Effects Of RN-1734 Injection Into Hypothalamus PO/AH Region On Increase Of Rat Body Temperature Induced By Progesterone

Objective: Body temperature is one of the important factors to maintain the homeostasis of the internal environment.In addition to the obvious increase or decrease of body temperature under pathological conditions,physiological fluctuations of body temperature are usually observed,especially for women in the menstrual cycle express bidirectional body temperature change,namely in the follicular phase temperature is lower about 0.3 to 0.6 ? than luteal phase.The mechanism of rising luteal phase body temperature during the menstrual cycle is generally considered as progesterone affecting on the hypothalamus thermoregulatory center,following by changing metabolic level or skin blood flow.However,the detail biological mechanism is remain unclear.Transient receptor potential vanilloid 4(TRPV4),a member of transient receptor potential(TRP)protein family,is a potential ion channel located on the cell membrane and participates in regulating process of various physiological functions in vivo.Researches have show that it is a multi-directional,non-selective cationic channel that can penetrate Ca2+,K+,Mg2+ and Na+,but the permeability of Ca2+ is the highest.In vivo,TRPV4 can be activated by a variety of stimulus,including physical factors(thermal stimulation more than 27 ?),endogenous and exogenous chemical factors(such as specific agonists 4?PDD),and low p H(p H<6).Along with the increasing researches on its temperature and osmotic pressure sensitivity,TRPV4 has been regarded as a thermal and osmotic pressure sensor in vivo.Furthermore,TRPV4 has been reported to be expressed in most tissues of mammals,including the heart,endothelium,peripheral nervous system and central nervous system.In particularly,it is mainly expressed in hypothalamus,hippocampus,cortex and other parts in central nervous system.Researches have found that TRPV4 was presented in the preoptic-anterior hypothalamus area(PO/AH)which is the thermoregulation center,and played an important role in the thermoregulation process,especially in the maintenance of normal body temperature.In summary,progesterone affected on the hypothalamic thermoregulation center resulting in the increase of luteal body temperature,while TRPV4 in the PO/AH was involved in maintaining normal body temperature.Therefore,this study aim to investigate whether TRPV4 in PO/AH was involved in the process of progesterone induced body temperature rising in female rats during the sexual cycle.Methods: The changes of body temperature and progesterone level in blood of normal female SD rats during sexual cycle were observed.The model of ovariectomized rats were prepared and the body temperature of ovariectomized rats were observed after different doses of progesterone.RN-1734 of TRPV4 specific blocker were given in the PO/AH area in the metestrus of normal rats to observe the changes of body temperature of rats.Rats were given progesterone and/or RN-1734 respectively to observe the changes of body temperature.The expression levels of TRPV4 in the PO/AH region of the rats sexual cycle were detected.The sexual cycle of rats were determined by taking vaginal secretion smears of rats and HE staining.The changes of body temperature of rats under various experimental conditions were detected by wireless remote sensing technology,progesterone concentration was detected by chemiluminescence(CL).The expression of TRPV4 was determined by immunofluorescence and the expression level of TRPV4 protein in PO/AH region of rats at different stages were detected by Real-time quantitative PCR and Western Blot.Results:1.At different phases of the sexual cycle in female rats,changing in body temperature was found to be positively correlated with progesterone levels.2.Different doses of progesterone were intraperitoneal injected into ovariectomized rats,indicating a dose-dependent increase of body temperature.3.RN-1734 were given in the PO/AH area of normal rats,increasing range of body temperature decreased significantly in the rats.4.RN-1734 injected into the PO/AH significantly reduced the increase range of body temperature in ovariectomized rats which were pre-intraperitoneal injection of progesterone.5.In metestrus phase,TRPV4 m RNA and protein expression in PO/AH were the highest.Conclusion: 1.Progesterone increased the body temperature of ovariectomized rats2.The specific antagonist of TRPV4 administrated in the PO/AH could result in decreasing the ascending range of temperature induced by progesterone in rats.