Background: Brain-derived neurotrophic factor (BDNF) and its receptor, neurotrophic tyrosine receptor kinase-2 (NTRK2), are well known for their roles in the central nervous and animal reproductive systems. Several studies have observed the extensive expression of BDNF and NTRK2 in non-neuronal tissues, especially reproductive organs. However, most of these studies focused on ovarian development and regulation; thus, scientific research on BDNF and NTRK2 in males is required to determine their roles in the male reproductive system. Therefore, this study aimed to investigate BDNF and NTRK2 expression in bovine testes. Methods: Testes were collected from six Hanwoo bulls (6-8 months old). Reverse transcription-polymerase chain reaction (RT-PCR) analysis was performed to investigate the mRNA expression of BDNF and NTRK2 in the testes. Western blot analysis was performed to verify the cross-reactivity of BDNF and NTRK2 antibodies with bovine testicular tissues. Immunohistochemistry was conducted to determine BDNF and NTRK2 protein expression in the testes. Results: RT-PCR analysis revealed BDNF and NTRK2 mRNA expression in bovine testes. In Western blotting, BDNF and NTRK2 protein bands were observed at 32 and 45 kDa, respectively. Immunofluorescence demonstrated BDNF expression in the nuclei of spermatogonia and Sertoli cells as well as in the cytoplasm of Leydig cells. NTRK2 was exclusively expressed in Sertoli cells. These results suggest that BDNF plays a potential role in spermatogenesis via BDNF and NTRK2 signaling in bovine testes, a finding supported by previous results in different animal species. Conclusions: The expression patterns of BDNF and NTRK2 indicate their functional importance in the bovine reproductive system.

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.

It is well known that the imbalance between epithelial cell growth and inhibitor factors may cause human epithelial cancer. Over-expression of the epidermal growth factor receptor(EGFR) has been implicated in the development of oral squamous cell carcinoma. ZD1839 inhibits selectively the EGFR tyrosine kinase activity and is clinically used for cancer patients. However the mechanisms by which it exerts its anti-tumor activity remains unclear. This study attempted to determine the mechanisms underlying the effects of ZD1839 on the cellular level and to characterize the effects of ZD1839 with regard to human oral squamous cell carcinoma(OSCC) cell growth. The YD-10B and YD-38 cell lines established from OSCC in the department of Oral Pathology, Yonsei University College of Dentistry and ZD1839(Iressa) were used for this study. The inhibition of cell proliferation induced by ZD1839 was reversible and the lowest dose of ZD1839 that produced statistically significant growth inhibition in YD cell lines were 0.1 μM. The delay in cell cycle progression was induced by 0.1 μM of ZD1839 treatment after 24 hr. This reduction in cell proliferation and cell cycle delay were associated with up-regulation of the cyclin dependent kinase inhibitor(CDKI), P21CIP1/WAF1 and P27KIP1. Reduced expression of cyclin D1 was also observed after treatment with ZD 1839 to YD-38 cells but not to YD-38. The present results suggest that the antiproliferative effects of ZD1839, in vitro was associated with degradation of cyclin D1, which may be used as a possible indicator of a high cell sensitivity to ZD1839.