不同糖化血红蛋白水平的2型糖尿病患者下丘脑-垂体-肾上腺轴功能分析

研究不同HbA1C水平2型糖尿病患者的下丘脑-垂体-肾上腺(HPA)轴功能.发现HbA1C≤7%组HPA轴功能无亢进[ACTH(18.03±8.39)ng/L,血皮质醇(49.22±8.68)μg/L],7%11%组HPA轴功能持续性亢进使得其负反馈环路消失[ACTH(26.08±15.41)ng/L,血皮质醇(55.64±24.27)μg/L].提示糖代谢紊乱程度不同的2型糖尿病患者HPA轴功能及其影响因素不同.

Abstract：

Hypothalamic-pituitary-adrenal(HPA)axis-related factors in patients with type 2 diabetes were studied according to different levels of HbA1C.It showed that HPA axis was normal in HbA1C≤ 7% group[ACTH (18.03±8.39)ng/L,blood cortisol(49.22±8.68)μg/L],hyperactive in 7%11% group with weak feedback regulation[ACTH(26.08±15.41)ng/L,blood cortisol(55.64±24.27)μg/L].These results suggest that HPA axis-related factors in type 2 diabetic patients are different with different grades of glucose metabolic turbulence.     

Endocannabinoid hydrolase and cannabinoid receptor 1 are involved in the regulation of hypothalamus-pituitary-adrenal axis in type 2 diabetes

Hypothalamus-pituitary-adrenal (HPA) axis, as the key moderator in energy metabolism, plays an important role in diabetes. The endogenous cannabinoid system (eCBs) involves in neuronal functions, and simultaneously cannabinoid receptors are almost expressed in all regions of the hypothalamus according to a spate of reports. However, few data investigate the changes of eCBs and HPA axis in type 2 diabetes. In this study, five diabetes mellitus rhesus monkeys, five prediabetes rhesus monkeys and five healthy rhesus monkeys were observed. In the present study, we detected cell swelling and necrosis extensively in the paraventricular nucleus (PVN) and neurohypophysis in prediabetes and overt diabetes monkeys. The adrenocorticotropic hormone in the pituitary gland, adrenocorticotropic hormone receptor, and 11β-hydroxysteroid dehydrogenase in the adrenal gland were all hyper-secreted and expressed from healthy to overt diabetes. Meanwhile, the cortisol concentration in the adrenal gland was increased along with the progress of diabetes. It could be concluded that hyperfunction of the HPA axis exists in the type 2 Diabetes pathogenesis. However, we also found a weakened expression and secretion of corticotrophin releasing hormone and glucocorticoids receptor in PVN. The expression of corticotropin releasing hormone receptor 1 in pituitary gland decreased in prediabetes monkeys, but increased in overt diabetes monkeys. The downregulation of cannabinoid receptor 1 and upregulation of monoglycerol lipase and fatty acid amide hydrolase in PVN was involved in the pathogenesis of type 2 diabetes. Collectively, we can conclude that changes in endocannabinoid hydrolase and cannabinoid receptor might indicate the effect of downregulation of eCBs. It can be assumed that hyper-function of the HPA axis from healthy to overt diabetes is due to the undermining inhibition of eCBs. However, the regulatory mechanism of eCBs targets on the HPA axis need to be further explored.     

2型糖尿病患者皮质醇水平及下丘脑-垂体-肾上腺轴活性

本研究评价2型糖尿病患者皮质醇水平及调节.测定血、尿皮质醇,行地塞米松抑制试验及醋酸可的松试验.糖尿病患者尿皮质醇水平高于正常对照组,其肝脏11β-羟类同醇脱氧酶活性较正常人群明显下降.提示2型糖尿病患者有较高的基础皮质醇水平,其原因可能为肝脏对皮质醇的降解代谢受损.     

The endogenous cannabinoid, anandamide, activates the hypothalamo-pituitary-adrenal axis in CB1 cannabinoid receptor knockout mice

The purpose of this study was to investigate the effects of the endogenous cannabinoid arachidonoyl-ethanolamide, anandamide (AEA), on the activity of the hypothalamo-pituitary-adrenal (HPA) axis in cannabinoid receptor (CB(1) receptor) inactivated (KO) mice. A low dose (0.01 mg/kg i.p.) of AEA significantly increased plasma corticotropin (ACTH) and corticosterone concentrations in both wild-type (+/+) and in mutant (-/-) animals. In each case, hormone levels reached their peaks at 90 min after AEA administration. In a parallel experiment, AEA administration was preceded by the injection of SR 141716A (1.0 mg/kg), a selective and potent CB(1) receptor antagonist, or of capsazepine (5.0 mg/kg), a potent vanilloid receptor of type 1 (VR1) antagonist. The latter drugs did not prevent the effects of AEA on the HPA axis. Using Fos protein immunohistochemistry, we observed that the parvocellular part of the hypothalamic paraventricular nucleus (PVN) was activated as early as 45 min after AEA injection and reached peak levels after 60 min in both +/+ and -/- mice. Furthermore, the CB(1) and VR1 receptor antagonists did not block the effects of AEA on Fos immunoreactivity. The results strongly support the view that activation of the HPA axis produced by AEA possibly occurs via a currently unknown (CB(x)) cannabinoid receptor present in PVN.     

11β-HSD1对下丘脑-腺垂体-肾上腺轴及海马的影响

糖皮质激素(GC)受11β-羟类固醇脱氢酶(HSD)1的调节,对大脑活动产生广泛的影响。11-βHSD1催化无活性的11-脱氧皮质酮转化为有活性的GC,从而提高组织局部的GC浓度,加强GC的作用。GC对下丘脑—腺垂体—肾上腺轴的负反馈调节作用受11-βHSD1的影响。海马是与认知、学习、记忆功能密切相关的重要脑区,极易受到随年龄增加的GC神经毒性的损伤。11-βHSD1活性降低有助于减轻与年龄相关的认知障碍。     

Evaluation of hypothalamic-pituitary-adrenal axis recovery after corticotherapy by using basal cortisol secretion

The glucocorticoid-induced inhibition that occurs after discontinuation of treatment is the most frequent cause of adrenal insufficiency. There are yet some doubts about the best way of evaluating the hypothalamic-pituitary-adrenal (HPA) axis in those patients. The main objective of this study was to evaluate the utility of basal cortisol in diagnosing adrenal insufficiency. Thirty-five children with acute lymphoid leukemia (ALL) receiving glucocorticoid therapy (median age of 6.9 years) were evaluated. A stimulus test with corticotropin releasing hormone (CRH-1 mcg/kg) was performed before the introduction of dexamethasone (6 mg/m2/day, for 28 days), in the 8th and the 28th days of glucocorticoid therapy, and 48 hours and one month after discontinuation of therapy. Suppression of the basal secretion as well as the maximum concentration of cortisol (post-CRH) occurred during glucocorticoid therapy, which persisted for 48 hours after the steroid was removed from treatment (p< 0.01 and p< 0.0001, respectively, for the three tests). One month after ceasing the administration of the glucocorticoid, the basal secretion, as well as the maximum concentration of cortisol, were similar to that before glucocorticoid therapy. There was a positive and statistically significant correlation between basal secretion and maximum concentration of cortisol in all tests. We observed 95% of specificity for the diagnosis of adrenal insufficiency when the inferior limit of basal cortisol was 8.5 mcg/dl. According to these results we concluded that basal secretion of cortisol is a good marker of supra-renal function in evaluating children after discontinuation of glucocorticoid therapy.     

Obese Zucker rats have reduced mineralocorticoid receptor and 11beta-hydroxysteroid dehydrogenase type 1 expression in hippocampus-implications for dysregulation of the hypothalamic-pituitary-adrenal axis in obesity

Obese Zucker rats have elevated basal corticosterone levels and an increased stress response suggestive of an increased activity of the hypothalamic-pituitary-adrenal (HPA) axis. We hypothesized that altered central expression of glucocorticoid receptors (GR), mineralocorticoid receptors (MR), and/or 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) contribute to these changes. In brains from young adult male rats, in situ hybridization and Western blotting showed that obese rats had normal hippocampal GR mRNA and protein levels. In contrast, in obese rats, 11betaHSD1 mRNA levels were reduced in a subpopulation of hippocampal cells in the main neuronal layers (by 37-47%, P < 0.05), whereas 11betaHSD1 levels in sparse high-expressing cells did not differ. MR mRNA was decreased in all regions of the hippocampus (by 37-49%, P < 0.05 for CA1-2 and P < 0.01 for dentate gyrus) and in frontal cortex (by 16%, P < 0.05) in obese rats. In whole hippocampal homogenates, however, neither the protein concentration of MR by Western blot nor activity of 11betaHSD1 was measurably different between the phenotypes. To test the functional importance of lower central MR expression, groups of lean and obese rats were given spironolactone before restraint stress. In vehicle-treated animals, obese rats had higher plasma corticosterone levels than lean rats after stress (by ANOVA, P < 0.05). Spironolactone markedly increased the corticosterone response in both groups, but the incremental rise was smaller in the obese rats, so that spironolactone abolished the differences between groups. We conclude that lower levels of MR, but not GR, contribute to the increased HPA activity in the obese Zucker rats and that this seems more influential during stress than in the basal state. This may be exacerbated by impaired local regeneration of corticosterone by 11betaHSD1. These abnormalities could contribute to the subtle changes in the HPA axis in rodent and human obesity.     

Evidence for ototopical glucocorticoid-induced decrease in hypothalamic-pituitary-adrenal axis response and liver function

To clarify whether ototopical glucocorticoid treatment is associated with impaired hypothalamic-pituitary-adrenal axis (HPA) activity and altered hepatic metabolism, one commercially available dexamethasone-containing ointment was tested. At present, very little is known about the effects of ototopical glucocorticoid treatment on HPA and liver function. Ten beagle dogs received two daily therapeutic doses of dexamethasone (0.6 mg/ear) in the outer auditory canal for 21 d in a single-blind, placebo-controlled study. Resting cortisol concentrations were assessed before, during, and after treatment using an RIA system. Adrenal function and HPA feedback sensitivity were measured by a standard dose (250 microg) ACTH stimulation test. Serum biochemical and hematological parameters were measured, whether ototopical glucocorticoids affect hepatic function was studied, and blood cell counts were made. Ototopical dexamethasone treatment induced a marked suppression (to about 100%) of resting plasma cortisol concentrations below the placebo effect (P < 0.0001) within the first 11 d, and these remained reduced during the entire treatment period up to d 19. As well, an ACTH stimulation test found a markedly reduced rise in plasma cortisol concentrations (P = 0.0004). Concomitantly, significant increases in serum activities of alkaline phosphatase, gamma-glutamyl transferase, alanine transaminase, and aspartate transaminase were detected. Moreover, we found a significant reduction in differential leukocyte counts of eosinophils and lymphocytes, whereas neutrophils increased. Although cortisol levels and hematological parameters returned to baseline 7 d after treatment cessation, liver enzyme activities remained elevated. In conclusion, these findings suggest that after ototopical application, dexamethasone is sufficiently absorbed from the auditory canal to suppress HPA function as well as to alter metabolic and hemopoietic profiles. Thus, in long-term treatment of otitis externa or media, the systemic adverse suppression of HPA has to be considered in relation to stress exposure, whereas changes in serum enzyme activities may not be interpreted as hepathopathy.     

Mechanisms of serotonin receptor agonist-induced activation of the hypothalamic-pituitary-adrenal axis in the rat

A substantial body of experimental evidence indicates that serotonin (5-HT) and several synthetic 5-HT receptor agonists activate the hypothalamic-pituitary-adrenal (HPA) axis. To explore the mechanism(s) by which 5-HT or 5-HT agonists enhance the activity of the HPA axis in vitro, we examined the stimulatory effects of the 5-HT1a agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), the 5-HT1c/5-HT1b agonist m-chlorophenylpiperazine (m-CPP), and the 5-HT2/5-HT1c agonist 1-(2,5-dimethoxy-4-iodophenyl)2-amino-propane (DOI) on plasma ACTH and corticosterone secretion in the rat. To test whether 8-OH-DPAT, m-CPP, or DOI increase plasma ACTH levels by stimulating the release of endogenous CRH, catheterized conscious male Sprague-Dawley rats were pretreated with hyperimmune CRH rabbit serum (TS-6) or normal rabbit serum and subsequently challenged with a maximally stimulatory dose of the above 5-HT agonists. Pretreatment with TS-6 completely suppressed the ACTH response to m-CPP and significantly blunted the responses to 8-OH-DPAT or DOI. To examine whether the remaining ACTH response to 8-OH-DPAT or DOI was also mediated by a pituitary site of action, we administered each of these agents to pituitary stalk-transected or sham-operated rats. The ACTH responses to 8-OH-DPAT and DOI in stalk-transected rats were preserved, although significantly blunted, compared to those in sham-operated rats. This suggested that both of these 5-HT agonists may also act at the pituitary level to stimulate ACTH release in vivo. Although the ACTH responses to 8-OH-DPAT, m-CPP, and DOI were blunted after both TS-6 pretreatment and pituitary stalk transection, corticosterone responses were only slightly affected, suggesting that some of these compounds may cause corticosterone release in the rat through another mechanism. To evaluate this hypothesis, ACTH and corticosterone responses to 8-OH-DPAT, m-CPP, and DOI were examined in rats whose HPA axis had been suppressed by a single high dose injection of dexamethasone. The corticosterone responses to 8-OH-DPAT and DOI were blunted compared to those of saline-pretreated rats, but were inappropriately high compared to the ACTH responses observed in these rats. On the other hand, both ACTH and corticosterone responses to m-CPP were completely abolished by dexamethasone.(ABSTRACT TRUNCATED AT 400 WORDS)     

Acute-stress-induced facilitation of the hypothalamic-pituitary-adrenal axis

It has been hypothesized that the hypothalamic-pituitary-adrenal (HPA) axis responds to a stressor by secreting facilitatory and inhibitory factors. During a stressor, the relative magnitude of secretion of these factors determines the responsiveness of the HPA axis to a subsequent stressor. Previous studies have suggested that corticosterone (B) secreted during the first stressor is an inhibitory factor. We hypothesized that the transient removal of the inhibitory factor, B, during the first stressor would result in the secretion of only facilitatory factors. This would cause the HPA axis to exist in a state of hyperresponsiveness, and to hypersecrete corticotropin (ACTH) and B in response to a second stressor. Therefore, our primary objective was to demonstrate stress-induced facilitation of the HPA axis response to a subsequent stressor. Male Sprague-Dawley rats were subjected to a 1-hour physical immobilization stressor (IMM) or administered a single dose of ACTH on day 1. B response during these treatments was markedly but transiently attenuated with an 100 mg/kg i.p. dose of aminoglutethimide (AG). Twenty-four hours later, rats were subjected to an intraperitoneal saline injection stressor. B and ACTH levels were measured 15 min after the injection stressor. Rats treated with AG plus IMM on day 1 hypersecreted B and ACTH after the injection stressor on day 2. These results suggest that immobilization stress induces facilitation of both pituitary and adrenal responses. Exogenous administration of ACTH- to AG-pretreated rats on day 1, in lieu of immobilization stress, did not affect the responsiveness of the HPA axis on day 2. This suggests that ACTH secreted during the first stressor does not play an important role in acute-stress-induced facilitation.     

Liver-selective transgene rescue of hypothalamic-pituitary-adrenal axis dysfunction in 11beta-hydroxysteroid dehydrogenase type 1-deficient mice

11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) acts as a reductase in vivo, regenerating active glucocorticoids within cells from circulating inert 11-keto forms, thus amplifying local glucocorticoid action. 11beta-HSD1 is predominantly expressed in liver and also adipose tissue and brain. Mice deficient in 11beta-HSD1 (11beta-HSD1(-/-)) exhibit adrenal hyperplasia, raised basal corticosterone levels, and increased hypothalamic-pituitary-adrenal (HPA) axis responses to stress. Whereas reduced peripheral glucocorticoid regeneration may explain adrenal hypertrophy and exaggerated stress responses, elevated basal glucocorticoid levels support a role for 11beta-HSD1 within the brain in amplifying glucocorticoid feedback. To test this hypothesis, apolipoprotein E-HSD1 mice overexpressing 11beta-HSD1 in liver were intercrossed with 11beta-HSD1(-/-) mice to determine whether complementation of hepatic 11beta-HSD1 can restore adrenal and HPA defects. Transgene-mediated delivery of 11beta-HSD1 activity to the liver rescued adrenal hyperplasia and reversed exaggerated HPA stress responses in 11beta-HSD1(-/-) mice. Unexpectedly, elevated nadir plasma corticosterone levels were also restored to control levels. Consistent with this, CYP11B1 mRNA expression in the adrenal cortex of 11beta-HSD1(-/-) mice was increased by 50% but returned to control levels in 11beta-HSD1(-/-) mice bearing the apolipoprotein E-HSD1 transgene. 11beta-HSD1(-/-) mice have lower plasma glucose levels, but the fall in plasma corticosterone with sucrose supplementation was similar in 11beta-HSD1(-/-) and control mice, suggesting glucose deficiency is not the main mechanism whereby basal corticosterone levels are elevated in the null mice. Thus, regeneration of glucocorticoids by 11beta-HSD1 in the liver normalizes all aspects of HPA axis dysregulation in 11beta-HSD1(-/-) mice, without restoration of enzyme activity in key feedback areas of the forebrain. Therefore, hepatic glucocorticoid metabolism influences basal as well as stress-associated functions of the HPA axis.     

Long-term basal and dynamic evaluation of hypothalamic-pituitary-adrenal (HPA) axis in acromegalic patients

Objective Long‐term effects of trans‐naso‐sphenoidal surgery (TNS) or long‐acting somatostatin analogs (SSA) on the function of hypothalamic–pituitary–adrenal (HPA) axis have been poorly investigated. Aim of this study was to evaluate HPA axis integrity during the follow‐up in patients with GH‐secreting pituitary adenomas and preserved HPA function post‐TNS or prior SSA. Design and patients This retrospective study investigated 36 acromegalic patients (16M and 20F, age: 47 ± 13 years), 20 of whom cured by TNS and 16 controlled by SSA therapy (12 previously operated and 4 in primary medical therapy), before and after long‐term follow‐up (median: 72 months, range: 12–240). No patient previously underwent radiotherapy. Measurements HPA function was studied by morning circulating cortisol and ACTH levels, 24‐h urinary free cortisol (UFC) and cortisol response to low‐dose short Synacthen test (LDSST, 1 µg) with a peak > 500 nmol/l as cut‐off for normal function. Results Serum basal cortisol, ACTH and UFC levels were in the normal range and did not significantly change over time. As far as the cortisol peak after LDSST is concerned, 12 patients (32%, 8 TNS and 4 SSA) developed biochemical hypoadrenalism. None of the patients in primary medical therapy showed cortisol peak < 500 nmol/l. No significant correlations between HPA axis deterioration and follow‐up duration, serum GH/IGF‐I levels, occurrence of other pituitary deficiencies, presence of secondary empty sella, changes in tumour or residual volume were observed. Conclusions The HPA axis function must be carefully monitored over the time by dynamic testing in all acromegalic patients, independently from the type of treatment.     

Overactive cannabinoid 1 receptor in podocytes drives type 2 diabetic nephropathy

Diabetic nephropathy is a major cause of end-stage kidney disease, and overactivity of the endocannabinoid/cannabinoid 1 receptor (CB₁R) system contributes to diabetes and its complications. Zucker diabetic fatty (ZDF) rats develop type 2 diabetic nephropathy with albuminuria, reduced glomerular filtration, activation of the renin-angiotensin system (RAS), oxidative/nitrative stress, podocyte loss, and increased CB₁R expression in glomeruli. Peripheral CB₁R blockade initiated in the prediabetic stage prevented these changes or reversed them when animals with fully developed diabetic nephropathy were treated. Treatment of diabetic ZDF rats with losartan, an angiotensin II receptor-1 (Agtr1) antagonist, attenuated the development of nephropathy and down-regulated renal cortical CB₁R expression, without affecting the marked hyperglycemia. In cultured human podocytes, CB₁R and desmin gene expression were increased and podocin and nephrin content were decreased by either the CB₁R agonist arachydonoyl-2′-chloroethylamide, angiotensin II, or high glucose, and the effects of all three were antagonized by CB₁R blockade or siRNA-mediated knockdown of CNR1 (the cannabinoid type 1 receptor gene). We conclude that increased CB₁R signaling in podocytes contributes to the development of diabetic nephropathy and represents a common pathway through which both hyperglycemia and increased RAS activity exert their deleterious effects, highlighting the therapeutic potential of peripheral CB₁R blockade.Diabetic nephropathy, a highly prevalent and serious complication of both type 1 and type 2 diabetes mellitus and a leading cause of renal failure, is characterized by albuminuria, decreased glomerular filtration rate (GFR), mesangial expansion, thickening of the glomerular basement membrane, and glomerular sclerosis (1). Multiple mechanisms have been implicated in the development of diabetic nephropathy, including activation of the renin-angiotensin system (RAS) (2), increase in oxidative (3) and nitrosative/nitrative stress (4), as well as an increase in local inflammation (5).The endocannabinoid system plays a well-documented role in obesity and its metabolic complications, including insulin resistance and type 2 diabetes (T2DM). Globally acting cannabinoid 1 receptor (CB₁R) antagonists/inverse agonists improve obesity-related insulin resistance, dyslipidemia, fatty liver, and β-cell loss, and attenuate obesity-related inflammatory changes both in preclinical models of diet-induced or genetic obesity and in clinical trials in overweight subjects with metabolic syndrome (reviewed in refs. 6 and 7). Global CB₁R blockade also has beneficial effects in mouse models of type 1 and type 2 diabetic nephropathy (8–11). However, the therapeutic development of this class of compounds has been halted because of adverse neuropsychiatric side effects in a small proportion of treated subjects (12). Recent studies in rodent models have demonstrated that peripherally restricted CB₁R antagonists are as effective as globally acting ones in reversing obesity and its metabolic sequelae (13, 14), and also delay the onset of overt T2DM (15) without inducing any behaviors that are predictive of adverse neuropsychiatric effects in humans (13, 14). Consequently, there is considerable interest in translating these findings to clinical practice by developing peripherally restricted CB₁R antagonists/inverse agonists for clinical use. In this study we used the Zucker diabetic fatty (ZDF) rat, a well-established model of type 2 diabetic nephropathy (16, 17), to explore the role of peripheral CB₁R in diabetic kidney disease, and the therapeutic potential of its inhibition by a nonbrain-penetrant CB₁R inverse agonist. We report that selective antagonism of peripheral CB₁R can both prevent the deterioration of kidney function when treatment starts in the prediabetic stage and reverse it when treatment is started after the full development of diabetic nephropathy. The results also indicate that increased endocannabinoid/CB₁R signaling in podocytes plays a key role in the development of nephropathy, which can be dissociated from the hyperglycemia and is likely induced via the RAS.     

Circadian rhythm of type II 5'deiodinase activity in the rat hypothalamic-pituitary-adrenal axis

Type II 5′ deiodinase (5′D-II) activity was assessed in the hypothalamus (HP), pituitary (PIT), and adrenal gland (AG) of adult male rats after two different photoperiodic regimes: (1) cyclic light-dark conditions (LD, 12∶12) or (2) 4 days in continuous darkness (DD). Under cyclic LD conditions HP, PIT and AG 5′D-11 activity showed a significant circadian rhythm (P<0.004−<0.0001). The acrophases obtained by cosinor analysis were: HP, 12∶37; PIT, 03∶04 and AG, 02∶30 h. In contrast, after 4 days in DD, HP 5′D-II rhythmicity was abolished and there was a significant shift in the acrophase of both PIT and AG enzyme activity. These results suggest that the 5′D-II oscillation in PIT and AG corresponds to an endogenous circadian rhythm and is not only a response to the presence of a L/D cycle.     

Acute cannabinoid receptor type 1 (CB1R) modulation influences insulin sensitivity by an effect outside the central nervous system in mice

Aims/hypothesis  

Modulation of central nervous system (CNS) and extra-CNS cannabinoid receptor type 1 (CB1R) affects metabolic conditions, independently of weight loss. Here we examined the relative contributions of acute CNS and extra-CNS CB1R modulation on insulin sensitivity using pharmacological gain- and loss-of-function of CB1R in mice.