Gender-specific Regulation of the Hypothalamo-pituitary-adrenal axis and the Role of Vasopressin during the Neonatal Period

Pre-Test Manipulation by Intraperitoneal Saline Injection with or without Isoflurane Pre-Treatment Does Not Influence the Outcome of Social Test in Male Mice

Preclinical studies on rodents should follow the 3R principle minimising the suffering of the animals. To do so, some researchers use inhalation anaesthetic induction even before intraperitoneal injection. However, several studies suggested that both interventions might influence the behaviour of the animals. We aimed to test whether intraperitoneal injection alone or in combination with isoflurane anaesthesia is a preferable treatment method 30 min before a social test. Male C57BL/6 mice were studied using a behavioural test battery comparing three groups (one control group and intraperitoneal saline-treated groups with or without short isoflurane inhalation). Our results confirmed that both interventions had no profound influence on the conventionally measured parameters of social tests (interest in sociability, social discrimination memory, social interaction as well as resident–intruder test) and were not acutely stressful (measured by similar ACTH levels between the groups) not even after repeated administration (similar body weight gain during the one-week observation period). Taking into consideration the possible long-term harmful effect of isoflurane inhalation, we recommend using intraperitoneal injection without it as saline injection did not violate the 3R principle inducing only mild stress.

Vasopressin deficiency diminishes acute and long-term consequences of maternal deprivation in male rat pups

Early life events have special importance in the development as postnatal environmental alterations may permanently affect the lifetime vulnerability to diseases. For the interpretation of the long-term consequences it is important to understand the immediate effects. As the role of vasopressin in hypothalamic-pituitary-adrenal axis regulation as well as in affective disorders seem to be important we addressed the question whether the congenital lack of vasopressin will modify the stress reactivity of the pups and will influence the later consequences of single 24h maternal deprivation (MD) on both stress-reactivity and stress-related behavioral changes. Vasopressin-producing (di/+) and deficient (di/di) Brattleboro rat were used. In 10-day-old pups MD induced a remarkable corticosterone rise in both genotypes without adrenocorticotropin (ACTH) increase in di/di rats. Studying the later consequences at around weaning (25-35-day-old rats) we found somatic and hormonal alterations (body weight reduction, dysregulation of the stress axis) which were not that obvious in di/di rats. The more anxious state of MD rats was not detectable in di/di rats both at weaning and in adulthood (7-12-week-old). The lack of vasopressin abolished all chronic stress and anxiety-like tendencies both at weaning and in adulthood probably as a consequence of reduced ACTH rise immediately after MD in pups. This finding suggests that postnatal stress-induced ACTH rise may have long-term developmental consequences.

Gender-related endocrinological dysfunction and mental disorders

PURPOSE OF REVIEW

The association between endocrine and neuropsychiatric disorders was established long ago, with solid evidence. According to a multidimensional model of mental disorders, one can conceptualize sex and gender-related endocrinological dysfunctions as a cluster of risk factors included in the biological determinants of those disorders.

RECENT FINDINGS

Gender and sexual dimorphism in brain functions and pathways may have a main impact and synergistic effects on health differences in both men and women. To explain these differences, hormonal reactivity to stress, sex hormones and gene-environment interactions are among the most researched mechanisms.

SUMMARY

In this paper, we review updated data on sex and gender differences in stress reactivity, concerning the hypothalamic-pituitary-adrenal axis, endocrinological dysfunction and vulnerability to major psychiatric disorders, in a stress-diathesis approach. Mainly schizophrenia and affective disorders are discussed, according to recent investigation, in terms of early determinants of stress reactivity, the interplay of genetic expression and gender role, their responsibility in biological modulation and their hypothetical contribution to explain gender differences in prevalence and clinical aspects of mental disorders.