Effects of Sex and Thyroid Hormones on Ageing in Female Rats

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Abstract
Expts. were performed in order to study the effects of ovari-ectomy and of estradiol benzoate-butyrate, progesterone, andro-sterone, and thyroid hormone, administered separately or in various combinations, on the process of ageing in ovari-ectomized rats. Involution of some organs as shown by changes in their relative wts., was taken as an indication of ageing. Ovariectomy[long dash]i.e., artificial "climacteric"[long dash]as judged by relative involution of organs, accelerates the process of ageing in rats. All the hormones investigated possess 2 more or less pronounced properties: a stimulating, in most cases hypertrophic, action and simultaneously, in some cases, a pathologic. or depressing effect on uterus, vagina, preputial glands, thymus, spleen, and such vital organs as adrenals, thyroid, hypophysis, liver, kidneys, and heart, also on fat deposition and body growth. These effects were exerted on all of these organs and functions, or on some of them only. The stimulation and hypertrophy of the organs and tissues bringing their structure nearest to normal were obtained when all 4 hormones were administered simultaneously in suitable, not excessive, doses. In this way a cooperation of useful properties and more or less complete neutralization of pathologic effects occurred. Thus simultaneous admn. of the hormones may prevent some damaging effects due to hyperhormonization produced by a single hormone. Such hypersecretion of a single hormone is unnatural in the normal organism, in which all hormones are secreted simultaneously in a certain balanced ratio. The plurihormonal treatment used stopped the ageing involution of some organs in ovariectomized rats and, moreover, brought the relative wts. of these organs up to the level observed at a younger age.