Biological correlates of women’s mood and orgasm

Abstract

Considerable data show that sexual dysfunction may have psychosocial and quality of life consequences in the partner of subjects with sexual dysfunction (Rosen and Althof, 2008). In addition, sexual satisfaction in any couple predicts marital satisfaction (Guo and Huang, 2005; Litzinger and Gordon, 2005). In subjects experiencing sexual dissatisfaction, stress, relational conflicts and communication difficulties exert an important impact on the subjects’ mood. In addition, some biological correlations may exist between sexual satisfaction and orgasm on the one hand, and mood level on the other hand which explains how sexual relationship quality may have an influence on mental health. In this article, these correlations will be examined in female subjects. It will be hypothesized that vagino-cervical stimulation and orgasm may exert an influence on women’s mood and on their capacity to face stressful life events since sexual intercourse and orgasm physiologically stimulate the vagal nerve and increase the release of oxytocin.

Since women diagnosed with ‘complete’ spinal cord injury could perceive genital sensations, including orgasm, it has been recognized that the vagus nerve, which bypasses the spinal cord in its course to the brain, is the afferent pathway that stimulates orgasm (Cole, 1975). In women with complete spinal cord injury, brain regions activated during vagal nerve stimulation have been found to be activated during vagino-cervical self stimulation-induced orgasms (Kamisaruk and Whipple, 2005). In 2005, the United States Food and Drug Administration approved vagal nerve stimulation for the adjunctive long-term treatment of chronic or recurrent depression for patients aged 18 years or older, who are experiencing a major depressive episode and have not had an adequate response to four or more adequate antidepressant treatments (Food and Drug Administration, 2003). Vagal nerve stimulation influences the functional activity of some central nervous system regions dysregulated in mood disorders such as orbital frontal cortex, insula, thalamus, hypothalamus, cingulate and hippocampus (Chae et al., 2003). Schematically, the nucleus of the tractus solitarius receives the greatest number of vagal afferent synapses which project to the noradrenergic locus coeruleus, to the serotonergic raphe nuclei, to the thalamus, hypothalamus, central amygdala nucleus, bed nucleus of the stria terminalis, nucleus accumbens and the reticular thalamic formation (Ressler and Mayberg, 2007). Furthermore, regional cerebral blood flow (rCBF) increases after vagal nerve stimulation in the left dorsolateral/ventrolateral prefrontal cortex, which is the main brain region targeted by high frequency repetitive transcranial magnetic stimulation (rTMS) during antidepressant treatment (Schutter, 2008; Kosel et al., 2011). Finally, vagal nerve stimulation antidepressant activity may be due to the fact that it alters the cerebrospinal fluid concentrations of neurotransmitters or their metabolites such as increasing gamma aminobutyric acid (GABA), 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (Carpenter et al., 2004). Accordingly, the stimulation of the vagal nerve in women during vagino-cervical stimulation and subsequent orgasm may result in the activation of brain regions implicated in maintaining a certain mood level as well as the interference with the release of some important neurotransmitters that play a role in the subject’s response to stress. Of course, conditions in which the vagal nerve’s stimulation takes place via vagino-cervical stimulation and subsequent orgasm differ from those conditions found during the device-stimulation of this nerve especially regarding the frequency, intensity and duration of the stimulation. Studies comparing these conditions in both means of vagal nerve stimulation are needed.

Another important effect of vagino-cervical stimulation and subsequent orgasm is the release of oxytocin via a physiologic phenomenon known as the Ferguson reflex (Ferguson, 1941). The origin of the oxytocin is predominantly in neurons of the paraventricular nucleus of the hypothalamus that project axons into the posterior pituitary, where they release the hormone into the systemic circulation in response to vagino-cervical and suckling stimulation (Swanson et al., 1980; Komisaruk and Steinman, 1986). Orgasm is also known to be responsible for oxytocin release. Studies of brain imaging indicate increased activation at women’s orgasm, compared with pre-orgasm, in the paraventricular nucleus of the hypothalamus (Meston et al., 2004). Many studies showed that, in mice, injected oxytocin has an effect on depressive parameters such as the forced swimming and the learned helplessness tests (Arletti and Bertolini, 1987; Ring et al., 2010). There has been at least one trial showing that, in humans, daily intranasal oxytocin led to improvements in depressive symptoms (Bakharev et al., 1986; Scantamburlo et al., 2007, 2011). Thus, the preclinical and clinical studies suggest that exogenously administered oxytocin may have an antidepressant effect, but the relationship between endogenous oxytocin and depressive symptoms remains unclear. The presence of oxytocin receptors on the noradrenergic terminals ensures that vagino-cervical stimulation-induced release of noradrenalin is enhanced and thereby facilitates the antidepressant effect of oxytocin. Finally, oxytocin release after paraventricular nucleus activation during orgasm is also linked to vagus nerve stimulation since the hypothalamic paraventricular nucleus is known to send projections to the dorsal medullary area where it appears to innervate the nucleus tractus solitarius and the dorsal motor nucleus of the vagus (Lawrence and Pittman, 1985). Accordingly, the release of oxytocin in women during vagino-cervical stimulation on the one hand and subsequent orgasm on the other hand may result in the activation of brain regions implicated in maintaining a certain mood level as well as the interference with the release of some important neurotransmitters that play a role in the subject’s response to stress. Of course, conditions in which oxytocin is released via vagino-cervical stimulation and subsequent orgasm differ from those conditions found during other causes of endogenous oxytocin release or during external oxytocin administration especially regarding the intensity, the brain regions targeted and the duration of this release. Studies comparing these conditions in all types of oxytocin release are needed.

Stimulation of the vagal nerve and the release of oxytocin via vagino-cervical stimulation and subsequent orgasm may be important factors in the maintenance of a stable mood level and psychological well-being in women. In men, the biological correlation between mood and orgasm intuitively exists and must constitute the subject of another overview regarding current knowledge on the subject. The relationship between mood level and orgasm may explain the inter-correlation between marital satisfaction, sexual satisfaction and psychological well-being in couples. It is difficult to consider that this theoretical correlation between mood level on the one hand and vagino-cervical stimulation and orgasm on the other hand have therapeutic clinical implications because of some major ethical considerations. In this regard, even if vagal nerve stimulation and oxytocin release were found to be equally conditioned by vagino-cervical stimulation and subsequent orgasm as well as by other physiological and therapeutic means, they cannot be used to treat patients suffering from symptoms of depressive mood. The manipulation of sexual relationships and behaviors of patients is seldom ethical even if it were proved to be efficient in the amelioration of these patients’ mood symptoms. However, evaluating the quality and the quantity of sexual relationships has to be an important part of any psychiatric clinical assessment of a patient presenting with mood symptoms. Accordingly, the management of sexual relationships problems with every available modality is hypothesized to be an important factor in the management of depressive symptoms in female partners at least.

Footnotes

Declaration of interest

The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper.

Funding

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

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