Sex and the subgingival microbiome: do female sex steroids affect periodontal bacteria?

Fluctuations in the levels of sex steroid hormones begin at menarche and end with menopause in the human female. The association between gingivitis and increases in systemic sex steroids has been extensively reported and the biological mechanisms underlying this florid inflammatory state have been examined over several decades. The purpose of this review is to critically examine the evidence in the literature on the effect of female sex steroids on oral bacterial communities.

[Neuroprotective properties of sex hormones]. / Wlasciwosci neuroprotekcyjne hormonów plciowych.

Sex hormones exert a substantial effect on brain function; their action is determined by the predominance of one hormone group over the remaining ones. Estrogens have indirect and direct neuroprotective effects. The indirect effects involve improved function of the vascular endothelium and increased blood flow through the brain. The direct effects (nervous cells and glia) consist in strong antioxidative properties, maintenance of Ca+2 homeostasis, blockage of activating amino acids, modification of tissue and humoral immune responses and inhibition of activity of immediate early genes. Gestagens, on the other hand, prevent neuronal death, inhibit lipid membrane peroxidation, and promote growth of nervous cells and formation of new synapses. The role of sex hormones within the brain is equally important. However, in cases of brain pathology, protective effects of gestagens seem to be much strongly expressed.

Muscle and tendon properties during menstrual cycle.

The present study aimed to investigate the changes in the mechanical properties of human muscle and tendon during the menstrual cycle in vivo. The subjects were young healthy women (n=8, age 22.5+/-0.9 years) with a normal menstrual cycle. Cycle phases were divided into the menstrual (when estradiol and progesterone concentrations were low), ovulatory (when estradiol was elevated and progesterone was low), and luteal (when progesterone was elevated). Measurements included maximal isometric voluntary contraction (MVC), muscle activation level (using interpolated twitch method), and tendon properties (using ultrasonography) in knee extensors and plantar flexors. No significant changes in MVC and muscle activation level were found during the menstrual cycle. Similarly, there were no significant differences in the maximal elongation and stiffness of tendons among the three phases. These results suggested that the changes in female steroid hormones during the menstrual cycle did not affect the mechanical properties of human muscle and tendon.

Role of progestins in contraception.

Progestins have been used for contraception for more than 30 years. The main goal was to develop a contraceptive method devoid of the metabolic or clinical side-effects associated with the use of estrogens. The development of new contraceptive methods and formulations is time-consuming and requires devotion, belief, and also strong economical basis. As a result of this endeavor new methods have been developed: oral progestins, implants, injectables, intrauterine hormonal systems, and vaginal rings. Progestin-only contraceptives may be preferable in some situations, which have absolute or relative contraindications to estrogen, side-effects to estrogen containing hormonal contraception, lactation, and comfort and feasibility of formulations for long-term use. At present, emergency contraception is also performed with progestin.

The nitric oxide pathway participates in estrous behavior induced by progesterone and some of its ring A-reduced metabolites.

Intracerebral and intravenous administration of progesterone (P) and its ring A-reduced metabolites induces intense sexual behavior (lordosis and proceptivity) in estrogen-primed rats. The present study tested the hypothesis that the nitric oxide-cGMP-protein kinase G pathway is involved in the facilitation of sexual behavior induced by the intracerebroventricular (i.c.v.) administration of P (130 ng) and its ring A-reduced metabolites 5alpha-dihydroprogesterone (5alpha-DHP; 13 ng) and 5alpha,3alpha-pregnanolone (5alpha,3alpha-Pgl; 13 ng). In Experiment 1, we tested the relevance of the nitric oxide/cGMP pathway by infusing a nitric oxide synthase inhibitor or a nitric oxide-dependent, soluble guanylyl cyclase inhibitor icv before progestin administration. The lordosis induced by P, 5alpha-DHP and 5alpha,3alpha-Pgl was significantly reduced at 2 h after progestin infusion by the previous injection of either a nitric oxide synthase inhibitor or by a soluble guanylyl cyclase inhibitor. Lordosis behavior returned to control values by 4 h. In Experiment 2, i.c.v. infusion of the protein kinase G inhibitor KT5823 significantly inhibited the lordosis behavior induced by all three progestins at 2 h. These data support the hypothesis that the nitric oxide/cGMP/protein kinase G pathway is involved in the lordosis induced by P and some of its ring A-reduced metabolites.