The Role of TNF-α in Hyperprolactinemia-Related Reproductive Dysfunction in Male Rats

• Main Authors: Yi-Ting Tsai, 蔡宜庭
• Other Authors: Hsiao-Fung Pu
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/98465664482174434248

碩士 === 國立陽明大學 === 生理學研究所 === 98 === Abstract Prolactin (PRL) has both stimulatory and inhibitory effects on testicular steroidogenesis. Hyperprolactinemia (hyperPRL) might suppress gonadotropin release and lead to low testosterone (T) production and disturbed spermatogenesis. Previous studies have shown that overproduction of PRL stimulates residential macrophages to secrete tumor necrosis factor-alpha (TNF-α), through which PRL inhibits Leydig cells (LC) to release adequate T in hyperPRL male rats. Previous study indicated that using anti-TNF-α antibody (Ab) on irritable bowel disorder (IBD) and rheumatolid arthritis (RA) patient would improve their pathologic features. Early experiments have indicated that co-culture of ovine prolactin (o-PRL) and anti-TNF-α antibody to the testicular interstitial cells (TIC, the mixture of LC, macrophage, myoid cell ...etc.) could increase T secretion in vitro to the level of the control groups. It showed a dose-dependent relationship. However, the effects of anti-TNF-α antibody in the testis in vivo are still unknown. In the present studies, we used the pituitary grafting hyperPRL model to investigate the anti-TNF-α antibody effects on testes of hyperPRL male rats. We grafted 2 anterior pituitary (AP) glands into the subcapsular space (AP group) to induce hyperPRL. The control rats were grafted with a similar volume of cerebral cortex (CX group). After 6 weeks, plasma PRL was determined by radioimmunoassay (RIA). One or 7-day prior to decapitation, we injected anti-TNF-α antibody into the left testes or into the muscle. The control groups were injected with saline. After decapitation, the testes were retrieved for protein isolation, paraffin block preparation, and TIC dispersion. Rat plasma was stocked for PRL RIA, the TIC incubation media were frozen for T RIA and TNF-α ELISA. The testicular tissue was processed for immunohistochemistry (IHC) study for TNF-α receptors, Fas, and Fas ligand (FasL). The protein isolated was for western blot (caspase 3) and testis tissue for terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labelling (TUNEL). T release was significantly higher in AP groups than in CX groups when anti-TNF-α antibody was given to the testes or the muscle. Besides, the phenomena in TIC were also observed in cells isolated from the testes without antibody injection (right testes). TNF-α concentration in TIC medium was significantly higher in AP groups than in the control groups, however, there was no difference observed in both AP and CX groups with or without antibody injection. Expression of caspase 3 and apoptotic cell were higher in AP groups than in the CX groups without antibody injection, but there were no difference between AP and CX groups after antibody injection. TNF receptor 2 and FasL in AP groups showed significantly stronger expression than the control groups. In conclusion, in hyperPRL status, the rats were exposed to more amount of PRL and TNF-α. Administrating anti-TNF-α antibody directly to the testis could reverse the suppression of release of T from the TIC. Stronger TNF receptor 2 expression might be related to the significant compensatory change to prevent germ cells from apoptosis induction by TNF receptor 1 or Fas expression. The therapeutic potential of anti-TNF-α Ab to hyperPRL deserves further studies to confirm.