A dual physiological character for sexual function: libido and sexual pheromones

Abstract

Human sexual response is a complex function involving many cerebral, spinal and peripheral aspects; the last are relatively known and benefit from good pharmacological control, as in the case of erectile dysfunction. Spinal cord sexual reflexes also have a good theoretical and experimental description. There is minimal understanding of the cerebral sexual processes (libido, sexual arousal, orgasm). The initial perspective was that the cerebral areas implied in sexuality exert descending stimulatory and inhibitory influences on spinal cord sexual centres/reflexes. This was a wrong supposition, which inhibited progress in this subject, with a considerable impact on a subject’s individual and social life. A new approach to sexual function arises from the idea that simple neurological structures can support only simple functions, while a more complex function requires correspondingly complex anatomical structures. For this reason the spinal cord would not be able to realise the integration of multiple (spinal and psychosensorial) stimuli into a unique and coherent ejaculation response. Consequently, all mechanisms implied in human sexuality would be cerebral processes, ejaculation reflexes ascending in evolution to the cerebral level. This new evolutionary concept was developed after 2001 in five distinct articles on the cerebral duality of sexual arousal, sexual hormones, ejaculation and serotonergic receptors. During this period other published results suggested a possible cerebral duality for sexual pheromones and libido in humans. All these dual physiological aspects are integrated in this review into one neurophysiological model, thus trying to further develop the new concepts of sexual function and perhaps relational behaviour. In conclusion, ejaculation is a dual cerebral process with arousal sensation (hormonally modulated) and libido perception (pheromonally modulated) as the afferent part. Two neurophysiological axes could exist in both men and women. In this assumption the mechanisms for libido and sexual arousal are not the only ones invoked, their correlations and implications are also suggested, perhaps critical aspects for further developments in the field.

A pilot study on the sexual side effects of finasteride as related to hand preference for men undergoing treatment of male pattern baldness

“…Regarding these sexual neuromodulators, specific sexual hormones presumably modulate distinct peripheral inputs (corresponding to visual images, sensations and haptic perception) [2,11], so that the impact on sexual functioning occurs at a higher level when hormonal drugs act on multiple neural receptor types. Thus, cyproterone acetate strongly interferes with the effects of the two classes of sexual hormones, blocking the androgenic receptors and decreasing the level of oestradiol.…”

Informational dichotomy of the mind; the role of sexual neuromodulators

“…This presumed competition between cognition and sexuality would be responsible for the first dichotomy of the mind, which is relational in nature. This relational dichotomy is physiologically possible through the intervention of distinct (cognitive or sexual) cerebral neuromodulators, which achieve the role of assigning external sexual stimuli to either a cognitive or sexual interpretation (10,11).…”

“…The second dichotomy refers to the informational dichotomy of the brain, which is generated by the intervention of sexual neuromodulators, acting either on the thalamic/ concrete domain of the mind (sexual pheromones) or on the hypothalamic/ abstract domain (sexual hormones) (5,11).…”

Pheromonal bile acid 3-ketopetromyzonol sulfate primes the neuroendocrine system in sea lamprey

“…Primer pheromones are exemplified by their effects on the onset of puberty, the length of estrous cycles in females, the success or failure of pregnancy, and shifts in hormone levels in mice [6]. Male pheromones have a direct impact on female sexual desire, menstrual cycles and ovulation in humans [7]. About 20% of women who have smelled male underarm secretions have an advanced onset of next luteinizing hormone (LH) pulse [8].…”