A.I. Bulava Junior Research Scientist, V.B. Shvyrkov Laboratory of Neuronal Bases of Mind, Institute of Psychology of Russian Academy of Sciences (Moscow) E-mail: ai.bulava@mail.ru Y.V. Grinchenko Ph.D. (Med.), Senior Research Scientist, V.B. Shvyrkov Laboratory of Neuronal Bases of Mind, Institute of Psychology of Russian Academy of Sciences (Moscow) E-mail: nyugrink@psychol.ras.ru

Psycho-emotional stress disturbs cognitive processes such as learning and memory, and leads to neurodegenerative changes [4]. It is widely accepted that the hypothalamic-pituitary-adrenal system plays a critical role in the stress response [6]. Action of corti-costerone in the brain are mediated by glucocorticoid receptors (GR) and mineralocorticoid receptors (MR). The highest MR ex-pression was found in the hippocampal fields CA1 and CA3. Activation of MR in the hippocampal CA1 area results in considerable excitatory hippocampal output. Activation of GR, after acute stress, generally depresses the CA1 hippocampal output [1]. Chronic stress negatively correlated with the hippocampal volume [2; 7]. In this work, we studied patterns of neural activity during active avoidance task. At the beginning, we trained animals (Long-Evans rats) to perform food-acquisition operant behavior. Then we trained rats in two different ways: an active avoidance task or an operant bar-pressing task. Fos protein served as a cellular marker of neuronal activity during the second learning. Immunohistochemical detection of Fos-positive neurons was performed in accordance to streptavidin-biotin-peroxidase protocol. Distribution and number of Fos-positive neurons of hippocampal fields (CA1/CA2/CA3) was analysed. The number of Fos-positive neurons was higher in both experimental groups than in intact rats. We have found different involvement of hippocampal fields CA1 and CA3. Decrease in the number of c-Fos positive neurons was found in the hippocampal field CA1 during more stressful active avoidance learning as compared to operant learning (Mann-Whitney U test z=-2.327; p=0.019; Effect size r=0.77). This study was supported by RFBR (grant # 15-06-99697) and is performed within the research programme of one of the Leading Scientific Schools of Russian Federation (9808.2016.6).

 

1. De Kloet E.R., Oitzl M.S., Joels M. Stress and cognition: are corticosteroids good or bad guys - // Trends in Neurosciences. 1999. V. 22. № 10. P. 422-426.
2. Gilbertson M.W., Shenton M.E., Ciszewski A., Kasai K., Lasko N.B., Orr S.P., Pitman R.K. Smaller hippocampal volume predicts pathologic vulnerability to psychological trauma // Nat Neurosci. 2002. V. 5. № 11. P. 1242-1247.
3. Herman, J.P., Ostrander M.M., Mueller N.K., Figueiredo H. Limbic system mechanisms of stress regulation: hypothalamo-pituitary-adrenocortical axis // Prog Neuropsychopharmacol Biol Psychiatry. 2005. V. 29. № 8. R. 1201-1213.
4. Kim J.J., Diamond D.M. The stressed hippocampus, synaptic plasticity and lost memories // Nat. Rev. Neurosci. 2002. V. 3. № 6. P. 453-462.
5. LaBar K.S., Disterhoft J.F. Conditioning, awareness, and the hippocampus // Hippocampus. 1998. V. 8. № 6. P. 620-606.
6. Swaab D.F., Bao A.M. The stress system in the human brain in depression and neurodegeneration // Lucassen Ageing Res Rev. 1992. V. 4. № 2. P. 141-194.
7. Teicher M.H., Anderson C.M., Polcari A. Childhood maltreatment is associated with reduced volume in the hippocampal subfields CA3, dentate gyrus, and subiculum // Proc Natl Acad Sci USA. 2012. V. 109. № 9. P. E563-E572.
8. Bulava A.I., Grinchenko JU.V. Transkripcionnaja aktivnost c-Fos v golovnom mozge krys v zadache passivnogo izbeganija posle obuchenija instrumentalnomu pishhedobyvatelnomu navyku // Biomedicinskaja radioehlektronika. 2015. № 4. S. 25-26.
9. Umrjukhin A.E. Nejjromediatornye gippokampalnye mekhanizmy stressornogo povedenija i reakcijj izbeganija // Vestnik novykh medicinskikh tekhnologijj (ehlektronnoe izdanie). 2013. № 1. S. 55.
10. Watson C., Paxinos G., et al. Chemoarchitectonic atlas of the rat brain. 2009. P. 319. 375 p.