A.I Karaev Institute of Physiology

This study focused on the redox homeostasis in the lenses of 20- and 30-day-old chinchilla rabbit kits exposed to a combination of hypoxia and electromagnetic radiation at a nonthermal intensity during their prenatal development. Adult rabbit does (n = 12) were divided into equal-sized experimental and control groups. After mating, pregnant animals from the experimental group were exposed to hypoxia and electromagnetic radiation for 6 days, while the control animals were sham-irradiated but not exposed to hypoxia. After birth the newborn rabbits were also divided into the experimental and control groups. Kits were slaughtered on the 20th and 30th days after birth and the lenses were removed. The lipid peroxidation intensity was estimated by the measurement of malondialdehyde in the lens tissue specimens. It was found that the redox status in the lenses of experimental rabbit kits changed towards oxidation, probably due to failure in the antioxidant defense mechanism. Thus, it was proven that prenatally induced disturbance of redox homeostasis negatively affected the postnatal period as well. No significant differences were found between the extent of lipid peroxidation by the 20th and 30th days of the postnatal period.

The study concerns evaluation of engagement of serotonergic system in the mechanisms of antimutagenic protection and survival under adverse conditions. It is shown that under long-term exposure to oil and industrial pollution, simultaneous sharp increase of mutations level in the erythrocytes and downregulation of serotonin-modulating anticonsolidation protein (SMAP; Mekhtiev 2000) in the livers of the sturgeon juveniles (Acipenser gueldenstaedtii persicus) is observed. Mutation level was evaluated by the micronucleus analysis and SMAP level-by the indirect ELISA-test utilizing anti-SMAP immunoglobulins. Intramuscular administration of SMAP leads to significant decrease of micronucleus amount in the erythrocytes of the sturgeon juveniles exposed to sediments polluted with PAH and heavy metals. Pre-conditioning of sazans by low dose of insecticide actara (100mg/l) leads to upregulation of SMAP and to survival of all the animals in the experimental group, kept under high concentration of actara (400mg/l), while all animals in the control group succumbed under these conditions. I.m. administration of SMAP prior to putting the sazans into the water containing high levels of actara (400mg/l), in contrast to controls, leads to their total survival. Participation of serotonergic system in the mechanisms of antimutagenic protection and survival promotion under damaging conditions is concluded.

It has been demonstrated in chronic experiments on wakeful rabbits that the posterolateral nucleus of the thalamus exerts tonic and phasic facilitatory influences on the formation of responses of the visual cortex elicited by a light flash. The tonic influences were expressed in an increase in the amplitude parameters of the responses of the visual cortex in conditions of the formation in the posterolateral nucleus of the thalamus of a focus of heightened excitability (anode polarization), and their perceptible diminution with potassium depression in this nucleus. The phasic influences were expressed in the formation in the visual cortex of thalamocortical responses elicited by pulse stimulation of the posterolateral nucleus of the thalamus, which displayed a close interaction with the responses of the cortex elicited by the light flash. This interaction consisted in a noticeable facilitation of the responses of the visual cortex against the background of a conditioning pulse stimulation of the posterolateral nucleus. The facilitatory effect of the phasic influences was more significant than the effect of the tonic influence.

The features of the exploratory behavior in the open field, of the learning of a conditioned-reflex food-procuring reaction, and of the shift in the level of biogenic amines of the brain was studied in Wistar rats with local injections of the specific neurotoxins 6-hydroxydopamine (6-OH-DA) and 5,7-dihydroxytryptamine (5,7-DHT). It was shown that damage to the structure of the serotoninergic or catecholaminergic systems of the frontal cortex and hippocampus caused by local injection of 6-OH-DA and 5,7-DHT into the neocortex is accompanied by multidirectional changes in the exploratory behavior and learning of the animals.