[Morphofunctional changes in the adenohypophysis in suspended rats under the effects of support loads and retabolil]

Histological and histomorphometric methods were used to study morphofunctional changes in adenohypophyseal somatotrophs and gonadotrophs in male rats with the hind limbs deprived of the support load (30 d tail-suspension). Suspension of the rats was found to inhibit the functional activity of somatotrophs and sharply activate the synthetic and secretory functions of gonadotrophs. Injection of retabolil at the total dose of 10 mg per 100 g of the rat's body mass stimulated the somatotrophs activity both in intact and suspended rats suppressing at the same time the functional activity of gonadotrophs. Graded support loads (3 hrs./d) increased the activity of somatotrophs (though to a less degree than retabolil) and activated a little bit the secretory function of gonadotrophs. Combination of the support loads and retabolil was favorable to normalization of the somatotrophs function in the suspended animals. The synthetic activity of gonadotrophs in rats receiving the support loads and retabolil injections was below the control level. Emphasized is the point that morphological criteria of the somatotrophs function normalization in suspended rats as a result of support loading and retabolil injection alone are not sufficient to judge about normalization of the somatotrophic function of the hypophysis, since the growth hormone may not possess the biological activity.