Post-hypoxic reaction of astrocytes of the visual cortex in the experiment

Abstract

Aim. To study the nature of reactive changes in astrocytic glia and oxidative metabolic status in the visual cortex of experimental animals after acute circulatory arrest. Methods. A series of experiments was performed on 47 mature males of noninbred white rats weighing 150-180 g. Under general ethereal anesthesia, a 5-minute anoxia was modelled by intrathoracic clamping of the vascular bundle of the heart followed by resuscitation and observation of the general state dynamics of the animals within 5 weeks after revitalization. Morphometric characteristics of reactive astrogliosis were studied with evaluation of a neurospecific protein (glial fibrillary acidic protein) by immunohistochemistry. The processes of free radical oxidation in brain homogenates were evaluated by determination of products reacting with thiobarbituric acid and by chemiluminescence analysis. The state of antioxidant system in the studied tissues was determined by recording the activity of superoxide dismutase and the level of reduced glutathione. Results. Regarding astroglial link, significant expression of glial fibrillar acidic protein was recorded throughout the observation period with maximum intensification on day 21 of the experiment. In the early periods and during the second week after recovery, the increase of the light sum of iron-induced chemiluminescence was noted, followed by a prolonged accumulation of secondary metabolites of lipid peroxidation. The investigated level of superoxide dismutase significantly increased not only on days 1-3, but also during the second week of the postresuscitation period. When assessing the level of reduced glutathione, a significant increase of its content occured during the first three days after recovery. Conclusion. The revealed activation of a neurospecific protein production with preceding shifts in pro- and antioxidative systems is indicative of hyperreactive character of astrogliosis formed in brain structures against the continuous oxidative stress, disrupting the functioning of neural networks in the visual cortex of experimental animals.

Features of Morphological Rearrangements of Structural Components in the Rat Pineal Gland Under the Impact of Heavy Metal Salts

“…In the parenchyma of the gland, especially in the subcapsular area and around the vessels, there was a slight degree of reactive astrocytic glial response, which can be considered an active adaptive response of neuroglia to the impact of heavy metal salts [12]. According to the literature [13], this pronouncement of the glial response in this particular area of the gland was explained by the participation of epiphyseal glia in the formation of the barrier zone in the ventricular area of the pineal gland, perivascular and external subarachnoid spaces. There was an increase in the number of astrocytes, a slight decrease in the number of pinealocytes and an increase in the gliocyto-neuronal index compared to the similar indices of the control animals.…”

A Response of the Pineal Gland in Sexually Mature Rats under Long-term Exposure to Heavy Metal Salts

“…The formed perivascular astroglial proliferates represent an adaptive response of glia to the action of the damaging agent (Drozdova et al, 2017) and may indirectly indicate more intensive processes of pineal cell apoptosis in these animals (Gubina-Vakulik, 2006). In addition, the increased number of glial elements in the pineal gland certainly has a definite compensatory-adaptive value, especially in the processes transferring RNA, amino acids and growth factors (Goryainov et al, 2013).…”

Effect of L–tocopherol on Morphological Reformations of Rat Pineal Gland Under the Impact of Heavy Metal Salts

“…The formed perivascular astroglial complexes according to [5] may indirectly indicate more intense processes of pineal cell apoptosis in these animals, as evidenced by a reliable decrease in the number of pinealocytes compared to the control animals' indices. In addition, the increase in the number of glial elements in the pineal gland certainly have a certain compensatory-adaptive value, especially in the transfer of RNA, amino acids, growth factors to pinealocytes and controlling water-ion homeostasis in the gland [3,4]. According to the authors, such proliferates perform a barrier function, preventing the penetration of heavy metals into the parenchyma of the gland.…”