Enrichment of the habitat of captive rodents Heterocephalus glaber (naked mole rats) to implement their innate behavioral pattern of digging dense soil in search of food, paradoxically led to the appearance of unusual animals in the colony. They showed signs of cachexia, distinguished from other animals by a lower temperature (from 31 degrees C to 26 degrees C) and body mass index with decreasing proportion of subcutaneous fat. This animal demonstrated aggressive feeding behavior, but didn't gain weight even after finishing experiment with intensive physical activity. In histochemical analysis of tissues from cachexic and normal animals of the same age and sex liver hyperlipofuscinos is was revealed and indicated that animals when being in a habitat with an increased oxygen content for them (21 % versus 8 % in their natural underground habitat), experienced severe oxidative stress during physical exercise. Stress led to a disruption of the body's regulatory systems, a sharp increase in metabolism even at rest, an overload of the cardiovascular and respiratory systems and damage to organs and tissues. To clarify the pathogenetic mechanism of the observed phenomenon, microRNA was extracted from the animal tissues and sequenced. Then bioinformatics analysis of differential expression of microRNAs between groups of healthy animals and animals with idiopathic cachexia was performed. (c) 2025 Elsevier B.V. and Soci & eacute;t & eacute; Fran & ccedil;aise de Biochimie et Biologie Mol & eacute;culaire (SFBBM). All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Enrichment of habitat of the captive rodents Heterocephalus glaber (naked mole rats) allowing them to implement the innate behavioral pattern of digging through hard soil somehow led to the emergence of unusual animals showing signs of cachexia in the colony; these differed from other animals by the reduced body mass index associated with subcutaneous fat reduction. Furthermore, the animals itself showed aggressive eating behavior, but showed no weight gain even after stopping digging due to detachment of the camera with soil. The study aimed to clarify the pathogenetic mechanism underlying the reported phenomenon. For that animals showing signs of cachexia (one female and two males aged 4-5 years) were withdrawn from the colony, along with the animals showing no such signs (two females and one male aged 4-5 years) as controls. Histologic assessment of tissues revealed cardiac hypertrophy and hyperlipofuscinosis of the liver. Cardiac hypertrophy was also suggested by the results of the animal heart microRNA sequencing bioinformatics analysis that revealed elevated levels of microRNA responsible for the increased cell division activity and reduced apoptotic activity in the heart. These data suggest that the animals living in the habitat with the increased oxygen content (21% vs. 8% in the natural habitat, underground) experienced severe oxidative stress during physical activity, which resulted in dysfunction of body's regulatory systems, increased metabolism at rest, cardiovascular system overload, and damage to organs and tissues. Thus, naked mole rats can have normal physical activity only under conditions of low oxygen content.