Widespread expression of GABA(A) receptor subunits in peripheral tissues.

The receptor subtypes involved in the physiological and pharmacological actions of gamma-amino butyric acid (GABA) in peripheral and endocrine tissues are not clear. Information about the molecular characteristics of GABA(A) receptors in peripheral endocrine tissues is only available for the pancreas and the adrenal medulla. Using reverse transcription (RT) polymerase chain reaction (PCR), the widespread expression of GABA(A) receptors subunits in rat peripheral tissues, including adrenal, ovary, testis, placenta, uterus, and small intestine is shown. It is shown that GABA(A) receptor subunits are expressed in multiple endocrine tissues in a tissue specific manner. These results give an insight into the likely pharmacological properties of these GABA(A) receptors in these tissues. The gonadal endocrine tissues such as the placenta, ovary and the testis express greater range of GABA(A) receptor subunits relative to the adrenal gland. The tissues with greater smooth muscle content, the small intestine and the uterus also express a smaller range of subunits subtypes.