25 March 2016

Sperm speed switch

The sperm accelerator will help in the creation of a unisex contraceptive

Oleg Lischuk, N+1

American scientists have discovered the mechanism of "switching speeds" of spermatozoa, thanks to which they come into contact with the egg membrane. This mechanism can help in creating a universal contraceptive that is suitable for both women and men. The results of the study are published in the journal Science (Miller et al., Unconventional endocannabinoid signaling governments sperm activation via sex hormone progesterone).

During the passage through the genital tract of a woman, the tail of the sperm moves sinusoidally, which ensures uniform translational movement. In the immediate vicinity of the egg, its movements become whiplash-like, which is why the sperm makes a sharp jerk to the membrane of the female germ cell and adjoins it, trying to get inside.

Sinusoidal movements of sperm tails – UC Berkeley, 
Preventing sperm’s ‘power kick’ could be key to unisex contraceptive.

Using their own method of applying electrodes to the tail of a sperm, Polina Lishko and Yuri Kirichok from the Universities of California at Berkeley and San Francisco found out that the CatSper calcium channel, activated by egg progesterone, is responsible for such acceleration.

In the course of the latest work, a team of California researchers with the participation of Yale University found out the mechanism of this activation. It turned out that when blocking metabolic serine hydrolases (enzymes involved in the exchange of phospholipids and endocannabinoids) of spermatozoa, progesterone does not act on them, that is, activation occurs indirectly.

Experiments with various phospholipids and cannabinoids have shown that the natural agonist of type 2 cannabinoid receptors 2-arachidonoylglycerin (2-AG) blocks CatSper. It was also found that serine hydrolase ABHD2 (a protein containing an alpha/beta hydrolase domain, type 2) binds to the progesterone receptor P4. When the receptor is activated, it cleaves 2-AG and eliminates its inhibitory effect on CatSper, which ensures the opening of the ion channel and acceleration of the sperm.

The researchers note that the discovered mechanism can help explain some forms of male infertility (currently, the cause of about 80 percent of its cases cannot be detected). In addition, it can serve to develop contraceptives that block the effect of progesterone on sperm, that is, suitable for use by both men and women.

The work of scientists is also of great theoretical importance. The "classical" functions of steroid hormones are due to their effect on DNA, followed by protein synthesis. The implementation of these effects takes time (hours and even days). Relatively recently, it has been shown that they can also act on the cell membrane through completely different receptors that provide an immediate response. Such membrane receptors for progesterone are found in many tissues. If the discovered mechanism of its action turns out to be universal, it will help to find out the role of this hormone in the regulation of pain, surfactant production in the lungs and smooth muscle contraction.

Portal "Eternal youth" http://vechnayamolodost.ru  25.03.2016

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