Serum markers of general body condition in rats with maxillofacial pain syndrome

Abstract

Relevance. Recognition of pain and stress presents significant difficulties due to the lack of highly informative, objective criteria for assessing the state of the animal body in experimental algology. Acute pain is a signal of the presence of damage and danger, that performs a protective function. However, chronic pain emerging in pathological conditions is accompanied by structural and functional damage at the molecular level. In pain syndromes, there are changes in hormone levels, disorders of physiological functions (immune and others) that require high energy expenditure, and deceleration of inflammatory reactions. To objectivize the integrative assessment of the mammalian body condition during the development of pain syndrome, we used the detection of serum structural markers with the Lithos System technology. Aim. Revealing specific features of serum markers for general body condition in rats with maxillofacial pain syndrome. Methods. The study was conducted on 32 female Wistar rats (body weight 252.0±18.0 g). Four experimental groups were formed: M1 and M2, rats injected with sodium monoiodoacetate (16 mg/kg) 0.04 ml into the temporomandibular joint; S1 and S2, rats that received an intra-articular injection of saline 0.04 ml. In rats of groups M1 and S1, blood for the study was collected on day 14, and in groups M2 and S2, on day 28 after the injection. Blood serum was studied by cuneiform dehydration using the Lithos System technology. Results. Rats with experimental pain syndrome were characterized by a shift in the expression degree of the systemic indicators for the structural organization of serum facies, “harmony” and “energetics”, towards moderate and low values compared with the control. Those changes are most pronounced at relatively early stages of observation, namely, two weeks after the sodium monoiodoacetate injection into the temporomandibular joint. In animals with induced pain syndrome, high expression of the “stress” marker was observed at late terms of the study, at 4 weeks after intra-articular injection of sodium monoiodoacetate. The number of rats with the presence of the “fibrosis” marker in serum facies two weeks after the sodium monoiodoacetate injection into the temporomandibular joint was greater than at the end of the 4th week of observation. These features may be related with the immune activation during a relatively late period after the induction of pain syndrome, which reduces the intensity of tissue sclerosing. Conclusion. The method for analyzing the systemic self-organization of non-cellular biological fluids, the “Lithos System” technology, is one of promising approaches to the unbiased assessment of the general state of the body in pain syndromes.