Gonads, implantation

What are the potential effects of a test article on gonad function, mating behavior, implantation, and general fertility in male and female rats when administered through mating and implantation ... 

Ravivarapu HB, Moyer KL, Dunn RL Sustained suppression of pituitary-gonadal axis with an injectable, in situ forming implant of... 

The sex hormones of the gonads interfere with gonadotropin production in the hypophysis. Thus, although FSH stimulates estrogen secretion in the ovaries, the increased estrogen levels in the blood that follow depress FSH secretion by the hypophysis. This ovarian hypophyseal balance can readily be disturbed by implantation of an ovary in the spleen of castrated men or women. Under those circumstances, estrogens never reach the hypophysis, FSH secretion is uninterrupted, and the implanted ovary hypertrophies. Under appropriate conditions, the implanted ovary may develop cancer. A similar mechanism has been invoked... 

Pituitary ablation with Y was successful in 2 of 5 patients with diabetic retinopathy but hyporesponsiveness of the hypophysis to stress caused death in 4 patients (Lomsky et al., 1966). However, such implants can control retinopathy and preserve the patient s sight (Jauregui et al., 1968). The procedure was used in 22 patients with 75% showing distinct improvement but 5 others died of complications (Ray et al., 1968). The cotton wool spots of diabetic retinopathy, when treated by Y pituitary implantation, disappear in about 2.3 months but the capillary closure persists (Kohner et al., 1969). New capOlaries arise from the optic disc after Y implantation but results are better in patients below 40 years of age (Panisset et al., 1971). Such treatment is also beneficial in cases of the thyrotoxic malignant exophthalmos but the patients may develop adrenocortical insufficiency and gonadal hypofunction (Molinatti, 1964). 

Ravivarapu, H.B., Moyer, K.L., and Dunn, R.L. (2000) Sustained suppression of pituitary-gonadal axis with an injectable, in situ forming implant of leuprolide acetate. J. Pharm. Sci., 89, 732-741. 

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