PITUITARY REPLACEMENT THERAPY IN PSEUDO-HYPOPHYSECTOMY EFFECTS OF PITUITARY IMPLANTS UPON ORGAN WEIGHTS OF STARVED AND UNDERFED RATS

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Abstract
A condition of pseudo-hypophysectomy was induced in [male] and [female] rats by chronic underfeeding. These rats were implanted with rat pituitary glands for varying periods and the effects compared with changes produced by pituitary implants in normal and in completely starved rats. The pituitary implants decreased thymus wt. This was mediated indirectly through the sex hormones since after castration pituitary implants did not result in thymic atrophy. Thyroid wt. was unaffected and affirms the difficulty of stimulating the thyroid gland of the rat. No increase in spleen wt. occurred, thus adducing no evidence for the presence of any marked amt. of splenotrophic hormone in this number of pituitary implants. Pituitary implants resulted in an increase in size of ovaries and testes. The accessory genital organs were stimulated. The estrual cycles of the normal rats were supplanted by anestrus. In the underfed rats, the anestrous smear was replaced by the cyclical type found in the normal state, and in the starved animals the implants resulted in signs of continuous estrus. 7 pituitary implants produced no change in adrenal wt. in the normally fed rats. In the chronically underfed rat receiving a similar or greater number of implants, the adrenal glands returned to normal wt. despite the continued underfeeding. In [female] rats this occurred in the absence of the ovaries as well, while in the [male] rat it occurred in the presence of the stimulated testes. Starvation resulted in an increase in adrenal wt. Pituitary implants injected daily from the 1st day of starvation resulted in still further enlargement of the adrenal glands. Since starvation was the only state in which pituitary implants resulted in enlargement of the adrenal glands to above the normal wt,, the adrenal glands of starved rats may be hypersensitive to the adreno-trophic hormone of the pituitary.