STUDY OF PROLIFERATIVE ACTIVITY OF PAROTID SALIVARY GLAND CELLS IN OUTBRED WHITE RATS WITH EXPERIMENTALLY INDUCED RHEUMATOID ARTHRITIS: THE ROLE OF KI-67

Extra-articular manifestations are a significant focus in rheumatoid arthritis research. Determination of the proliferation marker Ki-67 expression level is an effective method for evaluating quantitative and qualitative changes in digestive organs in rheumatoid arthritis. Objective. The aim of this study is to assess morphological changes in the glandular apparatus of the parotid salivary gland in outbred white rats subjected to a model of rheumatoid arthritis induced by Complete Freund's Adjuvant, using the expression level of the proliferation marker Ki-67 as an indicator of the inflammatory process severity. Materials and Methods: The experimental group comprised 30 four-month-old outbred white rats of both sexes, with a mean body weight of 170.5 ± 9.1 g. All laboratory animals were sourced from a single vivarium and maintained under standard conditions: 50–60% relative humidity, 19–22°C ambient temperature, and a 12-hour light/dark cycle. Rheumatoid arthritis was induced using Complete Freund's Adjuvant. All studies were approved by the Ethics Committee of the Bukhara State Medical Institute and adhered to bioethical standards, including justification for animal use; compliance with the 3Rs principles; use of humane methods; confirmation of researcher competence. Specimens were analyzed using a trinocular microscope at 200–400× magnification. Morphometric analysis was conducted with QuPhat 4.4.0 software. The percentage of Ki-67-positive cells was calculated relative to the total cell count in the field of view. Morphology of Salivary Glands in an Experimental Model of Rheumatoid Arthritis. Code: 14.00.02 Morphology. Implementation Years: 2024–2026. The study was conducted as part of the research plan of the Bukhara State Medical Institute. Results and Discussion. In all examined samples, Ki-67 expression levels ranged from 32.04% to 38.19%, indicating elevated cellular proliferation. High Ki-67 expression in the parotid gland in modeled rheumatoid arthritis does not allow definitive classification of the tumor as aggressive or non-aggressive but may reflect cell cycle activity and proliferation typical of inflammatory processes such as rheumatoid arthritis. Conclusions: The findings confirm proliferative activity in the parotid gland of outbred white rats with experimentally induced rheumatoid arthritis.

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