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The present study was undertaken in order to assess the role of dietary phosphate in growth. A diet deficient in phosphate led to a suppression of growth in juvenile rats. The phenomenon is similar to that described for diets deficient in other essential single components such as Mg, Zn or K. However, unlike the other constituents, dietary phosphate restriction affected the growth rate much more than it altered the serum phosphate concentration; addition of phosphate to the drinking water of rats fed a low-phosphate diet restored the growth rate without a concomitant change in serum phosphate concentration. The suppression of growth rate by the deletion of phosphate was associated with a delayed decrease in food intake. This finding implies that the variation in appetite was secondary to the change in growth. The increase in body weight following phosphate supplementation was associated with a concomitant increment in food intake. The phosphate-dependent growth was, however, evident also in rats that were pair-fed with those that were not supplied with phosphate. It is concluded that dietary phosphate-dependent growth is not mediated by changes in phosphate concentrations in the extracellular fluid. It is plausible that signals arising from receptors for phosphate in the digestive system constitute part of the growth control apparatus in rats. [ABSTRACT FROM PUBLISHER]

A ouabain like compound obtained from toad skin and plasma and identified to be a steroidal bufodienolide glycoside was found to displace ouabain from its binding site and to inhibit Na+-K+ATPase, and have positive inotropic effects on cardiac muscle. The ionic and rate dependence of this positive inotropy was studied in the frog atrium. The effect was dependent on extracellular potassium, sodium, and calcium concentrations and on the rate of stimulation, which is similar to the properties of cardiac glycosides. Occasionally, the compound gave transient or even negative inotropic responses, as do the glycosides. The action potential configuration was also affected by the compound in the same complex pattern as is that of cardiac glycosides.It is concluded that the endogenous bufodienolide compound has the same physiological effects as cardiac glycosides. Since the same compound is present in toad plasma it may serve as an intrinsic humoral regulator of cardiac contractility. This study is the first detailed characterisation of the cardioactive properties of this compound. [ABSTRACT FROM PUBLISHER]

Digitalis-like compounds in bovine lens capsule, cortex and nucleus were determined quantitatively, following extraction, by their ability to inhibit [3H]ouabain binding to red blood cells. These compounds were found to be highly concentrated in the epithelium capsule and were significantly diminished in the cortex and nucleus. Na+, K+-ATPase density in the different regions was determined by [3H]ouabain binding to membranes and by autoradiography of lens slices. The highest concentration of [3H]ouabain-binding sites was observed to occur in membranes prepared from the epithelial cells of the capsule, and was almost 100- and 200-fold higher than the concentrations observed in membranes prepared from fiber cells of the cortex and nucleus, respectively. In the autoradiography studies, strong labeling of [3H]ouabain appeared in the epithelial cell zone, and only weak specific labeling appeared in the lens cortex and nucleus. Almost all (99%) of the Na+,K+-ATPase specific activity was found to be in the capsule epithelium and only 0.5% was measured in the cortex and no activity was detected in the nucleus. These results indicate that the digitalis-like compounds and Na+, K+-ATPase are concentrated in the lens capsule epithelium and are present only at low levels in the cortex and nucleus, thus implying that the lens capsular epithelial layer is the major region of the lens responsible for the homeostasis of ions and water in this tissue. [ABSTRACT FROM AUTHOR]

Bipolar disorder (BD) is a severe and common chronic mental illness characterized by recurrent mood swings between depression and mania. The biological basis of the disease is poorly understood, and its treatment is unsatisfactory. Na + , K + -ATPase is a major plasma membrane transporter and signal transducer. The catalytic α subunit of this enzyme is the binding site for cardiac steroids. Three α isoforms of the Na + , K + -ATPase are present in the brain. Previous studies have supported the involvement of the Na + , K + -ATPase and endogenous cardiac steroids (ECS) in the etiology of BD. Decreased brain ECS has been found to elicit anti-manic and anti-depressive-like behaviors in mice and rats. However, the identity of the specific α isoform involved in these behavioral effects is unknown. Here, we demonstrated that decreasing ECS through intracerebroventricular (i.c.v.) administration of anti-ouabain antibodies (anti-Ou-Ab) decreased the activity of α1 +/- mice in forced swimming tests but did not change the activity in wild type (wt) mice. This treatment also affected exploratory and anxiety behaviors in α1 +/- but not wt mice, as measured in open field tests. The i.c.v. administration of anti-Ou-Ab decreased brain ECS and increased brain Na + , K + -ATPase activity in wt and α1 +/- mice. The serum ECS was lower in α1 +/- than wt mice. In addition, a study in human participants demonstrated that serum ECS significantly decreased after treatment. These results suggest that the Na + , K + -ATPase α1 isoform is involved in depressive- and manic-like behaviors and support that the Na + , K + -ATPase/ECS system participates in the etiology of BD.

The University of Miami Miller School of Medicine started a four-year MD/ MPH program in 2011 with a mission to graduate public health physician leaders to address the public health needs of the 21st century, with emphasis on three areas: leadership, research, and public health. A prospective cross-sectional survey of early graduates was conducted to understand how they incorporate public health training into their careers. There were two study questions: What are the self-described early career activities of the graduates of the first three cohorts in the areas of leadership, research, and public health and what are the perceptions regarding the influence of the public health training on their careers? In the summer of 2020, a survey was sent to graduates from the classes of 2015, 2016, and 2017. In addition to several multiple-choice questions, the survey included an open-ended question on the impact of public health training in their careers. Inductive content analysis was used to analyze the responses to the open-ended question. Eighty-two of the 141 eligible graduates (63%) completed the survey; 80 of whom had participated or was currently participating in residency training. Forty-nine joined a residency in a primary care field. Many graduates had leadership roles in their early careers, including 35 who were selected as chief residents. Fifty-seven participated in research, most commonly in quality improvement (40), clinical (34) and community based (19). Over one third (30) chose to do work in public health during residency. Themes that emerged regarding the influence of public health training on their careers were: 1) Shifts in perspective, 2) Value of specific skills related to public health, 3) Steppingstone for professional opportunities 4) Focus on health disparities, social determinants, and inadequacies of the healthcare system, 5) Perception as leaders and mentors for peers, and 6) Preparedness for the pandemic. Graduates self-reported involvement in leadership, research, and public health activities as well as a commitment towards addressing some of our most pressing public health needs. Although long-term career outcomes need to be determined over time, graduates currently report considerable benefits of their public health training for their professional outcomes., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Belkowitz et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Bipolar Disorder (BD) is a severe recurrent affective mood disorder characterized by a wide range of lifelong mood swings, varying between depressive and manic states. BD affects more than 1% of the world's population irrespective of nationality, ethnic origin, or socioeconomic status and is one of the main causes of disability among young people, leading to cognitive and functional impairment and raised mortality, particularly death by suicide. Trace elements play a vital role in many biochemical and physiological processes. Compelling evidence shows that element toxicity might play a crucial role in the onset and progression of neurodegenerative disorders, but their involvement in mood disorders has been scarcely studied. In the present investigation, we determined the concentration of 26 elements in the serum of BD patients before and after treatment and in postmortem brain samples from BD patients and compared them with matched controls. The only element that was reduced significantly in the serum following treatment was vanadium (V). Furthermore, the concentration of Al, B, Cu, K, Mg and V were significantly lower in the pre-frontal cortex of BD patients compared with those of the controls. A comparison of Spearman's rank correlation coefficients between the elements in the serum and brain of BD patients and control groups pointed to boron and aluminum as being involved in the disease. These results suggest that there is a disturbance in the elements' homeostasis and the inter-elements' relationship in the brain of BD patients and advocate a thorough examination of the possible involvement of chemical elements in different stages of the disease.

Bipolar disorder (BD) is a severe and common chronic mental illness. The biological basis of the disease is poorly understood and its treatment is unsatisfactory. Our previous studies supported the notion that alterations in Na + , K + -ATPase activity were involved in the etiology of BD. As various chemical elements inhibit Na + , K + -ATPase, we determined the concentration of 26 elements in the serum of BD patients before and after treatment and in postmortem brain samples from BD patients, and compared them with matched controls. The only element that was reduced significantly in the serum following treatment was vanadium (V). Furthermore, the concentration of V was significantly lower in the pre-frontal cortex of BD patients compared with that of the controls. Intracerebroventricular administration of V in mice elicited anxiolytic and depressive activities, concomitantly inhibited brain Na + , K + -ATPase activity, and increased extracellular signal-regulated kinase phosphorylation. A hypothesis associating V with BD was set forth decades ago but eventually faded out. Our results are in accord with the hypothesis and advocate for a thorough examination of the possible involvement of chemical elements, V in particular, in BD.

Bufalin and other cardiac steroids (CS) have been used for centuries for the treatment of congestive heart failure, arrhythmias, and other maladies. However, toxicity and the small therapeutic window of this family of steroids limit their use. Therefore, attempts to synthesize a potent, but less toxic, CS are of major importance. In the present study, two novel bufalin derivatives were synthesized and some of their pharmacological properties were characterized. The reaction of bufalin with Ishikawa's reagent resulted in the production of two novel bufalin derivatives: bufalin 2,3-ene and bufalin 3,4-ene. The compounds were purified with TLC and HPLC and their structure was verified with UV, NMR, and MS analyses. The biological activities of these compounds were evaluated by testing their ability to inhibit the Na + , K + -ATPase activity of the brain microsomal fraction to induce cytotoxic activity against the NCI-60 human tumor cell line panel and non-cancer human cells, and to increase the force of contraction of quail embryonic heart muscle cells in culture. The two steroids exhibited biological activities similar to those of other CS in the tested experimental systems, but with reduced cytotoxicity, advocating their development as drugs for the treatment of heart failure and arrhythmias.

Bipolar disorder (BD) is a severe psychiatric illness with a poor prognosis and problematic, suboptimal, treatments. Treatments, borne of an understanding of the pathoetiologic mechanisms, need to be developed in order to improve outcomes. Dysregulation of cationic homeostasis is the most reproducible aspect of BD pathophysiology. Correction of ionic balance is the universal mechanism of action of all mood stabilizing medications. Endogenous sodium pump modulators (collectively known as endogenous cardiac steroids, ECS) are steroids which are synthesized in and released from the adrenal gland and brain. These compounds, by activating or inhibiting Na + , K + -ATPase activity and activating intracellular signaling cascades, have numerous effects on cell survival, vascular tone homeostasis, inflammation, and neuronal activity. For the past twenty years we have addressed the hypothesis that the Na + , K + -ATPase-ECS system may be involved in the etiology of BD. This is a focused review that presents a comprehensive model pertaining to the role of ECS in the etiology of BD. We propose that alterations in ECS metabolism in the brain cause numerous biochemical changes that underlie brain dysfunction and mood symptoms. This is based on both animal models and translational human results. There are data that demonstrate that excess ECS induce abnormal mood and activity in animals, while a specific removal of ECS with antibodies normalizes mood. There are also data indicating that circulating levels of ECS are lower in manic individuals, and that patients with BD are unable to upregulate synthesis of ECS under conditions that increase their elaboration in non-psychiatric controls. There is strong evidence for the involvement of ion dysregulation and ECS function in bipolar illness. Additional research is required to fully characterize these abnormalities and define future clinical directions.

Dextromethorphan (DM) abuse produces mania-like symptoms in humans. ERK/Akt signaling activation involved in manic potential can be attenuated by the inhibition of ouabain-like cardiac steroids. In this study, increased phosphorylations of ERK/Akt and hyperlocomotion induced by DM (30 mg/kg, i.p./day × 7) were significantly protected by the ouabain inhibitor rostafuroxin (ROSTA), suggesting that DM induces the manic potential. ROSTA significantly attenuated DM-induced protein kinase C δ (PKCδ) phosphorylation, GluN2B (i.e., MDA receptor subunit) expression, and phospho-PKCδ/GluN2B interaction. DM instantly upregulated the nuclear factor erythroid-2-related factor 2 (Nrf2)-dependent system. However, DM reduced Nrf2 nuclear translocation, Nrf2 DNA binding activity, γ-glutamylcysteine mRNA expression, and subsequent GSH/GSSG level and enhanced oxidative parameters following 1-h of administration. ROSTA, PKCδ inhibitor rottlerin, and GluN2B inhibitor traxoprodil significantly attenuated DM-induced alterations in Nrf2-related redox parameters and locomotor activity induced by DM in wild-type mice. Importantly, in PKCδ knockout mice, DM failed to alter the above parameters. Further, ROSTA and traxoprodil also failed to enhance PKCδ depletion effect, suggesting that PKCδ is a critical target for the anti-manic potential of ROSTA or GluN2B antagonism. Our results suggest that ROSTA inhibits DM-induced manic potential by attenuating ERK/Akt activation, GluN2B/PKCδ signalings, and Nrf2-dependent system., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Bipolar disorder is a chronic multifactorial psychiatric illness that affects the mood, cognition, and functioning of about 1-2% of the world's population. Its biological basis is unknown, and its treatment is unsatisfactory. The α1, α2, and α3 isoforms of the Na + , K + -ATPase, an essential membrane transporter, are vital for neuronal and glial function. The enzyme and its regulators, endogenous cardiac steroids like ouabain and marinobufagenin, are implicated in neuropsychiatric disorders, bipolar disorder in particular. Here, we address the hypothesis that the α isoforms of the Na + , K + -ATPase and its regulators are altered in the prefrontal cortex of bipolar disease patients. The α isoforms were determined by Western blot and ouabain and marinobufagenin by specific and sensitive immunoassays. We found that the α2 and α3 isoforms were significantly higher and marinobufagenin levels were significantly lower in the prefrontal cortex of the bipolar disease patients compared with those in the control. A positive correlation was found between the levels of the three α isoforms in all samples and between the α1 isoform and ouabain levels in the controls. These results are in accordance with the notion that the Na + , K + -ATPase-endogenous cardiac steroids system is involved in bipolar disease and suggest that it may be used as a target for drug development.

An injury to peripheral nerves leads to skin denervation, which often is followed by increased pain sensitivity of the denervated areas and the development of neuropathic pain. Changes in innervation patterns during the reinnervation process of the denervated skin could contribute to the development of neuropathic pain. Here, we examined the changes in the innervation pattern during reinnervation and correlated them with the symptoms of neuropathic pain. Using a multispectral labeling technique-PainBow, which we developed, we characterized dorsal root ganglion (DRG) neurons innervating distinct areas of the rats' paw. We then used spared nerve injury, causing partial denervation of the paw, and examined the changes in innervation patterns of the denervated areas during the development of allodynia and hyperalgesia. We found that, differently from normal conditions, during the development of neuropathic pain, these areas were mainly innervated by large, non-nociceptive neurons. Moreover, we found that the development of neuropathic pain is correlated with an overall decrease in the number of DRG neurons innervating these areas. Importantly, treatment with ouabain facilitated reinnervation and alleviated neuropathic pain. Our results suggest that local changes in peripheral innervation following denervation contribute to neuropathic pain development. The reversal of these changes decreases neuropathic pain.

Na + , K + -ATPase is an essential membrane transporter. In the brain, the α3 isoform of Na + , K + -ATPase is vital for neuronal function. The enzyme and its regulators, endogenous cardiac steroids (ECS), were implicated in neuropsychiatric disorders. GABAergic neurotransmission was also studied extensively in diseases such as schizophrenia and bipolar disorder (BD). Post mortem brain samples from subjects with depression, schizophrenia or BD and non-psychiatric controls were provided by the Stanley Medical Research Institute. ECS levels were determined by ELISA. Expression levels of the three Na + , K + -ATPase-α isoforms, α1, α2 and α3, were determined by Western blot analysis. The α3 levels in GABAergic neurons in different regions of the brain were quantified by fluorescence immunohistochemistry. The results show that Na + , K + -ATPase α3 isoform levels were lower in GABAergic neurons in the frontal cortex in BD and schizophrenia as compared with the controls (n = 15 subjects per group). A study on a 'mini-cohort' (n = 3 subjects per group) showed that the α3 isoform levels were also lower in GABAergic neurons in the hippocampus, but not amygdala, of bipolar and schizophrenic subjects. In the temporal cortex, higher Na + , K + -ATPase α3 protein levels were found in the three psychiatric groups. No significant differences in ECS levels were found in this brain area. This is the first report on the distribution of α3 in specific neurons in the human brain in association with mental illness. These results strengthen the hypothesis for the involvement of Na + , K + -ATPase in neuropsychiatric diseases., (Copyright © 2019. Published by Elsevier Ltd.)

There is strong evidence that neuronal hyper-excitability underlies migraine, and may or may not be preceded by cortical spreading depression. However, the mechanisms for cortical spreading depression and/or migraine are not established. Previous studies reported that cerebrospinal fluid (CSF) [Na+] is higher during migraine, and that higher extracellular [Na+] leads to hyper-excitability. We raise the hypothesis that altered choroid plexus Na+, K+-ATPase activity can cause both migraine phenomena: inhibition raises CSF [K+] and initiates cortical spreading depression, while activation raises CSF [Na+] and causes migraine. In this study, we examined levels of specific Na+, K+-ATPase inhibitors, endogenous ouabain-like compounds (EOLC), in CSF from migraineurs and controls. CSF EOLC levels were significantly lower during ictal migraine (0.4 nM +/- 0.09) than from either controls (1.8 nM +/- 0.4) or interictal migraineurs (3.1 nM +/- 1.9). Blood plasma EOLC levels were higher in migraineurs than controls, but did not differ between ictal and interictal states. In a Sprague-Dawley rat model of nitroglycerin-triggered central sensitization, we changed the concentrations of EOLC and CSF sodium, and measured aversive mechanical threshold (von Frey hairs), trigeminal nucleus caudalis activation (cFos), and CSF [Na+] (ultra-high field 23Na MRI). Animals were sensitized by three independent treatments: intraperitoneal nitroglycerin, immunodepleting EOLC from cerebral ventricles, or cerebroventricular infusion of higher CSF [Na+]. Conversely, nitroglycerin-triggered sensitization was prevented by either vascular or cerebroventricular delivery of the specific Na+, K+-ATPase inhibitor, ouabain. These results affirm our hypothesis that higher CSF [Na+] is linked to human migraine and to a rodent migraine model, and demonstrate that EOLC regulates them both. Our data suggest that altered choroid plexus Na+, K+-ATPase activity is a common source of these changes, and may be the initiating mechanism in migraine., Competing Interests: The authors have declared that no competing interests exist.

Cardiac steroids (CSs), such as ouabain and digoxin, increase the force of contraction of heart muscle and are used for the treatment of congestive heart failure (CHF). However, their small therapeutic window limits their use. It is well established that Na + , K + -ATPase inhibition mediates CS-induced increase in heart contractility. Recently, the involvement of intracellular signal transduction was implicated in this effect. The aim of the present study was to test the hypothesis that combined treatment with ouabain and Akt inhibitor (MK-2206) augments ouabain-induced inotropy in mammalian models. We demonstrate that the combined treatment led to an ouabain-induced increase in contractility at concentrations at which ouabain alone was ineffective. This was shown in 3 experimental systems: neonatal primary rat cardiomyocytes, a Langendorff preparation, and an in vivo myocardial infarction induced by left anterior descending coronary artery (LAD) ligation. Furthermore, cell viability experiments revealed that this treatment protected primary cardiomyocytes from MK-2206 toxicity and in vivo reduced the size of scar tissue 10 days post-LAD ligation. We propose that Akt activity imposes a constant inhibitory force on muscle contraction, which is attenuated by low concentrations of MK-2206, resulting in potentiation of the ouabain effect. This demonstration of the increase in the CS effect advocates the development of the combined treatment in CHF.