2 Neuroscience2.7 Neural circuits
2.7.1.3 Sex, hormones and sexual function
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Written by Resident Doctor Committee · Published
Brain and spinal circuits
Region | Role |
|---|---|
Medial preoptic hypothalamus | Integrates hormonal and sensory signals |
Amygdala | Learned sexual significance; bilateral temporal injury can cause Klüver-Bucy hypersexuality |
Ventral striatum and mesolimbic dopamine | Motivation and anticipation |
Insula | Genital signals; subjective and genital arousal may differ |
Orbitofrontal cortex | Current value and behavioural regulation |
Sacral parasympathetic pathways (S2 to S4) and nitric oxide drive genital vasocongestion.
Thoracolumbar sympathetic pathways drive emission, and pudendal somatic pathways drive pelvic contractions.
Hypothalamic-pituitary-gonadal axis
Gonadotrophin-releasing hormone (GnRH) is released in pulses into pituitary portal blood.
Continuous GnRH agonists stimulate at first, then downregulate receptors and suppress gonadal steroids.
Hormone | Testis | Ovary |
|---|---|---|
Luteinising hormone (LH) | Leydig cell testosterone | Steroids, ovulation, corpus luteum |
Follicle-stimulating hormone (FSH) | Sertoli cells, spermatogenesis | Follicular growth, granulosa cells |
Feedback is mainly negative, but sustained high mid-cycle oestradiol causes positive feedback and the LH surge.
Inhibin suppresses FSH in particular, and testosterone can be aromatised to oestradiol.
Energy deficit, excessive exercise, severe stress, opioids and hyperprolactinaemia suppress the axis.
Neurotransmitters
Transmitter | Effect on sexual response |
|---|---|
Dopamine | Motivation; agonists can cause hypersexuality and other impulse-control problems |
Serotonin | More signalling often reduces desire and delays orgasm |
Oxytocin | Released during touch and orgasm |
Sex, gender and orientation
In complete androgen insensitivity, a 46,XY person has non-functioning androgen receptors, typically female external anatomy and usually a female gender identity.
Gender identity develops through interacting biological and psychosocial processes, and no scan, hormone result or genetic marker determines it.
Biological sex, gender identity, sexual orientation and sexual function are separate domains: one does not establish another, and identity and orientation are not disorders.
Hormonal treatments
Testosterone can raise libido and haematocrit.
Reproductive transitions and progestogens can affect mood in some people.
Gender-affirming hormones can alter libido, arousal and emotional experience.
Psychiatric illness
Depression lowers desire through anhedonia, fatigue and negative self-appraisal, and anxiety with performance monitoring impairs arousal.
Trauma cues can cause involuntary genital responses, which do not imply desire or consent.
Mania raises drive and disinhibition, and frontal disorders impair judgement about consent.
Psychotropic drugs
Cause | Effect |
|---|---|
Serotonin reuptake inhibitors | Reduced desire and arousal; delayed or absent orgasm |
Hyperprolactinaemia from dopamine D2 blockade | Gonadal suppression, galactorrhoea, menstrual and erectile problems, subfertility, bone effects |
Anticholinergic action | Impaired autonomic sexual response |
Valproate | Polycystic ovarian features |
Risperidone, amisulpride and many older antipsychotics raise prolactin, whereas aripiprazole often lowers it.