Leptin is a 17-kDa protein, secreted by fat, that controls adiposity and has been proposed to have numerous effects on reproduction in the mouse. To assess whether the effects of leptin on testicular function are direct, we determined whether leptin can cross the murine blood-testis barrier. Multiple time regression analysis showed that a small amount of blood-borne leptin is able to enter the testis but does so by a nonsaturable process. In addition, no significant expression of leptin receptors was found at the Leydig cells or Sertoli cells of the testis. This compares with the presence of a saturable transport system for leptin at the blood-brain barrier and abundant receptors for leptin at the leptomeninges, neurons, and choroid plexus of the central nervous system (CNS). These results support the hypothesis that the effects of leptin on reproductive function are not mediated at the level of the testis but indirectly, probably through the CNS.

OB protein; obesity; reproduction; gonad; transport

This article has been cited by other articles:

				T. J. Kowalski, S.-M. Liu, R. L. Leibel, and S. C. Chua Jr. Transgenic Complementation of Leptin-Receptor Deficiency: I. Rescue of the Obesity/Diabetes Phenotype of LEPR-Null Mice Expressing a LEPR-B Transgene Diabetes, February 1, 2001; 50(2): 425 - 435. [Abstract] [Full Text]

				W. A. Banks, C. M. Clever, and C. L. Farrell Partial saturation and regional variation in the blood-to-brain transport of leptin in normal weight mice Am J Physiol Endocrinol Metab, June 1, 2000; 278(6): E1158 - E1165. [Abstract] [Full Text] [PDF]