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PubMed1996

Induction of proteins in response to cold acclimation of rainbow trout cells.

The in vitro translation of poly(A)-RNA isolated from control and cold-treated cells showed that low temperatures induced changes in the population of translatable mRNAs. When cellular proteins extracted from cold-treated cells were subjected to two-dimensional gel electrophoresis, the 70 kDa protein was found to be synthesized during the cold treatment. N-terminal sequence analysis showed that the 70 kDa cold-inducible protein was a homolog of the mammalian valosin-containing protein and yeast CDC48p. The changes in mRNA and protein contents during cold acclimation may result from the expression of genes involved in the adjustment of cellular metabolism to low temperature or the induced proteins may be directly involved in the cold acclimation.

Acclimatization↗
PubMed1984

Cortisol and its effects on plasma thyroid hormone and electrolyte concentrations in fresh water and during seawater acclimation in yearling coho salmon, Oncorhynchus kisutch.

Plasma cortisol, thyroxine (T4), and triiodothyronine (T3) concentrations increased during seawater (SW) acclimation in yearling coho salmon, Oncorhynchus kisutch. Maximal concentrations of cortisol (220 ng/ml) occurred within 1.5 hr after the ambient water was changed from fresh water (FW) to SW; after 21 days in SW, cortisol levels were still slightly elevated (23 ng/ml) compared to those in FW fish (8 ng/ml). Plasma T4 concentrations peaked (14 ng/ml) at 12 and 72 hr after exposure to SW, and they were higher than those in FW fish (4 ng/ml) at all samples times. Maximal concentrations of T3 (8 ng/ml) occurred within 12 hr after exposure to SW, followed by a return to FW control levels (4 ng/ml) within 24 hr. Chronic treatment with cortisol significantly lowered plasma T3 concentrations in FW and during SW exposure, but it had no significant effect on T4 concentrations. Cortisol treatment lowered gill Na-K-ATPase activity in FW fish, but it did not affect plasma osmolarity, Na, K, Ca, or Mg in fish in FW or during SW acclimation.

Adaptation, Physiological↗
PubMed1985

Catecholamine effects on blood pressure and heart rate in warm- and cold-acclimated American bullfrogs (Rana catesbeiana).

The effects of epinephrine (E), norepinephrine (NE), phenylephrine (PHE), and isoproterenol (ISO) were studied in vivo on the blood pressure and heart rate of the conscious American bullfrog, Rana catesbeiana. Bullfrogs were chronically cannulated with a T cannula in the right sciatic artery. In warm-acclimated (22 degrees, W-A) bullfrogs, baseline mean systemic arterial blood pressure (SAP) prior to catecholamine infusion was 16.8 +/- 1.1 mm Hg and mean preinfusion heart rate (HR) was 36.4 +/- 2.1 beats per min. In contrast, cold-acclimated bullfrogs (5 degrees, C-A) had baseline SAP values of 7.4 +/- 0.7 mm Hg and HR values of 6.9 +/- 0.3 beats per min. W-A bullfrogs infused with ISO (0.03 to 30 micrograms/kg body wt) demonstrated a dose-related increase in HR, while the HR of C-A bullfrogs did not respond to any tested dose of ISO. ISO administered to W-A bullfrogs exposed to 5 degrees for 60 min produced no significant HR increase. When the animals were returned to 22 degrees, the HR response to ISO was restored. ISO did not affect SAP in either group. E, NE, and PHE increased SAP in both W-A and C-A bullfrogs, with E the most effective. All three catecholamines affected the SAP of C-A animals less than the W-A group. In W-A bullfrogs, E, NE, and PHE decreased HR, while no effect on HR was observed in the C-A group.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1987

Interrenal secretion of corticosteroids and plasma cortisol and cortisone concentrations after acute stress and during seawater acclimation in juvenile coho salmon (Oncorhynchus kisutch).

We determined the major corticosteroids secreted by interrenal tissue and those present in plasma of juvenile coho salmon (Oncorhynchus kisutch). Incubation medium of interrenal tissue, unstimulated or stimulated with exogenous ACTH in vitro, and plasma of resting or acutely stressed salmon were extracted and qualitatively analyzed for steroid composition using high-performance liquid chromatography. Concentrations of plasma cortisone and cortisol following an acute handling stress or exposure to seawater were quantitatively measured by radioimmunoassay (RIA). Cortisol was the only corticosteroid detected by HPLC in media after incubation of interrenal tissue in the absence or presence of ACTH in vitro. However, both cortisone and cortisol were detected by HPLC in plasma sampled 1 hr after fish were acutely stressed by handling. Stress and seawater acclimation produced marked elevations in plasma levels of both steroids as determined by RIA and also resulted in long-lasting changes in the plasma cortisone:cortisol ratios. In resting fish, cortisone concentrations were similar or higher than cortisol levels. We concluded that cortisol is the primary steroid secreted by the interrenal tissue of coho salmon, and that plasma cortisone arises primarily from the peripheral conversion of cortisol to cortisone. The relatively high levels of cortisone in resting fish and its increase following stress and seawater acclimation suggest the possibility of a biologically significant role for this hormone.

Acclimatization↗
PubMed1986

Effect of diet and temperature acclimation on thermoregulatory behaviour in piglets.

Piglets were weaned at 14 days and acclimated to 10 or 35 degrees C and kept either on a low or a high plant of nutrition. After 2 and 3 weeks of acclimation their operant thermoregulatory behaviour was observed at 15 degrees C. The pigs which had been living at 10 degrees C obtained more radiant heat than those from 35 degrees C and the animals on a low energy intake obtained more reinforcements than those on a high intake. There was no interaction between temperature and diet indicating that these two variables exerted their influence independently. Pigs tested 22 hr after a meal obtained more heat than when tested 1 hr after a meal. Rectal temperature before the test was significantly lower in the animals reared at 10 than at 35 degrees C, but the difference had disappeared at the end of the trial. By contrast, the pigs kept on different planes of nutrition had the same rectal temperatures before the test trial but afterwards the animals on a high diet had higher rectal temperatures. Body temperatures seemed to be the factor which influenced the demand for heat. The role of thermal comfort, body size, diet induced thermogenesis and separate sets of controls for autonomic and behavioural thermoregulatory responses in operant thermoregulatory behaviour is discussed.

Acclimatization↗
PubMed1994

Day-night changes of body temperature and feeding activity in heat-acclimated rats.

Male Wistar rats were divided into two groups. The controls (CN) were kept at a constant ambient temperature (Ta) of 24 degrees C throughout the experiment. Heat-acclimated rats (HA) were subjected to Ta of 33 degrees C in the last half of the dark phase for 16 consecutive days. After the schedule was terminated, hypothalamic temperature (Thy), oxygen consumption (VO2), heat loss, and feeding activity were measured for the following 2 days at Ta of 24 degrees C with a direct calorimeter in constant darkness. Hypothalamic temperature, VO2, and heat loss of the HA were significantly lower than those of the CN for 3-4 h during the period when the rats had been previously exposed to heat. Feeding activity during the specific period was significantly less in the HA than in the CN only on the first day. Under starved conditions, the decreases of Thy and VO2 during the previous heat exposure time were consistent in the HA. The results suggest that body core temperature and feeding behavior decrease during the previous heat exposure time in rats after subjection to repeated heat exposure at a fixed time daily. The characteristic fall in body core temperature is mainly attributed to the reduction of VO2. It also seems that a decrease in postprandial thermogenesis is not a predominant contributor to the depression of VO2 during the previous heat exposure time in heat-acclimated rats.

Acclimatization↗
PubMed1994

Quantitative evaluations of gap junctions in old rat brown adipose tissue after cold acclimation: a freeze-fracture and ultra-structural study.

The morphological and functional modifications of brown adipose tissue (BAT), the tissue responsible for non-shivering thermogenesis, are well established during the phases of active stimulation (i.e. neonatal period and cold acclimation) in young animals. The 'active' brown adipocytes are filled with numerous small lipid vacuoles and large mitochondria packed with cristae rich in the protonophore uncoupling protein (UCP), whereas the 'quiescent' cell shows larger, confluent vacuoles and smaller mitochondria with rarefied cristae poor of the uncoupling protein. It is well known from literature that also gap junctions (gjs), responsible for the electrical coupling among adjacent adipocytes, modify their size following the physiological stimulus in young animals. This is in agreement with the morphology of the functionally active brown adipocyte, i.e. the multilocular, UCP-positive cell. Although the presence of the BAT in old animals is well documented, less is known about its reactivity to physiological stimuli. The present work demonstrates that after cold acclimation brown adipocytes of old rats (2 years) change their ultrastructure in a similar way as in young rats. A quantitative analysis of gap junction areas on replicas obtained by the freeze fracture technique, showed that gj increase in size (mean area 53.2 vs 110.4 x 10(-3) microns2, p = 0.003). All these morphological modifications are quite similar to those observed in BAT of young and young adult rats, supporting the hypothesis of a physiological role of brown adipose tissue at every age.

Acclimatization↗
PubMed1995

Biodegradation of toluene diamine (TDA) in activated sludge acclimated with aniline and TDA.

The biodegradability of toluene diamine (TDA) which has been regarded as a "recalcitrant compound" was examined in activated sludges. In this study, a microorganic-enzyme system which metabolized TDA was obtained by acclimating the activated sludge with aniline and TDA. In the sludge subject to be 200 days' acclimation, the considerable increase in respiration rate with the addition of TDA, accompanied the sharp decrease in its concentration. This indicated that TDA was metabolized fortuitously. The rate of biodegradation of TDA in the absence of aniline was first order with respect to its concentration when the initial TDA concentration was less than about 5 mg/l. The rate constant in this relation was proportional to mixed liquor suspended solid (MLSS). However, when the initial TDA concentration exceeded 5 mg/l, the plots were deviated from a first order rate equation.

Aniline Compounds↗
PubMed1992

The CCK-A and CCK-B receptor antagonists, devazepide and L-365,260, enhance morphine antinociception only in non-acclimated rats exposed to a novel environment.

Devazepide, a potent CCK-A receptor antagonist, and L-365,260, a selective CCK-B receptor antagonist, have been introduced as pharmacologic tools for differentiating the physiologic roles of CCK-A and CCK-B receptor subtypes. In the present study, we tested the effects of devazepide and L-365,260, on morphine antinociception in rats using the thermal sensorimotor tail flick test. Both devazepide and L-365,260 significantly enhanced the antinociceptive action of morphine, but only in rats that had not been acclimated to the laboratory environment or habituated to investigator handling. When tested with fully acclimated animals, devazepide and L-365,260 had no effect whatsoever; they neither enhanced nor attenuated morphine-induced antinociception. These observations indicate that the effects of devazepide and L-365,260, CCK antagonists, on morphine antinociception appear to be dependent on the animal's response to a new environment or to the stress induced by an unaccustomed experimental paradigm.

Adaptation, Physiological↗
PubMed1995

Central mechanism of neural activation with cold acclimation of rats using Fos immunohistochemistry.

The expression of Fos protein in the rat diencephalon, brain stem, cerebellum, and spinal cord was investigated using immunohistochemistry during chronic cold exposure, in order to clarify the neural regions involved in the thermoregulatory responses and the central mechanism of neural activation with cold acclimation. Numerous Fos-positive cells were observed in many brain regions after cold exposure and changes in the number of Fos-positive cells were analyzed quantitatively. Fos-positive regions were classified into three groups on the basis of the expression period of Fos protein. The first group was where a significant number of Fos-positive cells were seen 3 h and 24 h after cold exposure, but not observed 14 days after exposure; the regions included the lateral septal nucleus (LS), parvocellular paraventricular hypothalamic nucleus (pPVN), posterior hypothalamic area (PH), supramammillary nucleus (SuM), locus coeruleus (LC), dorsal tegmental nucleus (DTg), vestibular nucleus (Ves), and nucleus of solitary tract (Sol). The second group was where a significant number of Fos-positive cells were found 3 h, 24 h and 14 days after cold exposure; the regions included the preoptic hypothalamic area (POA), paraventricular thalamic nucleus (PV), lateral preoptic area (LPO), zona incerta (ZI), subparafascicular thalamic nucleus (SPF), lateral dorsal central grey (CGLD), lateral ventral central grey (CGLV), microcellular tegmental nucleus (MiTg), lateral lemniscus nucleus (LL), dorsal parabrachial nucleus (DPB), and the cerebellum. The third group was where Fos-positive cells were more numerous 14 days after cold exposure than they were after 3 h and 24 h of exposure; these regions included the ventromedial hypothalamic nucleus (VMH) and the spinal cord. These results demonstrate that the numbers and regions of Fos-positive cells in the rat brains changed during chronic cold exposure, and such changes may reveal the cellular adaptation of the thermogenic responsive neurons in the rat brain to cold acclimation.

Adaptation, Physiological↗
PubMed1985

Acclimation to constant and variable temperatures in plethodontid salamanders--I. Rates of oxygen consumption.

In preliminary experiments, salamanders of three species (Desmognathus ochrophaeus, Plethodon cinereus and Plethodon jordani) required 5-11 days to complete metabolic acclimation to a constant warm temperature; the rate of oxygen consumption (VO2) decreased 16-28% during acclimation. Unfed animals of each species underwent cyclic exposure to 5 and 21 degrees C at three different cycle periods (12 hr, 4-5 days, 51 days), or constant exposure to 14 degrees C for 102 days. The experimental treatments significantly affected the VO2 measured at 5, 14, 17.5 and 21 degrees C. The direction and magnitude of the acclimatory effects upon VO2 were inconsistent among species and among experimental temperatures, and resulted in little energy saving. The VO2 during exposure to cyclic temperatures averaged only 83% of that during preliminary experiments, perhaps as a response to starvation.

Acclimatization↗
PubMed1986

Enhanced contractile activity of goldfish skeletal muscle related to cold acclimation.

Dorsal muscles were isolated from goldfish acclimated to 8 degrees C and 25 degrees C, and stimulated electrically at 5-35 degrees C. Contractile activity of isolated muscle from the 8 degrees C fish was highest at 15 degrees C, whilst that of the 25 degrees C fish was independent of experimental temperature. The activity was significantly increased with cold acclimation. Pyruvate and lactate contents of red and white muscles increased with work. Addition of iodoacetic acid into the incubation medium caused a decrease of lactate production and contractile activity in muscle from the 8 degrees C fish, suggesting that the increase of the activity was partly associated with an increased activity of anaerobic glycolysis of the tissues.

Acclimatization↗
PubMed1987

Time courses of thermal acclimation for critical thermal minima in the salamanders Desmognathus quadramaculatus, Desmognathus monticola, Desmognathus ochrophaeus, and Plethodon jordani.

1. We examined the time courses of thermal acclimation for critical thermal minima (CTMin) in the salamanders Desmognathus quadramaculatus, D. monticola, D. ochrophaeus, and Plethodon jordani. 2. D. quadramaculatus showed no annual differences in their time courses, but we noted seasonal differences in the CTMin with these salamanders having lower CTMin in the spring. 3. Gain in CTMin (25 degrees C to 5 degrees C transfer) was faster than its corresponding loss (5 degrees C to 25 degrees C transfer) in D. quadramaculatus. 4. Comparison of all three Desmognathus species revealed no differences in the CTMin for the 5 degrees C to 25 degrees C time courses, but P. jordani had lower CTMin than corresponding D. quadramaculatus. 5. Our results indicate that the pattern of CTMin acclimation correlates with the constraints acting on salamanders in their natural environment.

Acclimatization↗
PubMed1987

Involvement of the sympathetic nervous system in lipolytic activity in brown adipose tissue of cold acclimated rats.

In cold acclimated rats, in vitro, NE led to a significant increase in release of FFA and glycerol in denervated IBAT. In vivo, study of arteriovenous differences showed that the denervated BAT loses its full capacity to utilize FFA and glycerol released by NE. After denervation an increase of blood flow in Sulzer's vein was observed. This effect appeared immediately after intervention whereas the effect on fat metabolism appeared later. In cold acclimated rats, the sympathetic nervous system appears to be an important regulator of fatty acid metabolism in BAT.

Acclimatization↗
PubMed1988

Thermogenic capabilities of the opossum Monodelphis domestica when warm and cold acclimated: similarities between American and Australian marsupials.

1. Monodelphis domestica is a small marsupial mammal from South America. Its thermogenic abilities in the cold were determined when the opossums were both warm (WA) and cold (CA) acclimated. Maximum heat production of M. domestica was obtained at low temperatures in helium-oxygen. 2. Basal metabolic rate (BMR) in the WA animals was 3.2 W/kg and mean body temperature was 32.6 degrees C at 30 degrees C. These values were lower than those generally reported for marsupials. Nevertheless, these M. domestica showed considerable metabolic expansibility in response to cold. Sustained (summit) metabolism was 8-9 times BMR, while peak metabolism was 11-13 times BMR. These maximum values were equal to, or above, those expected in small placentals. 3. Cold acclimation altered the thermal responses of M. domestica, particularly in warm TaS. However, summit metabolism was not significantly increased; nor did M. domestica show a significant thermogenic response to noradrenaline, which in many small placentals elicits non-shivering thermogenesis. The thermoregulatory responses of this American marsupial were, in most aspects, similar to those of Australian marsupials. This suggests that the considerable thermoregulatory abilities of marsupials are of some antiquity.

Acclimatization↗
PubMed1993

Hyperosmotic acclimation in the leech, Hirudo medicinalis L.: energy metabolism, osmotic, ionic and volume regulation.

1. Acclimation of Hirudo medicinalis L. to hyperosmotic medium (12/1000 salinity) is characterized by changes in energy metabolism. A transient succinate fermentation is followed by malate accumulation in the tissue from the control level of 41.4 +/- 7.6 to 82.8 +/- 15.4 mumol/g dry weight after 9 days. 2. Initial osmotic water loss of 40% is restored in the intravasal space by isosmotic volume regulation after 9 days, but restoration is incomplete in the tissue even after 6 weeks of acclimation. 3. Elevation of SCCA anions in the blood is a mechanism of chloride hyporegulation.

Adaptation, Physiological↗
PubMed1992

Effect of cold acclimation on the expression of glucose transporter Glut 4.

Glucose uptake by brown adipose tissue, measured following deoxyglucose injection in vivo, was increased by 6- and 11-fold following 2 and 14 days of cold exposure, respectively. To look for the possible mechanism of these modifications, the glucose transporter Glut 4 has been characterized at the protein and mRNA levels in brown adipose tissue, skeletal muscle and white adipose tissue following cold acclimation. Crude membranes were prepared from those tissues, and Glut 4 was studied by Western blot analysis. In brown adipose tissue, the total Glut 4 amount was increased by 52 +/- 7% and by 104 +/- 12% following 2 and 14 days of cold exposure, respectively. By contrast, in white adipose tissue of 14-day-cold-exposed mice the total Glut 4 content was decreased by 42 +/- 5%. However, Glut 4 concentration, expressed per mg of membrane protein, was unchanged in both brown and white adipose tissues following cold exposure, since the membrane protein content increased in brown but decreased in white adipose tissue. No modification in Glut 4 content was observed in skeletal muscle from cold-exposed mice. Total RNA were prepared and analyzed for Glut 4, glyceraldehyde phosphate dehydrogenase (GAPDH) and actin. Glut 4 and GAPDH mRNA were increased 2-fold in brown adipose tissue from cold-exposed mice, while actin mRNA content was unmodified. Glut 4 mRNA content was not changed in white adipose tissue and skeletal muscle from cold-exposed mice. Our results suggest that Glut 4 expression is differently modulated in the three insulin-responsive tissues during cold acclimation.

Acclimatization↗