A pilot study on differential expression of microRNAs in the ventromedial prefrontal cortex and serum of sows in activity restricted crates or activity free pens

OBJECTIVE: Physical activity restriction in sows may lead to behavioral abnormalities and affective disorders. However, the psychophysiological state of these sows is still unclear. As miRNAs can be used as effective markers of psychopathy, the present study aimed to assess the difference in microRNA expression between the long-term activity restricted sows and activity free sows, thus contributing to the understanding of abnormal sow behavior. METHODS: Four dry sows (sixth parity, Large×White genetic line) were selected from activity restricted crates (RC) or activity free pens (FP) separately. microRNAs in the ventromedial prefrontal cortex (vMPFC) and serum were examined using real-time polymerase chain reaction, and the correlation between the miRNAs expressed in the vMPFC and serum was evaluated. RESULTS: miR-134 (1.11 vs 0.84) and miR-1202 (1.09 vs 0.85) levels were higher in the vMPFC of the RC sows than in the FP sows (p<0.01). Furthermore, miR-132 (1.27 vs 1.08) and miR-335 (1.03 vs 0.84) levels were also higher in the RC sows than in FP sows (p<0.05); however, miR-135a, miR-135b, miR-16, and miR-124 levels were not different (p>0.05). The relative expression of serum miR-1202 was higher in the RC sows than in the FP sows (1.04 vs 0.54) (p<0.05), and there was a strong correlation (R = 0.757, p<0.05) between vMPFC and Serum levels of miR-1202. However, no significant difference was observed in miR-16 levels in the serum of the RC sows and FP sows (p>0.05). CONCLUSION: This pilot study demonstrates that long-term activity restriction in sows likely results in autism or other complex psychopathies with depression-like behaviors. These observations may provide new insights for future studies on abnormal behavior in sows and contribute to research on human psychopathy.