Melatonin improves cryopreservation of ram sperm by inhibiting mitochondrial permeability transition pore opening. Issue 9 (2nd August 2020)

• Record Type: Journal Article
• Authors: Fang, Yi; Zhao, Chengzhen; Xiang, Hai; Jia, GongXue; Zhong, Rongzhen
• Is Part Of: Reproduction in domestic animals. Volume 55:Issue 9(2020)
• Page Start: 1240
• Page End: 1249
• Publication Date: 2020-08-02
• Subjects: cryopreservation -- melatonin -- mitochondrial permeability transition pore -- ram -- sperm; Animal breeding -- Periodicals; Veterinary pathology -- Periodicals; Livestock -- Breeding -- Periodicals; 636.082
• DOI: 10.1111/rda.13771
• Languages: English
• ISSNs: 0936-6768

Abstract

Abstract: Cryopreservation damages permeability of sperm mitochondrial membranes, with formation of a mitochondrial permeability transition pore (mPTP). Mitochondria are both a primary synthesis site and principle target for melatonin, which can directly inhibit mPTP formation. The objective was to determine effects of melatonin on mPTP opening of frozen‐thawed ram sperm and elucidate underlying pathways by antagonist and agonists of melatonin receptors (MTs), and antagonists of PI3K and GSK 3β treatments; furthermore, plasma membrane integrity, mitochondrial membrane potential (ΔΨm), mitochondrial cytochrome c (Cyt c) release and fertilization were analysed to assess the effect of mPTP status mediated by melatonin on quality of frozen‐thawed sperm. Fresh ram semen was diluted in glucose‐egg yolk buffer with 0 or 10 –7 M melatonin (frozen and frozen + melatonin groups, respectively) and slow‐frozen. In frozen‐thawed sperm, melatonin added at initiation of 4°C equilibration was most effective for inhibiting mPTP opening, decreasing peptidyl‐prolyl‐cis/trans isomerase activity of cyclophilin D and increasing plasma membrane integrity, ΔΨm, mitochondrial Cyt c concentration and fertilizing ability ( p < .05). In a mechanistic study, the melatonin receptor (MT)1 antagonist eliminated inhibition of melatonin on mPTP opening, whereas MT1 agonist had opposite effects ( p < .05). Neither MT2 antagonist nor agonist had significant effect, but PI3K and/or GSK 3β antagonist decreased inhibition of MT1 agonist on mPTP opening ( p < .05). In conclusion, melatonin improved sperm cryopreservation, perhaps by acting on MT1 via the PI3K‐Akt‐GSK 3β pathway to inhibit mPTP opening.