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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/08/03 15:33:25」(JST)

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Hyperactivation is a type of sperm motility. Hyperactivated sperm motility is characterised by a high amplitude, asymmetrical beating pattern of the sperm tail (flagellum). This type of motility may aid in sperm penetration of the zona pellucida, which encloses the ovum.

Hyperactivation could then be followed by the acrosome reaction where the cap-like structure on the head of the cell releases the enzymes it contains. This facilitates the penetration of the ovum and fertilisation.

Some definitions consider sperm activation to consist of these two processes of hyperactivation and the acrosome reaction

Hyperactivation is a term also used to express an X chromosome gene dosage compensation mechanism and is seen in Drosophila. Here, a complex of proteins bind to the X-linked genes to effectively double their genetic activity. This allows males (XY) to have equal genetic activity as females (XX), whose X's are not hyperactivated.

Mechanisms

Mammalian sperm cells become more active when they approach an egg cell in a process called sperm activation. Sperm activation has been shown to be caused by calcium ionophores in vitro, progesterone released by nearby cumulus cells and binding to ZP3 of the zona pellucida.

The initial change is called "hyperactivation", which causes a change in spermatozoa motility. They swim faster and their tail movements become more forceful and erratic.

A recent discovery links hyperactivation to a sudden influx of calcium ion into the tails. The whip-like tail (flagellum) of the sperm is studded with ion channels formed by proteins called CatSper. These channels are selective, allowing only calcium ion to pass. The opening of CatSper channels is responsible for the influx of calcium. The sudden rise in calcium levels causes the flagellum to form deeper bends, propelling the sperm more forcefully through the viscous environment. Sperm hyperactivity is necessary for breaking through two physical barriers that protect the egg from fertilization.

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English Journal

NEU4L sialidase overexpression promotes β-catenin signaling in neuroblastoma cells, enhancing stem-like malignant cell growth.

Tringali C, Cirillo F, Lamorte G, Papini N, Anastasia L, Lupo B, Silvestri I, Tettamanti G, Venerando B.SourceDepartment of Medical Chemistry, Biochemistry and Biotechnology, University of Milan, Segrate, Milan, Italy.
International journal of cancer. Journal international du cancer.Int J Cancer.2012 Oct 15;131(8):1768-78. doi: 10.1002/ijc.27450. Epub 2012 Mar 9.
Neuroblastoma (NB) is a frequently lethal tumor that occurs in childhood and originates from embryonic neural crest cells. The malignant and aggressive phenotype of NB is strictly related to the deregulation of pivotal pathways governing the proliferation/differentiation status of neural crest precu
PMID 22287118

Hyperactivation of right inferior frontal cortex in young binge drinkers during response inhibition: a follow-up study.

López-Caneda E, Cadaveira F, Crego A, Gómez-Suárez A, Corral M, Parada M, Caamaño-Isorna F, Rodríguez Holguín S.SourceDepartment of Clinical Psychology and Psychobiology, University of Santiago de Compostela, Galicia, Spain Department of Preventive Medicine and Public Health, University of Santiago de Compostela, Galicia, Spain.
Addiction (Abingdon, England).Addiction.2012 Oct;107(10):1796-808. doi: 10.1111/j.1360-0443.2012.03908.x. Epub 2012 May 29.
Aims The objective of this study was to examine brain activity, with particular attention to prefrontal function, during response execution and inhibition in youths who have engaged in binge drinking (BD) for at least 2 years. Design Event-related potentials (ERPs) were recorded twice within 3
PMID 22487028

Japanese Journal

カルシウムシグナルによる哺乳類精子超活性化の制御 (特集受精メカニズム新論争 : ドグマの再構築)

稲葉一男
細胞工学 33(4), 366-371, 2014
NAID 40020031674

Superoxide Dismutase Activity in the Oviductal and Uterine Fluid of the Bitch and the Effects of the Enzyme on Viability, Motility, and Hyperactivation of Canine Sperm in Vitro

KOBAYASHI Masanori,WADA Miho,HORI Tatsuya,KAWAKAMI Eiichi
Journal of Veterinary Medical Science, 2014
… The percentages of sperm with viability, motility, and hyperactivation in SOD-MEM were higher than those in MEM. …
NAID 130003391267

Suppression of Progesterone-enhanced Hyperactivation in Hamster Spermatozoa by γ-aminobutyric Acid

KON Hiroe,TAKEI Gen L.,FUJINOKI Masakatsu,SHINODA Motoo
Journal of Reproduction and Development, 2014
… In the present study, we investigated whether hyperactivation of hamster sperm is regulated by progesterone (P) and γ-aminobutyric acid (GABA). … Although sperm hyperactivation was enhanced by P, GABA significantly suppressed P-enhanced hyperactivation in a dose-dependent manner. … Suppression of P-enhanced hyperactivation by GABA was significantly inhibited by an antagonist of the GABAA receptor (bicuculline). …
NAID 130003390831