GABAA Receptor Subunits in Rat Testis and Sperm

Background
γ-Aminobutyric acid (GABA) is considered to be the predominant inhibitory neurotransmitter in mammalian central nervous systems (CNS). There are two major classes of GABA receptors: GABAARs and GABABRs. The GABAA receptor is derived from various subunits such as alpha1-alpha 6, beta1-beta 3, gamma1-gamma 4, delta, epsilon, pi, and rho1-3. Intensive research has been performed to understand and establish the distribution and functions of these receptors in the CNS and peripheral tissues. The presence of some GABAA receptors in sperm prompted us to explore the existence of GABAA receptors in rat testis and sperm.


Materials and methods
Total cellular RNA was isolated from Wistar rat sperm and testis and reverse transcriptased to cDNA. PCR reactions were performed in a 20μl (microliter) volume containing specific GABAAR subunits (forward and reverse primers) with other required materials. Reactions were carried out using a PCR machine to investigate the existence of GABAA receptor subunits in rat testis and sperm. The amplification products were analyzed on 2% agarose gels stained with ethidium bromide.


Results
Our results showed that GABAARs composed of α5, β1, β3, and γ1 subunits were expressed in both testis and sperm. These results indicate that, in sperm, GABAA receptors might have important functions.


Conclusion
Sperm could be a novel site of GABAA expression. Further studies should be taken to explore the role of these receptors on sperm acrosome reaction.