Cluster organization of neurons of the sensitive node of the rat spinal nerve

Objective - to analyze the morphological features of neurons containing TRPV1, substance P (SP), calcitonin a gene related peptide (CGRP), neurophilament protein 200 kDa (NF200), calbindin 28 kDa (SV) markers of the thoracic spinal ganglion in rat postnatal development. Material and methods. Immunoreactive (IR) neurons in 3-, 10-, 20-, 30-, 60- and 90 day old female Wistar rats were studied using immunohistochemical methods. Results. The study of neurons of sensitive ganglions at various ages shows both the general laws of the chemical organization of neurons and age related features of the dynamics of formation of the expression of the studied markers. At three days of age, the number of neurons of different IR populations was increasing depending on the marker: SP - CGRP - NF200 - TRPV1 - CB (9,5 % - 12,8 % - 20,6 % - 22,6 % - 37,4 %). Subsequently, the number changes were heterochronous: the percent of CGRP, NF200 and TRPV1 neurons increased, while the number of cells expressing SP and CB decreased. Immunoreactivity of CGRP, NF200 and CB was detected in heterogeneous sizes of neuron populations. Expression of TRPV1 and SP was shown by small (up to 600 μm2) and very small neurons (up to 300 μm2). Conclusion. On the section of the thoracic spinal ganglion, clear groupings of IR neurons are determined, combining from 2-3 to 8-10 cells. Neuronal clusters are formed according to the principle of heterogeneity: by neurochemical organization, by size-\\ from very small to very large neurons.