Regulation And Mechanism Of Androgen On The Expression Of Selected Synaptic Proteins In The Hippocampus Of Male Mice

Alzheimer's disease(AD)is a series of insidious onset and chronic progressive mental deterioration occurring in or pre the geratic-perioda which expresses some nerve energetic symptoms like memory disorders,behavioral disorders,speech disorders,cognitive impairment and personality disorders.The number of AD patient has been almost 20 million and it is on the increase presently.The morbidity of AD in our country was 5% over the age of 65,10% over the age of 75 and 20% over the age of 85.It seriously impact on socializing,occupation and vital function that has been one of the most difficult medical problems in aging society.Although there are some breakthrough treatments of AD in recent years,it is only a fraction of that.It brings out bearing financial and mental burden to families and societies,but also to nursing home and clinical care.Studies have proved that cognitive impairment is connected with the decline of androgen.Androgen mediates brain structure and function through two ways,one is the androgen receptor pathway directly,and another is estrogen receptor pathway by Arom indirectly.Our early studies found that giving male mice Arom inhibitor letrozole(LET)by intraperitoneal injection would decrease synapse proteins and change learning and memory behavior.But Orchiectomy(ORX)can decline synaptic plasticity slightly,not learning and memory behavior.It indicated that the pathway of endogenous estrogen function of androgen may play a main role in mediating synaptic plasticity especially the learning and memory parts,but it is not clear of its specific regulatory pathway.Although estrogen replacement therapy has used for clinic slightly,its curative effect is not well.Since endogenous function way of androgen may play a part in synaptic plasticity regulation,whether androgen replacement can improve synaptic plasticity.Researches show that steroid hormone like androgen can effect neural structure and function by its nuclear receptor.Nuclear receptors regulate target gene needs the coactivator,presently it mainly considered that steroid receptor coactivator-1(SRC-1)plays a leading role in nerve system.SRC-1 can significantly enhance transcriptional activity of various nuclear receptors by ligand dependent.Inhibiting the expression of brain SRC-1 leads to brain developmental,behavioral and physiological change.Steroid hormone affects central nervous system(CNS)through hippocampus.SRC-1 shows high expression in mice hippocampus nuclear.It has been verified to play an important role in brain synaptic plasticity,learning and memory or other advanced cognition.As an important steroid hormone molecular of regulating hippocampus synaptic plasticity,what role it does on hippocampus structure and function during ageing process.On account of these questions,we imitated decline of androgen after aging by classical ORX model and then we used immunohistochemistry(IHC)and Westen Blot(WB)to test androgen receptor(AR),estrogen Receptors(ER?,ER?),G Protein-coupled Receptor 30(GPR30)and synapse proteins GluR1 and PSD-95,spinophilin and SRC-1 expression after giving different dose of Testosterone(T)(0.5mg/kg?1.0mg/kg?2.0mg/kg)by 2 weeks and 4 weeks to clear the relation between androgen decline and cognition.And we used statistical approach to do correlation analysis to preliminary discuss the possible pathways of androgen regulating hippocampus synapse proteins.We do this to deeply illuminate AD pathogenesis and provide new initial value of exploiting more effective medicine to prevention and treatment which may relieve workload of nursing colleague.Main results:1.GluR1?PSD-95?AR?ER??ER? and SRC-1 express widely in hippocampus of adult male mice.Except GPR30 and Spinophilin,all of them expressed significant decrease after ORX and increase after T replacement.2.During the short time T replacement(2 weeks;0.5mg/kg,1.0mg/kg and 2.0mg/kg)after ORX,the expression of GluR1 decreased after ORX and slightly increased at the dose of 0.5mg/kg,significantly increased at the dose of 1.0mg/kg comparing to ORX,but decreased at the dose of 2.0mg/kg.Expression changing of AR of 4 weeks was the same as 2 weeks.The expression of PSD-95 decreased of 2 weeks after ORX and increased at the dose of 0.5mg/kg,significantly increased at the dose of 1.0mg/kg comparing to ORX and kept increase at the dose of 2.0mg/kg.Expression of Spinophilin had no significant difference.The expressions of AR?ER? and ER? decreased after ORX and slightly increased at the dose of 0.5mg/kg,significantly increased at the dose of 1.0mg/kg comparing to ORX,but decreased at the dose of 2.0mg/kg.Expression of GPR30 had no significant difference.The expression of SRC-1 decreased ORX and slightly increased at the dose of 0.5mg/kg,significantly increased at the dose of 1.0mg/kg comparing to ORX,but decreased at the dose of 2.0mg/kg.3.During the long time T replacement(4 weeks;0.5mg/kg,1.0mg/kg and 2.0mg/kg)after ORX,the expression of GluR1 and PSD-95 decreased after ORX and slightly increased at the dose of 0.5mg/kg,significantly increased at the dose of 1.0mg/kg comparing to ORX,but decreased at the dose of 2.0mg/kg.Spinophilin had no significant different change.The expression of AR decreased after ORX and slightly increased at the dose of 0.5mg/kg,significantly increased at the dose of 1.0mg/kg comparing to ORX,but decreased at the dose of 2.0mg/kg.The expression of ER? decreased after ORX and slightly increased at the dose of 0.5mg/kg and 1.0mg/kg,and then significantly increased at 2.0mg/kg.The expression of GPR30 has no obvious change after ORX,but significantly increased at the dose of 1.0mg/kg comparing to ORX.The expression of SRC-1 decreased ORX and slightly increased at the dose of 0.5mg/kg,significantly increased at the dose of 1.0mg/kg comparing to ORX,but decreased at the dose of 2.0mg/kg.4.Expressions of AR? ER??ER? and GluR1? PSD-95 in hippocampus of adult mice showed high linear correlation after giving different doses of a short time T replacement respectively.AR? ER??ER? and SRC-1 showed linear correlation.SRC-1 and GluR1?PSD-95 also showed linear correlation.Expressions of AR and ER??GluR1 in hippocampus of adult mice showed high linear correlation after giving different doses of long time T replacement respectively.For a long time T replacement,expressions of AR and ER??GluR1 showed linear correlation,and SRC-1 and GluR1 showed linear correlation.5.In cultured hippocampal cell line,androgen dose-dependently induced increase of GluR1?PSD-95?AR?ER??ER??GPR30 and SRC-1;expression of GluR1?PSD-95?SRC-1 decreased after giving antagonists of AR?ER??ER? and GPR30.Furthermore,expression of GluR1?PSD-95?AR?ER??ER??GPR30 decreased after giving antagonists of SRC-1.Main conclusions:1.Expression of hippocampus synapse proteins GluR1 and PSD-95 of adult mice decreased after ORX and increase by T replacement.With the vitro results,it indicated that androgen can up-regulate hippocampus synapse proteins expression and then affect synaptic plasticity.2.Expression of hippocampus nuclear receptors AR?ER? and ER? of adult mice decreased after ORX and increase by T replacement.And the variation tendency of them highly correlated with GluR1 and PSD-95 combing with the vitro showed that androgen affected synapse proteins through AR directly and ERs indirectly.3.Expression of hippocampus SRC-1 of adult mice decreased after ORX and increase by T replacement.The variation tendency of SRC-1 correlated with AR?ER??ER? and GluR1?PSD-95 combing with vitro results indicated that SRC-1 played a important role in androgen regulating synapse proteins.This regulatory may lead to hippocampus synaptic plasticity change and then induce decline of memory and learning ability in aging.4.ORX and T replacement for different dose and different time,a short time(2 weeks)and a long time(4 weeks),GluR1 and PSD-95 presented inverse “U” tendency,which indicated that excessive androgen may be neurotoxicity to induce expressive synapse proteins disorders.Conclusively,this research used IHC and WB to study hippocampus AR?ER??ER??GluR1?PSD-95?SRC-1 of adult mice and their correlations after ORX and T replacement.We preliminary discussed how androgen regulate synapse proteins and what role of SRC-1 in it that provided reliable evidence for intensive study mechanism of age-related diseases based on androgen and cognition.