Changes Of The Expression Of Vesicular Glutamate Transporters In Rat Brain By Chronic Morphine Exposure

ObjectiveTo investigate the changes of mRNA and protein expression of vesicular glutamate transporter 1 and 2(VGLUT1, 2)and their possible functions in the brain after chronic morphine treatment.MethodsSD rats were divided randomly into the treatment group (chronic morphine treatment) and the control group (saline treatment). According to the general method, we prepared the chronic morphine treatment model. Morphological method and molecular biology related method were used for investigating. Then we prepared the DIG-VGLUT1 and DIG-VGLUT2 probes and observed the changes of mRNA expression in the central nervous system with in situ hybridization, which included the Amyg, Hipp, PFC , Hypothalamus and Thalamus. We also extracted the mRNA of these nuclei and devised the primers and observed the changes of mRNA expression with Quantitative real-time RT-PCR method. The changes of protein expression of VGLUT1 and VGLUT2 were detected with immunohistochemistry and Western Blotting in VTA, NAc, Amyg and Thalamus respectively. Results were expressed as mean±SEM of n=3~6 animals per group. Statistical analysis of data was performed using Student's t-test. Significant difference should be P<0.05 for a statistically.ResultsIn comparison with control group, the expressional levels and distribution patterns of VGLUT1 mRNA and VGLUT2 mRNA were unaltered in PFC, Amyg, Hipp, Thalamus and Hypothalamus in the chronic morphine treatment group. The results were same from in situ hybridization also in Quantitative real-time RT-PCR method. The expression of VGLUT1 was enhanced in NAc and Thalamus while VGLUT2 expression was unchanged in those nuclei. The results of immunohistochemistry were consistent with those of Western Blotting method.ConclusionsThe expression and distribution of VGLUT1 mRNA was unaltered in PFC, Amyg, thalamus and Hipp and those of VGLUT2 mRNA was also unaltered in thalamus and hypothalamus. But the expression of VGLUT1 was enhanced in NAc and Thalamus while VGLUT2 expression was unchanged in those nuclei. Thus, it is suggested that VGLUT1, not VGLUT2 might be responsible for morphine addiction related nuclei after chronic morphine treatment.