Hippocampal glucocorticoid receptor and microRNA gene expression and serum cortisol concentration in foxes selected for behavior toward humans

In many cases, stress reactivity is one of the important bases of aggressive behavior. It appears as if reduced stress reactivity underlies an abrupt decrease in aggression towards man in domesticated animals. However, the mechanisms of this reduction have yet to be resolved. In this work, we used an experimental domestication model, the silver fox selected for many years for the response to humans to study cortisol stress reactivity in tame and aggressive foxes in response to immobilization in human arms. Additionally, these behavioral fox groups were explored for one of the important mechanisms of glucocorticoid negative feedback, the expression of the glucocorticoid receptor gene (NR3C1) in a portion of the dorsal hippocampus. In recent years, attention has been paid to differences in miRNA expression patterns between animals with different behavior and stress reactivity, as well as to miRNA regulation under stress. The same applies to NR3C1 mRNA as well. That is why we performed a miRNA-seq analysis on a portion of the fox dorsal hippocampus. It has been demonstrated that immobilization in human arms leads to significantly higher stressinduced cortisol levels in aggressive than tame foxes. At the same time, no differences have been found between hippocampal NR3C1 gene expression and the pattern of miRNA expression. Thus, reduced stress reactivity in foxes during selection for the absence of aggressive responses and for the presence of emotionally positive responses to humans does not seem to be associated with important mechanisms of regulation such as alterations in hippocampal NR3C1 gene expression or microRNA-mediated silencing.

domestication, cortisol, tame foxes, NR3C1, miR

1. Belyaev D.K. Destabilizing selection as a factor in domestication. Genetika i blagosostoyanie chelovechestva [Genetics and Animal Well-Being]. Moscow: Nauka Publ., 1981;53-66. (in Russian)

2. Belyaev D.K., Naumenko E.V., Trut L.N., Korshunov E.A. Function of the adrenal cortex and its seasonal changes in silver foxes. Doklady AN SSSR = Proceedings of the Academy of Sciences of the USSR. 1971;200(5):1249-1251. (in Russian)

3. Coppinger R., Coppinger L. Dogs: a New Understanding of Canine Origin, Behavior and Evolution. Chicago, 2002. de Kloet E.R., Ortiz Z., Meijer O.C. Manipulating the brain corticosteroid receptor balance: focus on ligands and modulators. Stress: Neuroendocrinology and Neurobiology. 2017;367-383.

4. Dow-Edwards D., Silva L. Endocannabinoids in brain plasticity: Cortical maturation, HPA axis function and behavior. Brain Res. 2017; 1654:157-164. DOI 10.1016/j.brainres.2016.08.037.

5. Dygalo N.N., Shishkina G.T., Borodin P.M., Naumenko E.V. Role of the brain neurochemical systems in altering the reactivity of the hypophyseal-adrenal system in the gray rat selected for behavior. Zhurnal evolyutsionnoy biokhimii i fiziologii = Journal of Evolutionary Biochemistry and Physiology. 1985;21(4):342-347. (in Russian)

6. Fromm B., Billipp T., Peck L.E., Johansen M., Tarver J.E., King B.L., Newcomb J.M., Sempere L.F., Flatmark K., Hovig E., Peterson K.J. A uniform system for the annotation of vertebrate microRNA genes and the evolution of the human microRNAome. Annu. Rev. Genet. 2015;49:213-242. DOI 10.1146/annurev-genet-120213-092023.

7. Fromm B., Worren M.M., Hahn C., Hovig E., Bachmann L. Substantial loss of conserved and gain of novel microRNA families in flatworms. Mol. Biol. Evol. 2013;30:2619-2628. DOI 10.1093/molbev/ mst155.

8. Hamilton D.E., Cooke C.L., Carter B.S., Akil H., Watson S.J., Thompson R.C. Basal microRNA expression patterns in reward circuitry of selectively bred high-responder and low-responder rats vary by brain region and genotype. Physiol. Genomics. 2014;46:290-301. DOI 10.1152/physiolgenomics.00152.2013.

9. Herbeck Y.E., Os’kina I.N., Gulevich R.G., Plyusnina I.Z. Effects of maternal methyl-supplement diet on hippocampal glucocorticoid receptor mRNA expression in rats selected for behavior. Cytology and Genetics. 2010;44:108-113. DOI 10.3103/S0095452710020064.

10. Hollins S.L., Cairns M.J. MicroRNA: Small RNA mediators of the brains genomic response to environmental stress. Prog. Neurobiol. 2016;143:61-81. DOI 10.1016/j.pneurobio.2016.06.005.

11. Jung S.H., Wang Y., Kim T., Tarr A., Reader B., Powell N., Sheridan J.F. Molecular mechanisms of repeated social defeat-induced glucocorticoid resistance: Role of microRNA. Brain Behav. Immun. 2015;44:195-206. DOI 10.1016/j.bbi.2014.09.015.

12. Kukekova A.V., Johnson J.L., Teiling C., Li L., Oskina I.N., Kharlamova A.V., Gulevich R.G., Padte R., Dubreuil M.M., Vladimirova A.V., Shepeleva D.V., Shikhevich S.G., Sun Q., Ponnala L., Temnykh S.V., Trut L.N., Acland G.M. Sequence comparison of prefrontal cortical brain transcriptome from a tame and an aggressive silver fox (Vulpes vulpes). BMC Genomics. 2011;12. DOI 10.1186/1471-2164-12-482.

13. Langmead B. Aligning short sequencing reads with Bowtie. Curr. Protoc. Bioinform. 2010;32:11.7.1-11.7.14. DOI 10.1002/0471250953. bi1107s32.

14. Liu D., Diorio J., Tannenbaum B., Caldji C., Francis D., Freedman A., Sharma S., Pearson D., Plotsky P.M., Meaney M.J. Maternal care, hippocampal glucocorticoid receptors, and hypothalamic-pituitaryadrenal responses to stress. Science. 1997;277:1659-1662. DOI 10.1126/science.277.5332.1659.

15. Luo W., Fang M., Xu H., Xing H., Fu J., Nie Q. Comparison of miRNA expression profiles in pituitary-adrenal axis between Beagle and Chinese Field dogs after chronic stress exposure. PeerJ. 2016;4:e1682. DOI 10.7717/peerj.1682.

16. Meerson A., Cacheaux L., Goosens K.A., Sapolsky R.M., Soreq H., Kaufer D. Changes in brain MicroRNAs contribute to cholinergic stress reactions. J. Mol. Neurosci. 2010;40:47-55. DOI 10.1007/ s12031-009-9252-1.

17. Oskina I.N., Herbeck Yu.E., Shikhevich S.G., Plyusnina I.Z., GulevichR.G. Alterations in the hypothalamus-pituitary-adrenal and immune systems during selection of animals for tame behavior. Informatsionnyy vestnik VOGiS = The Herald of Vavilov Society for Geneticists and Breeders. 2008:12(1/2):39-49. (in Russian)

18. Plyusnina I., Oskina I. Behavioral and adrenocortical responses to open-field test in rats selected for reduced aggressiveness toward humans. Physiol. Behav. 1997;61:381-385. DOI 10.1016/S0031- 9384(96)00445-3.

19. Popova N.K., Voǐtenko N.N., Pavlova S.I., Trut L.N., Naumenko E.V., Belyaev D.K. Genetics and phenogenetics of the hormonal characteristics of animals. VII. Correlation between brain serotonin and the hypothalamo-pituitary-adrenal system in domesticated and undomesticated silver foxes during emotional stress. Genetika = Genetics (Moscow). 1980;16:1865-1870. (in Russian)

20. Prasolova L.A., Gerbek Yu.E., Gulevich R.G., Shikhevich S.G., Konoshenko M.Yu., Kozhemyakina R.V., Oskina I.N., Plyusnina I.Z. The effects of prolonged selection for behavior on the stress response and activity of the reproductive system of male grey rats (Rattus norvegicus). Russian Journal of Genetics. 2014;50(8):846-852. DOI 10.1134/S1022795414080031.

21. Trut L.N., Naumenko E.V., Belyaev D.K. Change in the pituitary-adrenal function of silver foxes during selection according to behavior. Genetika = Genetics (Moscow). 1972;8(5):35-43. (in Russian)

22. Trut L., Oskina I., Kharlamova A. Animal evolution during domestication: The domesticated fox as a model. BioEssays. 2009;31:349-360. DOI 10.1002/bies.200800070.

23. Wang S-S., Mu R-H., Li C-F., Dong S-Q., Geng D., Liu Q., Yi L-T. microRNA-124 targets glucocorticoid receptor and is involved in depression-like behaviors. Prog. Neuropsychopharmacol. Biol. Psychiatry. 2017;79:417-425. DOI 10.1016/j.pnpbp.2017.07.024.

24. Weaver I.C.G., Cervoni N., Champagne F.A., D’Alessio A.C., Sharma S., Seckl J.R., Dymov S., Szyf M., Meaney M.J. Epigenetic programming by maternal behavior. Nat. Neurosci. 2004;7:847-854. DOI 10.1038/nn1276.