The neurohypophyseal hormone oxytocin and eating behaviors: a narrative review.

BACKGROUND: The neuropeptide oxytocin (OT) is crucial in several conditions, such as lactation, parturition, mother-infant interaction, and psychosocial function. Moreover, OT may be involved in the regulation of eating behaviors. METHODS: This review briefly summarizes data concerning the role of OT in eating behaviors. Appropriate keywords and medical subject headings were identified and searched for in PubMed/MEDLINE. References of original articles and reviews were screened, examined, and selected. RESULTS: Hypothalamic OT-secreting neurons project to different cerebral areas controlling eating behaviors, such as the amygdala, area postrema, nucleus of the solitary tract, and dorsal motor nucleus of the vagus nerve. Intracerebral/ventricular OT administration decreases food intake and body weight in wild and genetically obese rats. OT may alter food intake and the quality of meals, especially carbohydrates and sweets, in humans. DISCUSSION: OT may play a role in the pathophysiology of eating disorders with potential therapeutic perspectives. In obese patients and those with certain eating disorders, such as bulimia nervosa or binge/compulsive eating, OT may reduce appetite and caloric consumption. Conversely, OT administered to patients with anorexia nervosa may paradoxically stimulate appetite, possibly by lowering anxiety which usually complicates the management of these patients. Nevertheless, OT administration (e.g., intranasal route) is not always associated with clinical benefit, probably because intranasally administered OT fails to achieve therapeutic intracerebral levels of the hormone. CONCLUSION: OT administration could play a therapeutic role in managing eating disorders and disordered eating. However, specific studies are needed to clarify this issue with regard to dose-finding and route and administration time.

Dopamine in the Regulation of Glucose Homeostasis, Pathogenesis of Type 2 Diabetes, and Chronic Conditions of Impaired Dopamine Activity/Metabolism: Implication for Pathophysiological and Therapeutic Purposes.

Dopamine regulates several functions, such as voluntary movements, spatial memory, motivation, sleep, arousal, feeding, immune function, maternal behaviors, and lactation. Less clear is the role of dopamine in the pathophysiology of type 2 diabetes mellitus (T2D) and chronic complications and conditions frequently associated with it. This review summarizes recent evidence on the role of dopamine in regulating insular metabolism and activity, the pathophysiology of traditional chronic complications associated with T2D, the pathophysiological interconnection between T2D and chronic neurological and psychiatric disorders characterized by impaired dopamine activity/metabolism, and therapeutic implications. Reinforcing dopamine signaling is therapeutic in T2D, especially in patients with dopamine-related disorders, such as Parkinson's and Huntington's diseases, addictions, and attention-deficit/hyperactivity disorder. On the other hand, although specific trials are probably needed, certain medications approved for T2D (e.g., metformin, pioglitazone, incretin-based therapy, and gliflozins) may have a therapeutic role in such dopamine-related disorders due to anti-inflammatory and anti-oxidative effects, improvement in insulin signaling, neuroinflammation, mitochondrial dysfunction, autophagy, and apoptosis, restoration of striatal dopamine synthesis, and modulation of dopamine signaling associated with reward and hedonic eating. Last, targeting dopamine metabolism could have the potential for diagnostic and therapeutic purposes in chronic diabetes-related complications, such as diabetic retinopathy.

Neuroendocrine Modulation of Food Intake and Eating Behavior.

BACKGROUND: In the first section of this review, we examined the neuroanatomical and neurochemical data on hunger and satiety centers, glucose receptors, sensorial influences on eating behavior, and regulation of energy requirements. The second section is devoted to orexigenic and anorexigenic hormones. OBJECTIVE: This paper aimed to overview and summarize data regarding the role of neuroendocrine regulation of food intake and eating behavior. METHODS: Appropriate keywords and MeSH terms were identified and searched in MEDLINE/ PubMed. References of original articles and reviews were examined. RESULTS: Hunger and satiety center are located in the lateral (LH) and ventromedial hypothalamus (VMH). Lasting aphagia has been observed following a lesion of LH, while hyperphagia is induced by LH stimulation. On the other hand, increased food intake after VMH lesion and aphagia following VMH stimulation in hungry animals has also been reported. Intracellular glucopenia triggers food intake by reducing neuronal activity at the satiety center level. Moreover, sensory influences are regulated by food palatability as the positive hedonic evaluation of food and energy requirement indicates the average amount of food energy needed to balance energy expenditure. Orexigenic and anorexigenic hormones secreted from the gastrointestinal tract and adipose tissue regulate brain areas involved in eating behavior via gastric afferent vagal nerve, circumventricular organ area postrema, or transporter system. Finally, oxytocin (OT) plays a role in reward-related eating by inhibiting sugar intake and decreasing palatable food intake by suppressing the reward circuitry in the brain. Moreover, the anorectic effect of nesfatin-1 is abolished by an OT antagonist.

Endocrine-Disrupting Chemicals: Introduction to the Theme.

BACKGROUND: Endocrine-disrupting chemicals (EDCs) are natural or synthetic compounds deriving from different human activities and are widely spread into the environment, contributing to indoor and outdoor pollution. EDCs may be conveyed by food and water consumption and skin, airways, placental, and breastfeeding. Upon entering the circulation, they can interfere with endocrine system homeostasis by several mechanisms. AIM: In this narrative review, the authors overviewed the leading mechanisms by which EDCs interact and disrupt the endocrine system, leading to possible human health concerns. RESULTS: The leading mechanisms of EDCs-related toxicity have been illustrated in in vitro studies and animal models and may be summarized as follows: receptor agonism and antagonism; modulation of hormone receptor expression; interference with signal transduction in hormone-responsive cells; epigenetic modifications in hormone-producing or hormone-responsive cells; interference with hormone synthesis; interference with hormone transport across cell membranes; interference with hormone metabolism or clearance; interference with the destiny of hormone-producing or hormone- responsive cells. DISCUSSION: Despite these well-defined mechanisms, some limitations do not allow for conclusive assumptions. Indeed, epidemiological and ecological studies are currently lacking and usually refer to a specific cluster of patients (occupational exposure). Methodological aspects could further complicate the issue since these studies could require a long time to provide useful information. The lack of a real unexposed group in environmental conditions, possible interference of EDCs mixture on biological results, and unpredictable dose-response curves for some EDCs should also be considered significant limitations. CONCLUSION: Given these limitations, specific observational and long-term studies are needed to identify at-risk populations for adequate treatment of exposed patients and effective prevention plans against excessive exposure to EDCs.

Endocrine system dysfunction and chronic heart failure: a clinical perspective.

Chronic heart failure (CHF) leads to an excess of urgent ambulatory visits, recurrent hospital admissions, morbidity, and mortality regardless of medical and non-medical management of the disease. This excess of risk may be attributable, at least in part, to comorbid conditions influencing the development and progression of CHF. In this perspective, the authors examined and described the most common endocrine disorders observed in patients with CHF, particularly in individuals with reduced ejection fraction, aiming to qualify the risks, quantify the epidemiological burden and discuss about the potential role of endocrine treatment. Thyroid dysfunction is commonly observed in patients with CHF, and sometimes it could be the consequence of certain medications (e.g., amiodarone). Male and female hypogonadism may also coexist in this clinical context, contributing to deteriorating the prognosis of these patients. Furthermore, growth hormone deficiency may affect the development of adult myocardium and predispose to CHF. Limited recommendation suggests to screen endocrine disorders in CHF patients, but it could be interesting to evaluate possible endocrine dysfunction in this setting, especially when a high suspicion coexists. Data referring to long-term safety and effectiveness of endocrine treatments in patients with CHF are limited, and their impact on several "hard" endpoints (such as hospital admission, all-cause, and cardiovascular mortality) are still poorly understood.

Signal Transduction of Mineralocorticoid and Angiotensin II Receptors in the Central Control of Sodium Appetite: A Narrative Review.

Sodium appetite is an innate behavior occurring in response to sodium depletion that induces homeostatic responses such as the secretion of the mineralocorticoid hormone aldosterone from the zona glomerulosa of the adrenal cortex and the stimulation of the peptide hormone angiotensin II (ANG II). The synergistic action of these hormones signals to the brain the sodium appetite that represents the increased palatability for salt intake. This narrative review summarizes the main data dealing with the role of mineralocorticoid and ANG II receptors in the central control of sodium appetite. Appropriate keywords and MeSH terms were identified and searched in PubMed. References to original articles and reviews were examined, selected, and discussed. Several brain areas control sodium appetite, including the nucleus of the solitary tract, which contains aldosterone-sensitive HSD2 neurons, and the organum vasculosum lamina terminalis (OVLT) that contains ANG II-sensitive neurons. Furthermore, sodium appetite is under the control of signaling proteins such as mitogen-activated protein kinase (MAPK) and inositol 1,4,5-thriphosphate (IP3). ANG II stimulates salt intake via MAPK, while combined ANG II and aldosterone action induce sodium intake via the IP3 signaling pathway. Finally, aldosterone and ANG II stimulate OVLT neurons and suppress oxytocin secretion inhibiting the neuronal activity of the paraventricular nucleus, thus disinhibiting the OVLT activity to aldosterone and ANG II stimulation.

Angiotensin II-Vasopressin Interactions in The Regulation of Cardiovascular Functions. Evidence for an Impaired Hormonal Sympathetic Reflex in Hypertension and Congestive Heart Failure.

INTRODUCTION: Angiotensin II (ANG II) and vasopressin (VP) interact in several physiological mechanisms, playing a role in arterial hypertension and congestive heart failure. Aim and Methods of Search: To overview the primary mechanism involved in the regulation of cardiovascular function, PubMed/Medline was searched, and authors selected original articles and reviews written in English. RESULTS: Angiotensin II (ANG II) and vasopressin (VP) are involved in several physiological mechanisms. ANG II stimulates VP release via angiotensin receptor 1. ANG II and VP stimulate aldosterone synthesis and secretion and enhance its action at the renal collecting duct level. VP is also involved in the cardiovascular reflex control of the sympathetic nervous system (SNS). Also, VP potentiates vasoconstriction and cardiac contractility, enhancing the effect of ANG II on sympathetic tone and arterial pressure. On the other hand, ANG II and VP act antagonistically in regulating baroreflex control of the SNS. There is evidence that high VP plasma levels increase baroreflex sympatho-inhibitory responses, and the arterial baroreflex response is shifted to lower pressure. This cardiovascular reflex control is mediated mainly in the brain, specifically in the circumventricular organ area postrema (AP). The modulation of cardiovascular reflex control induced by VP is abolished after lesions of the AP. VP modulation of baroreflex function is also under the control of α2-adrenergic pathway arising from the nucleus of the solitary tract (NTS) and synapsing on VP-ergic neurons of supraoptic and paraventricular nuclei. Presynaptic α2-adrenergic stimulation within the NTS inhibits VP release induced by hypovolemia and the effects of VP and AP on baroreflex control of SNS, thus showing baroreceptor afferent inputs are processed within the NTS and contribute to the increased baroreflex sympatho-inhibitory responses. DISCUSSION: In patients with congestive heart failure (CHF), plasma VP levels are elevated, inducing an up-regulation of aquaporin 2 water channel expression in renal collecting duct (CD) cells provoking exaggerated water retention and dilutional hyponatremia. Antagonists of VP and ANG II receptors reduce edema, body weight, and dyspnea in CHF patients. CONCLUSION: Hormonal imbalance between ANG II, VP, and SNS may induce hypertension and impaired water-electrolyte balance in cardiovascular diseases.

Oxytocin Signaling Pathway: From Cell Biology to Clinical Implications.

BACKGROUND: In addition to the well-known role played in lactation and parturition, Oxytocin (OT) and OT receptor (OTR) are involved in many other aspects such as the control of maternal and social behavior, the regulation of the growth of the neocortex, the maintenance of blood supply to the cortex, the stimulation of limbic olfactory area to mother-infant recognition bond, and the modulation of the autonomic nervous system via the vagal pathway. Moreover, OT and OTR show antiinflammatory, anti-oxidant, anti-pain, anti-diabetic, anti-dyslipidemic and anti-atherogenic effects. OBJECTIVE: The aim of this narrative review is to summarize the main data coming from the literature dealing with the role of OT and OTR in physiology and pathologic conditions focusing on the most relevant aspects. METHODS: Appropriate keywords and MeSH terms were identified and searched in Pubmed. Finally, references of original articles and reviews were examined. RESULTS: We report the most significant and updated data on the role played by OT and OTR in physiology and different clinical contexts. CONCLUSION: Emerging evidence indicates the involvement of OT system in several pathophysiological mechanisms influencing brain anatomy, cognition, language, sense of safety and trust and maternal behavior, with the possible use of exogenous administered OT in the treatment of specific neuropsychiatric conditions. Furthermore, it modulates pancreatic ß-cell responsiveness and lipid metabolism leading to possible therapeutic use in diabetic and dyslipidemic patients and for limiting and even reversing atherosclerotic lesions.

Brain Angiotensinergic Regulation of the Immune System: Implications for Cardiovascular and Neuroendocrine Responses.

OBJECTIVE: The Renin-Angiotensin-Aldosterone System (RAAS) plays a major role in the regulation of cardiovascular functions, water and electrolytic balance, and hormonal responses. We perform a review of the literature, aiming at providing the current concepts regarding the angiotensin interaction with the immune system in the brain and the related implications for cardiovascular and neuroendocrine responses. METHODS: Appropriate keywords and MeSH terms were identified and searched in Pubmed. Finally, references of original articles and reviews were examined. RESULTS: Angiotensin II (ANG II), beside stimulating aldosterone, vasopressin and CRH-ACTH release, sodium and water retention, thirst, and sympathetic nerve activity, exerts its effects on the immune system via the Angiotensin Type 1 Receptor (AT 1R) that is located in the brain, pituitary, adrenal gland, and kidney. Several actions are triggered by the binding of circulating ANG II to AT 1R into the circumventricular organs that lack the Blood-Brain-Barrier (BBB). Furthermore, the BBB becomes permeable during chronic hypertension thereby ANG II may also access brain nuclei controlling cardiovascular functions. Subfornical organ, organum vasculosum lamina terminalis, area postrema, paraventricular nucleus, septal nuclei, amygdala, nucleus of the solitary tract and retroventral lateral medulla oblongata are the brain structures that mediate the actions of ANG II since they are provided with a high concentration of AT 1R. ANG II induces also T-lymphocyte activation and vascular infiltration of leukocytes and, moreover, oxidative stress stimulating inflammatory responses via inhibition of endothelial progenitor cells and stimulation of inflammatory and microglial cells facilitating the development of hypertension. CONCLUSION: Besides the well-known mechanisms by which RAAS activation can lead to the development of hypertension, the interactions between ANG II and the immune system at the brain level can play a significant role.

Neuroendocrine Mechanisms Involved in Male Sexual and Emotional Behavior.

OBJECTIVE: The aim of this narrative review was to analyze the role played by brain areas, neurohormones and neurotransmitters in the regulation of emotional and sexual behavior in the male. METHODS: We analyzed the currently available literature dealing with brain structures, neurotransmitters and neurohormones involved in the regulation of emotional and sexual behavior in the male. RESULTS: A common brain pathway is involved in these two aspects. The Hippocampus seems to control the signals coming from the external environment, while the amygdala and the hypothalamus control the response to social stimuli. Stimulation of amygdala in the animal models increases sexual performance, while it triggers violent emotional responses. Stimulation of the hypothalamus causes reactions of violent anger and increases sexual activity. Catecholaminergic stimulation of the amygdala and hypothalamus increases emotional and sexual behavior, while serotonin plays an inhibitory role. Cholinergic inhibition leads to a suppression of copulatory activity, while the animal becomes hyperemotive. Opioids, such as ß-endorphin and met-enkephalin, reduce copulatory activity and induce impotence. Gonadal steroid hormones, such as estrogen in female and testosterone in male, which play a major role in the control of sexual behavior and gender difference have been highlighted in this review. Vasopressin, oxytocin and their receptors are expressed in high density in the "social behavior neural network" and play a role as signal system controlling social behavior. Finally, the neuropeptide kisspeptin and its receptors, located in the limbic structures, mediate olfactory control of the gonadotropic axis. CONCLUSION: Further studies are needed to evaluate possible implications in the treatment of psychosexual and reproductive disorders.

Vigilance States: Central Neural Pathways, Neurotransmitters and Neurohormones.

BACKGROUND AND OBJECTIVE: The sleep-wake cycle is characterized by a circadian rhythm involving neurotransmitters and neurohormones that are released from brainstem nuclei and hypothalamus. The aim of this review is to analyze the role played by central neural pathways, neurotransmitters and neurohormones in the regulation of vigilance states. METHOD: We analyzed the literature identifying relevant articles dealing with central neural pathways, neurotransmitters and neurohormones involved in the control of wakefulness and sleep. RESULTS: The reticular activating system is the key center in the control of the states of wakefulness and sleep via alertness and hypnogenic centers. Neurotransmitters and neurohormones interplay during the dark-light cycle in order to maintain a normal plasmatic concentration of ions, proteins and peripheral hormones, and behavioral state control. CONCLUSION: An updated description of pathways, neurotransmitters and neurohormones involved in the regulation of vigilance states has been depicted.

Vasopressin in Heart Failure.

BACKGROUND AND OBJECTIVE: The nonapeptide hypothalamic hormone vasopressin (VP), exerts important effects on cardiovascular system via its receptors V1, V2 and V3. Patients with congestive heart failure (CHF) present elevated plasma VP levels. Aim of this paper is to review the role of vasopressin in CHF. METHODS: We analyzed the best of published literature dealing with the role of VP in patients affected by CHF, identifying keywords and MeSH terms in Pubmed and then searching them. The last search was performed on August 2017. RESULTS: Scientific articles dealing with the relationship between VP and CHF show that circulating high VP levels found in CHF despite an exaggerated increase in circulatory blood volume can contribute to CHF exacerbation. In particular, the stimulation of V1R induces vascular constriction responsible for increased systemic vascular resistance and afterload, and, in addition, coronary vasoconstriction with consequent reduced coronary circulation and cardiac contractility, whereas the stimulation of V2R induces free water reabsorption and this is responsible of preload increase and congestion of pulmonary vascular bed with edema and hyponatremia, markers of advanced CHF. CONCLUSION: VP can play an important role among the derangements of the endocrine system in CHF even being a possible target in the treatment of this condition. Vaptans, antagonists of VP receptors, in fact, are able to increase urine output and plasma sodium levels without the increased risk of arrhythmic death induced by diuretics, even though, further studies are needed to establish a possible role of these drugs in the treatment of CHF.

The Role of Neurohypophyseal Hormones Vasopressin and Oxytocin in Neuropsychiatric Disorders.

BACKGROUND AND OBJECTIVE: Although the neurohypophyseal hormones vasopressin (VP) and oxytocin (OT) are mostly known for their role respectively in antidiuresis, and in labour, lactation and maternal behavior, both might exert widespread influences either on emotion and cognition in healthy subjects, showing some gender-related differences. They interact with each other facilitating shifts between positive socially- oriented and defensive states. In fact, VP amplifies the reactivity to stressors showing also beneficial effects on attention, verbal learning as well as memory, whereas OT reduces the amplitude of the stress response, improves emotion processing, and can play a negative effect on memory and verbal learning in healthy individuals. Several data indicate the possible involvement of these neuropeptides in the pathophysiology of psychiatric conditions involving social interactions, such as autism, as well as in schizophrenia and depression. The aim of this paper is to review the literature relating to the role played by neurohypophyseal hormones in neuropsychiatric disorders. METHODS: We analyzed the best of published literature dealing with the relationships between neurohypophyseal hormones and neuropsychiatric conditions like autism (AD), major depressive disorder (MDD), bipolar disorder (BD) and schozophrenia, identifying keywords and MeSH terms in Pubmed and then searching them. The last search was performed on December 2017. RESULTS: Several studies indicate a role played by OT and VP in AD, schizophrenia, MDD and BD. Even if conflicting data have been reported, several mechanisms may be involved in these behavioral diseases, such as differences in aminoacid sequence and peptide biological activity, neurotransmission and genetic disorders involving OT and VP receptors. CONCLUSION: The involvment of VP and OT in neurpopsychiatric disorders can support a possible beneficial therapy with OT or with VP antagonists. The target may be obtained using effective drug delivery methods as well as the association with other drugs.

Oncologic outcomes following laparoscopic colon cancer resection for T4 lesions: a case-control analysis of 7-years' experience.

BACKGROUND: According to many Societies' guidelines, patients presenting with clinical T4 colorectal cancer should conventionally be approached by a laparotomy. Results of emerging series are questioning this attitude. METHODS: We retrospectively analysed the oncologic outcomes of 147 patients operated on between June 2008 and September 2015 for histologically proven pT4 colon cancers. All patients were treated with curative intent, either by a laparoscopic or open "en bloc" resection. RESULTS: Median operative time, blood loss and hospital length of stay were significantly reduced in the laparoscopic group. Postoperative surgical complication rate and 30-day mortality did not significantly differ between the two groups ( p = 0.09 and p = 0.99, respectively). R1 resection rate and lymph nodes harvest, as well, did not remarkably differ when comparing the two groups. In the laparoscopic group, conversion rate was 19%. Long-term outcomes were not affected in patients who had undergone conversion. Five-year overall survival and disease-free survival did not significantly differ between the two groups (44.6% and 40.3% vs. 39.4% and 38.9%). Locally advanced stages (IIIB-IIIC) and R1 resections were detected as independent prognostic factors for overall survival. CONCLUSION: Laparoscopic approach might be safe and acceptable for locally advanced colon cancer and does not jeopardize the oncologic results. Conversion to open surgery should be a part of a strategy as it does not seem to adversely affect perioperative and long-term outcomes. We consider laparoscopy, in expert hands, the last diagnostic tool and the first therapeutic approach for well-selected locally advanced colon cancers. Larger prospective studies are needed to widely assess this issue.

Synaptic Inputs of Neural Afferent Pathways to Vasopressin- and Oxytocin-Secreting Neurons of Supraoptic and Paraventricular Hypothalamic Nuclei.

BACKGROUND: Magnocellular neurosecretory neurons of the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei synthesize vasopressin and oxytocin in response to signals generated by osmoreceptors and baroreceptors and, respectively, by receptors of the nipples and cervix. METHODS: We analyzed the literature identifying relevant articles dealing with synaptic inputs of neural afferent pathways to Vasopressin-and Oxytocin-secreting neurons of SON and PVN. RESULTS: This article focuses on the multisynaptic pathways involved in the regulation of Vasopressin and Oxytocin secretion. CONCLUSION: An updated topographic description of the afferent pathways involved in the regulation of VPergic and OTergic neurons and their synaptic inputs inducing the stimulus-secretion-coupling has been depicted.

Hypopituitarism in Neurocritical Patients: A Case Report.

BACKGROUND: Besides changes in pituitary hormones secretion observed during the acute phase of stroke as an adaptive response to injury or an effect of drugs, a true hypopituitarism due to ischemic and/or hemorrhagic damage at the hypothalamus and/or pituitary gland can develop after a stroke. CASE REPORT: We report a case of a 72-year-old woman showing clinical signs and laboratory data suggesting a secondary adrenal insufficiency following a recent acute brain ischemia. Cortisone therapy significantly improved this pituitary dysfunction. CONCLUSIONS: Clinicians must pay attention to the hypothalamic-pituitary axis in neurocritical patients because hormonal replacement therapy may be life-saving.

False positive diagnosis on (131)iodine whole-body scintigraphy of differentiated thyroid cancers.

(131)Iodine is used both to ablate any residual thyroid tissue or metastatic disease and to obtain whole-body diagnostic images after total thyroidectomy for differentiated thyroid cancer (DTC). Even though whole-body scan is highly accurate in showing thyroid residues as well as metastases of DTC, false positive results can be found, possibly leading to diagnostic errors and unnecessary treatments. This paper reviews the physiological and pathological processes involved as well as the strategy to recognize and rule out false positive radioiodine images.

Sevelamer carbonate markedly reduces levothyroxine absorption.

We report the case of a young woman affected by hypothyroidism due to Hashimoto's thyroiditis, previously well compensated with a full replacement therapy (150 mcg/day of levothyroxine), presenting a clinical picture of myxedema, with a TSH=650 mU/L. Two years earlier she had started a dialysis treatment because of a chronic renal failure and had been under treatment for the last 18 months with sevelamer carbonate, a phosphate binder. No improvement of clinical conditions nor reduction in TSH serum levels was observed even on increasing the dose of levothyroxine up to 300 mcg/day, whereas euthyroidism finally restored by administering the first morning dose of sevelamer carbonate at least 4 hours after levothyroxine administration. This case shows that sevelamer carbonate, in analogy with what has been already reported for sevelamer hydrochloride, can interfere with levothyroxine absorption leading to a condition of hypothyroidism in patients previously well compensated with a given replacement dose.

Amiodarone-induced SIADH: two cases report.

Amiodarone-induced SIADH is a rare but serious side effect of this drug. We report two cases of mild hyponatremia, observed in the last five years, and discuss the role played by age, sex and dose of amiodarone as well as the influence that this molecule may have on aquaporin-2 water channel expression in the renal collecting ducts.