The primary objectives of this study were to follow the temporal patterns of testicular LH and FSH receptor (LH-R and FSH-R) concentrations and affinity (Ka) during sexual maturation in bulls and to see if such patterns could help explain the control of rapid testicular growth that occurs after 25 weeks of age, when serum gonadotropin concentrations are low. Separate groups of Hereford x Charolais calves (n = 6) were castrated every 4 weeks from 5 to 33 weeks of age and at 56 weeks of age. A week prior to castrations, from 5 to 33 weeks of age, blood was collected every 15 min for 10 h. The transition from indifferent supporting cells to Sertoli cells in seminiferous tubules was rapid between 13 and 25 weeks and rapid testis growth occurred after 25 weeks of age. Serum LH and FSH concentrations were transiently elevated at 12 weeks of age (P < 0.05). LH-R concentrations decreased from 13 to 25 weeks of age and increased to 56 weeks of age (P < 0.05). LH-RKa decreased from 9 to 17 weeks of age, increased to 29 weeks of age and declined to 33 weeks of age (P < 0.05). FSH-R concentrations declined from 17 to 25 weeks of age then increased to 56 weeks of age (P < 0.05). FSH-RKa increased from 17 to 25 weeks of age (P < 0.05). High concentrations of gonadotropins and their receptors may be critical to initiate testis growth postnatally and support it after 25 weeks of age in the face of low serum gonadotropin concentrations.

译文

:本研究的主要目的是追踪公牛性成熟过程中睾丸LH和FSH受体(LH-R和FSH-R)浓度和亲和力(Ka)的时间模式,并观察这种模式是否有助于解释控制因素血清促性腺激素浓度低时,在25周龄后出现睾丸快速生长的情况。从5到33周龄和56周龄每4周cast割一次赫瑞福德x夏洛来牛犊(n = 6)组。 5至33周龄weeks割前一周,每15分钟收集一次血液,持续10 h。在13至25周之间,从生精小管中的冷漠支持细胞向Sertoli细胞的过渡迅速,并且25周龄后睾丸迅速生长。血清LH和FSH浓度在12周龄时短暂升高(P <0.05)。 LH-R浓度从13周下降到25周,并增加到56周(P <0.05)。 LH-RKa从9周龄降低到17周龄,增加到29周龄,下降到33周龄(P <0.05)。 FSH-R浓度从17周下降到25周,然后上升到56周(P <0.05)。 FSH-RKa从17周龄增加到25周龄(P <0.05)。高浓度的促性腺激素及其受体对于出生后开始睾丸生长并在25周龄后面对低血清促性腺激素浓度的情况下支持睾丸生长可能至关重要。

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