Immunohistochemical Evaluation of Calretinin in the Periaqueductal Gray Matter of Rats Treated with Monosodium Glutamate

Abstract

Received: Revised: Accepted: Published online: December 20, 2018 June 22, 2019 June 25, 2019 November 23, 2019 Calretinin (CR) protects neurons against uncontrolled ions influx during glutamate induced toxicity. CR-positive cells are present in the periaqueductal gray matter (PAG) which is composed of dorsomedial (dm), dorsolateral (dl), lateral (l) and ventrolateral (vl) parts. The aim of the study was to assess distribution, morphology and morphometry of CR-immunoreactive (CR-IR) neurons in PAG of adult rats treated with monosodium glutamate (MSG). For 3 consecutive days the animals received physiological saline solution (group C), 2 g/kg BW (group I) or 4g/kg BW (group II) of MSG s.c. Brain slices of PAG were immunohistochemically stained for CR using a specific antibody in peroxidase-antiperoxidase method. In PAG of all animals CR-IR neurons were morphologically and morphometrically analysed under a light microscope. The density of CR-IR and all cells, the digital immunostaining intensity and the surface area of CR-IR cells bodies were measured. Microscopic analyses revealed the presence of CR-IR neurons in PAG in all animals. In the control these neurons were mainly localised in dm, dl and vl of PAG. Less number of CR-IR neurons was observed in dm and vl of PAG in group I of rats, while in group II they were present throughout the whole PAG. At the same time the overall number of cells was reduced. The analyses demonstrated an increase in the digital immunostaining intensity of CR-IR neurons of PAG under the influence of MSG. The obtained results may indicate the loss of CR-IR neurons in PAG of rats receiving MSG. ©2019 PVJ. All rights reserved