Fig. 1
From: Psychoactive drugs and male fertility: impacts and mechanisms
The hypothalamic-pituatary-testicular axis +  = stimulatory effect;—= inhibitory effeect. The hypothalamic-pituitary–testicular axis tightly regulates the male reproductive function. Gonadotropin releasing hormone (GnRH) is released in pulsatile manner from the hypothalamus to stimulate the release of the gonadotropins, which include the follicle stimulating hormone (FSH) and luteinizing hormone (LH). These gonadotropins stimulate the testes to maintain optimal testicular function. FSH stimulates the Sertoli cells to drive spermatogenesis, while LH stimulates the Leydig cells to promote testosterone biosynthesis, which is also required for sexual drive (libido) and spermatogenesis