Effect of anti-luteinizing hormone antibodies on the gonadotropic cells of the pituitary in immature male rats: an electron microscopic study.

Treatment of immature rats with antigonadotropic serum results in atrophy of gonads and castration-like changes of gonadotroph cells in the pituitary gland. Newborn male albino Wistar rats were daily and subcutaneously inoculated with 0.1 to 0.8 ml of anti-luteinizing hormone (LH) sera from the first 24 hours of age, through the first 5 weeks. For controls, a similar schedule with normal rabbit serum was used. Rats were killed at weekly intervals and pituitaries were fixed for electron microscopy. The anti-LH titer, determined by microhemagglutination, was between 1:2, 560 and 1:10,240; the greatest contaminant was follicle-stimulating hormone, with the antiserum ranging from 1:160 to 1:320. Absorbed antisera, checked by double agar diffusion against unabsorbed antisera, showed no precipitin lines, indicating no antigen excess. There was no significant cytologic difference between control and experimental pituitaries during the 1st week of treatment. At the end of the 2nd week, gonadotroph cells contained a highly developed Golgi complex; by the 3rd week these cells contained pronounced, dilated, saclike ergastoplasmic cisternae, with few secretory granules in the cytoplasm of one type; by the 4th week, ergastoplasmic cisternae had broken down to form the first large vacuoles of "castration" LH gonadotrophs, some of which contained typical granules. Numerous mitotic and chromophobe cells were also observed. At the end of the 5th week castration LH cells persisted, in addition to mitotic cells, chromophobes, and numerous follicle-stimulating hormone gonadotrophs with degenerated features. The effect of anti-LH antisera on pituitary gonadotrophs could be explained as a neutralization of endogenous LH, probably not only inhibiting the long feedback mechanism, but also the short feedback loop at the level of the same pituitary cells.