Environmental events, both physical and emotional, can produce stress reactions to widely varying degrees. Stress can affect many aspects of physiology, and levels of stress, emotional status, and ...means of coping with stress can influence health and disease. The stress system consists of brain elements, of which the main components are the corticotropin-releasing hormone (CRH) and locus ceruleus (LC)-norepinephrine (NE)/autonomic systems, as well as their peripheral effectors, the pituitary-adrenal axis and the autonomic system, which function to coordinate the stress response. Activation of the stress system results in behavioral and physical changes which allow the organism to adapt. This system is closely integrated with other central nervous system elements involved in the regulation of behavior and emotion, in addition to the axes responsible for reproduction, growth and immunity. With current trends in stress research which focus on understanding the mechanisms through which the stress-response is adaptive or becomes maladaptive, there is a growing association of stress system dysfunction, characterized by hyperactivity and/or hypoactivity to various pathophysiological states. The purpose of this review is to 1) define the concepts of stress and the stress response from a historical perspective, 2) present a dynamic overview of the biobehavioral mechanisms that participate in the stress response, and 3) examine the consequences of stress on the physiologic and behavioral well-being of the organism by integrating knowledge from apparently disparate fields of science.
The third trimester of human pregnancy is characterized by a hyperactive hypothalamic-pituitary-adrenal axis, possibly driven by progressively increasing circulating levels of placental CRH and ...gradually decreasing levels of CRH-binding protein. The postpartum period, on the other hand, is characterized by an increased vulnerability to psychiatric manifestations (postpartum "blues," depression, and psychosis), a phenomenon compatible with suppressed hypothalamic CRH secretion. To investigate the hypothesis that the postpartum period is associated with suppression of hypothalamic CRH secretion, we studied prospectively 17 healthy euthymic women (mean +/- SE age, 32.0 +/- 1.1 yr) with no prior history of depression, starting at the 20th week of gestation. Psychometric testing was performed monthly during pregnancy and postpartum on day 2 and weeks 2, 3, 6, 8, 12, 16, and 20, whereas serial ovine (o) CRH tests were performed postpartum at 3, 6, and 12 weeks. While pregnant, all 17 subjects remained euthymic; in the postpartum period, 7 women developed the "blues," and 1 developed depression. Overall, the mean plasma ACTH response to an iv bolus of 1 microgram/kg oCRH was markedly blunted at 3 and 6 weeks, but normal at 12 weeks postpartum, whereas the mean plasma cortisol response was at the upper limit of normal at all 3 times. These data are compatible with a suppressed hypothalamic CRH neuron that gradually returns to normal while hypertropic adrenal cortexes are progressively down-sizing. When the postpartum ACTH responses to oCRH were analyzed separately for the euthymic women and the women who had the "blues" or depression, the blunting of ACTH was significantly more severe and long lasting in the latter group; this was observed at all 3 times of testing. We conclude that there is central suppression of hypothalamic CRH secretion in the postpartum, which might explain the increased vulnerability to the affective disorders observed during this period. The suppressed ACTH response to oCRH might serve as a biochemical marker of the postpartum "blues" or depression.
: Corticotropin‐releasing hormone (CRH), its natural homologs urocortins (UCN) 1, 2, and 3, and several types of CRH receptors (R), coordinate the behavioral, endocrine, autonomic, and immune ...responses to stress. The potential use of CRH antagonists is currently under intense investigation. Selective antagonists have been used experimentally to clarify the role of CRH‐related peptides in anxiety and depression, addictive behavior, inflammatory disorders, acute and chronic neurodegeneration, and sleep disorders, as well as preterm labor.
From a transactional developmental perspective, the authors review findings from studies of animals and humans regarding a proposed relation between stress system abnormalities and major depression. ...The stress system has evolved to promote successful adaptation across the life span, but disruptions in its functioning may increase the risk of pathological outcomes. Emphasis is placed on the role of prenatal and early postnatal experience in contributing to individual differences in postnatal stress reactivity, which may interact with cognitive and psychosocial vulnerabilities to increase susceptibility to later onset of depression. Findings regarding cognitive, psychosocial, and medical sequelae of depression are also reviewed, with a focus on the possible mediating role of the stress system. The authors highlight the importance of multidisciplinary, longitudinal studies in attempting to gain a deeper understanding of the complex developmental processes involved in the onset and course of depression.
Leptin, an adipocyte hormone, is a trophic factor for the reproductive system; however, it is still unknown whether there is a dynamic relation between fluctuations in circulating leptin and ...hypothalamic--pituitary-ovarian (HPO) axis hormones. To test the hypothesis that fluctuations in plasma leptin concentrations are related to the levels of luteinizing hormone (LH) and estradiol, we sampled plasma from six healthy women every 7 min for 24 h during days 8-11 of the menstrual cycle. Cross-correlation analysis throughout the 24-h cycle revealed a relation between release patterns of leptin and LH, with a lag of 42-84 min but no significant cross-correlation between LH and estradiol. The ultradian fluctuations in leptin levels showed pattern synchrony with those of both LH and estradiol as determined by cross-approximate entropy (cross-ApEn). At night, as leptin levels rose to their peak, the pulsatility profiles of LH changed significantly and became synchronous with those of leptin. LH pulses were fewer, of longer duration, higher amplitude, and larger area than during the day. Moreover, the synchronicity of LH and leptin occurred late at night, at which time estradiol and leptin also exhibited significantly stronger pattern coupling than during the day. We propose that leptin may regulate the minute-to-minute oscillations in the levels of LH and estradiol, and that the nocturnal rise in leptin may determine the change in nocturnal LH profile in the mid-to-late follicular phase that precedes ovulation. This may explain the disruption of hypothalamic--pituitary-ovarian function that is characteristic of states of low leptin release, such as anorexia nervosa and cachexia.
Glucocorticoid receptor gene polymorphisms are associated with glucocorticoid hypersensitivity and visceral obesity. Perturbations in HPA axis sensitivity to glucocorticoids implicated in the ...pathogenesis of major depression may result from functional alterations in the glucocorticoid receptor gene. We 1) examined the prevalence of genotype distribution of specific polymorphisms of the glucocorticoid receptor gene (Bcl1, N363S, rs33388, rs33389) in a subset of women from the P.O.W.E.R. Study (which enrolled 21- to 45-year-old premenopausal women with major depression and healthy controls) and 2) explored whether such polymorphisms were associated with visceral obesity and insulin resistance. Women with major depression had a higher body mass index, a higher waist:hip ratio, and more body fat than did controls. No differences were observed in plasma and urinary cortisol or in insulin sensitivity. The G/G genotype of the Bcl1 polymorphism was significantly more common (p<0.03) in women with major depression (n=52) than in controls (n=29). In addition, GG homozygotes (depressed n=10; controls n=2) had higher waist:hip ratios than did non-GG carriers (p<0.02). N363S, rs33388, and rs33389 polymorphisms were not different between groups. In conclusion, premenopausal women with both major depression and the GG genotype of the Bcl1 polymorphism had greater abdominal obesity compared with non-GG carriers.
Previous studies have reported hyperactivation of catecholaminergic systems and elevated concentrations of corticotropin-releasing-hormone (CRH) in the cerebrospinal fluid (CSF) of child maltreatment ...victims or combat veterans with post-traumatic stress disorder (PTSD). This study investigated the CSF concentrations of CRH and monoamine metabolites in rhesus macaque mothers that physically abused their infants and had themselves been abused as infants. Ten abusive mothers and 10 controls served as study subjects. All animals were sampled for CSF during pregnancy and the postpartum period. Focal observations of social and maternal behavior were also made. Abusive mothers had significantly higher CSF concentrations of CRH and 5-HIAA than controls. Across both subjects and controls, higher CRH, 5-HIAA and MHPG concentrations were associated with anti-social behavior patterns including a high frequency of maternal aggression, infant rejection, and a low frequency of contacts received from other individuals. These findings are consistent with those of previous primate and human studies and suggest that the neurobiological alterations associated with infant abuse may play an important role in the occurrence of maladaptive behavior in adulthood, including the perpetuation of infant abuse across generations.
Inbred Lewis (LEW/N) female rats develop an arthritis in response to group A streptococcal cell wall peptidoglycan polysaccharide (SCW), which mimics human rheumatoid arthritis. Histocompatible ...Fischer (F344/N) rats do not develop arthritis in response to the same SCW stimulus. To evaluate this difference in inflammatory reactivity, we examined the function of the hypothalamic-pituitary-adrenal (HPA) axis and its ability to modulate the development of the inflammatory response in LEW/N and F344/N rats. We have found that, in contrast to F344/N rats, LEW/N rats had markedly impaired plasma corticotropin and corticosterone responses to SCW, recombinant human interleukin 1α , the serotonin agonist quipazine, and synthetic rat/human corticotropin-releasing hormone. LEW/N rats also had smaller adrenal glands and larger thymuses. Replacement doses of dexamethasone decreased the severity of LEW/N rats' SCW-induced arthritis. Conversely, treatment of F344/N rats with the glucocorticoid receptor antagonist RU 486 or the serotonin antagonist LY53857 was associated with development of severe inflammatory disease, including arthritis, in response to SCW. These findings support the concept that susceptibility of LEW/N rats to SCW arthritis is related to defective HPA axis responsiveness to inflammatory and other stress mediators and that resistance of F344/N rats to SCW arthritis is regulated by an intact HPA axis-immune system feedback loop.
Sustained responsiveness of the hypothalamic–pituitary–adrenal (HPA) axis during chronic or repeated stress is associated with continuous activation of ascending noradrenergic neurons from the ...brainstem to the hypothalamic paraventricular nucleus (PVN). The fact that glucocorticoid receptor (GR) exists in the brainstem noradrenergic neurons including locus coeruleus (LC) suggests that glucocorticoids play a modulatory role in maintaining the activity of these neurons during chronic stress. To determine whether alterations in the sensitivity of noradrenergic neuronal activity to endogenous CORT occur during chronic or repeated stress, tyrosine hydroxylase (TH) and GR mRNA expressions in the LC were examined in acute (2 h) and repeated (2 h daily, 14 days) immobilization stress, using sham-operated rats and adrenalectomized rats with a moderate dose of CORT replacement (ADX+CORT group). In acute stress, TH mRNA in the LC increased in the ADX+CORT rats, but not in sham operated rats. In repeated stress, however, elevated endogenous CORT failed to inhibit TH mRNA responses in sham rats; LC TH mRNA in sham rats responded to the same extent as in ADX+CORT rats. A reduction of GR mRNA in the LC was observed in the acutely stressed and repeatedly stressed sham group, but not in the ADX+CORT groups. The decrease in LC GR mRNA levels in sham rats tended to be greater after repeated than after acute stress. LC GR mRNA levels decreased in response to systemic CORT treatment (200 mg pellet sc, for 14 days) and increased in response to adrenalectomy; neither CORT treatment nor adrenalectomy influenced TH mRNA levels in the LC. These results suggest that glucocorticoid responses to acute immobilization prevent LC TH mRNA levels from rising significantly, while glucocorticoids appear to decrease their capacity to restrain LC TH mRNA during repeated immobilization. Although the results clearly show glucocorticoid-dependent alterations in LC GR mRNA expression, the association between increased TH mRNA and decreased GR mRNA in the LC remains to be elucidated.
Endogenous Cushing's syndrome (CS) is associated with significant psychopathology during the course of the disease. The purpose of this study was to evaluate the psychological and endocrine status of ...patients with CS after correction of their hypercortisolism. Thirty-three patients with active CS were examined before and at 3 months (28 patients), 6 months (25 patients), and 12 months (29 patients) after correction of hypercortisolism. Before cure, 66.7% of the patients had significant psychopathology, with the predominant diagnosis of atypical depressive disorder (AD) in 51.5% and/or major affective disorder in 12%. After cure, overall psychopathology decreased significantly to 53.6% at 3 months, 36% at 6 months, and 24.1% at 12 months, when there was a parallel recovery of the hypothalamic-pituitary-adrenal axis assessed by serial morning ACTH stimulation tests. There was an inverse correlation between psychological recovery and baseline morning cortisol, but no correlation with ACTH-stimulated cortisol values at 60 min. AD continued to be the prevailing diagnosis after correction of hypercortisolism, whereas the frequency of suicidal ideation and panic increased. The presence of AD before and after correction of hypercortisolism might be due to glucocorticoid-induced suppression of hypothalamic CRH secretion. The slight increase in the incidence of panic after correction of hypercortisolism might be due to a decreased glucocorticoid restraint at the central arousal/sympathetic catecholaminergic system. We conclude that CS is associated with AD symptomatology, which gradually improves with time after correction of hypercortisolism. Health care providers should be aware of changes in symptomatology, including suicidal ideation and panic attacks, that occur in a subgroup of patients.
PDF
