Rat transtibial hindlimb amputation model: characteristic of the central nervous system functional state, physical endurance and body mass in dynamic
Authors: Hutorka Mykyta , Kyrylov Dmytro , Meklenburtsev Oleksandr , Shtrygol’ Sergiy , Taran Andrii , Ruban Olena 
Published: December 2024

Limb loss is a relevant medical and social problem. In a full-scale war environment, amputation became a frequent occasion, which requires adequate rehabilitation measures in preparation for prosthetic procedures. The post-traumatic period's peculiarities, specifically the central nervous system (CNS) functional characteristics and physical endurance, must be known. Experimental studies on animal models play an important role; however, there is no information available about such studies.
The aim. To determine the influence of hindlimb loss on the state of the central nervous system in terms of behavioural responses, physical endurance, and body mass dynamics of rats in the early and late post-amputation period. To characterise the indicated amputation model for further use in experimental studies.
Materials and methods. The experiment was conducted on white male rats. Transtibial amputation at the level of the lower third of the hind limb was performed in aseptic conditions in 6 animals under thiopental-sodium anaesthesia (40 mg/kg intraperitoneally). The state of CNS and physical endurance was determined during the early (3-4 days after amputation) and long-term (2 months after surgery) periods. Locomotor and exploratory activity, emotional responses and vegetative support were determined in the Open field test, and anxiety was determined in the Light-dark box test. The coordination of animal movement was measured in the rotarod test, and the depression level was measured in the Porsolt swim test. The physical endurance of the rats was studied using the forced swimming test with a load (5 % of the body mass at the base of the tail) as a control were used rats with comparable body mass. STATISTICA 12.0 was used to process the results.
Results. In the early post-amputation period, exploratory behaviour and emotional results of rats in the Open field test were significantly suppressed, while in the long-term period of significance, only the reduction of emotional responses. In the Light-dark box test, the latency to enter the darkened compartment of the chamber increases reliably in both periods of observation (especially in the early period). Collectively, these results indicate changes in the reaction of animals with amputation of the hindlimb to stressful experimental conditions, in particular, an anxiety reduction, which requires further research. In the rotarod test, a significant deterioration of movement coordination of rats with amputation was found in both observation periods. After amputation, the manifestations of depressive behaviour in the Porsolt swimming test progressed, and the physical endurance in the forced swimming test with a load was significantly reduced. The body mass of rats with hindlimb amputation was significantly increased after 2 months (22 % average increase vs 4 % average increase in control, p<0.01). Results are important for experimental-based optimal rehabilitation programs after lower limb amputation.
Conclusion. An easy-to-perform model of transtibial amputation at the level of the lower third of the hindlimb in rats is proposed. It is concluded that after amputation, exploratory behaviour and emotional responses were suppressed, which indicates changes in the responses of animals with amputation of the hindlimb to stressful experimental conditions, in particular, an anxiety reduction, which differentiates this animal amputation model from human amputation. After amputation, the depressed behaviour of rats progresses, movement coordination steadily worsens, and physical endurance is significantly reduced. The body mass of rats with hindlimb amputation increases considerably