The purpose of the study was to analyze the features of bioelectric activity of dorsal horn interneurons of the gray matter of the spinal cord under conditions of prolonged hypoandrogenemia by analyzing evoked potentials of the dorsal surface of the spinal cord. Materials and methods. The study was performed on Wistar male rats 5-6 months of age and weighing 180-260 g, which were divided into experimental (n=18) and control (n = 13) groups. Androgenemia was modeled by bilateral orchectomy. The dorsal root of L5 was stimulated by bipolar electrodes. The potentials of the dorsal surface of the spinal cord was evoked in the focus of maximum activity using a monopolar electrode. Threshold and chronoxia, latent period duration, total potentials of the dorsal surface of the spinal cord duration, duration and amplitude of afferent peak, N1, N2, N3 components and P-waves were studied, as well as presynaptic inhibition processes using paired stimulus method with intervals between 2 and 1000 ms. Results and discussion. The occurrence threshold for potentials of the dorsal surface of the spinal cord increased to 230.77±2.33% (p<0.001). Chronoxia in animals with experimental hypoandrogenemia decreased by 18.28±2.31% (p<0.001). In animals with hypoandrogenemia, the afferent peak amplitude increased by 98.33±5.88%, N1 increased by 51.08±2.86%, N2 increased by 49.64±2.40%, N3 increased by 207.41±4.82%. The P-wave amplitude showed an upward trend (p> 0.05). The latent period of occurrence of potentials of the dorsal surface of the spinal cord decreased almost twice (47.27±3.85%). The overall duration of the potentials of the dorsal surface of the spinal cord decreased to 78.40±3.32% (p <0.001). The P-wave duration decreased to 73.72±3.2% of the control value. Other components of the potentials of the dorsal surface of the spinal cord did not undergo any significant changes. When using pairwise stimuli, the rate of increase of the amplitude of the N1 component of the second response in animals with orchectomy lagged behind the values of the control group, especially at intervals from 6 to 50 ms. Conclusion. The results showed the development of multidirectional processes in the structures of the posterior horn of the spinal cord under conditions of experimental hypoandrogenemia. Thus, despite the increase in the occurrence of potentials of the dorsal surface of the spinal cord in the animals of the experimental group, probably by reducing the excitability of the primary afferents, the activity of the interneuron pool increases, primarily due to the inhibition of segmental and non-segmental interneurons, and some increase in the activity of the neuron amplitude of the P-wave. There is a slowdown of signals with a follow-up frequency exceeding 20 Hz with regard to nerve transmission in the structures of the posterior horn of the spinal cord, then under conditions of a long-term testosterone deficiency.
Keywords: spinal cord, dorsal horn, interneuron, androgen
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