Experimental Study On Sweat Gland Exposured To The Hot And Humidity Environment

Background:It plays an irreplaceable role of the sweat gland in homeostasis of body.The main function of sweat gland is to regulate temperature.The main components of sweat are water(98~99%),inorganic salts and organic matter.It is a necessary prerequisite for sustained secretion of sweat to evaporate effectively sweat.Within the increase of the relative humidity in air to a saturant status,the evaporation of sweat on body surface will be more difficult.Meanwhile the ambient temperature is increasing,it is more difficult to dissipate the body heat.Sweat secretion is an important route to reduce the core body temperature.Once the route is blocked,the core temperature would rise,which leads to the thermal damages to internal organs.Hot and humid environment usually is more 36℃ at the ambient temperature and more 60%in the relative humidity[1].Clinical datas show that the high temperature and humidity environment can lead to heat stroke,which gives rise to high fever,dry skin,emotional disorder,and even systemic seizures symptoms[2].The dry in the skin means the reduction of sweat secretion,but the reasons for the reduction are not clear,Meanwhile the mechanism of the effect of the high temperature and humidity environment on the sweat gland function is not yet clear.This study was to investigate the effect of high temperature and humidity environment on the cell function of sweat gland in the foot pad skin of Sprague-Dawley(SD)rats,and to explore its possible mechanism of funcional changes of sweat gland.Part Ⅰ Effect of high temperature and humidity environment on the rat sweat glandObjective:To study the effects of high temperature and humidity environment on cell functions of sweat gland and to explore its possible mechanism.Methods:Fourteen SD rats were randomly assigned into the normal temperature and humidity(NTH)group and high temperature and humidity(HTH)group.Seven rats in each group.HTH group were put in a little house with a high temperature and humidity ambience for 2 hours;the NTH group was in indoor conditions for 2 hours.After 72 hours,the rats was given a deep anesthesia by 1%pentobarbital sodium,then their circulate blood were collected from the abdominal aorta.The level of acetylcholine(ACH)in the blood was measured by colorimetric method.The left posterior foot skin was peel off and fixed with 10%formalin,in that the expression of acetylcholine transferase(ChAT)was detected by immunohistochemical method.The right posterior foot skin was cut off and incubated at-80℃,in which the total superoxide dismutase(SOD)activity was detected by biochemical method and the expression of M3 receptor was detected by Western Blot method.Results:Under the light microscope,there were less vacuoles at the epithelium of sweat secretion department in the test,which were more in the NTH group.And the apoptosis of the sweat cells was increased.The apoptotic index of HTH group was(70.7±14.0)%,which was significantly higher than that of NTH group(58.6 ± 14.0%),the difference was statistically significant(t = 2.478,P = 0.021).The results of Western Blot showed that the relative expression of M3 receptor in HTH group was(1.21 ± 0.16)%,which was significantly higher than that in NTH group[(1.81 ± 0· 41)%,t = 2.711,P = 0.035].The expression of acetylcholine in serum of HTH group was significantly lower than that of NTH group.And the activity of superoxide dismutase(SOD)in HTH group was(13.65±5.14)U/mg,was significantly lower than that of NTH group(T = 2.633,P = 0.023).Conclusion:The high temperature and humidity environment can cause the morphological changes of the sweat glands,and the damage to the sweat glands may be due to the decrease of the antioxidant capacity of the tissue.Part Ⅱ Study on Vitamin E Protecting Sweat Glands in Rats exposured to the high temperature and humidity environmentObjective:To investigate whether vitamin E(VE)can improve the antioxidant capacity of skin tissue after high temperature and humidity stress,thereby protecting the the sweat gland from high temperature and humidity stress.Methods:Twenty-one SD rats were randomly assigned into the normal temperature and humidity(NTH)group,high temperature and humidity(HTH)group and high temperature and humidity group intervened by VE(VHTH).Seven rats in each group.HTH group and VHTH group were put in a little house with a high temperature and humidity ambience for 2 hours.Then the HTH group was orally administered saline(lml)using feeding needles,and VE was given to the VHTH group(100IU/kg preparation with saline to lml).The NTH group was in indoor conditions for 2 hours,then administered of saline lml by gavage.After 72 hours,the rats was given a deep anesthesia by 1%pentobarbital sodium.The left posterior foot skin was peel off and fixed with 10%formalin.Tissue morphology was observed by HE staining.The expression of aspartic acid-specific cysteine protease-3(Caspase-3)and heat shock protein70(HSP70)in the foot pad skin was detected by immunohistochemistry.The right posterior foot skin was cut off and incubated at-80℃,in which the total superoxide dismutase(SOD)activity was detected by biochemical method and the expression of HSP70 was detected by Western Blot method.Results:Under the light microscope,we can observed the glandular cavity of sweat gland secretion in HTH group and VHTH group were expansed,and that in NTH group was smaller;However,in the HTH group,the epithelium was loose;the vacuoles of the epithelial cells were reduced;the nucleolus was stained.In the NTH group and the VHTH group,the glandular epithelial cells was neat,the glandular cavity were smaller than the HTH group,and the vacuoles under the nucleolus of epithelial cells were more than the HTH group,also the glandular epithelial cytoplasm were rich,and the nucleolus were deep dye.The activity of SOD in the VHTH group was(35.18±8.19)U/mg,which was significantly higher than that in the HTH group[(13.65±5.14)U/mg],which compared with the NTH group[(25.90 ±11.05)U/mg]wasn’ t significant difference.The expression of Caspase-3 and HSP70 by immunohistochemical method showed that the expression in VHTH group was significantly higher than that in HTH group,and there was not significant difference with NTH group.Western blot was used to detect the expression of HSP70,and the results were consistent with the immunohistochemistry.Conclusion:VE can improve the redox imbalance caused by high temperature and humidity environment,and protect the sweat glands cell of rats from the stress.