Effect Of ADX Research Articles

Clinical and biochemical outcomes after adrenalectomy and medical treatment in patients with unilateral primary aldosteronism.

Current clinical guidelines of primary aldosteronism recommend adrenalectomy (AdX) for unilateral primary aldosteronism based on the studies showing the potential superiority of AdX over the medical treatment. However, since most medically treated cases consisted of bilateral primary aldosteronism and all surgically treated cases consisted of unilateral primary aldosteronism, the different subtype of primary aldosteronism could be a bias for their effects. This study compared the effects of AdX and medical therapy in patients with unilateral primary aldosteronism confirmed by adrenal vein sampling. Of the 339 patients with unilateral primary aldosteronism in the Japan Primary Pldosteronism Study data base, unilateral AdX and treatment with mineral corticoid receptor antagonists (MRAs) was done in 276 patients (AdX group) and in 63 patients (MRAs group), respectively. The effects were compared by the clinical (improvement of blood pressure) and biochemical outcomes (improvement of hypokalemia). At baseline, use of potassium replacement, plasma aldosterone concentration, aldosterone-to-renin ratio, estimated glomerular filtration rate, and prevalence of adrenal mass on imaging were higher in the AdX group than in the MRAs group. At 6 months after commencement of specific treatment for primary aldosteronism, clinical outcome and biochemical outcome in the AdX group were superior than those in the MRAs group. The difference of the outcome between the two groups were the case even after adjusting for the different clinical backgrounds in the two groups before the specific treatment. Our study provides evidence that AdX is the first choice of treatment in the patients with unilateral primary aldosteronism in terms of clinical and biochemical outcome.

Quality of Life in Primary Aldosteronism: A Comparative Effectiveness Study of Adrenalectomy and Medical Treatment.

In primary aldosteronism (PA), two subtypes are distinguished: aldosterone-producing adenoma (APA) and bilateral adrenal hyperplasia (BAH). In general, these are treated by adrenalectomy (ADX) and mineralocorticoid receptor antagonists (MRA), respectively. To compare the effects of surgical treatment and medical treatment on quality of life (QoL). Post hoc comparative effectiveness study within the Subtyping Primary Aldosteronism: A Randomized Trial Comparing Adrenal Vein Sampling and Computed Tomography Scan (SPARTACUS) trial. Twelve Dutch hospitals and one Polish hospital. Patients with PA (n = 184). ADX or MRAs. At baseline and 6-month and 1-year follow-up, we assessed QoL by two validated questionnaires: RAND 36-Item Health Survey 1.0 (RAND SF-36) and European Quality of Life-5 Dimensions (EQ-5D). At baseline, seven of eight RAND SF-36 subscales and both summary scores, as well as three of five EQ-5D dimensions and the visual analog scale, were lower in patients with PA compared with the general population, especially in women. The beneficial effects of ADX were larger than for MRAs for seven RAND SF-36 subscales, both summary scores, and health change. For the EQ-5D, we detected a difference in favor of ADX in two dimensions and the visual analog scale. Most differences in QoL between both treatments exceeded the minimally clinically important difference. After 1 year, almost all QoL measures had normalized for adrenalectomized patients. For patients on medical treatment, most QoL measures had improved but not all to the level of the general population. Both treatments improve QoL in PA, underscoring the importance of identifying these patients. QoL improved more after ADX for suspected APA than after initiation of medical treatment for suspected BAH.

Systemic Aldosterone, But Not Angiotensin II, Plays a Pivotal Role in the Pathogenesis of Renal Injury in Chronic Nitric Oxide-Deficient Male Rats

Chronic inhibition of nitric oxide synthase by N(ω)-nitro-L-arginine methyl ester (L-NAME) causes progressive renal injury and systemic hypertension. Angiotensin II (Ang II) has been conventionally regarded as one of the primary causes of renal injury. We reported previously that such renal injury was almost completely suppressed by both an Ang II type I receptor blocker and an aldosterone antagonist. The aldosterone antagonist also inhibited the systemic Ang II elevation. Therefore, it remains to be elucidated whether Ang II or aldosterone directly affects the development of such renal injury. In the present study, we investigated the role of aldosterone in the pathogenesis of renal injury induced by L-NAME-mediated chronic nitric oxide synthase inhibition in male Wistar rats (aged 10 wk). Serial analyses demonstrated that the renal injury and inflammation in L-NAME-treated rats was associated with elevation of both Ang II and aldosterone. To investigate the direct effect of aldosterone on the renal injury, we conducted adrenalectomy (ADX) and aldosterone supplementation in L-NAME-treated rats. In ADX rats, aldosterone was undetectable, and renal injury and inflammation were almost completely prevented by ADX, although systemic and local Ang II and blood pressure were still elevated. Aldosterone supplementation reversed the beneficial effect of ADX. The present study indicates that aldosterone rather than Ang II plays a central and direct role in the pathogenesis of renal injury by L-NAME through inflammation, independent of its systemic hemodynamic effects.

Regulatory mechanism of hypothalamo-pituitary–adrenal (HPA) axis and neuronal changes after adrenalectomy in type 2 diabetes

Diabetes, especially type 2, is closely associated with hypothalamo-pituitary–adrenal (HPA) axis regulation. Short-term effects of adrenalectomy (ADX) in type 2 diabetes are well characterized; however, there have been few reports on the long-term effects of ADX in genetically engineered type 2 diabetes and the neuroendocrine system. We performed bilateral ADX in Zucker Lean Control rats (ZLC; ADX-ZLC), Zucker Diabetic Fatty rats (ZDF; ADX-ZDF), and sham control rats to evaluate how the HPA axis would be regulated in long-term corticosterone deficient type 2 diabetic animals. We evaluated arginine vasopressin (AVP), glucocorticoid receptor (GR), and corticotropin-releasing hormone (CRH) expression with immunohistochemistry (IHC), immunofluorescence, real-time PCR, and Western blot analysis in each treatment group 7 weeks post ADX to assess HPA axis regulatory patterns in connection with type 2 diabetes. Additionally, mRNA expression of AVP and CRH receptors (V1aR, V1bR, CRHR1, and CRHR2) was also measured and adrenocorticotropin hormone (ACTH) immunoreactivity was surveyed by IHC to add to data regarding the regulatory mechanism. AVP and CRH protein expression levels increased after ADX in the hypothalamus of diabetic rats based on IHC results; however, we found that the subtypes of each receptor may be regulated differently in ADX groups compared to sham groups. Immunoreactivity of ACTH in the pituitary gland was enhanced in ADX groups and GR expression levels in the hypothalamic paraventricular nuclei (PVN) remained high, as determined by IHC as well as Western blot analysis. Without the negative feedback system of corticosterone, CRH is highly enhanced and may primarily combine with CRHR1 to stimulate negative feedback through ACTH in the pituitary gland in type 2 diabetic rats with long-term ADX. Although the negative feedback signal was not transmitted appropriately following long-term ADX with type 2 diabetes, a high GR protein level was maintained as in type 2 diabetes. The long-termed lack of corticosterone in the blood stream is a very important factor for normal regulation of the HPA axis even in diabetic animals. From the data, we can conclude that the stimulated HPA axis regulation in the developing type 2 diabetic animals following long-term adrenalectomy has remained elevated rather than diminished. Therefore, the current study may provide useful information to better understand patients suffering from both type 2 diabetes and Addison's disease.

Rat hepatic cytochrome P450 oxidoreductase is up‐regulated by low dose dexamethasone and down‐regulated by adrenalectomy

Microsomal cytochrome P450 (CYP) enzyme activity requires cytochrome P450 oxidoreductase (POR). We studied rat hepatic POR after adrenalectomy (ADX) since some CYP activities are decreased by ADX. The effects of ADX or glucocorticoids on POR are not clear. Male ADX or SHAM‐ADX rats were treated with dexamethasone (DEX) once 6 h before euthanasia, 4 days post‐ADX (acute), or once daily in the third week post‐ADX (subacute). A DEX time‐course study was also performed in intact rats. Hepatic POR was measured by quantitative RT‐PCR and by immunoblot. Hepatic POR protein but not mRNA was decreased at 4 days and 3 weeks post‐ADX. Subacute DEX dosing (1 mg/kg) returned hepatic POR protein in ADX rats to SHAM levels; a single dose (1.5 mg/kg) showed a similar trend. DEX induced hepatic POR mRNA in SHAM and ADX rats in both dosing regimens. DEX is a selective glucocorticoid receptor (GR) agonist at low doses but activates the pregnane X receptor (PXR) at higher doses. CYP3A23, a PXR target gene, was measured to determine whether DEX activated the PXR. Hepatic CYP3A23 mRNA was not induced up to 27 h post‐DEX in the time‐course but showed a modest 30% increase with subacute DEX dosing in SHAM rats. In this study, DEX induced POR mRNA and protein but not CYP3A23 mRNA, suggesting a role for GR in POR regulation. Further studies are needed to determine how DEX at low doses acts to induce the obligate redox partner for all microsomal CYPs. [Support: CIHR]

Behavioral sensitization to cocaine: cooperation between glucocorticoids and epinephrine.

RationaleStressful life experiences facilitate responsiveness to psychostimulant drugs. While there is ample evidence that adrenal glucocorticoids mediate these effects of stress, the role of the sympatho-adrenal system in the effects of psychostimulants is poorly understood.ObjectivesThe present study investigated the role of the two adrenal stress hormones, corticosterone and epinephrine, in sensitization to the locomotor stimulant effects of cocaine.Materials and methodsThe DBA/2 mouse strain was used, as behavioral sensitization in this strain critically depends on adrenal hormones. Animals were subjected to adrenalectomy (“ADX”, surgical removal of the adrenals) or SHAM surgery, and ADX mice were given replacement of epinephrine (5 × 10−3 mg/kg subcutaneously (s.c.) just prior to each drug administration), corticosterone (20%, s.c., pellet), or both. Mice were subjected to a cocaine sensitization regimen (15.0 mg/kg cocaine on nine consecutive days followed by a 7.5 mg/kg cocaine challenge after a 5-day withdrawal).ResultsIn agreement with our previous observations, ADX prevented initiation and expression of cocaine-induced locomotor sensitization. Whereas neither corticosterone nor epinephrine alone were sufficient to reverse the ADX effect, both hormones were necessary to fully restore initiation and retention of sensitization to levels observed in SHAM animals.ConclusionsThe present findings indicate that corticosterone and epinephrine cooperate to facilitate behavioral responsiveness to cocaine. These data emphasize that in addition to the hypothalamic–pituitary–adrenal axis, the sympathetic nervous system plays a critical role in psychostimulant sensitivity.

Regulation of Pituitary Gene Expression by Adrenalectomy

Excessive secretion of adrenal hormones, such as glucocorticoid and mineralocorticoid, leads to metabolic syndrome, including insulin resistance, obesity, and hypertension. These metabolic abnormalities are ameliorated by adrenalectomy (ADX). To identify pituitary mediators for ADX-induced physiological alterations, such as weight loss and hypotension, we investigated the effect of ADX on the pituitary transcriptome using serial analysis of gene expression (SAGE). SAGE method is based on isolation of short sequence tags, which usually correspond to unique mRNA species. The SAGE libraries were constructed from pituitary gland of intact (n = 51) and ADX (n = 12) mice. Thirty-one transcripts were differentially expressed between intact and ADX. Three transcripts encoding for proopiomelanocortin and three other transcripts involved in regulation of hormone secretion (neuromedin B, proprotein convertase subtilisin/kexin type 2, and IA-2) were induced by ADX. In addition, ADX increased the expression levels of genes encoding for cation extracellular matrix (matrix gamma-carboxyglutamate protein) and transport (solute carrier family 22 member 17). Conversely, ADX downregulated two transcripts involved in mitochondrial oxidative phosphorylation (nicotinamide adenine dinucleotide (NADH) dehydrogenase 3 and cytochrome c oxidase 3). Moreover, ADX significantly modulated the expression levels of one gene with uncharacterized function and 20 novel transcripts. This study reveals alterations of pituitary gene expressions that may be associated with ADX-induced physiological changes including weight loss.

Strain differences in the effects of adrenalectomy on the midbrain dopamine system: Implication for behavioral sensitization to cocaine

Adrenalectomy (ADX) abolishes behavioral sensitization to cocaine in DBA/2, but not C57BL/6 inbred mice. The present study tests the hypothesis that this ADX effect on behavioral sensitization in the DBA/2 strain involves changes in midbrain dopamine systems that do not occur in the C57BL/6 strain. For that purpose, we have measured tyrosine hydroxylase (TH) and dopamine transporter (DAT) mRNA and D1- and D2-like receptor binding in C57BL/6 and DBA/2 mice that were i) unoperated, ii) ADX or sham (SHAM) operated, or iii) ADX or SHAM operated and subjected to a cocaine sensitization regimen (15.0 mg/kg cocaine on nine consecutive days, followed by a 7.5 mg/kg challenge after a 5-day withdrawal). ADX prevented behavioral sensitization to cocaine in the DBA/2, but not the C57BL/6 strain [ de Jong IEM, Oitzl MS, de Kloet ER (2007) Adrenalectomy prevents behavioural sensitisation of mice to cocaine in a genotype-dependent manner. Behav Brain Res 177:329–339]. Mice were killed under basal conditions, in the latter case 24 h after the cocaine challenge. ADX did not affect the dopaminergic markers in drug naïve mice. By contrast, strain-dependent neuroadaptations were found in the midbrain dopamine system of mice subjected to the sensitization regimen. In the DBA/2 strain, sensitization-resistant ADX mice were characterized by reduced D2 binding in the nucleus accumbens core and rostral caudate putamen. Furthermore, ADX prevented the increase in TH and DAT mRNA expression in the substantia nigra, and the decrease in D2 binding in the dorsomedial subdivision of the caudal caudate putamen associated with sensitization in SHAM mice. In the C57BL/6 strain ADX only marginally affected dopaminergic adaptations. These data suggest that adrenal hormones modulate behavioral sensitization to cocaine in a genotype-dependent fashion possibly through adaptations in pre- and post-synaptic components of the midbrain dopamine system. During cocaine sensitization, the DBA/2, but not the C57BL/6 strain, was susceptible to ADX in the dopamine system with respect to presynaptic TH and DAT and terminal D2 receptor expression.

Corticotropin-releasing factor and its receptors in the brain of rats with insulin and corticosterone deficits

The expression of genes encoding corticotropin-releasing factor (CRF) and its receptor type-1 (CRF1R) and type-2alpha (CRF2R) has been studied in the brain of rats with streptozotocin (STZ)-induced diabetes and adrenalectomy (ADX). Diabetic rats had a lower body weight compared to control rats. Food and water intake were increased in diabetic rats and decreased in ADX animals. The plasma corticosterone levels measured at the nadir of the circadian rhythm were significantly higher in diabetic rats compared to non-diabetic animals. STZ-diabetic rats demonstrated an induction of expression of CRF mRNA in the magnocellular part of the paraventricular hypothalamic nucleus (PVN) and in the supraoptic nucleus (SON), whereas the CRF transcript in the parvocellular PVN was significantly lower in rats with insulin deficiency. ADX strongly triggered the expression of CRF mRNA in the parvocellular neurons of the PVN in both non-diabetic and diabetic rats, and it decreased magnocellular CRF mRNA in diabetic animals. The expression of the CRF1R in the parvocellular and magnocellular PVN and in the SON was induced by diabetes and decreased after ADX. The levels of the CRF2R mRNA in the ventromedial hypothalamic nucleus (VMH) were significantly lower in diabetic rats without any noticeable effects of ADX. The present results suggest opposite effects of insulin and corticosterone deficiency on the hypophysiotropic CRF and the CRF1R mRNA contents, whereas the expression of CRF2R was mostly related to insulin, but not to the corticosterone status.

Adrenalectomy promotes a permanent decrease of plasma corticoid levels and a transient increase of apoptosis and the expression of Transforming Growth Factor beta1 (TGF-beta1) in hippocampus: effect of a TGF-beta1 oligo-antisense.

BackgroundCorticosterone reduction produced by adrenalectomy (ADX) induces apoptosis in dentate gyrus (DG) of the hippocampus, an effect related to an increase in the expression of the pro-apoptotic gene bax. However it has been reported that there is also an increase of the anti-apoptotic gene bcl-2, suggesting the promotion of a neuroprotective phenomenon, perhaps related to the expression of transforming growth factor β1 (TGF-β1). Thus, we have investigated whether TGF-β1 levels are induced by ADX, and whether apoptosis is increased by blocking the expression of TGF-β1 with an antisense oligonucleotide (ASO) administered intracerebrally in corticosterone depleted rats.ResultsIt was observed an increase of apoptosis in DG, 2 and 5 days after ADX, in agreement with a reduction of corticosterone levels. However, the effect of ADX on the number of apoptotic positive cells in DG was decreased 5 days after the lesion. In CA1–CA3 regions, the effect was only observed 2 days after ADX. TGF-β1 mRNA levels were increased 2 days after ADX. The sustained intracerebro-ventricular administration of a TGF-β1 ASO via an osmotic mini pump increased apoptosis levels in CA and DG regions 5 days after ADX as well as sham-operated control animals. No significant effect was observed following a scrambled-oligodeoxynucleotide treatment.ConclusionThe changes in both the pattern and the magnitude of apoptotic-cell morphology observed 2 and 5 days after ADX suggest that, as a consequence of the reduction of corticosteroids, some trophic mechanisms restricting cell death to a particular time window are elicited. Sustained intracerebral administration of TGF-β1 ASO increased the apoptosis promoted by ADX, suggesting that TGF-β1 plays an anti-apoptotic role in vivo in hippocampus.

Corticosterone regulates expression of CCL2 in the intact and chemically injured hippocampus

Expression of the chemokine (C–C motif) ligand 2 (CCL2), also known as, monocyte chemoattractant protein (MCP)-1, increases in response to disease-, trauma-, or toxicant-induced damage to the central nervous system (CNS). In the periphery, endogenous and exogenous glucocorticoids are known to suppress CCL2 expression associated with inflammatory conditions. However, such actions of glucocorticoids on CCL2 expression in the CNS remain unknown. Here, we explored the effects of the glucocorticoid, corticosterone (CORT), on the expression of CCL2 and its receptors, CCR2 and CCR5, in the hippocampal formation using intact, adrenalectomized (ADX) and trimethyltin (TMT)-treated rats. An immunosuppressive regimen of CORT did not alter the mRNA expression of CCL2 or its receptors in the hippocampus. ADX, however, markedly increased the expression of CCL2 and CCR2 mRNAs in the hippocampus, while CORT replacement reversed the effects of ADX on CCL2 gene expression. Hippocampal damage resulting from systemic administration of the organometallic neurotoxicant, TMT, was associated with microglial activation, as evidenced by enhanced expression of microglial markers integrin αM (CD11b) and F4/80, as well as, microglia-associated factors, CCL2 and IL-1α. An immunosuppressive dose of CORT, suppressed TMT-induced expression of CCL2. Given the association of CCL2 with microglial activation, it appears that CORT may play a role in regulating microglial activation. However, CORT treatment did not alter TMT-mediated neuronal damage and astrogliosis. Such observations suggest that injury-related expression of microglia-associated chemokines and cytokines may subserve a role unrelated to neuronal damage. In summary, our data indicate that in the CNS, CCL2 gene expression is under negative regulation by glucocorticoids.

Orexin Expression and Function: Glucocorticoid Manipulation, Stress, and Feeding Studies

We investigated the effects of glucocorticoid manipulation on orexin-A-induced feeding and prepro-orexin mRNA levels in the lateral hypothalamic area (LHA) of the rat brain. Adrenalectomy (ADX) reduced orexin-A-induced feeding over 4 h by about 60%, compared with shams, an effect that was reversed by corticosterone (CORT) replacement. ADX had no effect on prepro-orexin mRNA levels in the LHA in either the morning or the evening; however, message was up-regulated by CORT in the morning but not the evening. An increased number of emulsion grains per cell in the LHA suggests that this is a specific increase in prepro-orexin mRNA and is not due to an increased number of cells expressing message. Prepro-orexin mRNA levels in the LHA were elevated 4 h after injection of lipopolysaccharide, compared with saline-injected controls. Partial but not complete abolition of orexin-A-induced feeding by ADX suggests that orexin-A-induced feeding may be mediated through glucocorticoid-dependent and glucocorticoid-independent pathways. In the morning increased prepro-orexin mRNA after CORT replacement demonstrates that orexin expression is sensitive to increased concentrations of glucocorticoids. However, the lack of effect of ADX on prepro-orexin mRNA levels suggests that endogenous glucocorticoids are not involved in tonic regulation of basal prepro-orexin expression. Overall our data constitute a body of evidence for an integrated relationship between central orexin expression, stress, glucocorticoid manipulation, and feeding patterns in the rat.

Physiological regulation of hypothalamic IL-1beta gene expression by leptin and glucocorticoids: implications for energy homeostasis.

Interleukin-1beta (IL-1beta) is synthesized in a variety of tissues, including the hypothalamus, where it is implicated in the control of food intake. The current studies were undertaken to investigate whether hypothalamic IL-1beta gene expression is subject to physiological regulation by leptin and glucocorticoids (GCs), key hormones involved in energy homeostasis. Adrenalectomy (ADX) increased hypothalamic IL-1beta mRNA levels twofold, measured by real-time PCR (P < 0.05 vs. sham-operated controls), and this effect was blocked by subcutaneous infusion of a physiological dose of corticosterone. Conversely, hypothalamic IL-1beta mRNA levels were reduced by 30% in fa/fa (Zucker) rats, a model of genetic obesity caused by leptin receptor mutation (P = 0.01 vs. lean littermates), and the effect of ADX to increase hypothalamic IL-1beta mRNA levels in fa/fa rats (P = 0.02) is similar to that seen in normal animals. Moreover, fasting for 48 h (which lowers leptin and raises corticosterone levels) reduced hypothalamic IL-1beta mRNA levels by 30% (P = 0.02), and this decrease was fully reversed by refeeding for 12 h. Thus leptin and GCs exert opposing effects on hypothalamic IL-1beta gene expression, and corticosterone plays a physiological role to limit expression of this cytokine in both the presence and absence of intact leptin signaling. Consistent with this hypothesis, systemic leptin administration to normal rats (2 mg/kg ip) increased hypothalamic IL-1beta mRNA levels twofold (P < 0.05 vs. vehicle), an effect similar to that of ADX. These data support a model in which expression of hypothalamic IL-1beta is subject to opposing physiological regulation by corticosterone and leptin.

Excretion of electrolytes in Brown Norway and Fischer 344 rats: effects of adrenalectomy and of mineralocorticoid and glucocorticoid receptor ligands.

Our previous studies showed that adrenalectomy (ADX) has surprisingly no effect on body weight and fluid intake in the Brown Norway rat strain, suggesting that mineralocorticoid receptor (MR)-mediated effects are present even in absence of corticosteroids in this strain. Moreover, glucocorticoid receptor (GR)-mediated mechanisms are more effective in Brown Norway than in Fischer 344 rats. Such functional differences in corticosteroid receptor pathways between Brown Norway and Fischer 344 rats led us to compare the effect of ADX and MR/GR-mediated actions on sodium and potassium excretion between these two rat strains. To this end, we first measured the effect of an acute high dose of aldosterone on the urinary Na+/K+ concentration ratio in intact and ADX Brown Norway and Fischer 344 rats. Second, to discriminate mineralocorticoid from glucocorticoid actions, we treated chronically ADX rats with increasing doses of aldosterone or RU28362, a pure GR agonist, in the drinking fluid. As sodium homeostasis involves salt appetite regulation, behaviour under mineralocorticoid control, we also measured saline preference in Brown Norway and Fischer 344 rats. Our data illustrate: (1) the very limited effect of ADX on body weight, food and fluid intake, diuresis, natriuresis, kaliuresis and salt appetite in Brown Norway rats, supporting the presence of MR signalling pathways in the absence of adrenal steroids in these rats; (2) the insensitivity of MR to aldosterone in intact Brown Norway rats, and the reduced sensitivity of MR to aldosterone in ADX Brown Norway rats compared with ADX Fischer 344 rats; and (3) the greater sensitivity of GR-related mechanisms to RU28362 in Brown Norway than in Fischer 344 rats in terms of body weight gain and electrolyte excretion. Considering that both MRs and GRs regulate hypothalamic-pituitary-adrenal axis processes, such functional differences in corticosteroid receptors could be at the origin, at least partly, of the strain differences in corticotropic activity/reactivity to stress previously described.

Cytokines participate in neuronal death induced by trimethyltin in the rat hippocampus via type II glucocorticoid receptors.

We investigated the role of IL-1alpha and IL-1beta expressed in the reactive gliosis following hippocampal damage induced by trimethyltin (TMT). IL-1alpha immunoreactivity was expressed earlier in small glial cells on day 4 post-TMT, while IL-1beta expression was obvious in large swollen glial cells on day 14 post-TMT. Both IL-1alpha and IL-1beta immunoreactivities were double-labeled with astrocyte marker, vimentin, but not with a microglia marker, OX-42. The expression of both IL-1alpha/beta was enhanced by adrenalectomy (ADX) prior to TMT administration. Corticosterone (CORT) or dexamethasone (DEX) supplementation not only cancelled effects of ADX, but also partially reversed TMT-induced enhancement of IL-1alpha/beta expressions. These changes coincided with TMT-induced neuronal death in CA3 pyramidal cells of the hippocampus. It is suggested that IL-1alpha/beta expressed in reactive astrocytes participate in TMT neurotoxicity via type II glucocorticoid receptors.

Differential effects of adrenalectomy on melanin-concentrating hormone and orexin A.

Removal of glucocorticoids by adrenalectomy (ADX) reduces food intake and body weight in rodents and prevents excessive weight gain in many genetic and dietary models of obesity. Glucocorticoids play a key role to promote positive energy balance in normal and pathological conditions, at least in part, by altering the sensitivity to hypothalamic peptides. The hyperphagia after central neuropeptide Y administration, for example, is attenuated by ADX, and there is evidence that glucocorticoids influence both MCH and orexin A activity. In the present study, feeding responses to third ventricular MCH and orexin A were measured in rats after bilateral ADX or sham surgery. ADX rats were significantly less sensitive to the orexigenic action of third ventricular MCH, whereas orexin A-induced hyperphagia was unaffected. Replacement of corticosterone in the drinking water of ADX rats reversed the effects of ADX on MCH sensitivity. Although we found significant populations of glucocorticoid receptors in the lateral hypothalamus, none were colocalized with either MCH or orexin A-containing cell bodies. Furthermore, whereas ADX significantly reduced hypothalamic MCH and orexin gene expression, this could not be restored by glucocorticoids in the drinking water. Collectively, the present data suggest that glucocorticoids may promote food intake in part by potentiating the orexigenic actions of MCH without affecting the actions of orexin A and that glucocorticoids act indirectly to influence the effects of MCH on food intake.

Adrenalectomy abolishes fasting-induced down-regulation of NADPH-diaphorase in the rat paraventricular nucleus.

This study was conducted to define the molecular mechanism of fasting-induced down-regulation of neuronal nitric oxide synthase (nNOS) expression in the hypothalamic paraventricular nucleus (PVN). Rats were adrenalectomized (ADX), and then either underwent food deprivation or received varying doses of dexamethasone for 48 h. The brain tissues were processed for NADPH-diaphorase (NADPH-d) staining, a histochemical marker of nNOS enzyme activity. Both the ADX and the sham operated rats showed a significant weight loss after 48 h of food deprivation. Food deprivation decreased the number of NADPH-d containing cells in the PVN of sham rats, however, not in the ADX rats. Dexamethasone dose- dependently decreased NADPH-d cells in the PVN of ADX rats. The effect of ADX or dexamethasone was limited to the parvocellular subdivision of PVN. These results suggest that the adrenal glucocorticoids may down-regulate nNOS expression in the PVN during food deprivation.

Adrenalectomy alters the sensitivity of the central nervous system melanocortin system.

Removal of adrenal steroids by adrenalectomy (ADX) reduces food intake and body weight in rodents and prevents excessive weight gain in many genetic and dietary models of obesity. Thus, glucocorticoids appear to play a key role to promote positive energy balance in normal and pathological conditions. By comparison, central nervous system melanocortin signaling provides critical inhibitory tone to regulate energy balance. The present experiments sought to test whether glucocorticoids influence energy balance by altering the sensitivity to melanocortin receptor ligands. Because melanocortin-producing neurons are hypothesized to be downstream of leptin in a key weight-reducing circuit, we tested rats for their sensitivity to leptin and confirmed reports that the hypophagic response to third ventricular (i3vt) leptin is increased in ADX rats and is normalized by glucocorticoid replacement. Next we tested rats for their sensitivity to the melanocortin agonist melanotan II and found that, as for leptin, ADX enhanced the hypophagic response via a glucocorticoid-dependent mechanism. The central nervous system melanocortin system is unique in that it includes the endogenous melanocortin receptor antagonist, AgRP. The orexigenic effect of i3vt AgRP was absent in ADX rats and restored by glucocorticoid replacement. We conclude that the potent weight-reducing effects of ADX likely involve heightened responsiveness to melanocortin receptor stimulation.

Gonadal and adrenal effects on the glucocorticoid receptor in the rat hippocampus, with special reference to regulation by estrogen from an immunohistochemical view-point

Focusing on the hippocampal CA1 region, effects of peripheral gonadal and adrenal steroids on the glucocorticoid receptor (GR) were immunohistochemically evaluated in male and female adult rat brains after adrenalectomy (ADX), gonadectomy (GDX), and administration of estradiol (E2) and/or corticosterone (CS). In ADXed male rats, the hippocampal nuclear GR decreased and turned back to the cytoplasm, whereas in females, nuclear localization persisted even after ADX. In GDX+ADXed female rats, the GR was dispersedly translocated from the nucleus to the cytoplasm as well as in GDX+ADXed males. The dispersed cytoplasmic GR was again translocated into the nucleus by administration of CS. In addition, administration of a small dose of E2 for 4–13 days was found to sufficiently recover the nuclear location of GR in GDX+ADXed rat brains, whereas medium-to-large doses could not do this. Also, a longer administration more strongly enhances the nuclear GR location and expression. The present study provided strong immunohistochemical evidence that the sexually dimorphic effects of ADX on hippocampal GR are attributable to gonadal hormones, and that E2 is implicated in the effects in inversely-dose- and directly-duration-dependent manner. Taken together, intriguing gonadal and adrenal crosstalk is considered to play some important role in regulating hippocampal GR morphology and to have a possibly crucial influence on stress-related disorders such as depression.

Effects of adrenalectomy on AGRP, POMC, NPY and CART gene expression in the basal hypothalamus of fed and fasted rats

Glucocorticoids regulate body energy balance through both peripheral and central mechanisms. In order to understand the central mechanisms that mediate these effects of glucocorticoids we studied the effects of adrenalectomy (ADX) and food deprivation on the expression of four neuropeptide genes (measured by S1 nuclease protection assay) in the medial basal hypothalamus (MBH), which are known to regulate energy balance: pro-opiomelanocortin (POMC), agouti-related peptide (AGRP), neuropeptide Y (NPY), and cocaine and amphetamine regulated transcript (CART). Adult male rats were ADX or sham operated (SHAM), and studied 1–2 weeks later. In the first study effects of ADX and corticosterone replacement on POMC and AGRP expression were determined. ADX decreased POMC and AGRP gene expression in the MBH by 27 and 38%, respectively, compared to SHAM rats. Corticosterone treatment increased the expression of POMC by 87% and AGRP by 45% in ADX rats. The second study was designed to determine if glucocorticoids are necessary for the fasting induced changes in POMC, AGRP, NPY and CART in the MBH. ADX caused a 20–30% decrease in the expression of all four neuropeptide genes in the MBH. As expected, fasting suppressed POMC and CART expression and increased AGRP and NPY expression. The fasting-induced increases in AGRP and NPY persisted after ADX but no further significant decreases in POMC or CART were noted after fasting in ADX rats. Plasma leptin and insulin declined significantly after ADX and increased with corticosterone replacement; both leptin and insulin declined further in fasted, ADX animals. In conclusion, ADX decreases both anorexigenic, POMC and CART, and orexigenic, AGRP and NPY, neuropeptide gene expression in the MBH. AGRP and NPY decrease after ADX despite the fall in plasma leptin and insulin concentrations which in other situations would increase these neuropeptides. Furthermore, glucocorticoids are not required for fasting-induced upregulation of AGRP and NPY expression.