title: Energy Utilization for Survival and Fertilization-Parsimonious Quiescent Sperm Turn Extravagant on Motility Activation in Rat.
abstract: Quiescent sperm survive in cauda epididymis for long periods of time under extreme crowding conditions and with a very limited energy substrate, while after ejaculation, motile sperm live for a much shorter period with an unlimited energy resource and without crowding. Thus, the energy metabolism in relation to the energy requirement of the two may be quite different. A simple physiological technique was evolved to collect viable quiescent sperm from rat cauda epididymis to compare its energy metabolism with motile sperm. Quiescent sperm exhibited 40%-60% higher activities of mitochondrial electron transport chain complexes I-IV and ATP synthase in comparison to motile sperm and accumulated Ca(2+) in the midpiece mitochondria to enhance oxidative phosphorylation (OxPhos). In contrast, motile sperm displayed up to 75% higher activities of key glycolytic enzymes and secreted more than two times the lactate than quiescent sperm. Quiescent sperm phosphorylated AMPK and MAPK-p38, while motile sperm phosphorylated AKT and MAPK/ERK. Glycolytic inhibitor iodoacetamide prevented motility activation of quiescent rat sperm and inhibited conception in rabbits more effectively than OxPhos uncoupler 2,4-dinitrophenol. Apparently, quiescent sperm employ the most energy efficient OxPhos to survive for extended periods of time under extreme conditions of nutrition and crowding. However, on motility initiation, sperm switch predominantly to glycolysis to cater to their high- and quick-energy requirement of much shorter periods. This study also presents a proof of concept for targeting sperm energy metabolism for contraception.
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Lokesh
authors.initials: L
authors.lastname: Kumar
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Yadav
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Bhavana
authors.initials: B
authors.lastname: Kushwaha
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Aastha
authors.initials: A
authors.lastname: Pandey
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Sharma
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Verma
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Jagdamba P
authors.initials: JP
authors.lastname: Maikhuri
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Singh
authors.initials: S
authors.lastname: Rajender
authors.affiliation: Division of Medicinal & Process Chemistry, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Vishnu L
authors.initials: VL
authors.lastname: Sharma
authors.affiliation: Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow, India g_gupta@cdri.res.in.
authors.forename: Gopal
authors.initials: G
authors.lastname: Gupta
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004734:Energy Metabolism; D005260:Female; D005298:Fertility; D006019:Glycolysis; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism; D011817:Rabbits; D017207:Rats, Sprague-Dawley; D013081:Sperm Motility
chemical_list: C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D019344:Lactic Acid; D025261:Mitochondrial Proton-Translocating ATPases; D002118:Calcium
keywords: epididymis; gamete biology; metabolism; sperm; sperm motility and transport