外源性促性腺激素對發身前與發身後貓隻下視丘-腦下垂體-性腺調控的作用

Abstract

許多品種的動物，促性腺激素刺激試驗是一種常常用來評估異常生殖功能的診斷方法，這些動物當然也包括貓。但是到目前為止，卻沒有針對正常貓隻對於促性腺素刺激試驗的報告。因此，此篇論文的目的是在評估發身前公貓與姆貓對於外源的促性腺激素刺激試驗的反應，此外也針對發身後公貓與母貓對於不同劑量外源的促性腺激素刺激試驗的反應。於發身前，血液樣本的收集分別於給予10 µg/kg 外源的促性腺激素之前與給予10 µg/kg外源的促性腺激素後各時間點，收集後的血液樣本，於公貓則檢測睪固酮，母貓則檢測發情素與助孕酮。另外，針對發身後貓隻對於不同劑量的性腺刺激素刺激試驗的反應，分別給予 20 與 40 µg/kg性腺刺激素，然後收集血液樣本 ，於公貓檢測睪固酮的濃度，於母貓則檢測發情素與助孕酮的濃度。此次試驗的結果顯示，無論是在發身前或是發身後，公貓對於外源性促性腺激素都會有反應，於給予促性腺激素60分鐘與120分鐘後的時間點，都顯著高於給予促性腺激素之前或是給予後10分鐘。但是卻沒有劑量依賴的現象，也就是說睪固酮的濃度並不會因為促性腺激素的濃度增加而增加。. 平均血漿發情素濃度在給予 10 µg/kg 促性腺激素後，於發身前的濃度為，發身後為，兩者並沒有顯著差異。同時，個體對於促性腺激素刺激後的反應也不盡相同，因而推論具有個體差異，但是原因不明。此外，助孕酮的濃度都低於 1.5 ng/ml ，無論是在給予促性腺激素之前或是之後。因此本實驗顯示在發身前與發身後的公貓對於促性腺激素會有較高的反應，而非母貓，這可能為腦下垂體對於外源性促性腺激素的調控，從發身前就已經不同了。

The exogenous gonadotropin stimulation (GnRH) test is diagnostic method used to evaluate the abnormal reproductive functions in many species, including cat. However, the GnRH challenge test in normal cat has not been studies. Therefore, the aims of this study were to evaluate the response of ovarian and testis hormones to exogenous gonadotropin in nine prepubertal and pubertal cats and to evaluate the dosage response of exogenous gonadotropin in pubertal cats. The blood samples were collected at time before and multiple times after 10 µg/kg GnRH intravenous administration for determining the concentration of estradiol-17β, progesterone, and testosterone. Twenty and forty µg/kg GnRH were administrated intravenous in the same pubertal cats for evaluation of dosage response. The mean plasma testosterone before and 10 minutes were significantly lower than 60 and 120 minutes after 10 µg/kg GnRH administration in prepubertal cats and in male pubertal cats after 10, 20, and 40 µg/kg GnRH administration. In high dosage of GnRH, 20 and 40 µg/kg GnRH could not induce an increase of plasma testosterone concentrations when compared with 10 µg/kg GnRH. The means plasma estradiol in prepubertal and pubertal female cats after 10 µg/kg GnRH administration were 18.4±4.45 and 14.40±5.89 pg/ml respectively. The mean plasma estradiol-17β between before and after GnRH administration was not significant in all dosage of GnRH. Moreover, the response to GnRH in each cat was individual. Additionally, the mean plasma progesterone in all pubertal female cats was lower than 1.5 ng/ml both before and after GnRH administration. In conclusion this study indicated the different of response to exogenous GnRH in prepubertal male and female cats. it may be ascribed to the regulation of supra-pituitary in prepubertal male and female cats.