Hypoactive Libido: Neurohumoral Characteristics, Regions of the Brain Regulating Sexual Desire, and Its Reactions to Erotic Stimuli

Abstract

The article indicates that sexual desire is considered to result from a complex balance between inhibitory and stimulating factors (neurotransmitters, hormones), which influence functioning of the brain. For example, dopamine, oxytocin, estrogens, noradrenalin, melanocortin, norepinephrine and testosterone produce excitory influence, while serotonin, endocannabinoiids, prolactin (PRL) and opioids produce inhibitory influence. The article contains data of researches, which informed about peculiarities in reactions of the brain in people with hypoactive sexual desire to erotic stimuli as well as sex differences of the above reactions to these stimuli. Also, key regions in the brain that regulate sexual desire (the prefrontal cortex, locus coeruleus, medial preoptic area, paraventricular nucleus, and reward- and attention-processing centers of the ventral tegmental area and the nucleus accumbens) are listed. Information about hormonal regulation of sexual desire in men is given. The article informs about studies that are not consistent with the established view about an inhibitory influence of hyperprolactinaemia (HP) on sexual functions in men (G. Corona et al., 2007, 2014), whose authors, on the contrary, note that analysis of the relation between PRL level and sexual disorders revealed a strong correlation between lower PRL levels and reduced pleasure from orgasm. They also revealed that a low PRL level was associated with erectile dysfunction (ED) and early ejaculation. This phenomenon may be explained by the fact that the low PRL level was associated with bad health. G. Corona et al. (2007, 2014) insist that severe HP may be associated with ED only because of HP, which in its turn is caused by hypogonadal state. Moreover, and what is especially important for the problem in question, severe HP was associated with hypoactive sexual desire (HSD), an increased level of thyrotropin and hypogonadism. A relationship between severe HP and HSD was confirmed after correction of testosterone and thyrotropic hormone levels and use of psychotropic agents. The cited authors conclude that in compliance with their findings severe, rather than mild, HP is an important determinant of HSD. Nevertheless they believe that PRL can produce more positive than negative effects in initiating and maintaining sexual behavior. Our article also discusses hormonal regulation of sexual desire in women. Though before it was supposed that adrenal androgens played a pivotal role for appearance of sexual desire in them, later an opinion formed that it was not so and the focus was shifted to ovarian corticosteroids, including estradiol and testosterone. It is noted that though ovarian corticosteroids can produce some effect on sexual desire in women, their exact role in the appearance of HSD disorder in females remains unclear.