MORPHOLOGICAL CHANGES AND SERINE RACEMASE EXPRESSION IN RAT HIPPOCAMPUS UNDER COMBINED STRESS CONDITION

Structural changes and serine racemase expression in the ventral hippocampus in response to combined stress were studied in 12- and 24-month-old rats. Four groups of 10 animals each were used: group 1 - control rats aged 12 months; group 2 - control rats aged 24 months; group 3 - rats aged 12 months that underwent 30-minute stress daily during 7 days; group 4 - rats aged 24 months that underwent similar stress. The stress was modeled in a special chamber consisting of 6 isolated compartments of equal volume which allowed combination of different stress-inducing factors (pulsating bright light, noise, vibration). In experimental animals, the stress resulted in an increase of the proportion of shrunken hyperchromatic neurons in the CA3 area, decreased density of neurons in the ventral hippocampus, as well as pericellular edema, vacuolization of cytoplasm, decreased expression of serine racemase in the neuropil of radial layer of CA1 and CA3. It was concluded that stress produced pronounced changes in pyramidal neurons of CA3 in the ventral hippocampus , combined with reduction of serine racemase expression in the dendrites of radial layers of CA1 and CA3, which is regarded as a sign of disturbance of NMDA-dependent neurotransmission in the hippocampus.

hippocampus, neurons, serine racemase, aging, stress, rat