N. Yu. Kudryashova

Elucidation and Characteristics of Non-opioid β-Endorphin Receptors in Rat Adrenal Cortex

Abstractβ-Endorphin-like decapeptide immunorphin (SLTCLVKGFY), a selective agonist of non-opioid β-endorphin receptor, was labeled with tritium to specific activity of 24 Ci/mmol. It was used for the detection and characterization of nonopioid β-endorphin receptors on rat adrenal cortex membranes (Kd1 = 39.6 ± 2.0 nM, Bmax1 = 40.7 ± 2.3 pmol/mg protein; Kd2 = 0.25 ± 0.01 μM, Bmax2 = 187.8 ± 9.4 pmol/mg protein). β-Endorphin was found to inhibit the [3H]immunorphin specific binding to membranes (Ki = 70.0 ± 9.2 nM); naloxone, [Met5]enkephalin, and α- and γ-endorphins tested in parallel were inactive. Immunorphin at concentrations of 10–9-10–6 M was found to inhibit the adenylate cyclase activity in adrenocortical membranes, while intramuscular injection of immunorphin at doses of 10-100 μg/kg was found to reduce the secretion of 11-oxycorticosteroids from the adrenals to the bloodstream.

Effects of GSM-Frequency Electromagnetic Radiation on Some Physiological and Biochemical Parameters in Rats

Single exposure of white outbred rats to electromagnetic radiation with a frequency 905 MHz (GSM frequency) for 2 h increased anxiety, reduced locomotor, orientation, and exploration activities in females and orientation and exploration activities in males. Glucocorticoid levels and antioxidant system activity increased in both males and females. In addition to acute effects, delayed effects of radiation were observed in both males and females 1 day after the exposure. These results demonstrated signifi cant effect of GSM-range radiation on the behavior and activity of stress-realizing and stress-limiting systems of the body.

Effect of hypoxia during early organogenesis on cardiac activity and noradrenergic regulation in the postnatal period

Cardiac activity in rats during the postnatal period was studied in vitro and in vivo after exposure of rat pups to antenatal acute hypobaric hypoxia at the stage of organogenesis (day 9–10 of gestation). Cultured cardiomyocytes from rat pups exposed to antenatal hypoxia were characterized by increased rate of contractions and decreased reactivity to norepinephrine. Heart rate elevation, predominance of sympathetic influences on cardiac activity, and significant increase in norepinephrine concentration in the cerebral cortex were found in freely moving animals exposed to antenatal hypoxia. Our results indicate that hypoxia at the stage of organogenesis modulated cardiac activity during the postnatal period, which manifested at the level of effector structures in the heart and activity of regulatory systems.

Synthetic peptide immunocortin stimulates the production of 11-oxycorticosteroides by rat adrenal cortex through ACTH receptors

Adrenocorticotropic hormone (ACTH)-like peptide immunocortin (IMC) VKKPGSSVKV, corresponding to the amino acid sequence 11-20 of the variable part of human immunoglobulin G (IgG) 1 heavy chain, at concentrations of 10(-9)-10(-6) I was found to increase the adenylate cyclase activity in adrenal cortex membranes, while intramuscular injection of immunocortin at doses of 10-100 microg/kg was found to stimulate the secretion of 11-oxycorticosteroids (CS) from the adrenals to the bloodstream. Immunocortin was labeled with tritium to specific activity of 22 Ci/mmol. Receptor binding studies revealed that [(3)H]immunocortin ([(3)H]IMC) bound with high affinity and specificity to ACTH receptors on rat adrenal cortex membranes (K(d)=2.1+/-0.2 nM, B(max)=1.1+/-0.1 pmol/mg protein).

Effect of antenatal hypoxia on age-specific dynamics of ECG parameters and content of biogenic amines in the central nervous system.

We studied the effect of acute antenatal hypoxia during the stages of progestation and early organogenesis on some ECG parameters and level of biogenic amines in brain structures in rats. The effect of acute hypoxic exposure during the organogenesis period on the studied parameters was more pronounced than the effect of acute hypoxic exposure during the progestation period. The shift of the autonomic balance towards the sympathetic regulation of cardiac activity is linked with increased content of biogenic amines in the brain stem and cortical structures.

[An ACTH-like peptide immunocortin: effect on the activity of cells from the rat adrenal cortex].

The effect of immunocortin, an ACTH-like decapeptide VKKPGSSVKV corresponding to the 11–20 sequence of the variable part of the human IgG1 heavy chain on the content of 11-hydroxycorticosteroids (CS) in rat adrenal glands and blood serum in vivo was studied. An intramuscular injection of immunocortin at a dose of 10 μg/kg was found in an hour to induce a twofold decrease in CS content in the adrenal glands and a 1.8-fold increase in the blood serum CS content. At the same time, an immunocortin dose of 100 μg/kg exerted practically no effect on the CS content and its dose of 1000 μg/kg increased the CS content both in adrenal glands and in blood serum by 1.6 and 2.2 times, respectively. Four hours after the injection of any of the three doses of immunocortin, the CS content in adrenal glands did not differ from the control value, and after 24 h the content decreased threefold. Immunocortin was shown to be bound by the ACTH receptors in the membranes of the rat adrenal cortex with a high affinity and specificity (inhibiting the specific binding of 125I-labeled ACTH-(11–24) peptide with Ki of 1.2 nM).

Possibilities of using the protective activity of MIGI-K under conditions of radionuclide contamination

Experimental studies of mussel hydrolyzate MIGI-K show that this drug has the ability to increase the general and radiation resistance of the human body. Moreover, MIGI-K facilitates elimination of incorporated radionuclides from the body. A series of properties of this drug, in particular, the absence of toxicity or harmful side effects, makes it possible to apply MIGI-K as an adaptogen (a food supplement exhibiting therapeutic and preventive action and used to increase excretion of radionuclides from people who took part in the liquidation of the accident at the Chernobyl Nuclear Plant).

Changes of glucocorticoid level in plasma and adrenal glands of pregnant rats and their offspring after antenatal stress of different etiology

We investigated the glucocorticoid level in plasma and adrenal glands of pregnant rats in the period of early organogenesis. Tests were performed 24 hours after stress of different etiology (acute hypobaric hypoxia, intermittent normobaric hypoxia, and immobilization) and then repeated in the adult offspring. There was a significant decrease in the glucocorticoid level in pregnant rats 24 hours after hypoxic stress. Various changes of the basal glucocorticoid level were found in the offspring after antenatal stress. Changes were mostly found in female offspring.

Effects of single immobilization stress on the GABA metabolism and behavior of pregnant and nonpregnant female rats during early post-stress period

We studied the effects of a single immobilization stress on pregnant (9th or 10th day of pregnancy) and nonpregnant female rats in the early post-stress period (1 day after a stress). We analyzed the changes in behavioral responses, activity of antioxidant systems (ASs), and GABA metabolism. It was shown that control unstressed pregnant rats had a higher level of locomotor and exploratory activities and a lower level of anxiety and emotional tension as compared to nonpregnant rats. The pregnant rats were characterized by a higher activity of glutamate decarboxylase (GDC). In nonpregnant rats in the early post-stress period, the locomotor and exploratory activity and “risk behavior” increased, while anxiety decreased. These changes were not related to changes in the GABA metabolism, while the efficacy of ASs was increased. In the group of pregnant rats, the consequences of immobilization included only a significant increase in the activity of GABA transaminase (GABA-T). Thus, pregnant rats had higher stress resistance than the nonpregnant rats, according to behavioral indices and activities of systems of GABA metabolism and ASs.

The effect of acute progestational hypoxia on ECG parameters and contractility of lymphatic vessels in mature white rats

Acute progestational hypoxia induced hyperactivity with low anxiety level and bradycardia in female descendants only. The experimental males demonstrated a significant increase in the duration and frequency of contractions of lymphatic vessels following NE application, while females showed no difference compared to the control.