A comparison of the uterotrophic response in cyclic and ovariectomized normotensive and spontaneously hypertensive rats

The uterotrophic response in the normotensive (CD) and the hypertensive (SHR) rat was compared in intact cyclic rats and in ovariectomized rats given oestradiol. The parameters measured were blood flow, and uterine wet and dry weights. In the cyclic animals blood flow to the oestrogen target tissue varied throughout the oestrous cycle, peak flows being achieved at pro-oestrus; in the SHR rat, however, the pro-oestrous maximum was significantly attenuated compared with the CD rat. Uterine wet and dry weights were similar. The temporal response to oestradiol in ovariectomized rats showed that the CD rat the hyperaemic response peaked earlier than in the SHR rat, significant changes in terms of increased water imbibition also occurred more quickly in the CD strain. In both strains, uterine dry weight was the last parameter to be significantly increased, the maximum weight being attained more quickly in the SHR rat. The results of this study indicated that it is the blood flow to the oestrogen target tissues of the uterus and vagina that is most susceptible to change with strain of rat.