Glucocorticoid regulation of mRNA encoding (Na+K) ATPase alpha 3 and beta 1 subunits in rat brain measured by in situ hybridization

Neglected tropical rheumatic diseases

The complexities of dealing with rheumatic diseases in tropical countries are diverse and likely due to limited health care infrastructure, lack of diagnostic and therapeutic facilities, impact of dominant prevailing diseases, and the challenges of differentiating from infectious and non-infectious disease mimics. Several tropical diseases present with musculoskeletal and rheumatic manifestations and often pose a diagnostic dilemma to rheumatologists. The diagnosis is often delayed or the disease is misdiagnosed, leading to poor patient outcomes. Endemic tropical diseases like tuberculosis and leprosy have myriad rheumatic presentations and remain important differentials to consider in patients with rheumatic manifestations. Infection with human immunodeficiency virus is a great masquerade and can mimic manifestations of multiple diseases. The role of viral infections in triggering and perpetuating autoimmunity is well known and chikungunya arthritis is a classic example of the same. This review highlights the rheumatic manifestations of tropical diseases and aims to create awareness among the caregivers. Key Points • It is crucial to be aware and identify infectious diseases presenting with rheumatic manifestations in the tropics. • Presentations akin to classic rheumatic syndromes such as rheumatoid arthritis, spondyloarthritis, systemic lupus erythematosus and vasculitis are common.

Intravenous Immunoglobulin in the Treatment of Alternating Hemiplegia of Childhood

ABSTRACT

Alternating hemiplegia of childhood (AHC) is a neurological disorder with early-onset alternating hemiplegia and other paroxysmal events such as epilepsy and dystonia due to de novo pathogenic mutations in the ATP1A3. Physicians and scientists investigated several agents in the treatment without strong evidence of definitive long-term benefit. Knowledge regarding utility of anti-inflammatory agents in the treatment is scarce except the anecdotal report of corticosteroid use. We described 2 patients with AHC who were exposed to intravenous immunoglobulin (IVIG) treatment because of an alternative diagnosis. An 8-year-old girl received 4 years of periodic IVIG infusion and was free of paroxysmal events during the first 16 months of therapy. A 2-year-old boy received IVIG infusion for 10 months and remained seizure-free for 2 years since the beginning of the treatment, but without a definite change in hemiplegic episodes. Our report is the first description of IVIG use in patients with AHC. Although these patients did not achieve complete remission, partial responsiveness was noted. Although the definite role of IVIG in the treatment of AHC cannot be extrapolated from our study, further prospective controlled studies should be done because of the recent discovery of the connection between an anti-inflammatory hormone (Oubain) and Na+/K+ ATPase.

Management of Alternating Hemiplegia of Childhood: A Review

Alternating hemiplegia of childhood is a severe neurological disorder with infantile-onset recurrent episodes of hemiplegia on either side of the body and other paroxysmal events such as seizures, dystonia, tonic episodes, abnormal eye movements or autonomic dysfunction, primarily due to de novo pathogenic mutations in the ATP1A3 gene. The burden of neuromorbidities is significant and includes epilepsy; attention-deficit/hyperactivity disorder; behavioral difficulties; motor, cognitive, adaptive, and learning impairment; ataxia; movement disorders; and migraine. Comprehensive multispecialty clinic with the availability of various specialists with considerable experience in alternating hemiplegia of childhood is beneficial. A comprehensive treatment plan including strict maintenance of a diary about different paroxysmal events is helpful. Disease-modifying therapy of alternating hemiplegia of childhood does not exist, and several agents such as benzodiazepines, flunarizine, topiramate, ketogenic diet, triheptanoin, steroid, amantadine, memantine, aripiprazole, oral ATP, coenzyme Q, acetazolamide, dextromethorphan, and vagus nerve stimulator have been tried with various rates of success by aborting attacks or reducing the frequency or severity of paroxysmal spells. The apparent efficacy of flunarizine is based on its use in hundreds of patients, albeit in open-label experience, but most of the other agents' reports of efficacy were from single case reports or case series of only a handful of patients. Besides reviewing existing data about individual agent active against paroxysmal events, we also review the management principles for coexisting neurological issues. However, with rapid advancement in the understanding of molecular pathogenesis and network abnormality of this disease, the treatment paradigm of alternating hemiplegia of childhood may significantly alter over the next decade.

ATP1A3 mutation in a Chinese girl with alternating hemiplegia of childhood--Potential target of treatment?

BACKGROUND

This Chinese girl had alternating hemiplegia of childhood (AHC) since 2 months. She failed to respond to anticonvulsants, antimigrainous drugs and calcium channel blockers but achieved complete remission steroid treatment for 4 weeks and relapsed after stopping steroid.

PURPOSE

In order to clarify the unknown etiology, genetic analysis of ATP1A3 gene, which encodes the alpha3-subunit of the sodium/potassium-transporting ATPase (Na, K-ATPase), has been done by Sanger sequencing.

RESULTS

A de novo heterozygous missense mutation (c.2401G>A; p.D801N) was identified in exon 17 of ATP1A3 gene and this is one of the hotspot mutations found in AHC patients.

CONCLUSION

It will be interesting to further investigate whether Na, K-ATPase was the target of corticosteroid treatment.

Na+, K+ ATPase activity is reduced in amygdala of rats with chronic stress-induced anxiety-like behavior

In this study, we examined the effects of two chronic stress regimens upon anxiety-like behavior, Na(+), K(+)-ATPase activity and immunocontent, and oxidative stress parameters (antioxidant enzymes and reactive oxygen species production) in the amygdala. Male rats were subjected to chronic unpredictable and to chronic restraint stress for 40 days. Subsequently, anxiety-like behavior was examined. Both stressed groups presented increased anxiety-like behavior. Reduced amygdalal Na(+), K(+)-ATPase activity in the synaptic plasma membranes was also observed, without alterations in the amygdala immunocontent. In addition, when analyzing oxidative stress parameters, only superoxide dismutase activity was decreased in the amygdala of animals subjected to unpredictable stress. We conclude that both models of chronic stress lead to anxiety-like behavior and decreased amygdalal Na(+), K(+)-ATPase activity, which appears not to be related to oxidative imbalance. The relationship between this decreased activity and anxiety-like behavior remains to be studied.

Effects of progesterone in the spinal cord of a mouse model of multiple sclerosis

The spinal cord is a target of progesterone (PROG), as demonstrated by the expression of intracellular and membrane PROG receptors and by its myelinating and neuroprotective effects in trauma and neurodegeneration. Here we studied PROG effects in mice with experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis characterized by demyelination and immune cell infiltration in the spinal cord. Female C57BL/6 mice were immunized with a myelin oligodendrocyte glycoprotein peptide (MOG(40-54)). One week before EAE induction, mice received single pellets of PROG weighing either 20 or 100 mg or remained free of steroid treatment. On average, mice developed clinical signs of EAE 9-10 days following MOG administration. The spinal cord white matter of EAE mice showed inflammatory cell infiltration and circumscribed demyelinating areas, demonstrated by reductions of luxol fast blue (LFB) staining, myelin basic protein (MBP) and proteolipid protein (PLP) immunoreactivity (IR) and PLP mRNA expression. In motoneurons, EAE reduced the expression of the alpha 3 subunit of Na,K-ATPase mRNA. In contrast, EAE mice receiving PROG showed less inflammatory cell infiltration, recovery of myelin proteins and normal grain density of neuronal Na,K-ATPase mRNA. Clinically, PROG produced a moderate delay of disease onset and reduced the clinical scores. Thus, PROG attenuated disease severity, and reduced the inflammatory response and the occurrence of demyelination in the spinal cord during the acute phase of EAE.

Effects of postnatal steroids on Na+/K+-ATPase activity and alpha1- and beta1-subunit protein expression in the cerebral cortex and renal cortex of newborn lambs

Na(+)/K(+)-ATPase is a membrane-bound enzyme responsible for Na(+)/K(+) translocation across cell membranes. It is essential for the generation of electrochemical gradients, which control the ionic environment necessary for electrical activity and water and electrolyte balance. Newborn infants who are at risk of developing bronchopulmonary dysplasia (BPD) are frequently treated with corticosteroids. Although these infants are at risk for neurological, water and electrolyte abnormalities, there is little information regarding the effects of clinically relevant doses of corticosteroids on Na(+)/K(+)-ATPase activity and protein isoform expression in the brain and kidney of newborns. In the present study, we examined the effects of dexamethasone on cerebral cortical and renal cortical Na(+)/K(+)-ATPase activity and alpha1- and beta1-protein isoform expression in newborn lambs. Lambs were given four injections of a placebo (n = 11) or one of three different doses of dexamethasone (0.01 mg kg(-1), n = 9; 0.25 mg kg(-1), n = 11; or 0.50 mg kg(-1), n = 9) 12 h apart on Postnatal Days 3 and 4 up to 18 h before harvest of the cerebral cortex and renal cortex. We selected doses in a range to approximate those used to treat infants with BPD. Na(+)/K(+)-ATPase activity was measured in membrane preparations as ouabain-sensitive inorganic phosphate liberation from ATP and alpha1- and beta1-subunit abundance by Western immunoblot. Postnatal treatment of lambs with dexamethasone resulted in a 21.4% increase in Na(+)/K(+)-ATPase activity and a 30.4% increase in catalytic alpha1-protein expression in the cerebral cortex at a dose of 0.50 mg kg(-1) dexamethasone, but not at the lower doses. Dexamethasone treatment was not associated with changes in beta1-isoform expression in the cerebral cortex. In the kidney, dexamethasone treatment was not associated with significant changes in Na(+)/K(+)-ATPase activity or alpha1- or beta1-isoform expression for the doses we examined. Therefore, clinically relevant corticosteroid treatment exerts dose-related, differential organ-specific effects on Na(+)/K(+)-ATPase activity and protein isoform expression in newborn lambs.

Progestin regulation of galanin and prolactin gene expression in oestrogen-induced pituitary tumours

Galanin is a peptide widely distributed in the hypothalamic-pituitary axis. In the female rat pituitary, galanin is mainly present in lactotrophs, where it regulates their secretion and proliferation. Galanin expression is increased in oestrogen-induced prolactinomas, and it has been proposed that oestrogen effects on lactotroph function and proliferation could be mediated by galanin. Previous studies from our laboratory demonstrated that the synthetic progestin levonorgestrel antagonizes pituitary tumorigenesis of rats given oestrogen, reducing the number of proliferating cells and increasing cell death by nonapoptotic mechanism(s). To elucidate the role of galanin in levonorgestrel effects on the tumours, we examined galanin and prolactin mRNA and peptide expression in prolactinomas of rats receiving the progestin. Levonorgestrel reduced the pituitary weight and serum prolactin concentrations in oestrogen-treated rats. Galanin mRNA expression (determined by in situ hybridization), and the number of galanin expressing cells (determined by immunocytochemistry) were also reduced by the progestin in tumour-bearing rats. However, neither prolactin mRNA content, nor the number of prolactin-expressing cells, were modified by levonorgestrel treatment of oestrogen-receiving rats. The present study suggests that levonorgestrel controls pituitary growth by diminishing galanin expression. In contrast, changes in serum prolactin concentration seem to be more related to the reduction in tumour size, since the reduction in galanin expression was not large enough to regulate prolactin mRNA expression or the percentage of lactotrophs.

Increased expression of magnocellular vasopressin mRNA in rats with deoxycorticosterone-acetate induced salt appetite

The neuropeptides arginine vasopressin (AVP) and oxytocin (OT) have been implicated in the genesis of hypertension due to deoxycorticosterone acetate (DOCA)-salt treatment of uninephrectomized rats. In this work, we studied if DOCA treatment of intact rats in doses arousing a salt appetite (a prehypertensive state), modulated mRNA for AVP and OT in the hypothalamus. Male Sprague-Dawley rats were offered both tap water and 3% NaCl in separate bottles and received vehicle or subcutaneous injections of 10 mg DOCA on alternate days for 7 days (4 injections) or 17 days (9 injections). They developed a preference for 3% NaCl solutions 24-48 h after treatment. Brain slices from rats killed on the 8th or 18th day were exposed to 35S-labeled probes encoding prepro-AVP mRNA or OT mRNA, respectively. Expression of these mRNAs was measured in the magnocellular and parvocellular divisions of the paraventricular nucleus (PVN) and magnocellular cells of the supraoptic nucleus (SON). No changes were obtained in neuropeptide mRNA levels in the parvocellular division of the PVN between control and the two groups of DOCA-treated rats. However, DOCA-treated animals presented an increased number of grains per cell for AVP mRNA in the magnocellular division of the PVN and in magnocellular cells of the SON, as shown by group mean comparisons and frequency histograms. No changes were detected for OT mRNA. In a second series of studies, control or DOCA-treated rats were offered 3% NaCl or water as the only choice. Animals drinking 3% NaCl showed increased AVP and OT mRNA levels, whether they received DOCA or not. However, AVP mRNA levels in both nuclei were higher in DOCA-treated rats drinking 3% NaCl than in controls drinking salt solution. In comparison, control and DOCA-treated rats drinking water showed lower levels of AVP mRNA. OT mRNA levels in the SON remained unchanged in the same groups. The results suggest that in the magnocellular cells of the PVN and SON, increments in AVP mRNA are obtained following increments in salt intake produced by either mineralocorticoid treatment or exclusive salt drinking. In rats offered salt solution and water to drink, DOCA effects on AVP mRNA developed before changes occurred in serum sodium levels. Because combined DOCA + salt treatment induced a higher response in terms of AVP mRNA expression, we suggest that AVP could be a target of the central effects of the mineralocorticoid.

Regulation of gene expression by corticoid hormones in the brain and spinal cord

Glucocorticoids (GC) and mineralocorticoids (MC) have profound regulatory effects upon the central nervous system (CNS). Hormonal regulation affects several molecules essential to CNS function. First, evidences are presented that mRNA expression of the alpha3 and beta1-subunits of the Na,K-ATPase are increased by GC and physiological doses of MC in a region-dependent manner. Instead, high MC doses reduce the beta1 isoform and enzyme activity in amygdaloid and hypothalamic nuclei, an effect which may be related to MC control of salt appetite. The alpha3-subunit mRNA of the Na,K-ATPase is also stimulated by GC in motoneurons of the injured spinal cord, suggesting a role for the enzyme in GC neuroprotection. Second, we provide evidences for hormonal effects on the expression of mRNA for the neuropeptide arginine vasopressin (AVP). Our data show that GC inhibition of AVP mRNA levels in the paraventricular nucleus is sex-hormone dependent. This sexual dimorphism may explain sex differences in the hypothalamic-pituitary-adrenal axis function between female and male rats. Third, steroid effects on the astrocyte marker glial fibrillary acidic protein (GFAP) points to a complex regulatory mechanism. In an animal model of neurodegeneration (the Wobbler mouse) showing pronounced astrogliosis of the spinal cord, in vivo GC treatment down-regulated GFAP immunoreactivity, whereas the membrane-active steroid antioxidant U-74389F up-regulated this protein. It is likely that variations in GFAP protein expression affect spinal cord neurodegeneration in Wobbler mice. Fourth, an interaction between neurotrophins and GC is shown in the injured rat spinal cord. In this model, intensive GC treatment increases immunoreactive low affinity nerve growth factor (NGF) receptor in motoneuron processes. Because GC also increases immunoreactive NGF, this mechanism would support trophism and regeneration in damaged tissues. In conclusion, evidences show that some molecules regulated by adrenal steroids in neurons and glial cells are not only involved in physiological control, but additionally, may play important roles in neuropathology.

Sex difference in glucocorticoid regulation of vasopressin mRNA in the paraventricular hypothalamic nucleus

1. Arginine vasopressin (AVP) is synthesized in specific brain regions including the magnocellular and parvocellular divisions of the paraventricular nucleus (PVN). Whereas magnocellular AVP responds to osmotic stimuli and functions mainly--although not exclusively--as an antidiuretic hormone, that produced in the parvocellular region controls the hypothalamus-pituitary-adrenal (HPA) axis, in conjunction with CRF. 2. In view of the reported sex differences in control of the HPA axis, we studied if these also pertain to AVP mRNA in the PVN of ovariectomized-estrogenized female rats and male rats determined by in situ hybridization. AVP mRNA was measured in intact rats, adrenalectomized (ADX) rats and ADX receiving dexamethasone (DEX) of both sexes. 3. Computerized autoradiography showed that in both sexes, AVP mRNA levels in the parvocellular division of the PVN increased after adrenalectomy and decreased following DEX. However, the reduction by DEX was more pronounced in female rats. No changes were found for the magnocellular region. Grain counting analysis of the medial-medial (MMP) and medial-lateral (MLP) subdivisions of the parvocellular region showed that the average number of grains per cell area in the MMP region of adrenally intact female rats was higher than that in males. However, in females there was no clear-cut effect of adrenalectomy on AVP mRNA levels, although the reduction after DEX treatment was again greater than that in male rats. Frequency histograms constructed by plotting the number of cells vs the number of grains per area substantiated the enhanced glucocorticoid negative control of AVP mRNA in the MMP and MLP of female rats. 4. The results indicated a sexual dimorphism in the glucocorticoid-dependent plasticity of AVP mRNA levels in the PVN. Because AVP mRNA expression differs between sexes under basal levels, after adrenalectomy, and after DEX treatment, these plastic changes may differentially condition the response to stress. Taking into consideration that stress and AVP may play a role in neurogenic hypertension, the possibility of sexual dimorphisms in AVP control may be important to assess the role of sex hormones in stress and steroid-derived hypertension.

Aldosterone up-regulates mRNA for the alpha3 and beta1 isoforms of (Na,K)-ATPase in several brain regions from adrenalectomized rats

In physiological doses, mineralocorticoids (MC) normalize the high salt intake developed after adrenalectomy. We have studied whether this effect of MC is accompanied by changes in the mRNA of neuronal alpha3 and beta1 subunits of the (Na,K)-ATPase because this enzyme could by a mediator of MC action in target cells. We employed [35S]oligonucleotide probes for the mentioned subunits hybridized to brain sections from adrenalectomized rats and adrenalectomized rats receiving aldosterone (ALDO) during 4 days. Using t-test statistics to measure differences in mean levels of grain density, and the Kolmogorov-Smirnov non-parametric test applied to frequency histograms, we showed that ALDO increased the alpha3 subunit mRNA in the septum medialis, preoptic area medialis, caudate-putamen, periventricular gray substance, amygdala lateralis, hippocampal subfields CA1 to CA4 and the gyrus dentatus. Significant increases for the beta1 subunit mRNA were found in periventricular gray substance, the CA1-CA4 hippocampal subfields and gyrus dentatus. Therefore, the salt-suppression effect of MC was accompanied by coordinate increases in (Na,K)-ATPase alpha3 and beta1 subunit mRNA in the hippocampus, gyrus dentatus and periventricular gray substance, whereas in other regions the stimulatory effect was exclusive of the alpha3 subunit mRNA only. The results suggest that the enzyme could be a target of ALDO action not only in areas related to salt appetite control (amygdala, preoptic area) but also in brain regions subserving other functions of the MC.