Oxytocin (OT) and vasopressin (VP) are neurohypophyseal hormones with potent stimulatory actions on the uterus. In order to determine whether these hormones may have a paracrine action on the uterus, OT and VP gene expression was studied in myometrium from pregnant rats at gestational ages of 14 and 20 days, and from ovariectomized animals treated with oestradiol and progesterone. OT and VP mRNA concentrations were measured using real-time quantitative reverse transcription-PCR, and OT-and VP-like immunoreactivities were determined using RIA. OT mRNA was detected in the uterus from pregnant rats, but did not differ between the groups of different gestational ages. Oestradiol significantly (P!0 . 05) stimulated OT gene expression in ovariectomized rats. Progesterone alone was without effect on OT mRNA concentrations, but significantly (P!0 . 05) reduced the oestradiol-induced OT mRNA accumulation. The OT-like immunoreactivity in an extract of myometrium from pregnant rats was eluted from a reverse-phase HPLC column with a retention time identical to that of synthetic OT. Neither VP mRNA nor VP-like immunoreactivity was detected in the myometrium from pregnant or ovariectomized rats. The study demonstrates steroid-dependent expression of the OT gene in the rat uterus and processing of uterine preprooxytocin to the mature nonapeptide. The data support the theory that this peptide may act in a paracrine pathway. No evidence was found for the presence of VP in the uterus so that, if the hormone is involved in a stimulatory action on this tissue, it probably acts via an endocrine mechanism.

The chronotropic, calorigenic, and thermogenic effects of isopropyl noradrenalin (INA) and of the vapor mixture of INA and propranolol were studied in 86 adult male albino rats over the course of development of hyperthyrosis induced by 1 to 12 injections of triiodothyronin in a dose of 100 \xg/kg. The Pl-adrenergic reaction of the heart and the calorigenic and thermogenic reactions undergo several phases upon stimulation with isadrin in a dose of 2.0 pg/kg/min: latent period, period of high reactivity, and period of reduction of this activity. The efficacy of inderal (25 \ig/kg/min) adrenoblocking of the positive chronotropic effect of exogenously administered isadrin decreases with the progress of hyperthyrosis.

В работе изучено действие тиреоидных гормонов на выраженность физиологических реакций при адренергической стимуляции (в дозе 2,0 мкг•кг-1 •мин-1 в течение 20 мин) в ходе развития экспериментального гипертиреоза. Создано две группы крыс. Животным 1-й группы вводили трийодтиронин. Продолжительность инъекций колебалась от 1 до 12 сут. Следовательно было 12 подгруп получавщих 1, 2, 3 и т.д. вплоть до 12 инъекций гормона. Вторая группа была контрольной. Показано что в процессе развития экспериментального гипертиреоза все физиологические реакции изменяются в соответствии с законом, который может быть описан параболой общего вида при значении степени в уравнении, равной трем.

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