Testicular Endocrine Function in GH Receptor Gene Disrupted Mice

The consequences of disruption of GH receptor gene in GH receptor knockout mice on testicular function were evaluated. Adult male GH receptor knockout mice and their normal siblings were divided in to two subgroups and treated with either saline or ovine LH (0.3 μg/g BW) in saline. One hour after saline or LH administration, blood was obtained via heart puncture. Plasma IGF-I, LH, FSH, PRL, androstenedione, and testosterone levels were measured by RIAs. Testicular LH and PRL receptor numbers as well as pituitary LHβ-subunit and testicular sulfated glycoprotein-2 mRNA levels were measured. Also, testicular morphometric analysis was performed. Unlike in normal, wild-type mice, the circulating IGF-I was undetectable in GH receptor knockout mice. The plasma PRL levels were (P < 0.01) higher in GH receptor knockout mice than in their normal siblings. The basal LH secretion was similar in normal and GH receptor knockout mice. However, the circulating FSH levels were lower (P < 0.001) in GH receptor gene disrupt...