The effects of different periods of co-administration of oral and long-acting injectable aripiprazole: A propensity score analysis.

OBJECTIVE: Long-acting injectable (LAI) aripiprazole is recommended to be combined with oral aripiprazole for 2 weeks after its introduction. However, we often experience patients who require more than 2 weeks of combined use. Therefore, differences in combination periods need to be examined. METHODS: This was a case-control study. We surveyed prescription profiles for oral aripiprazole administration in conjunction with LAI aripiprazole introduction and assessed the clinical course during a 12-week follow-up period. RESULTS: Among 121 patients, 58 (47.9%) were administered both oral and LAI aripiprazole for more than 2 weeks. Although there was no significant difference in treatment failure (defined as psychiatric hospitalization or discontinuation of LAI aripiprazole from any cause) between the two groups, the group that was administered oral aripiprazole for more than 2 weeks received less additional benzodiazepines compared with that of the 2 weeks group (adjusted odds ratio, 0.055; 95% confidence interval [0.0060, 0.50]; p < 0.01). CONCLUSIONS: Our data support a flexible co-administration period for oral and LAI aripiprazole in consideration of the pharmacokinetics, but further studies are needed.

Novel splice site variant of TMEM38B in osteogenesis imperfecta type XIV.

Osteogenesis imperfecta (OI) is a rare genetic disorder characterized by brittle bones. In this case report, we describe a patient who suffered from OI type XIV with a novel splice site variant in the TMEM38B gene. Further research is needed to better understand the relationship between the phenotype of OI type XIV and this variant.

Plasma dehydroepiandrosterone sulphate and insulin-like growth factor I levels in obstructive sleep apnoea syndrome.

CONTEXT: We aimed to assess whether obstructive sleep apnoea syndrome (OSAS) affects plasma IGF-1 and dehydroepiandrosterone sulphate (DHEA-S) levels in men, factors implicated in the development of age-related metabolic disorders. DESIGN: We conducted a cross-sectional and longitudinal clinical study. PATIENTS AND SETTING: We measured plasma IGF-1 and DHEA-S levels in 191 non-drug-treated Japanese men (34 primary snorers (PS), 88 patients with mild-to-moderate OSAS and 69 patients severe OSAS ). RESULTS: Plasma IGF-1 and DHEA-S were negatively correlated with age. Plasma IGF-1 was also negatively correlated with plasma glucose, HOMA-IR and systolic blood pressure and apnoea parameters such as the apnoea-hypopnea index, minimum oxygen saturation and slow-wave sleep (SWS) time. Plasma DHEA-S was associated with plasma glucose, HbA1c and free fatty acid and was negatively correlated with SWS time. To eliminate the influence of age, PS, patients with mild-to-moderate OSAS and severe OSAS were divided into three groups by age: young (<40 years), middle-aged (40-59 years) and elderly (≥ 60 years). Patients with severe OSAS aged <40 or <60 years had lower plasma IGF-1 or DHEA-S levels, respectively, than did the corresponding snorers and mild-to-moderate OSAS groups. Continuous positive airway pressure therapy for generally 16-18 months increased plasma IGF-1 levels in patients with severe OSAS aged <40 years (n = 18). Plasma DHEA-S levels were increased in patients with severe OSAS aged <60 years, whose DHEA-S level was below the mean value for that age (n = 23/41). CONCLUSION: Severe OSAS could reduce plasma IGF-1 and DHEA-S levels in younger, but not elderly Japanese men, which is potentially associated with the development of metabolic abnormalities.

Animal Models of Cushing's Syndrome.

Endogenous Cushing's syndrome is characterized by unique clinical features and comorbidities, and progress in the analysis of its genetic pathogenesis has been achieved. Moreover, prescribed glucocorticoids are also associated with exogenous Cushing's syndrome. Several animal models have been established to explore the pathophysiology and develop treatments for Cushing's syndrome. Here, we review recent studies reporting animal models of Cushing's syndrome with different features and complications induced by glucocorticoid excess. Exogenous corticosterone (CORT) administration in drinking water is widely utilized, and we found that CORT pellet implantation in mice successfully leads to a Cushing's phenotype. Corticotropin-releasing hormone overexpression mice and adrenal-specific Prkar1a-deficient mice have been developed, and AtT20 transplantation methods have been designed to examine the medical treatments for adrenocorticotropic hormone-producing pituitary neuroendocrine tumors. We also review recent advances in the molecular pathogenesis of glucocorticoid-induced complications using animal models.

Tissue-specific regulation of 11ß hydroxysteroid dehydrogenase type-1 mRNA expressions in Cushing's syndrome mouse model.

The 11ß hydroxysteroid dehydrogenase type-1 (11ßHSD-1) is a predominant 11ß-reductase regenerating bioactive glucocorticoids (cortisol, corticosterone) from inactive 11-keto forms (cortisone, dehydrocorticosterone), expressed mainly in the brain, liver and adipose tissue. Although the expression levels of 11ß HSD-1 mRNA are known to be influenced by glucocorticoids, its tissue-specific regulation is not completely elucidated. In this study, we examined the effect of persistent glucocorticoid excess on the expression of 11ß HSD-1 mRNA in the hippocampus, liver, and abdominal adipose tissue in vivo using quantitative real-time PCR. We found that, in C57BL/6J mice treated with corticosterone (CORT) pellet for 2 weeks, 11ß HSD-1 mRNA decreased in the hippocampus (HIPP) and liver, whereas it increased in the abdominal fat (FAT), compared with placebo treatment [HIPP: placebo 1.00 ± 0.14, CORT 0.63 ± 0.04; liver: placebo 1.00 ± 0.08, CORT 0.73 ± 0.06; FAT: placebo 1.00 ± 0.16, CORT 2.26 ± 0.39]. Moreover, in CRH transgenic mice, an animal model of Cushing's syndrome with high plasma CORT level, 11ß HSD-1 mRNA was also decreased in the hippocampus and liver, and increased in the abdominal adipose tissue compared to that in wild-type mice. These changes were reversed after adrenalectomy in CRH-Tg mice. Altogether, these results reveal the differential regulation of 11ß HSD-1 mRNA by glucocorticoid among the tissues examined.

Corticotropin-releasing hormone (CRH) transgenic mice display hyperphagia with increased Agouti-related protein mRNA in the hypothalamic arcuate nucleus.

Although glucocorticoid-induced hyperphagia is observed in the patients with glucocorticoid treatment or Cushing's syndrome, its molecular mechanism is not clear. We thus explored the expression of neuropeptide mRNAs in the hypothalamus related to appetite regulation in CRH over-expressing transgenic mice (CRH-Tg), a model of Cushing's syndrome. We measured food intake, body weight (including body fat weight) and plasma corticosterone levels in CRH-Tg and their wild-type littermates (WT) at 6 and 14 weeks old. We also examined neuropeptide Y (NPY), proopiomelanocortin (POMC) and Agouti-related protein (AgRP) mRNAs in the arcuate nucleus (ARC) using in situ hybridization. Circulating corticosterone levels in CRH-Tg were markedly elevated at both 6 and 14 weeks old. Body fat weight in CRH-Tg was significantly increased at 14 weeks old, which is considered as an effect of chronic glucocorticoid excess. At both 6 and 14 weeks old, CRH-Tg mice showed significant hyperphagia compared with WT (14w old: WT 3.9±0.1, CRH-Tg 5.1±0.7 g/day, p<0.05). Unexpectedly, NPY mRNA levels in CRH-Tg were significantly decreased at 14 weeks old (WT: 1571.5±111.2, CRH-Tg: 949.1±139.3 dpm/mg, p<0.05), and there were no differences in POMC mRNA levels between CRH-Tg and WT. On the other hand, AgRP mRNA levels in CRH-Tg were significantly increased compared with WT at both ages (14w old: WT 365.6±88.6, CRH-Tg 660.1±87.2 dpm/ mg, p<0.05). These results suggest that glucocorticoid-induced hyperphagia is associated with increased hypothalamic AgRP. Our results also indicate that hypothalamic NPY does not have an essential role in the increased food intake during glucocorticoid excess.

Relationships between time in range, glycemic variability including hypoglycemia and types of diabetes therapy in Japanese patients with type 2 diabetes mellitus: Hyogo Diabetes Hypoglycemia Cognition Complications study.

AIMS/INTRODUCTION: Continuous glucose monitoring (CGM) metrics, such as times in range (TIR) and time below range, have been shown to be useful as clinical targets that complement glycated hemoglobin (HbA1c) for patients with type 2 diabetes mellitus. We investigated the relationships between TIR, glycemic variability and patient characteristics in patients with type 2 diabetes mellitus. MATERIALS AND METHODS: We carried out continuous glucose monitoring in 281 outpatients with type 2 diabetes mellitus who participated in a multicenter cohort (Hyogo Diabetes Hypoglycemia Cognition Complications) study. RESULTS: The results are shown as the median (interquartile range). The age, disease duration and HbA1c were 68 years (62-71 years), 13 years (7-23 years) and 6.9% (6.5-7.5%), respectively. TIR and standard deviation obtained by continuous glucose monitoring worsened significantly with increasing disease duration. Multiple regression analyses showed that disease duration (standard partial regression coefficient, ß = -0.160, P = 0.003), diabetic peripheral neuropathy (ß = -0.106, P = 0.033) and urinary albumin excretion (ß = -0.100, P = 0.043) were useful explanatory factors for TIR. In contrast, HbA1c (ß = -0.398, P < 0.001) and the use of antidiabetic drugs potentially associated with severe hypoglycemia (ß = 0.180, P = 0.028), such as sulfonylureas, glinides and insulin, were useful explanatory factors for time below range in the elderly patients with type 2 diabetes mellitus. CONCLUSIONS: The results of this study suggest that disease duration and diabetic complications are associated with TIR deterioration. In addition, low HbA1c levels and the use of antidiabetic drugs potentially associated with severe hypoglycemia might worsen the time below range in the elderly.

A case of abrupt onset autoimmune type 1 diabetes mimicking fulminant type 1 diabetes.

A 63-year-old male was admitted to our hospital with diabetic ketoacidosis. He had flu-like symptoms 10 days before admission and developed thirst, polyuria and anorexia with 9 kg of body weight loss in a week. Plasma glucose level on admission was 983 mg/dL and HbA1c was 7.5%. Despite high levels of serum pancreatic enzymes, lack of severe abdominal pain and no morphological change of pancreas in the abdominal CT scan eliminated the complication of classical acute pancreatitis. These findings suggested the diagnosis of fulminant type 1 diabetes. However, urinary and plasma C-peptide levels showed that insulin secretion was not completely depleted at onset. Furthermore, an examination of islet-related antibodies revealed the presence of high titer anti-GAD antibody. His HLA typing showed that DRB1*0901-DQB1*0303 and A24 were present. He has been doing well with continuation of insulin therapy. Over two years after onset, his plasma C-peptide level was gradually lowered, and anti-GAD antibody was still positive. Taken together, this is a rare case of abrupt onset autoimmune type 1 diabetes with transient but apparent exocrine pancreatic impairment at onset. Similar cases should be accumulated to clarify pathophysiological similarities and/or differences between fulminant type 1 diabetes and abrupt onset autoimmune type 1 diabetes.

A case of Graves' disease developing with exacerbation of sarcoidosis.

A 53-year old female was referred to our hospital with bilateral abnormal shadow in the chest X-ray. Computed tomography revealed multifocal ill-defined densities and thickening of bronchial wall and pulmonary vessels by fine nodules combined with massive enlargement of bilateral mediastinal and hilar lymph nodes. Analyses of bronchoalveolar lavage fluid and transbronchial lung biopsy specimen showed the increase in CD4/CD8 ratio and the presence of non-caseating granulomas, respectively. In addition, serum angiotensin-converting enzyme was extremely high, leading to the diagnosis of sarcoidosis. Simultaneously, she complained of palpitation and sweating. Endocrinological examination showed comorbid hyperthyroidism without anti-TSH receptor antibody (TRAb). In the first 2-3 months, pulmonary shadow gradually disappeared without steroid administration. In parallel, serum thyroid hormone levels were gradually normalized in the beginning, but increased after 3 months with an appearance of TRAb. After initiation of treatment with antithyroid agent, hyperthyroidism was improved within 9 months, and changed into hypothyroidism thereafter. The clinical course of this rare case suggest that immunological storm by exacerbation of sarcoidosis may trigger the onset of autoimmune thyroid disease, in which hyperthyroidism with stimulating type of TRAb subsequently changed into hypothyroidism with blocking-type TRAb.

CRH mRNA expression in the hypothalamic paraventricular nucleus is inhibited despite the activation of the hypothalamo-pituitary-adrenal axis during starvation.

Corticotropin-releasing hormone (CRH) is one of the anorexigenic neuropeptides, and indeed the expression of hypothalamic CRH is known to be inhibited by starvation. To clarify whether elevated plasma glucocorticoid during starvation is responsible for the CRH suppression, we examined the expression level of hypothalamic CRH mRNA after food deprivation in adrenalectomized, plasma corticosterone (B)-clamped animals. Male Wistar rats were divided into 2 groups: one group had adrenalectomy (ADX) and B pellet implantation (ADX+B, n=42), and the other group had only sham operation (sham, n=42). Rats were then treated with either ad libitum food supply or food deprivation for up to 96 h. The expression of CRH mRNA in the paraventricular nucleus (PVN) was estimated by in situ hybridization. After food deprivation, mean plasma B level was markedly elevated in sham group, but almost clamped in the ADX+B group. In this experimental condition, CRH mRNA in the PVN was significantly decreased in the sham group, whereas no change was obtained in the ADX+B group. Our data suggest the decrease in CRH mRNA seems to be related to the elevated glucocorticoid level during starvation. The status of hyperadrenocorticism without activation of CRH led us to speculate that adrenocortical function is predominant in the hypothalamic-pituitary-adrenal (HPA) axis during starvation.

Association between nighttime sleep duration, midday naps, and glycemic levels in Japanese patients with type 2 diabetes.

OBJECTIVES: To clarify the relationship between nighttime sleep duration, midday naps, and glycemic control in Japanese patients diagnosed with type 2 diabetes (n = 355) or impaired glucose tolerance (n = 43). METHODS: A total of 398 patients completed a self-administered questionnaire on sleep duration/quality and were divided into five groups according to their self-reported nighttime sleep duration: <5 h, 5-6 h, 6-7 h, 7-8 h, and >8 h. Each group was further divided into two subgroups each according to the presence or absence of midday naps. Poor glycemic control was defined as HbA1c ≥ 7.0%. RESULTS: Short nighttime sleep (<5 h), poor sleep induction, daytime sleepiness, and low sleep satisfaction were associated with high HbA1c levels. HbA1c was higher in the short nighttime sleep/no nap group than in non-nappers with different nighttime sleep duration, whereas the short nighttime sleep/nap group showed similar HbA1c levels to the other nap subgroups. In multivariate logistic regression models, after adjusting for a number of potential confounders, short (<5 h) nighttime sleep without nap was significantly associated with poor glycemic control compared with 6-7 h nighttime sleep without nap (OR [95% CI]: 7.14 [2.20-23.20]). However, taking naps reduced this risk for poor glycemic control in short sleepers. Other risk factors for poor glycemic control were low sleep satisfaction (1.73 [1.10-2.70]) and poor sleep induction (1.69 [1.14-2.50]). CONCLUSIONS: Poor sleep quality and quantity could aggravate glycemic control in type 2 diabetes. Midday naps could mitigate the deleterious effects of short nighttime sleep on glycemic control. CLINICAL TRIALS REGISTRATION: UMIN 000017887.

Central type 2 corticotropin-releasing hormone receptor mediates hypothalamic-pituitary-adrenocortical axis activation in the rat.

In an attempt to clarify the role of the type 2 corticotropin-releasing hormone (CRH) receptor (CRHR-2) in the brain in activation of the hypothalamic-pituitary-adrenocortical axis, we conducted experiments using male Wistar rats. First, an injection of urocortin-2 (7.5 microg) into the lateral ventricle resulted in transient increases in CRH heteronuclear RNA (hnRNA) in parvocellular paraventricular nucleus (PVN) and in plasma adrenocorticotropic hormone (ACTH), whereas sustained increases in arginine vasopressin (AVP) hnRNA and c-fos mRNA in the parvocellular PVN were observed as compared with vehicle treatment. Pretreatment with the selective CRHR-2 antagonist antisauvagine-30 (20 microg) into the lateral ventricle 15 min prior to agonist injection attenuated the stimulatory effects of urocortin-2 on the above-mentioned hypothalamic-pituitary-adrenal axis variables. These effects were similar or rather more potent than those induced by pretreatment with 50 microg of alpha-helical CRH. Second, we found longer-lasting increases in CRH and AVP hnRNA and c-fos mRNA in parvocellular PVN and in plasma ACTH following central administration of urocortin-3 (7.5 microg) than following urocortin-2. Pretreatment with antisauvagine-30 antagonized the effects of urocortin-3 on the above-mentioned variables. Finally, central administration of antisauvagine-30 as well as alpha-helical CRH profoundly attenuated restraint-stress-induced increases in AVP hnRNA. However, alpha-helical CRH, but not antisauvagine-30, attenuated restraint-stress-induced increases in CRH hnRNA in the PVN. Both antagonists transiently attenuated stress responses of c-fos mRNA in PVN and plasma ACTH. These results indicate that there is a CRHR-2-mediated mechanism in the brain that stimulates CRH- and AVP-producing neurons in the PVN which results in the promotion of plasma ACTH secretion.

Expression of type 1 corticotropin-releasing hormone (CRH) receptor mRNA in the hypothalamic paraventricular nucleus following restraint stress in CRH-deficient mice.

Previous studies have demonstrated that various types of stress increase type 1 corticotropin-releasing hormone (CRH) receptor (currently abbreviated to CRF1 receptor) mRNA in the hypothalamic paraventricular nucleus (PVN) of rats, but not mice. This study investigated whether different sensitivities of glucocorticoid-mediated negative feedback effects can explain this species difference in stress-induced PVN CRF1 receptor mRNA expression. First, the CRF1 receptor mRNA level in the PVN of CRH knockout (KO) mice during acute restraint stress was compared with that in wild-type (WT) mice. Consistent with previous findings, WT mice showed no induction of CRF1 receptor mRNA in the PVN following acute restraint, regardless of normal hypothalamic-pituitary-adrenocortical responses. In contrast, CRF1 receptor mRNA in the PVN of CRH KO mice was increased following 2 h of restraint. Since the response of tyrosine hydroxylase (TH) mRNA in the locus coeruleus (LC) to restraint was similar between CRH KO and WT mice, it is unlikely that enhanced noradrenergic input into the PVN was responsible for the CRF1 receptor mRNA induction in CRH KO mice. Second, to determine whether CRH KO per se or a low corticosterone response to stress is required to induce CRF1 receptor mRNA expression in the PVN in mice, the response of adrenalectomized WT mice was examined. Acute restraint increased the CRF1 receptor mRNA level in the PVN of adrenalectomized WT mice, similar to the case for CRH KO mice. TH mRNA in the LC showed similar increases in sham and adrenalectomized WT mice. These results indicate that PVN CRF1 receptor mRNA is much more sensitive to glucocorticoid-mediated negative feedback in mice than in rats, such that a normal increase in plasma corticosterone during stress can mask CRF1 receptor mRNA induction in the PVN of mice.

Recovery from alopecia areata in a patient with autoimmune polyglandular syndrome type 3.

UNLABELLED: Recovery from alopecia is rare in autoimmune polyglandular syndrome (APS). A 41-year-old male was admitted to our hospital with hyperglycemia. He developed alopecia areata (AA) 5 months before admission and developed thirst, polyuria, and anorexia in 2 weeks. His plasma glucose level upon admission was 912 mg/dl (50.63 mmol/l) and HbA1c was 13.7%. Although urinary and plasma C-peptide levels showed that insulin secretion was not depleted, anti-insulinoma-associated antigen 2 antibody was present. In addition, measurement of thyroid autoantibodies revealed the presence of Hashimoto's thyroiditis. These findings suggested a diagnosis of APS type 3. The patient has showed signs of improvement with the continuation of insulin therapy. During the successful control of diabetes, he had total hair regrowth within 2-3 months. Human leukocyte antigen typing showed that DRB1*1501-DQB1*0602 and DQB1*0301 were present. Similar cases should be accumulated to clarify the association of APS type 3 with recovery from AA. LEARNING POINTS: Alopecia in diabetic patients is a suspicious manifestation of autoimmune type 1 diabetes.Patients with autoimmune type 1 diabetes specifically manifesting alopecia should be further examined for diagnosis of APS.Insulin-mediated metabolic improvement may be a factor, but not the sole factor, determining a favorable outcome of alopecia in patients with autoimmune type 1 diabetes.

Urocortins and corticotropin releasing factor type 2 receptors in the hypothalamus and the cardiovascular system.

In addition to urocortin (Ucn I), Ucn II and Ucn III were identified as endogenous ligands for corticotropin-releasing factor type 2 receptor (CRF2 receptor). CRF2 receptor is abundantly located in central hypothalamic ventromedial nucleus (VMH) and in peripheral cardiovascular system. In this mini-review, we focused on the roles of these urocortins and CRF2 receptor in the hypothalamus and the cardiovascular system. Ucn II mRNA was increased in the parvocellular part or the magnocellular part of the hypothalamic paraventricular nucleus (PVN) following immobilization stress or 3 days of water deprivation, respectively. Therefore, it is thought that Ucn II may modulate CRF and vasopressin synthesis in the PVN in a paracrine or autocrine fashion through PVN CRF2 receptor. The early and later phases of Ucn I-mediated feeding suppression may be CRF1 and CRF2 receptor-mediated events, respectively. Ucn II decreases food intake at a later phase, beyond 4 h post injection. A large dose of corticosterone increased plasma leptin and insulin levels as well as the levels of CRF2 receptor mRNA. Adrenalectomy, starvation, and immobilization each lowered plasma leptin and insulin levels and were associated with decrements in CRF2 receptor mRNA levels in the VMH. Peripheral injection of leptin increased VMH CRF2 receptor mRNA, as can induce reductions of food intake and body weight, indicating that circulating leptin is involved in the regulation of VMH CRF2 receptor mRNA expression. Therefore, it is also plausible that VMH CRF2 receptor transduces the anorexogenic effects of leptin as well as those of urocortins. The systemic administration of Ucn II decreases mean arterial pressure (arterial vascular tone) and causes tachycardia via vascular CRF2 receptor in rats, similar to the effects of Ucn I. Thus, CRF2 receptor seems to mediate cardioprotective effects of urocortins.

Regulatory role of glucocorticoids and glucocorticoid receptor mRNA levels on tyrosine hydroxylase gene expression in the locus coeruleus during repeated immobilization stress.

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.

Brain oxytocin augments stress-induced long-lasting plasma adrenocorticotropic hormone elevation in rats.

Single stress induces long-lasting changes in the hypothalamo-pituitary--adrenal (HPA) axis of adult animals. Selective oxytocin (OXT) receptor antagonist was administrated into the cerebroventricle of male rats to test its influence on plasma adrenocorticotropic hormone (ACTH) responses induced by immobilization stress. The ACTH level is significantly higher than the control level (P<0.05) up to 6 days after single stress. Although the OXT antagonist did not change the plasma ACTH level at the end of single stress (P=0.59), the antagonist significantly decreased the ACTH concentration at the end of repeated (3 days) stress and 2 days after single stress (P<0.05) compared with controls. The results suggest that endogenous brain OXT enhances the long-lasting but not immediate HPA axis response to stress.

Multiple feedback mechanisms activating corticotropin-releasing hormone system in the brain during stress.

Stress-associated disorders such as melancholic depression are characterized by persistent hypothalamic-pituitary-adrenocortical (HPA) axis activation and intensive anxiety. Corticotropin-releasing hormone (CRH) appears to play an essential role in pathophysiology of such disorders. In an attempt to elucidate possible mechanisms underlying persistent activation of CRH in the central nervous system (CNS), we examined responses of hypothalamic and extrahypothalamic CRH systems to the stressors (immobilization stress or psychological stress) and interactions between these CRH systems and glucocorticoids in rats. We propose multiple feedback loops activating central CRH system: (1) attenuation of glucocorticoid-induced negative feedback on the activity of the hypothalamic and brainstem nuclei during chronic stress, (2) autoregulation of CRH biosynthesis in the hypothalamic paraventricular nucleus (PVN) through up-regulation of Type-1 CRH receptor (CRHR-1), and (3) glucocorticoid-mediated positive effects on the amygdaloid CRH system. Stress initially activates the hypothalamic CRH system, resulting in the hypersecretion of glucocorticoids from the adrenal gland. In addition, the psychological component of the stressor stimulates the amygdaloid CRH system. In the chronic phase of stress, down-regulation of GR in the PVN and other brain structures such as the locus coeruleus (LC) fails to restrain hyperfunction of the HPA axis, and persistent activation of the HPA axis further up-regulates the amygdaloid CRH system. Thus, the hypothalamic and the amygdaloid CRH systems cooperatively constitute stress-responsive, anxiety-producing neurocircuitry during chronic stress, which is responsible for the clinical manifestations of stress-associated disorders. Effects of tricyclic antidepressants (TCAs), which appear to mitigate the above mentioned multiple feedback loop forming the vicious circle to activate central CRH systems, will also be discussed.

Regulation of glucocorticoid receptor transcription and nuclear translocation during single and repeated immobilization stress.

We have previously reported reduced glucocorticoid receptor (GR) mRNA levels in the hippocampus and hypothalamic paraventricular nucleus (PVN) during repeated immobilization, which is potentially associated with persistent activation of the hypothalamic-pituitary-adrenocortical axis. We used in situ hybridization and Western blot to examine the transcriptional regulation of the GR gene, GR nuclear translocation, and expression of cytosolic heat shock protein 90 (hsp90), a chaperone protein essential for GR nuclear translocation, in the hippocampus, PVN, and anterior pituitary (AP) during single immobilization (sIMO) and the final immobilization on d 7 after daily IMO for 6 days (rIMO). As with GR mRNA, GR heteronuclear RNA levels decreased in the hippocampus and PVN and increased in the AP during sIMO and rIMO, indicating that the GR mRNA levels in these regions were regulated at the transcriptional level. In both sIMO and rIMO, nuclear GR levels were significantly increased in the hippocampus, medial basal hypothalamus (MBH), and AP. However, GR nuclear translocation was reduced in the hippocampus, unchanged in the MBH, and enhanced in the AP during rIMO, as compared with sIMO. Cytosolic hsp90 expression was unchanged in the hippocampus and MBH, whereas it significantly increased in the AP at 30 min during rIMO but not during sIMO. These results suggest that the site-specific changes in GR nuclear translocation during sIMO vs. rIMO are partially linked to hsp90 responses to immobilization. The reduced nuclear translocation of GR in the hippocampus during rIMO may reflect decreased glucocorticoid-mediated negative feedback on the hypothalamic-pituitary-adrenocortical axis.