Abstract
Gamma-aminobutyric acid (GABA), GABA-A receptors and GABA transporter 1 (GAT1) were reported to be involved in the proliferation of Leydig cells, testosterone production and spermatogenesis. Since methamphetamine (METH) has been reported to have adverse effects on testis and its functions, the aim of this study was therefore to determine the changes of GABAergic activity in testis after METH exposure. Male Sprague-Dawley rats were divided into control, acute binge (AB-METH), escalating dose (ED METH) and escalating dose-binge (ED-binge METH) groups. After sacrifice, rat testes were removed and used to estimate GABA concentration and the expression of GABA-A receptor, GAD1, GAD2 and GAT1 genes by using HPLC and RT-PCR, respectively. The GABA concentration was significantly increased in all METH-administrated groups. In addition, significant increases of GABA-A α1 receptor and GAD1 genes expression were found in the ED-binge METH group. Gene expressions of GAT1 were numerically decreased in all METH-administrated rats and reached significant in the ED METH group. These results indicated a compensatory upregulation of GABA production and its functions in testis after METH exposure. Thus, these changes might represent a homeostatic response of GABAergic to the adverse effects of METH.