EXPRESSION OF TOLL-LIKE RECEPTOR GENES IN RAT SPLEEN AND HYPOTHALAMUS UNDER CONDITIONS OF STRESS EXPOSURE AND ADMINISTRATION OF RAT DEFENSIN RATNP-3

Infectious diseases and immune disorders have been a problem for humanity for centuries. To combat various diseases and infections, it is essential to gain a deep understanding of how immune responses are triggered and modulated. In this regard, Toll-like receptors (TLRs) have become one of the main topics of biomedical research, since this family of proteins acts as one of the early determinants of immune response activation. One of the most common causes of changes in the immune response are stressful effects, which lead to redistribution reactions of blood leukocytes, changes in hormonal levels and cytokine production. It has also been shown that under stressful conditions, TLR4 gene expression increases. It is known that endogenous damage-associated molecular factors (DAMPs, or alarmins) can be ligands of Toll-like receptors. It can be assumed that among the endogenous compounds whose concentration increases under unfavorable conditions, there may be TLR antagonists, whose task is to prevent excessive expression of these receptors. The aim of the study was to determine how preventive administration of the endogenous antimicrobial peptide defensin RatNP-3 affects TLR3 and TLR4 gene expression in the hypothalamus and spleen of rats after acute emotional and physical stress induced by forced swimming in cold water for two minutes. Three hours after the application of stress to the rats, the spleen and hypothalamus were removed from the animals, RNA was isolated and a reverse transcription reaction was performed to obtain cDNA. The expression of the TLR3 and TLR4 genes was assessed relative to the expression of the housekeeping gene GAPDH (glyceraldehyde-3-phosphate dehydrogenase) by real-time PCR. It was found that three hours after stress exposure the expression of TLR3 and TLR4 genes increases in the hypothalamus and spleen. However, preliminary intraperitoneal administration of defensin reduces the expression level of these genes only in splenocytes, but does not affect their expression in the hypothalamus. Conclusions: These results indicate systemic activation of Toll-like receptors in hypothalamic structures of the brain and spleen in response to acute stress. The fact that administration of endogenous defensins does not affect the expression of TLR genes in the hypothalamus may indicate that the regulatory action of neutrophil granulocyte defensins is not mediated through central regulatory mechanisms.