Temporal Changes in the Local Expression of Central Hormone-Regulating Factors in Rat Testis

Abstract

Present study aimed to investigate the temporal changes in expression of some reproductive hormones in testis, originally found in hypothalamus and pituitary. Rats were sacrificed on postnatal day 23 (PND23; immature), pubertal (PND53) and PND 81 (young adult). The testicular RNAs were extracted, and semi-quantitative PCRs for gonadotropin-releasing hormone (GnRH), kisspeptin 1 (KiSS1), pituitary adenylate cyclase-activating polypeptide (PACAP), LH subunits and LH receptor were performed. Transcript levels of GnRH and KiSS1 at PND23 were significantly higher than levels of PND53 and PND81 (p<0.001). PACAP mRNA level at PND23 was significantly lower than those of PND53 and PND81 (p<0.001). The mRNA levels of both testis type and pituitary type luteinizing hormone β subunit (tLHβ and pLHβ, respectively) at PND23 were significantly lower than levels of PND53 and PND81 (p<0.001). The mRNA level of glycoprotein hormone common alpha subunit (Cgα) at PND23 was significantly lower than those of PND53 and PND81 (p<0.001). Present study revealed the intratesticular expression of KiSS1 and GnRH showed a very similar trend while the expression of PACAP in the testis showed reversed pattern. The expressions of LHβ subunits (tLHβ and pLHβ) were very low during immature stage then increased significantly during puberty and early adulthood. Our attempt to study the local role(s) of intratesticular factors will be helpful to achieve precise understanding on the testis physiology and pathology.

Fig. 1.. Temporal changes in expressions of GnRH, KiSS1, and PACAP genes in rat testis.

To compare gene expression in testicular tissues of three developmental periods, testicles from postnatal day 23 (PND23) designated immature stage, PND53 designated pubertal stage, and PND81 designated early adult stage were used (n=5). (A) Expression of GnRH gene was significantly higher in PND23 group, and the expression level was similar between groups PND53 and PND81. (B) Expression of the KiSS1 (kisspeptin) gene showed significant differences among all groups, being highest in group PND23 and lowest in group PND81. (C) Expression of the PACAP gene was lowest in group PND23 and highest in group PND53, and no significant difference was observed between groups PND53 and PND81. * p<0.05, *** p<0.001. GnRH, gonadotropin-releasing hormone; PACAP, pituitary adenylate cyclase-activating polypeptide.

Fig. 2.. Temporal changes in expressions of tLHβ, pLHβ, Cgα, LHCGR genes in rat testis at three developmental periods (immaturity, puberty, and maturity).

To compare gene expression in testicular tissues of three developmental periods, testicles from postnatal day 23 (PND23) designated immature stage, PND53 designated pubertal stage, and PND81 designated early adult stage (n=5). (A) Expression of testis type luteinizing hormone β (tLHβ) gene showed significant differences among all groups, being lowest in group PND23 and highest in group PND53. (B) Expression of pituitary type luteinizing hormone β (pLHβ) gene was lowest in group PND23 and highest in group PND53, and the expression level was similar between groups PND53 and PND81. (C) Expression of the common alpha subunit of gonadotropin (Cgα) gene showed significant differences among all groups, being lowest in group PND23 and highest in group PND53. (D) Expression of the luteinizing hormone/choriogonadotropin receptor (LHCGR) gene was lowest in group PND23 and highest in group PND53, and no significant difference was observed only between groups PND53 and PND81. * p<0.05, ** p<0.01, *** p<0.001.