STRUCTURAL CHANGES IN THE SUBNUCLEI OF PARABRACHIAL COMPLEX IN THE DEFICIENCY OF SEROTONINERGIC SYSTEM IN THE PRENATAL PERIOD OF RAT DEVELOPMENT

The study was performed on the offspring, obtained from 8 female Wistar rats, which were administered parachlorophenylalanine on day 16 of gestation, to deplete the endogenous serotonin in their offspring. Dorsal and ventral subnuclei of the parabrachial complex lateral part were studied in rats on postnatal days 10 and 14 days (5–6 animals for each time point) using histological, immunocytochemical and morphometric methods. It was shown that serotonin deficiency changed the structure of the subnuclei. In the ventral subnucleus, the population of large multipolar neurons was more sensitive to low levels of serotonin. In experimental animals, the size of neuron cell bodies was reduced 1.6 times in comparison with the control, while cell numbers in the population remained practically unchanged. Morphological characteristics of smaller neurons corresponded to those in the control group, but their numbers were reduced, which probably can explain some rarefaction of neurons in the nucleus. In dorsal subnucleus of the experimental animals, the neurons of both populations had more pronounced changes. Sizes of the cell bodies in both large and small neurons was significantly decreased 2.0 and 1.8 times, respectively; the volume of their cytoplasm was significantly reduced, compared to that in control animals, while the number of cells in both populations remained practically unchanged. The reaction demonstrating glial fibrillary acidic protein has shown that the astrocytic glial population was increased in both subnuclei in the experimental animals in the early postnatal period.

neurons, parabrachial subnuclei, serotonin, prenatal period