Distribution of the P2X2 receptor and chemical coding in ileal enteric neurons of obese male mice(ob/ob)

AIM:To investigate the colocalization,density and profile of neuronal areas of enteric neurons in the ileum of male obese mice.METHODS:The small intestinal samples of male mice in an obese group(OG)(C57BL/6J ob/ob)and a control group(CG)(+/+)were used.The tissues were analyzed using a double immunostaining technique for immunoreactivity(ir)of the P2X2 receptor,nitric oxide synthase(NOS),choline acetyl transferase(ChAT)and calretinin(Calr).Also,we investigated the density and profile of neuronal areas of the NOS-,ChAT-and Calrir neurons in the myenteric plexus.Myenteric neurons were labeled using an NADH-diaphorase histochemical staining method.RESULTS:The analysis demonstrated that the P2X2receptor was expressed in the cytoplasm and in the nuclear and cytoplasmic membranes only in the CG.Neuronal density values(neuron/cm2)decreased 31%(CG:6579±837;OG:4556±407)and 16.5%(CG:7796±528;OG:6513±610)in the NOS-ir and calretininir neurons in the OG,respectively(P<0.05).Density of ChAT-ir(CG:6200±310;OG:8125±749)neurons significantly increased 31%in the OG(P<0.05).Neuron size studies demonstrated that NOS,ChAT,and Calr-ir neurons did not differ significantly between the CG and OG groups.The examination of NADH-diaphorase-positive myenteric neurons revealed an overall similarity between the OG and CG.CONCLUSION:Obesity may exert its effects by promoting a decrease in P2X2 receptor expression and modifications in the density of the NOS-ir,ChAT-ir and CalR-ir myenteric neurons.