Testicular steroidogenesis in the rhesus monkey (Macaca mulatta

Area of Science:

• Reproductive biology
• Endocrinology
• Primate physiology

Background:

• Testicular steroidogenesis is crucial for male reproductive health.
• Understanding steroid conversion pathways in non-human primates like the Rhesus monkey (Macaca mulatta) provides comparative insights.

Purpose of the Study:

• To investigate the pathways of steroidogenesis in Rhesus monkey testicular tissue.
• To determine how pregnenolone and progesterone are metabolized by testicular fragments.

Main Methods:

• Incubation of Rhesus monkey testicular fragments (50 mg) for 3 hours.
• Use of radiolabeled pregnenolone-7-3H and progesterone-7-3H as substrates.
• Analysis of major metabolites using chromatography and radioactivity detection.

Main Results:

• Pregnenolone was primarily converted to progesterone (70.1%), with smaller amounts of 17-hydroxyprogesterone, androstenedione, and testosterone.
• The delta-5 pathway intermediates 17-hydroxypregnenolone and dehydroepiandrosterone were identified from pregnenolone.
• Progesterone metabolism yielded 17-hydroxyprogesterone, androstenedione, and testosterone, with 80.1% remaining unmetabolized.

Conclusions:

• Rhesus monkey testicular fragments can convert pregnenolone to testosterone.
• Both delta-4 and delta-5 steroidogenesis pathways appear to be active in Macaca mulatta testes.
• These findings contribute to understanding primate reproductive endocrinology.