Rodinsky A. G., Zinov’eva E. G., Mozgunov A. V., Trushenko A. S.

CLINICAL AND EXPERIMENTAL MEDICINE

Scentific article

Diabetic neuropathy (DN) that accompanies diabetes mellitus (DM) is one of the most common and dangerous complications of the latter, and it involves the peripheral and central nervous system. The development of these complications is explained with inadequate glycemic control, in which there are fluctuations of glucose levels during the day. Previous studies have demonstrated that DN develops in the early stages of the disease, both at the level of the peripheral neuromuscular system unit and disrupts the afferent link of the reflex arcs of the spinal cord. Most researchers note the development of DN in humans but experimental researches have shown the development of neuropathy in early onset (several weeks to months). In the literature, there are especially deep illuminated the sensory link of DN, but little attention is paid to the development of motor neuropathy, so the problem is the least understood, especially when it comes to the functional state of the efferent fibers. Therefore, the aim of this study was to investigate the bioelectric activity of efferent fibers of the sciatic nerve in experimental DM one month after the beginning of the disease. DM was modeled by a single intraperitoneal administration alloksane monohydrate at the dose of 170 mg/kg. The animal was taken into acute experiment on the 30-th day after the modeling (onset of the disease) of diabetes. After the laminectomy and opening of the dura mater of the spinal cord, the were then isolated the ventral roots (VR) of spinal cord and cut at the entrance to the spinal cord. The stimulating electrodes were put on the sciatic nerve, the registration of bioelectric activity was carried out from the central segments of VR. There were analyzed the threshold chronaxy, latent period, duration and amplitude of the action potential (AP) of VR. Also the analysis of the dynamics of refractory phases was performed by applying the paired stimuli to the sciatic nerve (interval of 2-20 ms). The reliability of the data was evaluated by calculating the Student’s t-test and Mann-Whitney criterion, which were considered to be reliable at p < 0,05. It was found that in experimental DM was a tendency to increase the threshold of AP of VR (17 %, p > 0,05), as well as some increase in chronaxy (15 %, p > 0,05). It was found an increase in the duration of AP of VR (up to 38 %, p < 0,001) and reduce in amplitude (8 %, p < 0,01). In the study of inhibitory processes in the VR there was seen the tendency to increase the amplitude of the AP in response to the 2nd stimulus (p > 0,05) in animals with experimental DM. It was concluded that under experimental DM there disturbance took place function of not in only sensory fibers, as it was described in our previous studies, but also the motor fibers, of though when compared to the sensory deficit, the pathology of this type of fiber is expressed somewhat weaker because of the likely possibility of remodeled properties. Therefore, under conditions of hyperglycemia, a decrease in conductivity and a tendency to decrease in excitability are observed. So hyperglycemia provides obvious imbalance in the synchronization of the activity of VR fibers of the spinal cord. The revealed changes induce a more detailed study of the processes that occur in the VR of the spinal cord under hyperglycemia, such as the status of synaptic transmission and monosynaptyc reaction of VR.

diabetes mellitus, diabetic neuropathy, action potential, ventral root of spinal cord.

«Bulletin of problems biology and medicine» Issue 1 (106), 2014 year, 167-171 pages, index UDK 616. 379-008. 64-092. 9:612. 833