Effect of Oligopeptides-Homologues of the Fragment of ACTH on Morphogenetic Markers of Stress in the Adrenal Glands on the Model of Acute Cold Injury in Rats.

Objectives: Aim of the current study was to evaluate the stress-protective effect of oligopeptides-homologues of the adrenocorticotropic hormone (ACTH) fragment 15-18 on morphogenetic signs of stress reaction of the adrenal glands under acute cold exposure (CE) in rats.

Materials And Methods: The acute cold stress was reproduced by placing random-bred male rats in a freezer at a temperature of -18°C for 2 hours. The peptides-homologous of ACTH acetyl-(D-Lys)-Lys-Arg-Arg-amide (KK-1) and acetyl-(D-Lys)-Lys-(D-Arg)-Arg-amide (KK-5) and the reference medicine (Sema) were administered intranasally in a dose of 20 mg/kg 30 minutes before and after CE. Rectal temperature was measured before and 10 min after CE. , and the area of cells and nuclei of adrenocorticocytes of the were measured.

Results: KK-1 significantly prevented structural changes in the adrenal cortex and medulla and stabilized the secretory activity of glucocorticoid-producing cells. However, the congestion of the capillaries of the and remained in some locations. cells had a marked tendency to decrease, and the area of nuclei significantly decreased (<0.05) recovering the width to control animals' markers. KK-5 had a more marked recovery of the adrenal glands (a greater saturation of cytoplasm of adrenocorticocytes of and ). The number of chromaffin cells at rest was increased in the . KK-5 statistically significantly normalized both the area of cells (<0.05) and the area of nuclei (<0.05) of the , unlike KK-1, which reliably restored only the marker of the nuclei area. Some morphometric parameters of acute stress hypertrophy remained in the adrenal glands of rats receiving Sema.

Conclusion: KK-1 and KK-5 prevented the manifestation of acute stress reactions in the adrenal cortex of rats. KK-5 had a more marked stress-protective effect compared with the peptide KK-1. Both study substances exceeded the reference medicine Sema. KK-5 is a promising stres-sprotector and frigoprotector.