Changes in the activity of the brain renin-angiotensin system and in the functional state of the pituitary-adrenal system of rats under the influence of captopril]

While studying the effect of peroral captopril injections on the activity of renin-angiotensin system (RAS), the activity of angiotensin-converting enzyme (ACE) and angiotensin II content from anterior and mediobasal hypothalamus, medulla and adenohypophysis of intact rats has been established to decrease. Captopril administration decreases ACE activity which increases after hydrocortisone injection in rat medulla and striatum. Captopril results in no potentiation of hormonal effect in hypothalamus and in adenohypophysis where ACE activity decreases following hydrocortisone injection. A decrease in the RAS activity of brain structures and adenohypophysis induced by captopril administration to rats is accompanied by the inhibition of the activity in the pituitary-adrenal system. A decrease in ACTH level and in 11-hydroxycorticosteroids of the rat blood plasma has been determined after single captopril injection in the dosage of 10 and 50 mg/kg of body weight. Duration of the effect depends on the captopril dosage.     

Cholinesterase activity of the hypothalamo-hypophysial neurosecretory system in rats during the ontogenetic development

Summary The hypothalamic region and the neural lobe of rats from the 16th foetal day to adult animals have been studied for acetylcholinesterase and cholinesterase activity after Karnovsky. The attention was focused on the magnocellular nuclei-supraoptic and paraventricular, the median eminence and the neural lobe. Acetylcholinesterase activity appears in the paraventricular nucleus on the 18th foetal day, i.e. prior to that in the supraoptic nucleus. Heterochronic development and heteromorphism of paraventricular neurosecretory cells have been noticed. The median eminence shows no clear acetylcholinesterase activity. There are acetylthiocholine and butyrylthiocholine positive structures in the posterior pituitary. These structures are especially pronounced in 30–47-day rats. The cholinergic mechanism of release of neurohormones from the neural lobe is suggested. The results are discussed in functional and phylogenetic aspects.     

Effect of immunization on functional state of thyroid gland and thyroxine binding in rat organs

A number of modern research methods were used in experiments on 220 white rats to examine thyroid function at varying times after single immunization with typhoid vaccine. It was found that on the 1st and 2nd days of the observation period, only cAMP level of the thyroid parenchyma decreases. Three, four and seven days following immunization, thyroid function is drastically reduced, which manifests by a decrease in 131I uptake by the thyroid gland. Also decreased were the conversion ratio, the levels of thyroxine and triiodothyronine in blood serum and incorporation of labeled thyroxin by the heart, liver and spleen. During the productive phase of the immunogenesis (days 10, 15, 20 and 25), all the test indicators considerably increase. The phases of the reaction obtained seem likely to be a consequence of reciprocal relationship between the thyroid and sympathoadrenal systems (the inductive period), as well as by the feedback effect (the productive period of antibody formation). The reaction of thyroid function to immunization is regarded as a component of non-specific adaptation response of the body to an extreme irritant, that provides for metabolic reconstruction necessary for the synthesis of antibodies and formation of immune lymphocyte populations.