Do neurohormonal changes contribute to differences in post-coital behavior between males and females?

Neurohormonal Basis of Sex Differences in Post-Coital Behavior

Yes, neurohormonal changes are fundamentally responsible for differences in post-coital behavior between males and females, driven primarily by sexually dimorphic brain development established during critical prenatal and early postnatal periods, with acute hormonal fluctuations during sexual activity further modulating these responses.

Developmental Programming of Sexual Dimorphism

The foundation for sex differences in post-coital behavior is established during critical developmental windows when gonadal hormones permanently organize brain structures and neural circuits:

Critical Period Timing

• In humans, the critical period begins at 7-8 weeks of gestation when testicular testosterone production starts, peaking at 14-16 weeks at adult male levels 1
• A second critical window occurs postnatally, with male testosterone levels surging from birth to peak at 1-3 months of life before declining to prepubertal levels by 4-6 months 1, 2
• These organizational effects permanently masculinize or feminize neural circuits controlling sexual behavior, creating the substrate for sex-specific post-coital responses 1

Mechanism of Brain Masculinization

• Testosterone enters sexually dimorphic brain regions (particularly the preoptic area) where it is converted to estradiol by aromatase enzyme 1
• Estradiol then binds estrogen receptors to promote masculine neural differentiation, paradoxically making estrogen more effective than testosterone for masculinizing reproductive behavior in animal models 1
• Female brains develop in the relative absence of androgens, as maternal estrogens are bound to α-fetoprotein and cannot cross the blood-brain barrier 1
• This creates permanent structural differences, including larger sexually dimorphic nuclei in the preoptic area in males compared to females 1

Acute Neurohormonal Mechanisms During Sexual Activity

Beyond developmental programming, acute hormonal and neurotransmitter changes during and after sexual activity differ between sexes:

Neurotransmitter Systems

• Dopamine release in the medial preoptic area (MPOA), nigrostriatal system, and mesolimbic system promotes sexual motivation and copulatory efficiency, with testosterone permissively enabling this DA release 3
• Serotonin (5-HT) release in the lateral hypothalamic area (LHA) at ejaculation inhibits sexual behavior and promotes sexual satiety, explaining post-coital refractory periods 3
• The balance between dopaminergic facilitation and serotonergic inhibition differs between males and females due to their different androgen/estrogen ratios 4

Sex-Specific Hormonal Responses

• Oxytocin levels increase significantly after orgasm in women (p < 0.05), playing a major role in sexual response and post-coital bonding behavior 5
• The different balance of androgens and estrogens in men versus women generates asymmetric effects on autonomic nervous system components, explaining sex differences in arousal patterns and post-coital responses 4
• Gonadal hormones modulate neural activity differentially in males and females, affecting dopaminergic, serotonergic, adrenergic, cholinergic, and nitergic systems 6

Integration of Organizational and Activational Effects

The sexually dimorphic post-coital behaviors result from the interaction between:

• Organizational effects: Permanent brain masculinization or feminization during critical developmental periods (prenatal and early postnatal) 1
• Activational effects: Acute hormonal fluctuations during sexual activity that trigger sex-specific neural responses based on the underlying organizational template 1

Clinical Implications

• Hormonal influences on sexual differentiation exist on a continuum rather than being all-or-nothing, with the amount, duration, and timing of hormone exposure determining the degree of masculinization or feminization 1
• Disruption of endocrine, neural, or vascular systems through aging, disease, surgery, or medications can impair these neurohormonal mechanisms and alter post-coital responses 6
• Exposure to endocrine-disrupting compounds with estrogenic or anti-androgenic activities can interfere with normal sexual behavior patterns by disrupting hormonal regulation 7

Important Caveats

While neurohormonal mechanisms provide the biological substrate for sex differences in post-coital behavior, psychological and relationship factors also significantly modulate sexual response and may enhance or impair functioning independent of hormonal status 6. The human sexual response represents an integration of both physiological and psychological processes that cannot be reduced to hormones alone, though hormones establish the foundational framework upon which these responses are built 4.