Sex hormones, orcadian rhythms, and depressive vulnerability

Sexual dimorphism in pre-clinical studies of depression

Although there is a sex bias in the pathological mechanisms exhibited by brain disorders, investigation of the female brain in biomedical science has long been neglected. Use of the male model has generally been the preferred option as the female animal model exhibits both biological variability and hormonal fluctuations. Existing studies that compare behavioral and/or molecular alterations in animal models of brain diseases are generally underrepresented, and most utilize the male model. Nevertheless, in recent years there has been a trend toward the increased inclusion of females in brain studies. However, current knowledge regarding sex-based differences in depression and stress-related disorders is limited. This can be improved by reviewing preclinical studies that highlight sex differences in depression. This paper therefore presents a review of sex-based preclinical studies of depression. These shed light on the discrepancies between males and females regarding the biological mechanisms that underpin mechanistic alterations in the diseased brain. This review also highlights the conclusions drawn by preclinical studies to advance our understanding of mood disorders, encouraging researchers to promote ways of investigating and managing sexually dimorphic disorders.

ORIGINAL RESEARCH—PATHOPHYSIOLOGY: Clinical Biologic Pathophysiologies of Women's Sexual Dysfunction

INTRODUCTION

Data concerning the biologic pathophysiology of desire, arousal, and orgasm in women are limited.

AIM

To gain knowledge of biologic pathophysiology of female sexual function. METHODS. To provide state-of-the-art knowledge concerning female sexual dysfunction, representing the opinions of seven experts from five countries developed in a consensus process over a 2-year period.

MAIN OUTCOME MEASURE

An International Consultation in alliance with key urological and sexual medicine societies convened over 200 multidisciplinary specialists from 60 countries into 17 consultation committees. The aims, goals and intentions of each committee were defined. Expert opinion was based on grading of evidence-based medical literature, extensive internal committee dialogue, open presentation, and debate.

RESULTS

Three critical physiologic requirements, including intact sex steroids, autonomic/somatic nerves, and arterial inflow/perfusion pressure to women's genital organs play fundamental roles in maintaining women's sexual function. Despite this, there are nominal data supporting a direct pathophysiologic involvement of abnormal sex steroid values, and/or damage/injury to neurologic and/or blood flow integrity in women with problems in sexual desire, arousal, and/or orgasm. This summary details the available literature concerning hormonal, neurologic, and vascular organic pathophysiologies of women's sexual dysfunctions.

CONCLUSIONS

Additional research on clinical pathophysiologies in women's sexual dysfunction is needed. This chapter encompasses data presented at the 2nd International Consultation on Sexual Medicine in Paris, France, June 28-July 1, 2003.

Gender differences in depression. Critical review

BACKGROUND

With few exceptions, the prevalence, incidence and morbidity risk of depressive disorders are higher in females than in males, beginning at mid-puberty and persisting through adult life.

AIMS

To review putative risk factors leading to gender differences in depressive disorders.

METHOD

A critical review of the literature, dealing separately with artefactual and genuine determinants of gender differences in depressive disorders.

RESULTS

Although artefactual determinants may enhance a female preponderance to some extent, gender differences in depressive disorders are genuine. At present, adverse experiences in childhood, depression and anxiety disorders in childhood and adolescence, sociocultural roles with related adverse experiences, and psychological attributes related to vulnerability to life events and coping skills are likely to be involved. Genetic and biological factors and poor social support, however, have few or no effects in the emergence of gender differences.

CONCLUSIONS

Determinants of gender differences in depressive disorders are far from being established and their combination into integrated aetiological models continues to be lacking.