgehogs, common dormice, and garden dormice].

The plasmatic rate of Ca, Na and K are nearly constant during the deep lethargy of hedgehogs, common dormice and garden dormice and little differ from those measured in the active animals at 22 degrees C. Only the kaliemies of the hibernating common dormice and garden dormice are very low. The evolution of the three parameters during the alternance lethargy and periodic arousal has been analysed in terms of the metabolic and endocrinian changes which occur at those moments.

Adrenal Glands↗
PubMed1992

[The vagotropic action of peptides isolated from the brain of hibernating susliks].

Dipeptide ASP-TYR extracted from the brain of hibernating squirrels was found to potentiate vagal effect on the cardiac rhythm, whereas pentapeptide neokyotorphin--to diminish it. In both cases the effect was due to an alteration of the tonic component's strength in the vagal chronotropic effect. The selective peptidergic modulation of the vagal effect on the cardiac rhythm suggests different physiological roles of the tonic and synchronizing components in regulation of the heart.

Animals↗
PubMed1998

[Ischemic preconditioning of the heart can be simulated by pharmacologic hibernation enkephalins].

The protective effects of ischemic preconditioning on the myocardium can be abolished by pretreatment with opioid receptor antagonists. We investigated, if--vice versa--the protective effect of preconditioning may be induced by systemic pretreatment with the delta-opioid receptor agonist D-Ala2-DLeu5-enkephalin (DADLE). DADLE is known to be very similar to the trigger substance that induces natural hibernation. Isolated working rat hearts of male Wistar rats (n = 32) were subjected to 45 minutes of global hypothermic ischemia at 30 degrees C followed by 25 minutes of normothermic reperfusion. Hearts from rats injected with 1 mg/kg DADLE intravenously 1 hour before isolated perfusion were either preconditioned by one cycle of 5 minutes of normothermic ischemia followed by 5 minutes of normothermic reperfusion or hearts were not preconditioned during preischemic perfusion. Untreated preconditioned and non-preconditioned hearts served as controls. Ischemic preconditioning alone and DADLE alone improved the recovery of aortic flow and reduced the creatine kinase leakage significantly during postischemic reperfusion. Over and above that, pretreatment with DADLE prior to ischemic preconditioning significantly further enhanced functional recovery and reduced the creatine kinase leakage, when compared to DADLE alone and preconditioning alone. Therefore we conclude, that DADLE attenuates ischemic injury in isolated rat hearts and enhances the protective effects of ischemic preconditioning. The data suggest that ischemic preconditioning and DADLE act via a similar pathway.

Animals↗
PubMed1978

[Lethargic hypothermia induced by a protein free diet in a hibernating rodent, the dormouse (Eliomys quercinus L.)].

In garden dormouse protein deficiency leads to reversible hypothermic torpor, comparable with that provoked by starvation or occuring naturally during hibernation, whether the diet consists wholly of apples or of synthetic protein-free food. Torpor induced by protein deficiency occurs even though the energy requirements of the animal are amply satisfied. These phases of lethargy occur after a certain delay and with a variable frequency, both of which vary with the ambient temperature.

Animals↗
PubMed2006

[Low-molecular peptides from tissues of hibernating and cold-adapted animals influence cell proliferation in the Ehrlich ascitic carcinoma].

Polypeptides with cytostatic activity are known to be present in animal tissues during winter dormancy. A 1-10 kDa polypeptide fraction with cytostatic activity was obtained from brain tissue of hibernating ground squirrels and cold-adapted Yakut horses. The pattern of cytostatic activity of this fraction towards tumor cells is of great interest. We present results testifying to cytostatic activity of this fraction towards the Ehrlich ascitic carcinoma cells. The cytostatic effect is realized in tumor cells at the genetic level.

Adaptation, Physiological↗
PubMedDate not supplied

[Changes in thermoregulation, sleep and the thyroid hormone concentration of the blood in the "critical" period of the entry into hibernation of the suslik Citellus parryi].

During the first entering into hibernation in the ground squirrels there are periodic cessations of the process, especially during the transition to moderate and deep torpidity ("critical" periods) which significantly increase energy expenditure in animals during the phase of entering. During this period, high amplitude near-the-hour fluctuations are observed in total duration of wakefulness and sleep, contractile muscle activity, oxygen consumption, heart rate, brain temperature, and thyroid hormone concentration in the blood; at the end of this period, as well as during the exiting from it the duration of deep slow wave sleep significantly increases, paradoxical sleep is not identified. The data obtained confirm a hypothesis of "kindling" homeostasis as neuro-hormonal mechanism of the increase in thermal range of the activity of functional systems of the organism during the entering into torpidity in homoiothermic animals.

Animals↗
PubMedDate not supplied

[Features of the interconversion of alpha-ketoglutarate--glutamate in brain mitochondria of exothermic animals during hibernation].

It has been found that there exists a correlation in the dynamics of changes in the amount of glutamate, alpha-ketoglutarate, glutamine, ammonia and activity level or alpha-ketoglutarate dehydrogenase, NADP-glutamate dehydrogenase, glutamine synthetase and glutaminase in the brain of young carp in the process of winter starvation. It has been stated that under condition of energy deficiency and meaningful amount of ammonia in the organism of hibernating fish, its binding parallel with the known glutamine synthetase mechanism may proceed in the course of the NADP-glutamate dehydrogenase reaction which balance is shifted towards the glutamate synthesis. This reaction is supposed to provide the outflow of alpha-ketoglutarate from the citric cycle, which intensifies energy deficiency of the organism.

Ammonia↗