Effect of tetrapeptide Acetyl-(D-Lys)-Lys-Arg-Arg-amide on immunological and biochemical parameters of Wistar rats using passive smoking models

Tetrapeptides, the homologues of adrenocorticotropic hormone fragment (15-18), play a special role among the bioregulators of the immune system. These compounds have cerebroprotective, neuroprotective and antioxidant properties. However, no available studies concerned the immunotropic properties of tetrapeptides in the models with exposure to xenobiotics, thus making such research quite relevant. Our study concerned the effects of tetrapeptide Acetyl-(D-Lys)-Lys-Arg-Arg-amide (laboratory code KK1) on the immunological and biochemical parameters of 72 female Wistar rats exposed to passive smoking. The experimental animals were fumigated with tobacco smoke for 8 hours. Synthetic peptide KK1 was administered intranasally at a dose of 40 µg/kg/day five times a day for 10 days. Cotinine was detected only in blood serum of rats from experimental groups, thus confirming a contribution of this tetrapeptide to the trend for normalization of some immunological parameters in experimental animals subjected to passive tobacco smoking, expressed as an increase in thymus mass and the number of splenocytes, and a decrease in the circulating immune complexes compared to the parameters of smoking rats of the group. We revealed that passive tobacco smoking in rats was accompanied by a general tendency to accumulation of iron, lead and nickel in peripheral blood. There was a marked increase in the concentration of cadmium, lead and cobalt in rats of the experimental group compared with the content of these trace elements in the liver of smoking animals injected with tetrapeptide KK1. The revealed shifts in immunological indices may be based, firstly, on hepatotoxic effect of ecotoxicants, The lymphoid lineage is mostly affected thus causing hypoplasia of the central and peripheral immunity organs. An evident sign of such pathology is a decreased cellularity of hematopoietic and lymphoid organs found in the present study. Secondly, the tobacco smoke components with prooxidant action may disrupt cellular redox homeostasis, causing damage to cell membranes, resulting in necrosis or apoptosis, thus explaining the revealed decrease in the number of thymocytes, splenic karyocytes and a decrease in the weight of organs. Thus, our results suggest usage of experimental passive smoking in order to evaluate efficiency of the tetrapeptides. Administration of Acetyl-(D-Lys)-Lys-Arg-Arg-amide peptide to the passively smoking rats is associated with tendency to normalize the mass of the thymus and spleen, the number of thymocytes and splenocytes, and a decrease in circulating immune complexes. Further studies are required to elucidate the effects of tetrapeptides upon the immune system.