The mammalian testis is a highly organized organ essential for male reproduction. Its structure comprises seminiferous tubules lined with Sertoli cells, which support spermatogenesis, surrounded by peritubular myoid cells. Within the connective tissue framework lie the Leydig cells, which synthesize testosterone in response to luteinizing hormone. Research has highlighted the importance of various ion channels and proteins in testicular function. The TWINK-related acid-sensitive potassium channel 1 (TASK-1), a two-pore channel, is vital for several physiological functions in the testis. Furthermore, Leydig cells uniquely express several key proteins, including c-kit, and platelet-derived growth factor receptor α. The co-expression of these proteins, including TASK-1, in Leydig cells suggest the presence of complex regulatory mechanisms critical for modulating testosterone production, release, and overall testicular function. Transient receptor potential vanilloid-1 (TRPV1), a member of the transient receptor potential channel family, also plays a crucial role in testicular function, influencing processes such as sensory function, steroidogenesis, and sperm function. Hormonal fluctuations and aging affect both the presence and function of TRPV1. This channel is thought to contribute programmed cell death within the testes, particularly impacting Leydig cell survival. Notably, testosterone appears to counteract these detrimental effects by downregulating TRPV1 expression, indicating a complex interplay between TRPV1, testosterone, and overall testicular function. Therefore, we aim to discuss the critical role of ion channels, specifically focusing on TASK-1 and TRPV1 channels, in the physiological and pathophysiological functions of testicular cells.

Background: Platelet-derived growth factor receptor alpha (PDGFRα) is essential for various biological processes, including fetal Leydig cell differentiation. The PDGFRαEGFP mouse model, which expresses an eGFP fusion gene under the native Pdgfrα promoter, serves as a valuable resource for exploring PDGFRα’s expression and function in vivo. This study investigates PDGFRα expression in adult testicular cells using PDGFRαEGFP mouse model. Methods: Genotyping PCR and gel electrophoresis were used to confirm the zygosity of PDGFRαEGFP mice. Histological examination and fluorescence imaging were used to identify PDGFRα expression within testicular tissue. Immunohistochemical analysis assessed the co-expression of PDGFRα with c-Kit, ANO-1, and TASK-1 in testicular cells. Results: Genotyping confirmed the heterozygous status of the mice, which is crucial for studies due to the embryonic lethal phenotype observed in homozygotes. Histological and fluorescence imaging revealed that PDGFRα+ cells were primarily located in the interstitial spaces of the testis, specifically within Leydig cells and peritubular myoid cells (PMCs). Immunohistochemical results showed PDGFRα co-localization with c-Kit and ANO-1 in Leydig cells and a complete co-localization with TASK-1 in both Leydig cells and PMCs. Conclusions: The findings demonstrate specific expression of PDGFRα in Leydig cells and PMCs in adult testicular tissue. The co-expression of PDGFRα with c-Kit, ANO-1, and TASK-1 suggests complex regulatory mechanisms, possibly influencing testicular function and broader physiological processes.

Receptor tyrosine kinase c-Kit, a marker found on interstitial cells of Cajal (ICCs), is expressed in Leydig cells, which are testicular interstitial cells. The expression of other ICC markers has not yet been reported. In this study, we investigated the expression of c-Kit and anoctamin 1 (ANO1), another ICC marker, in mouse testes. In addition, the relationship between c-Kit and ANO1 expression and Leydig cell function was investigated. We observed that c-Kit and ANO1 were predominantly expressed in mouse Leydig cells. The mRNA and protein of c-Kit and ANO1 were expressed in TM3, a mouse Leydig cell line. LH induced an increase in intracellular Ca2+ concentration, membrane depolarization, and testosterone secretion, whereas these signals were inhibited in the presence of c-Kit and ANO1 inhibitors. These results show that c-Kit and ANO1 are expressed in Leydig cells and are involved in testosterone secretion. Our findings suggest that Leydig cells may act as ICCs in testosterone secretion.