Stimulatory Action of Ovine LH Releasing Factor on Synthesis of Luteinizing Hormone (LH) Demonstrated by the Rat Intratesticular Test System

概要

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Owing to the action of the intratesticular LH release reported in the previous paper (Suzuki et al., 1970), LH content of the rat anterior pituitary implanted into the rat testis rapidly decreased to about 1/100 of the original amount at 25 hr after the implantation. By this time, once highly stimulated testosterone output from the treated testis by the action of released LH, returned to almost the intact level again. The anterior pituitary of extremely low LH content thus obtained was utilized to see whether LRF induces LH release after promoting de novo synthesis of LH, or not. An ovine LRF preparation was infused for 20 minutes into the testis bearing a pituitary implant from 28 hrs after the pituitary implantation. At the assessment of 2 hrs after the start of infusion, LH content of the implant elevated from nearly zero level to the amount surpassing the pre-implanting level by 40%. And a concommitant maximal increase of testosterone output from the testis bearing the implant was also observed. At least in the preparation used, it is reasonably concluded that the LRF possesses the dual action of release and synthesis of LH as its primary action.