[Investigation of beta-endorphin nonopioid reception in preimplantation development of mouse embryo in vitro].

The effect of beta-endorphin on 2-, 4- and 8-cell embryo development in vitro was studied. It is shown, that hormone has no effect on 2-cell embryos development, but it has enhanced viability of 4- and 8-cell mouse embryos. The number ofblastocyst formation increases in presence of 0.1 microM beta-endorphin in embryo cultured medium but the number of blastocyst with abnormal structure decreases. The effect of hormone on the change of intracellular concentration of Ca2+ ion in 2-, 4- and 8-cell mouse embryo has been studied with the help of fluorescent microscopy. The effect of adenylate cyclase, and phospholipase activity blockers and opioid blocker naloxone on the change of intracellular concentration of Ca2+ ion in early mouse embryo in the presence of beta-endorphin have been also studied. It is shown that 2-cell embryo has opioid and nonopioid beta-endorphin receptors, whereas 4- and 8-cell mouse embryos have only nonopoioid beta-endorphin receptors. It is also shown that the effect of beta-endorphin in the early mouse embryo through a nonopioid receptors occurs with the participation of intracellular Ca2+ and adenylate cyclase signaling system.

[Synthetic peptide immunorphin as an instrument for studying nonopioid beta-endorphin receptor].

Research results of the synthetic decapeptide SLTCLVKGFY (the author's term is immunorphin) corresponding to the 364-373 sequence of G heavy-chain human immunoglobulin are summarized. Special attention is paid to the interaction between immunorphin and a nonopioid (insensitive to the opioid antagonist naloxone) beta-endorphin receptor. Using radioligand analysis, data were found regarding the distribution and functions of a nonopioid beta-endorphin receptor in human and animal bodies and the binding characteristics of immunorphin with a nonopioid receptor.

[Stress-protective activity of the CH3CO-Lys-Lys-Arg-Arg-NH2 synthetic peptide (protektin)].

The CH3CO-Lys-Lys-Arg-Arg-NH2 peptide (the author has named it protectin) was synthesized, and its activity was studied during different stress actions. Protectin was found to normalize the content of corticosterone and adrenalin in adrenal glands and blood after its intranasal administration to rats one day before a cold or heat shock, or hypobaric hypoxia at doses of 1-10 microg/animal and after its intravenous administration just after acute hemorrhage at doses of 0.5-2 microg/animal. The intranasal administration of protectin at doses of 1-10 microg/rat one day before the heat or cold shock was also shown to prevent a change in the content of free histamine and the activity of diamine oxidase in myocardium, which was induced by the dramatic change in the activity of the enzyme after the temperature actions.

[Synthetic peptide KKRR corresponding to the human ACTH fragment 15-18 is an antagonist of the ACTH receptor].

Tritium-labeled synthetic fragments of human adrenocorticotropic hormone (ACTH) [3H]ACTH (11-24) and [3H]ACTH (15-18) with a specific activity of 22 and 26 Ci/mmol, respectively, were obtained. It was found that [3H]ACTH (11-24) binds to membranes of the rat adrenal cortex with high affinity and high specificity (Kd 1.8 +/- 0.1 nM). Twenty nine fragments of ACTH (11-24) were synthesized, and their ability to inhibit the specific binding of [3H]ACTH (11-24) to adrenocortical membranes was investigated. The shortest active peptide was found to be an ACTH fragment (15-18) (KKRR) (Ki 2.3 +/- 0.2 nM), whose [3H] labeled derivative binds to rat adrenocortical membranes (Kd 2.1 +/- 0.1 nM) with a high affinity. The specific binding of [3H]ACTH-(15-18) was inhibited by 100% by unlabeled ACTH (11-24) (Ki 2.0 +/- 0.1 nM). ACTH (15-18) in the concentration range of 1-1000 nM did not affect the adenylate cyclase activity of adrenocortical membranes and, therefore, is an antagonist of the ACTH receptor.

[Binding of beta-endorphin and its fragments to the non-opiod receptor of murine peritoneal macrophages].

The tritium-labeled selective agonist of the nonopioid beta-endorphin receptor the decapeptide immunorphin ([3H]SLTCLVKGFY) with a specific activity of 24 Ci/mmol was prepared. It was shown that [3H]immunorphin binds with a high affinity to the non-opioid beta-endorphin receptor of mouse peritoneal macrophages (Kd 2.4 +/- 0.1 nM). The specific binding of [3H]immunorphin to macrophages was inhibited by unlabeled beta-endorphin (Ki of the [3H]immunorphin-receptor complex 2.9 +/- 0.2 nM) and was not inhibited by unlabeled naloxone, alpha-endorphin, gamma-endorphin, and [Met5]enkephalin (Ki > 10 microM). Thirty fragments of beta-endorphin were synthesized, and their ability to inhibit the specific binding of [3H]immunorphin to macrophages was studied. It was found that the shortest peptide having practically the same inhibitory activity as beta-endorphin is its fragment 12-19 (Ki 3.1 +/- 0.3 nM).

[Stress-protective effect of the synthetic ACTH-like peptide leucocorticotropin].

We found that the tritium-labeled synthetic ACTH-like octapeptide leucocorticotropin corresponding to the 81-88 sequence of the precursor of human interleukin-1alpha ([3H]GKVLKKRR) is bound by the ACTH receptor of rat adrenal cortex with a high affinity and specificity (Kd 2.2 +/- 0.1 nM). This peptide was shown to exert no effect on the adenylate cyclase activity of the membranes of rat adrenal cortex in the concentration range from 1 to 1000 nM. Leucocorticotropin administration three times at doses of 10-20 microg/animal did not change the level of hydroxycorticosteroids (11-HOCS) in the rat adrenal glands in the absence of temperature action. At the same time, the peptide abolishes (at a dose of 20 microg/animal, three times) or significantly decreases (at a dose of 10 microg/animal, three times) the dramatic increase in the 11-HOCS content in the adrenal glands occurring in the case of cold or heat shock. Thus, leucocorticotropin normalizes the 11-HOCS level in the rat adrenal cortex during stress. The stress-protective effect of the peptide is mediated through the ACTH receptor.