title: Upregulation of uncoupling protein Ucp2 through acute cold exposure increases post-thaw sperm quality in zebrafish.
abstract: Oxidative stress plays an important role in sperm damage during cryopreservation. Mild mitochondrial uncoupling has been shown to reduce excessive reactive oxygen species (ROS) and thus mitigate oxidative stress. Uncoupling protein (Ucp2) regulates mitochondrial uncoupling and can be induced by temperature fluctuation. In the present study, we explored a novel approach of acute cold exposure on Ucp2 activation and its association with oxidative damage and post-thaw sperm quality in zebrafish. Our study revealed that acute cold exposure of zebrafish at 18 °C for 24 h led to significant increase of ucp2 mRNA and Ucp2 protein in zebrafish fresh sperm as well as thawed sperm after cryopreservation. Although cold exposure had no effect on fresh sperm quality except for decreasing lipid peroxidation, sperm collected from cold-exposed zebrafish exhibited higher resistance to cryodamage, which was demonstrated by increased post-thaw motility, decreased lipid peroxidation, increased ATP production, and ultimately increased fertilization success. However, except for reduced lipid peroxidation, we did not observe any significant ROS reduction associated with increased Ucp2 activation in cold-exposed group, suggesting mechanisms other than mitochondrial uncoupling could have contributed to cold exposure associated benefits in post-thaw sperm survival. Nevertheless, our findings indicate that acute cold exposure prior to sperm cryopreservation is beneficial for post-thaw sperm survival in zebrafish, and this novel approach may be used to improve post-thaw sperm quality for other aquatic species.
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China.
authors.forename: Gongfa
authors.initials: G
authors.lastname: Wang
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China.
authors.forename: Ning
authors.initials: N
authors.lastname: Kang
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Gong
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China.
authors.forename: Chenglian
authors.initials: C
authors.lastname: Bai
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China.
authors.forename: Yuanhong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Ji
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China.
authors.forename: Changjiang
authors.initials: C
authors.lastname: Huang
authors.affiliation: Institute of Environmental Safety and Human Health, Wenzhou Medical University, Wenzhou 325035, PR China; School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou 325035, PR China. Electronic address: dqxdong@163.com.
authors.forename: Qiaoxiang
authors.initials: Q
authors.lastname: Dong
mesh_terms: D000818:Animals; D003080:Cold Temperature; D015925:Cryopreservation / Q000379:methods*; D007473:Ion Channels / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000502:physiology; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism*; D000071246:Uncoupling Protein 2; D015854:Up-Regulation; D015027:Zebrafish / Q000378:metabolism
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; C000604389:UCP2 protein, human; D000071246:Uncoupling Protein 2
keywords: Cold exposure; Sperm cryopreservation; Uncoupling protein (Ucp2); Zebrafish