scholarly journals A thermoregulatory role of the medullary raphe in birds

2021 ◽  
pp. jeb.234344
Author(s):  
Caroline Cristina-Silva ◽  
Luciane H. Gargaglioni ◽  
Kênia Cardoso Bícego
Keyword(s):  
Body Temperature ◽  
Heat Loss ◽  
Neural Mechanism ◽  
Medullary Raphe ◽  
Defence Responses ◽  
Loss Index ◽  
Higher Doses ◽  
Heat Loss Index ◽  
Shivering Thermogenesis

The brainstem region medullary raphe modulates non-shivering and shivering thermogenesis and cutaneous vasomotion in rodents. Whether the same scenario occurs in the other endothermic group, i.e. birds, is still unknown. Therefore, we hypothesised that the medullary raphe modulates heat gain and loss thermoeffectors in birds. We investigated the effect of glutamatergic and GABAergic inhibitions in this specific region on body temperature (Tb), oxygen consumption (thermogenesis), ventilation (O2 supply in cold, thermal tachypnea in heat) and heat loss index (cutaneous vasomotion) in one-week-old chicken exposed to neutral (31°C), cold (26°C) and heat (36°C) conditions. Intra-medullary raphe antagonism of NMDA glutamate (AP5; 0.5, 5 mM) and GABAA (bicuculline; 0.05, 0.5 mM) receptors reduced Tb of chicks at 31°C and 26oC, due mainly to an O2 consumption decrease. AP5 transiently increased breathing frequency during cold exposure. At 31°C, heat loss index was higher in the bicuculline and AP5 groups (higher doses) than vehicle at the beginning of the Tb reduction. No treatment affected any variable tested at 36oC. The results suggest that glutamatergic and GABAergic excitatory influences on the medullary raphe of chicks modulate thermogenesis and glutamatergic stimulation prevents tachypnea, without having any role in warmth-defence responses. A double excitation influence on the medullary raphe may provide a protective neural mechanism for supporting thermogenesis during early life, when energy expenditure to support growth and homeothermy is high. This novel demonstration of a thermoregulatory role for the raphe in birds suggests a convergent brainstem neurochemical regulation of body temperature in endotherms.

MAINTENANCE OF BODY TEMPERATURE OF RESTRAINED ADRENALECTOMIZED RATS EXPOSED TO COLD: EFFECT OF ADRENAL CORTICAL HORMONES

1956 ◽  
Vol 34 (4) ◽  
pp. 721-729
Author(s):  
P. F. Iampietro ◽  
M. J. Fregly ◽  
E. R. Buskirk
Keyword(s):  
Body Temperature ◽  
Cooling Rate ◽  
Adrenal Glands ◽  
Cold Effect ◽  
Desoxycorticosterone Acetate ◽  
Pass Through ◽  
Colonic Temperature ◽  
Higher Doses ◽  
Adrenalectomized Rats

Experiments were performed to determine the role of the adrenal glands in the maintenance of colonic temperature of rats which were restrained and exposed to air at 5 °C. Colonic temperature decreased linearly with time in the cold air; hence, colonic cooling rate (CCR) was adopted as a measure of response to cold. Bilateral adrenalectomy increased CCR. Administration of cortisone acetate, adrenal cortical extract (ACE) or desoxycorticosterone acetate to adrenalectomized rats decreased CCR. Maximal decrease occurred with administration of 1.00 mgm. cortisone/rat/day or 0.25 ml. ACE/rat/day; higher doses of each hormone were less and less effective in returning CCR toward that of sham-operated rats. An adrenalectomized rat could not be rendered normal with respect to CCR no matter what dose of either ACE or cortisone was administered. In contrast, only the highest dose of DOCA administered (4.0 mgm./rat/day) significantly reduced CCR to that of sham-operated rats. The cooling test is similar to the standard growth test in that the response to administration of cortisone and ACE passes through a maximum and then declines with increasing dosage. The lower colonic temperature of adrenalectomized rats in air at 25 °C. was returned to that of sham-operated rats when cortisone (1.00 mgm. or more) or ACE (0.25 ml. or more) was administered; however, colonic temperature did not appear either to increase incrementally or to pass through a maximum with increasing doses of either hormone. DOCA had no effect on initial colonic temperature. Untreated adrenalectomized rats rarely survived lowering of colonic temperature to 22.5 °C; hence, the minimum colonic temperature to which adrenalectomized rats can be cooled and subsequently survive is considerably above that for normal rats (LD50 15.3 °C). Administration of any of the above hormones increased survival even in those doses which did not affect CCR.

scholarly journals 14-3-3ζ mediates an alternative, non-thermogenic mechanism to reduce heat loss and improve cold tolerance

2019 ◽  
Author(s):  
Kadidia Diallo ◽  
Sylvie Dussault ◽  
Christophe Noll ◽  
Angel F. Lopez ◽  
Alain Rivard ◽  
...  
Keyword(s):  
Body Temperature ◽  
Energy Expenditure ◽  
Heat Loss ◽  
Cold Exposure ◽  
Thermal Conductance ◽  
Body Temperatures ◽  
Molecular Scaffold ◽  
Over Expression ◽  
Reduce Heat Loss

SummaryFollowing prolonged cold exposure, adaptive thermogenic pathways are activated to maintain homeothermy, and elevations in body temperature are generally associated with UCP1-dependent and -independent increases in energy expenditure. One of the earliest, identified functions of the molecular scaffold, 14-3-3ζ, was its role in the synthesis of norepinephrine, a key endogenous factor that stimulates thermogenesis. This suggests that 14-3-3ζ may have critical roles in cold-induced thermogenesis. Herein, we report that transgenic over-expression of TAP-14-3-3ζ in mice significantly improved tolerance to prolonged cold. When compared to wildtype controls, TAP mice displayed significantly elevated body temperatures and paradoxical decreases in energy expenditure. No changes in β-adrenergic sensitivity or oxidative metabolism were observed; instead, 14-3-3ζ over-expression significantly decreased thermal conductance via increased peripheral vasoconstriction. These findings suggest 14-3-3ζ mediates alternative, non-thermogenic mechanisms to mitigate heat loss for homeothermy. Our results point to an unexpected role of 14-3-3ζ in the regulation of body temperature.Graphical abstract

MAINTENANCE OF BODY TEMPERATURE OF RESTRAINED ADRENALECTOMIZED RATS EXPOSED TO COLD: EFFECT OF ADRENAL CORTICAL HORMONES

1956 ◽  
Vol 34 (1) ◽  
pp. 721-729 ◽  
Author(s):  
P. F. Iampietro ◽  
M. J. Fregly ◽  
E. R. Buskirk
Keyword(s):  
Body Temperature ◽  
Cooling Rate ◽  
Adrenal Glands ◽  
Cold Effect ◽  
Desoxycorticosterone Acetate ◽  
Pass Through ◽  
Colonic Temperature ◽  
Higher Doses ◽  
Adrenalectomized Rats

Experiments were performed to determine the role of the adrenal glands in the maintenance of colonic temperature of rats which were restrained and exposed to air at 5 °C. Colonic temperature decreased linearly with time in the cold air; hence, colonic cooling rate (CCR) was adopted as a measure of response to cold. Bilateral adrenalectomy increased CCR. Administration of cortisone acetate, adrenal cortical extract (ACE) or desoxycorticosterone acetate to adrenalectomized rats decreased CCR. Maximal decrease occurred with administration of 1.00 mgm. cortisone/rat/day or 0.25 ml. ACE/rat/day; higher doses of each hormone were less and less effective in returning CCR toward that of sham-operated rats. An adrenalectomized rat could not be rendered normal with respect to CCR no matter what dose of either ACE or cortisone was administered. In contrast, only the highest dose of DOCA administered (4.0 mgm./rat/day) significantly reduced CCR to that of sham-operated rats. The cooling test is similar to the standard growth test in that the response to administration of cortisone and ACE passes through a maximum and then declines with increasing dosage. The lower colonic temperature of adrenalectomized rats in air at 25 °C. was returned to that of sham-operated rats when cortisone (1.00 mgm. or more) or ACE (0.25 ml. or more) was administered; however, colonic temperature did not appear either to increase incrementally or to pass through a maximum with increasing doses of either hormone. DOCA had no effect on initial colonic temperature. Untreated adrenalectomized rats rarely survived lowering of colonic temperature to 22.5 °C; hence, the minimum colonic temperature to which adrenalectomized rats can be cooled and subsequently survive is considerably above that for normal rats (LD50 15.3 °C). Administration of any of the above hormones increased survival even in those doses which did not affect CCR.

scholarly journals Combined stimuli of cold, hypoxia, and dehydration status on body temperature in rats: a pilot study with practical implications for humans

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Tadashi Uno ◽  
Tatsuya Hasegawa ◽  
Masahiro Horiuchi
Keyword(s):  
Body Temperature ◽  
Environmental Conditions ◽  
Multiple Stressors ◽  
Core Body Temperature ◽  
Area Under The Curve ◽  
Ambient Temperatures ◽  
Hypoxic Conditions ◽  
Loss Index ◽  
Core Body ◽  
Heat Loss Index

Abstract Objective As human thermoregulatory responses to maintain core body temperature (Tcore) under multiple stressors such as cold, hypoxia, and dehydration (e.g., exposure to high-altitude) are varied, the combined effects of cold, hypoxia, and dehydration status on Tcore in rats were investigated. The following environmental conditions were constructed: (1) thermoneutral (24 °C) or cold (10 °C), (2) normoxia (21% O2) or hypoxia (12% O2), and (3) euhydration or dehydration (48 h water deprivation), resulted in eight environmental conditions [2 ambient temperatures (Ta) × 2 oxygen levels × 2 hydration statuses)]. Each condition lasted for 24 h. Results Normoxic conditions irrespective of hypoxia or dehydration did not strongly decrease the area under the curve (AUC) in Tcore during the 24 period, whereas, hypoxic conditions caused greater decreases in the AUC in Tcore, which was accentuated with cold and dehydration (Ta × O2 × hydration, P = 0.040 by three-way ANOVA). In contrast, multiple stressors (Ta × O2 × hydration or Ta × O2 or O2 × hydration or Ta × hydration) did not affect locomotor activity counts (all P > 0.05), but a significant simple main effect for O2 and Ta was observed (P < 0.001). Heat loss index was not affected by all environmental conditions (all P > 0.05). In conclusion, decreases in Tcore were most affected by multiple environmental stressors such as cold, hypoxia, and dehydration.

FEEDBACK CONTROL OF FSH IN THE MALE: ROLE OF OESTROGEN

1973 ◽  
Vol 74 (3) ◽  
pp. 449-460 ◽  
Author(s):  
Patrick C. Walsh ◽  
Ronald S. Swerdloff ◽  
William D. Odell
Keyword(s):  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Oestrogen Therapy ◽  
Serum Concentrations ◽  
Elderly Men ◽  
Normal Range ◽  
Oestrogen Treatment ◽  
Serum Lh ◽  
Higher Doses

ABSTRACT Serum follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured by radioimmunoassay in a group of elderly men following castration and oestrogen therapy. Prior to orchiectomy, mean serum concentrations of LH and FSH were within the normal range. Two days following castration, serum LH concentrations increased in all eight patients; higher levels of LH were subsequently measured in all but one patient after periods of time ranging from 49 to 210 days. Serum FSH levels, measured in three patients following castration, increased in a pattern parallel to LH changes. Ethinyl oestradiol (EOe) in doses ranging from 5 to 300 μg/day was administered to ten men who had been castrated 3 to 72 months earlier. Oestrogen treatment suppressed both LH and FSH in a parellel manner in nine of ten patients. LH was first suppressed to intact levels in one of eight patients treated with 20 μg/day of EOe, in two of six patients treated with 50 μg/day, and in one patient by 80 μg/day. FSH was not suppressed to precastration levels until 50 μg/day of EOe was administered; this dose suppressed three of six patients. Higher doses of EOe (150–300 μg/day) suppressed both LH and FSH to levels below the sensitivity of the assay. These data fail to demonstrate any differential effect of oestrogen on LH and FSH release.

Comparison of the effect of isopropyl alcohol and chlorhexidine solution rinses on body temperature of female cats undergoing sterilization surgery

2021 ◽  
pp. 1098612X2097956
Author(s):  
Rachael E Kreisler ◽  
Michelle L Douglas ◽  
Karissa N Harder
Keyword(s):  
Body Temperature ◽  
Heat Loss ◽  
Isopropyl Alcohol ◽  
Body Condition Score ◽  
High Volume ◽  
Veterinary Students ◽  
Reversal Agents ◽  
Duration Of Surgery ◽  
Chlorhexidine Solution ◽  
Recovery Temperature

Objectives Isopropyl alcohol 70% as a rinse agent for chlorhexidine scrub has been shown to decrease body temperature more quickly than chlorhexidine solution in mice prepared aseptically prior to surgery. For this reason, some high-quality, high-volume (HQHV) surgical sterilization clinics use chlorhexidine solution rather than alcohol. We sought to determine if temperature upon entry to recovery, heat loss per kg and rate of temperature decline during surgery were different between cats rinsed with chlorhexidine solution vs 70% isopropyl alcohol following surgical scrub, and if there were significant predictors of recovery temperature. Methods Female cats admitted for surgery to trap–neuter–return (TNR) clinics at a veterinary college were assigned chlorhexidine solution or alcohol rinse agents via block randomization. Veterinary students and veterinarians performed spay surgeries using HQHV techniques. In recovery, heat support and reversal agents were available for cats with a low body temperature or that were slow to recover. Baseline values, outcome variables and duration of each stage (preparation, surgery, recovery) were assessed using Wilcoxon rank-sum and t-tests. Recovery temperature was evaluated using random effects multiple linear regression. Results The recovery temperature, heat loss per kg, heat loss per min, need for reversal and need for heat support in recovery were not significantly different between rinse groups. Weight <2.3 kg, body condition score <4, duration of surgery and postinduction temperature were predictors of recovery temperature. The rate of heat loss in the first 30 mins of surgery was slightly lower for cats in the alcohol rinse group and the recovery duration was shorter for cats weighing less <2.3 kg in the alcohol rinse group. Conclusions and relevance There were no clinically meaningful differences in body temperature between chlorhexidine and alcohol rinses. Both chlorhexidine solution and isopropyl alcohol 70% are appropriate rinse agents for aseptic preparation of feline spay surgeries.

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