Expression levels of brain muscarinic acetylcholine receptor in offspring rats of drinking-water borne fluorosis / 中华地方病学杂志

Objective To observe the changes of learning and memory ability and detect the expression of muscarinic acetylcholine receptor (mAChR,M receptor) at mRNA and protein levels in brains of offspring rats with chronic fluorosis,and to reveal the mechanism of the central nervous system damage.Methods Forty healthy SD rats were divided into two groups (20 in each group,half male and half female) by random number table according to body weight.In the control group,the rats were fed with drinking water containing no more than 0.5 mg/L fluoride;in the fluoride group,the rats were fed with high dose of sodium fluoride in drinking water (50.0 mg/L fluoride).Each group was fed with normal diet (6.2 mg/kg fluoride).After exposed to fluoride for 6 months,each group was mated,and brains of newborn offspring rats aged 1,7,14,21 and 28 days were taken,and expression of M1 and M3 receptors at mRNA and protein levels were analyzed by real-time PCR and Western blotting,respectively.Behavioral changes were measured by Morris water maze test at the 28 days after birth.The correlations between protein levels of M1 and M3 receptors and the ability of learning and memory at the 28 days after birth were analyzed.Results In fluoride group of the offspring rats at 28 days after birth,the escape latency time [(35.61 ± 9.00)s] was significantly longer than that in control group [(8.46 ± 3.09)s,P ＜ 0.05],while the numbers of crossing the platforms and the time of staying the platforms [(5.00 ± 2.90)times,(16.66 ± 2.79)s] were significantly decreased as compared to that of control group [(15.17 ± 3.66)times,(22.51 ± 2.66)s,all P ＜ 0.05].Furthermore,the mRNA expression and the protein levels of M1 and M3 receptors in rat brain at each phase in fluoride group were significantly decreased as compared to controls [M1 mRNA in control groups:(100.00 ± 11.00)％,(100.00 ± 17.57)％,(100.00 ± 9.14)％,(100.00 ± 7.52)％,(100.00 ± 15.78)％;M1 mRNA in fluoride groups:(20.47 ± 8.07)％,(14.00 ± 4.53)％,(16.57 ± 7.62)％,(25.56 ± 12.78)％,(16.27 ± 4.82)％;M3 mRNA in control groups:(100.00 ± 16.30)％,(100.00 ± 14.40)％,(100.00 ± 7.20)％,(100.00 ± 14.31)％,(100.00 ± 13.16)％;M3 mRNA in fluoride groups:(29.17 ± 8.00)％,(12.77 ± 2.22)％,(26.40 ± 7.20)％,(15.74 ± 3.55)％,(28.14 ± 7.53)％;M1 protein in control groups:(100.00 ± 2.24)％,(100.00 ± 8.30)％,(100.00 ± 4.61)％,(100.00 ± 13.78)％,(100.00 ± 11.72)％;M1 protein in fluoride groups:(20.47 ± 8.07)％,(14.00 ± 4.53)％,(16.57 ± 7.62)％,(25.56 ± 12.78)％,(16.27 ± 4.82)％;M3 protein in control groups:(100.00 ± 16.30)％,(100.00 ± 14.40)％,(100.00 ± 7.20)％,(100.00 ± 14.31)％,(100.00 ± 13.16)％;M3 protein in fluoride groups:(29.17 ± 8.00)％,(12.77 ± 2.22)％,(26.40 ± 7.20)％,(15.74 ± 3.55)％,(28.14 ± 7.53)％,P ＜ 0.05 or ＜ 0.01].The escape latency and M1,M3 receptors protein levels were negatively correlated (r =-0.827,-0.742,all P ＜ 0.05),and the number of space exploration and M1,M3 receptors protein levels were positively correlated (r =0.843,0.806,all P ＜ 0.05).Conclusion The expression of M receptor at protein and mRNA levels in offspring rat brains of different ages are significantly declined,which might be one of the mechanism of the decreased ability of learning and memory induced by fluoride toxicity.

Expression of muscarinic acetylcholine receptors in the brain of rats with chronic fluorosis / 中华地方病学杂志

Objective To detect the expression of muscarinic acetylcholine receptors (mAChRs) at mRNA and protein levels in the brain of rats with chronic fluorosis and to reveal the role of the receptors in brain injury and learning and memory deficits.Methods Sixty healthy SD rats were divided into two groups (30 rats in each group,half males and half females) by random number table method according to body weight.In the control group,the rats were fed with drinking water containing no more than 0.5 mg/L fluoride; in the fluoride group,the rats were fed with high doses of sodium fluoride in drinking water (50.0 mg/L).Each group was fed with normal diet (6.2 mg/kg).After being exposed to fluoride for 10 months,behavioral performance was measured with Morris water maze,including the escape latency time and the numbers of crossing platforms.After being sacrificed,rat brains were taken and weighted.M1 and M3 subunits at mRNA and protein levels were detected by real-time PCR and Western blotting,respectively; the correlation between protein levels of the receptor subunits and the ability of learning and memory was analyzed.Results In fluoride group,the escape latency time [(21.68 ± 2.90)s] was significantly longer than that of control group [(6.14 ± 1.71)s,t =0.289,P ＜ 0.05]; and the number of crossing platforms [(11.62 ± 2.26)times] was significantly decreased as compared to that of control group [(19.00 ± 3.69)times,t =0.352,P ＜ 0.05].Furthermore,the mRNA expression [(17.07 ± 6.89)％,(12.25 ± 5.03)％] and the protein levels [(71.07 ± 6.89)％,(32.25 ± 4.66)％] of M1 and M3 receptors in rat brains were significantly lower as compared to those of controls [(100.00 ± 3.00)％,(100.00 ± 2.15)％ and (100.00 ± 9.01)％,(100.00 ± 10.33)％,t =0.210,0.157,0.095,0.296,all P ＜ 0.05].The escape latency and M1,M3 protein levels were negatively correlated (r =-0.683,-0.700,all P ＜0.05),and the number of space exploration and M1,M3 protein levels were positively correlated (r =0.867,0.837,all P ＜ 0.05).Conclusion Declined expression of mAChRs at mRNA and protein levels have been detected in the brain of rats with chronic fluorosis,which may be one of the main mechanism concerning the learning and memory deficits.

Expression and function of G-protein-coupled receptorsin the male reproductive tract

This review focuses on the expression and function of muscarinic acetylcholine receptors (mAChRs), α1-adrenoceptors and relaxin receptors in the male reproductive tract. The localization and differential expression of mAChR and α1-adrenoceptor subtypes in specific compartments of the efferent ductules, epididymis, vas deferens, seminal vesicle and prostate of various species indicate a role for these receptors in the modulation of luminal fluid composition and smooth muscle contraction, including effects on male fertility. Furthermore, the activation of mAChRs induces transactivation of the epidermal growth factor receptor (EGFR) and the Sertoli cell proliferation. The relaxin receptors are present in the testis, RXFP1 in elongated spermatids and Sertoli cells from rat, and RXFP2 in Leydig and germ cells from rat and human, suggesting a role for these receptors in the spermatogenic process. The localization of both receptors in the apical portion of epithelial cells and smooth muscle layers of the vas deferens suggests an involvement of these receptors in the contraction and regulation of secretion.

Esta revisão enfatiza a expressão e a função dos receptores muscarínicos, adrenoceptores α1 e receptores para relaxina no sistema reprodutor masculino. A expressão dos receptores muscarínicos e adrenoceptores α1 em compartimentos específicos de dúctulos eferentes, epidídimo, ductos deferentes, vesícula seminal e próstata de várias espécies indica o envolvimento destes receptores na modulação da composição do fluido luminal e na contração do músculo liso, incluindo efeitos na fertilidade masculina. Além disso, a ativação dos receptores muscarínicos leva à transativação do receptor para o fator crescimento epidermal e proliferação das células de Sertoli. Os receptores para relaxina estão presentes no testículo, RXFP1 nas espermátides alongadas e células de Sertoli de rato e RXFP2 nas células de Leydig e germinativas de ratos e humano, sugerindo o envolvimento destes receptores no processo espermatogênico. A localização de ambos os receptores na porção apical das células epiteliais e no músculo liso dos ductos deferentes de rato sugere um papel na contração e na regulação da secreção.

Effect on antagonism of muscarinic acetylcholine receptors antagonists by desensitization of nicotinic acetylcholine receptors / 中国药理学通报

Aim To investigate the effect on antagonism of benthiactzine and atropine against the function of muscarinic acetylcholine receptors by desensitization of nicotinic acetylcholine receptors. Methods The whole cell recording configuration of patch-clamp technique was used and the cell model was rat SCG neurons. To identify antagonists' antimuscarinic effect, mAchRs mediated IM-inhibition was measured and nicotine and oxotremorine were used. Results After de sensitization of nAChRs,the antimuscarinic effect ofboth benthiactzine and atropine decreased compared to the normal condition. The decreased antimuscarinic effect of benthiactzine was weaker than that of atro-pine. The antimuscarinic effect of both benthiactzine and atropine recovered gradually with the recovery of nAChRs from desensitization. Conclusion Desensiti-zation of nAChRs weakens the antagonists' antimuscarinic effect.

Detection of the expression and function of m3AChR-G11 fusion protein / 中国药理学通报

Aim To generate m3AChR-G11 fusion protein in baculovirus-Sf9 cells and test the couping function,the interation and the influence factors be-tween m3AChR and G11 protein,as well as screen the specific ligands for m3AChR. Methods m3AChR-G11 fused DNA was generated through a two-step PCR and then expressed in Sf9 cells to produce fusion protein. The total concentration for membrane protein was de-tected by BCA method,[3H]QNB and [35 S]GTP?S binding experiment as perfomed to study the function of m3AChR-G11 fusion protein. Results The expression level of m3AChR-G11 was 7. 76 ? 10 -9 mol?g -1. The affinity of GDP to G11 partner changed in the presence of different muscarinic ligands. IC50 values of GDP in the presence of ACh,Pilo,CCh,MCN-A-343,Atro,4-Damp and Dafi were 82. 2,93. 70,12. 10,14. 30, 1. 93,1. 37,0. 72 ? 10 -6 mol ? L -1 respectively,and that in the absence of muscarinic was 1. 99 ? 10 -6 mol ?L-1.Concluslons The m3AChR-G11 fusion protein has the pharmacological specificity of m3 receptor and the efficient coupling interaction of the two partners. Affinity of GDP to ligand-bound fusion protein represents the species of muscarinic ligands. This is helpful in screening and detecting the new specific ligands to muscarinic receptors.