Physiology and miRNA expression in confined sows with different pupillary light reflex

Abstract

Long-term physical restriction may lead to affective and physiological disorders in sows; pupillary light reflex (PLR) characteristics might be a good indicator to diagnose these symptoms. Accordingly, the physiological and psychological states of sows with different PLR characteristics were investigated in this study. Gestating sows of three parities (parity 0, 2, and 5) were divided into strong reflex (SR) and weak reflex (WR) groups, according to a PLR test. In each group, miRNA expression and serum physiological indices were detected. Compared with the SR group, WR group showed lower 5-hydroxytryptamine levels and higher cortisol, interleukin-6, and beta-endorphin levels (p < .05) in all parities; higher immunoglobulin A and tumour necrosis factor-α levels in the parity 0 and 2 sows (p < .05); and lower miR-335, miR-16, and miR-1202 expression (p < .05) and higher miR-132, miR-504, miR-34a, and miR-30e expression in the parity 2 and 5 sows. Compared with the parity 0 sows, parity 5 sows showed higher cortisol, interleukin-6, tumour necrosis factor-α, and beta-endorphin levels; higher miR-504 and miR-34a expression (p < .05); and lower miR-335, miR-16, miR-134, and miR-1202 expression in both groups. Thus, psychophysiological state differs among sows with different PLR characteristics, and, that of sows with weak PLR characteristics, is consistent with depression disorder, and as parity increases, these psychophysiological differences widen. HIGHLIGHTS PLR characteristics could reflect different physiological states including neurophysiological and immunological states in sows. The miRNA molecular markers and serum physiological indices of sows with weak pupillary light responses were consistent with depression disorder. Long-term physical restriction might worsen physiological and psychological disorders in sows.