Psychoneuroendocrinology
-
Psychoneuroendocrinology · Oct 2008
Activation of 5-HT1A autoreceptors in the dorsal raphe nucleus reduces the behavioral consequences of social defeat.
In animal models, serotonin (5-HT) activity contributes to stress-induced changes in behavior. Syrian hamsters (Mesocricetus auratus) exhibit a stress-induced change in behavior in which social defeat results in increased submissive and defensive behavior and a complete loss of normal territorial aggression directed toward a novel, non-aggressive opponent. We refer to this defeat-induced change in agonistic behavior as conditioned defeat. ⋯ In addition, we found that WAY 100635 enhanced conditioned defeat when injected either before social defeat or before testing. These data support the hypothesis that the activity of 5-HT cells in the DRN, as regulated by 5-HT1A autoreceptors, contributes to the formation and display of conditioned defeat. Further, our results suggest that 5-HT release in DRN projection regions augments defeat-induced changes in social behavior.
-
Hyperactivity of the hypothalamic-pituitary-adrenal (HPA)-axis is a common finding in major depressive disorder. Similar studies on suicide attempters are less abundant, and the results are divergent. The main aim of the present study was to investigate HPA-axis parameters by the time of a suicide attempt and at follow-up in search for associations between HPA-axis function and suicidal behavior. ⋯ We found evidence for an association between low HPA-axis activity and suicidal behavior. This could be due to long-lasting and severe psychiatric morbidity, which in turn has exhausted the HPA-axis of these patients. The potential role of hypocortisolism should be given more attention in studies on suicidal patients.
-
Psychoneuroendocrinology · Aug 2008
The cortisol awakening response: a pilot study on the effects of shift work, morningness and sleep duration.
This study concerned the possible influence of experimental shift work, morningness and sleep length on the cortisol awakening response (CAR). Eight morning-oriented (MT) and eight evening-oriented (ET) healthy young men (19-27 years) slept after three consecutive day shifts during the night and after three consecutive night shifts during the day in the laboratory. Salivary cortisol concentrations were ascertained after each sleep period upon awakening and half an hour later, half-hourly during work shifts, and hourly during two 24-h periods, after the three day shift/night sleep sequences and after the three night shift/day sleep sequences. ⋯ But neither the CARs nor the cortisol concentrations during the following work shifts or during the 24h profiles were different in both diurnal types. The cortisol concentrations during work shifts correlated significantly with the previous post-awakening concentrations in MT but not in ET. Due to the small samples further studies are needed.
-
Psychoneuroendocrinology · Jul 2008
Chronic psychosocial stress affects corticotropin-releasing factor in the paraventricular nucleus and central extended amygdala as well as urocortin 1 in the non-preganglionic Edinger-Westphal nucleus of the tree shrew.
Stressful stimuli evoke neuronal and neuroendocrine responses helping an organism to adapt to changed environmental conditions. Chronic stressors may induce maladaptive responses leading to psychiatric diseases, such as anxiety and major depression. A suitable animal model to unravel mechanisms involved in the control of adaptation to chronic stress is the psychological subordination stress in the male tree shrew. ⋯ In the pPVN, the number of CRF-immunoreactive neurons and the specific signal density of CRF-immunoreactive fiber terminals in the CeA were strongly reduced (-300 and -40%, respectively; P<0.05), whereas no significant difference in CRF fiber density was found in BNSTdl. The npEW revealed 4 times less Ucn1-immunoreactive neurons (P<0.05). These clear effects on both Ucn1- and CRF-neuropeptide contents may reflect a crucial mechanism enabling the animal to adapt successfully to the stressors, and point to the significance of the pPVN, CeA and npEW in stress-induced brain diseases.
-
Psychoneuroendocrinology · Jul 2008
Randomized Controlled TrialHPA axis activation by a socially evaluated cold-pressor test.
The cold-pressor test (CPT) in which subjects immerse their hand in ice water is among the most commonly used laboratory stressors. While the CPT elicits strong sympathetic nervous system activation, cortisol elevations indicative for the reactivity of the hypothalamus-pituitary-adrenal (HPA) axis are moderate to low in response to the CPT. In the present study, we assessed whether cortisol responses to the CPT can be increased by adding social-evaluative elements. ⋯ Social evaluation during hand immersion in warm water did not affect saliva cortisol levels suggesting that both social evaluation and a challenge are required for HPA axis activation. These findings indicate that the incorporation of social-evaluative elements increases HPA axis responses to the CPT. The SECPT can serve as a tool for future stress research.