Basal testosterone secretion and response to human luteinizing, follicle-stimulating, and growth hormones in culture of cells isolated from testes of infants and children.

Little is known on the hormonal regulation of the early postnatal phase of Leydig cell activation in the human. Testosterone secretion by prepubertal testicular cells in culture was studied in two different age groups, 0-7-mo-old (group 1) and 16-36-mo-old (group 2) boys. A mixed cell preparation was isolated from testes collected at necropsy and maintained in culture for 6 d. Cells were cultured in serum-free medium in basal conditions and under the stimulation of human (h)LH, hFSH, or recombinant hGH, and the secretion of testosterone was determined on d 6 by RIA. In basal conditions, cells of group 1 secreted more testosterone (median 5.83 pmol/10(6) cells.d, n = 7) than cells of group 2 (median 1.73, n = 5), p < 0.05, reflecting the steroidogenic potential of the testes in vivo. Under hLH stimulation, cells of group 1 responded by increasing testosterone secretion significantly. Surprisingly, hFSH stimulation elicited a similar response in cells of group 1. Because FSH receptors are presumably located in Sertoli cells, it is concluded that these cells secreted a paracrine factor that stimulated testosterone secretion by Leydig cells. On the other hand, recombinant hGH also stimulated the secretion of testosterone by cells of group 1. Recombinant hGH could have interacted with either GH or prolactin receptors of testicular cells. Cells of group 2 did not respond to any stimulus. Because serum levels of LH, FSH, GH, and prolactin are higher during the first months of life than later in childhood, it is possible that the early postnatal activation of the testis is under multiple pituitary hormone influence.