Abstract: 337

PULSATILE 'PHYSIOLOGICAL' INFUSION OF RECOMBINANT SINGLE CHAIN HUMAN LUTEINIZING HORMONE (schLH) STIMULATES PRECOCIOUS SERTOLI CELL PROLIFERATION IN THE PREPUBERTAL MALE RHESUS MONKEY.

Suresh Ramaswamy¹ , Tony M Plant^{1 *}, William H Walker¹ , Gary R Marshall^{1 2 *}
University of Pittsburgh School of Medicine, Department of Cell Biology and Physiology, Pittsburgh, PA ¹
University of Pittsburgh School of Medicine, Department of Pediatrics, Pittsburgh, PA ²

In the male rhesus monkey, a marked proliferation of Sertoli cells occurs at puberty and this may be induced precociously by pulsatile gonadotropin stimulation. The present study determined the relative roles of FSH and LH in initiating the pubertal proliferation of Sertoli cells. 12 juvenile monkeys (16-19 mo of age; 2.4-3.7 kg bw) were used: groups of 4 received an intermittent bolus iv infusion of either schLH (3 IU/kg), recombinant human (rh) FSH (2 IU/kg), or vehicle every 3h for 11 days. Blood samples were collected during LH and FSH stimulation to document the circulating profiles of infused gonadotropins and the response of testicular hormones. On day 11, the monkeys were castrated. The testes were weighed and one-half of a testis was fixed in Bouin's fluid and embedded in paraffin. The number of Sertoli cells per testis was estimated stereologically. LH and FSH concentrations during pulsatile infusion of gonadotropins were episodic and apparently physiologic, as reflected by circulating T and inhibin B levels, respectively. Peak levels of infused gonadotropins were approximately 4 (hLH) and 16 (hFSH) IU/L. Both LH and FSH infusion induced a significant increase in testicular weight compared to vehicle treatment (1.05±0.15, 0.91±0.12, and 0.56±0.14 g, mean±SD, respectively). Interestingly, LH resulted in a marked proliferation of Sertoli cell number (3.0±0.6 × 10⁸ and 1.9±0.3 × 10⁸, LH and vehicle), and this was indistinguishable from the effect of FSH (3.4±0.9 × 10⁸). These results are consistent with an earlier observation (Schlatt et al, Eu J Endo., 133:235, 1995) and indicate that, in primates, LH and FSH both contribute to the pubertal initiation of Sertoli cell proliferation.

    This abstract is being presented on Monday, August 2 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.