Effects of confinement on physiological and psychological responses and expression of interleukin 6 and brain derived neurotrophic factor mRNA in primiparous and multiparous weaning sows

  • Zhang, Mingyue (College of Animal Science and Technology, Northeast Agricultural University) ;
  • Li, Xiang (College of Animal Science and Technology, Northeast Agricultural University) ;
  • Li, Jianhong (College of Life Science, Northeast Agricultural University) ;
  • Sun, Hanqing (College of Animal Science and Technology, Northeast Agricultural University) ;
  • Zhang, Xiaohui (College of Animal Science and Technology, Northeast Agricultural University) ;
  • Bao, Jun (College of Animal Science and Technology, Northeast Agricultural University)
  • Received : 2017.01.06
  • Accepted : 2017.03.22
  • Published : 2017.09.01


Objective: The present study aimed to investigate whether the long-lasting, recurrent restricting of sows leads to the physiological and psychological reaction of discomfort. Methods: Sows (Large White) that had experienced restricting for about 0.5 or 3 years and agematched sows kept in a group housing system (loose sows) were compared. Pupillary light reflex parameters were measured at the weaning stage. Immediately after slaughter, blood samples were taken to measure serum cortisol levels, and the brain was dissected, gene expression in the hippo-campus, frontal cortex and hypothalamus was analyzed. Results: The serum cortisol levels were higher in the confined sows than in the loose sows. The full maturity, but not the young adolescent, confined sows had longer latency time in the onset of pupil constriction than their loose counterparts. Real-time polymerase chain reaction analyses revealed an increased expression of interleukin 6 mRNA in the hippocampus and decreased expression of brain derived neurotrophic factor mRNA in hippocampus and hypothalamus and to a lesser extent in the frontal cortex of the full maturity confined sows, compared with the full maturity loose sows. Conclusion: Taken together, these data indicated that recurrent restricting stress in full maturity sows leads to the physiological and psychological reaction of discomfort.


Confinement Sows;Pupillary Light Reflex;Brain Derived Neurotrophic Factor;Cotisol;Interleukin 6;Hippocampus


Supported by : National Nature Science Foundation of China


  1. Marchant JN, Broom DM. Factors affecting posture changing in loose-housed and confined gestating sows. Anim Sci 1996;63:477-85.
  2. Averos X, Brossard L, Dourmad JY, et al. Quantitative assessment of the effects of space allowance, group size and floor characteristics on the lying behaviour of growing-finishing pigs. Animal 2010;4:777-83.
  3. van der Staay FJ, Schuurman T, Hulst M, et al. Effects of chronic stress: A comparison between confined and loose sows. Physiol Behav 2010;100:154-64.
  4. Sokolski KN, Nguyen BD, DeMet EM. Decreases in dilated pupil size in depressed patients with age may reflect adrenergic changes. Psychiatry Res 2000;94:267-72.
  5. Bao J, Li X, Lv FL, et al. Prolonged latency of pupillary light reflex in confined sows: Possible stress-related symptom? J Vet Behav Clin Appl Res 2013;8:475-8.
  6. Grandin T. Effect of rearing environment and environmental enrichment on behavior and neural development in young pigs [Ph.D Dissertation]. Urbana-Champaign, IL, USA: University of Illinois; 1988.
  7. Karl JB, Wolf G, Jochum T, et al. The influence of major depression and its treatment on heart rate variability and pupillary light reflex parameters. J Affect Disord 2004;82:245-52.
  8. Fotiou F, Goulas A, Fountoulakis K, Papakostopoulos D. Changes in psychophysiological processing of vision in myasthenia gravis. Int J Psychophysiol 1998;29:303-10.
  9. Theofilopoulos N, Mcdade G, Szabadi E, Bradshaw CM. Effects of reboxetine and desipramine on the kinetics of the pupillary light reflex. Br J Clin Pharmacol 1995;39:251-5.
  10. Ribeiro AP, Junior DP, Champion T, et al. Effects of topical levobunolol or fixed combination of dorzolamide-timolol or association of dorzolamide-levobunolol on intraocular pressure, pupil size, and heart rate in healthy cats. Arq Bras Med Vet Zoo 2008;60:1045-52.
  11. Bar KJ, Greiner W, Jochum T, et al. The influence of major depression and its treatment on heart rate variability and pupillary light reflex parameters. J Affect Disord 2004;82:245-52.
  12. Heller PH, Perry F, Jewett DL, Levine JD. Autonomic components of the human pupillary light reflex. Invest Ophthalmol Vis Sci 1990;31:156-62.
  13. Erickson K, Drevets W, Schulkin J. Glucocorticoid regulation of diverse cognitive functions in normal and pathological emotional states. Neurosci Biobehav Rev 2003;27:233-46.
  14. Ma D, Zhang M, Zhang K, et al. Identification of three novel avian beta-defensins from goose and their significance in the pathogenesis of Salmonella. Mol Immunol 2013;56:521-9.
  15. Willner P. Validity, reliability and utility of the chronic mild stress model of depression: a 10-year review and evaluation. Psychopharmacol 1997;134:319-29.
  16. Pignatelli D, Maia M, Castro AR, et al. Chronic stress effects on the rat adrenal cortex. Endocr Res 2000;26:537-44.
  17. Henry JP. Biological basis of the stress response. Physiol Behav Sci 2002;27:66-83.
  18. Mostl E, Palme R. Hormones as indicators of stress. Domest Anim Endocrinol 2002;23:67-74.
  19. Andres R, Marti O, Armario A. Direct evidence of acute stress-induced facilitation of ACTH response to subsequent stress in rats. Am J Physiol 1999;277:863-8.
  20. Mormede P, Andanson S, Auperin B, et al. Man Exploration of the hypothalamic-pituitary-adrenal function as a tool to evaluate animal welfare. Physiol Behav 2007;92:317-39.
  21. Joels M, Karst H, Krugers HJ, Lucassen PJ. Chronic stress: implications for neuronal morphology, function and neurogenesis. Front Neuroendocrinol 2007;28:72-96.
  22. Kim JJ, Haller J. Glucocorticoid hyper-and hypofunction: stress effects on cognition and aggression. Ann NY Acad Sci 2007;1113:291-303.
  23. Boev AN, Fountas KN, Karampelas I, et al. Quantitative pupillometry: normative data in healthy pediatric volunteers. J Neurosurg 2005;103:496-500.
  24. Bitsios P, Szabadi E, Bradshaw CM. The inhibition of the light reflex by the threat of an electric shock: a potential laboratory model of human anxiety. J Psychopharmacol 1996;10:279-87.
  25. Aguilera G. Regulation of pituitary ACTH secretion during chronic stress. Front Neuroendocrinol 1994;15:321-50.
  26. Bakes A, Bradshaw CM, Szabadi E. Attenuation of the pupillary light reflex in anxious patients. Br J Clin Pharmacol 1990;30:377-81.
  27. Karege F, Perret G, Bondolfi G, et al. Decreased serum brain-derived neurotrophic factor levels in major depressed patients. Psychiatry Res 2002;109:143-8.
  28. Duman RS, Heninger GR, Nestler EJ. A molecular and cellular theory of depression. Arch Gen Psychiatry 1997;54:597-606.
  29. McEwen B. Stress and hippocampal plasticity. Annu Rev Neurosci 1999;22:105-22.
  30. Matrisciano F, Bonaccorso S, Ricciardi A, et al. Changes in BDNF serum levels in patients with major depression disorder (MDD) after 6 months treatment with sertraline, escitalopram, or venlafaxine. J Psychiatr Res 2009;43:247-54.