Inhibin

Inhibin belongs to the class of proteohormones, i.e. it has a protein structure (protein = egg white). In women it is produced in certain cells of the ovaries, the so-called granulosa cells, and in men in the testicles. Inhibin is responsible for inhibiting the release of FSH from the frontal lobe of the pituitary gland, but without influencing the release of the second gonadotropin, namely LH.

Thus, inhibin, together with estradiol, is responsible for the peak of LH release. As already described, the LH peak again triggers the entry. Inhibin also plays an important role in the sex differentiation in the womb.

The secretion of the hormone inhibin also decreases with increasing age of the woman. Inhibin levels are not determined in the blood because no standard values of inhibin are known. The hormone oxytocin is produced in the hypothalamus and, after being transported to the posterior lobe of the pituitary gland, is stored there and released as required.

The release of oxytocin, which is sometimes also called the “cuddling hormone”, is stimulated by any kind of comfortable skin contact. Mechanical stimuli to the nipple, such as when breastfeeding, to the vagina and to the uterus also cause a release of oxytocin. This is attributed an important role in the birth process.

It causes a contraction of the muscle layer of the uterus (myometrium) and thus triggers the contractions. Because of this effect, it is also available in obstetrics as a drug to stimulate the contractions. Oxytocin is also responsible for the afterpains, which are intended to prevent postpartum bleeding and cause involution of the uterus.

Oxytocin is responsible for the emptying of the mammary gland, which leads to the release of milk during breastfeeding (milk ejection). In addition, oxytocin also has effects on the interaction between mother and child and between sexual partners and also on further social behaviour. A good example of the influence of oxytocin on mother-child interaction is the period after birth.

Here, oxytocin creates pleasant, pleasurable feelings that are intended to deepen the mother’s emotional bond with her newborn child. Many other physiological effects of the hormone oxytocin are already known or are still being investigated. Oxytocin levels in the blood can also be measured. The standard values for oxytocin depend on whether the woman is currently breastfeeding a newborn. For non-pregnant and pregnant women, the standard value is 1-2 mIE/ml, while the oxytocin level is significantly higher during the breastfeeding period at 5-15 mIE/ml.