Endogenous peripheral hydrogen sulfide is propyretic: its permissive role in brown adipose tissue thermogenesis in rats.

NEW FINDINGS: What is the central question of this study? In fever, the most striking response in the acute phase reaction of systemic inflammation, plasma H2 S concentration increases. However, the role of endogenous peripheral H2 S in fever is unknown. What is the main finding and its importance? Endogenous peripheral H2 S is permissive for increased brown adipose tissue thermogenesis to maintain thermal homeostasis in cold environments as well as to mount fever. This finding expands the physiological role of the gaseous modulator as a key regulator of thermal control in health (thermal homeostasis) and disease (fever in systemic inflammation). ABSTRACT: In recent years, hydrogen sulfide (H2 S) has been reported as a gaseous modulator acting in several tissues in health and disease. In animal models of systemic inflammation, the plasma H2 S concentration increases in response to endotoxin (bacterial lipopolysaccharide, LPS). The most striking response in the acute phase reaction of systemic inflammation is fever, but we found no reports of the peripheral action of H2 S on this thermoregulatory response. We aimed at investigating whether endogenous systemic H2 S modulates LPS-induced fever. A temperature datalogger capsule was inserted in the abdominal cavity of male Wistar rats (220-270 g) to record body core temperature. These animals received an i.p. injection of a systemic H2 S inhibitor (propargylglycine; 50 or 75 mg kg-1 ), immediately followed by an i.p. injection of LPS (50 or 2500 µg kg-1 ), and were exposed to different ambient temperatures (16, 22 or 27°C). At 22°C, but not at 27°C, propargylglycine at 75 mg kg-1 significantly attenuated (P < 0.0001) the fever induced by LPS (50 µg kg-1 ), indicating a modulatory (permissive) action of endogenous peripheral H2 S on brown adipose tissue (BAT) thermogenesis. Evidence on the modulatory role of peripheral H2 S in BAT thermogenesis was strengthened when we discarded (i) the possible influence of the gas on febrigenic signalling (when measuring plasma cytokines), and (ii) its interaction with the nitric oxide pathway, and mainly when (iii) we carried out physiological and pharmacological activations of BAT. Endogenous peripheral H2 S modulates (permits) BAT activity not only in fever but also during maintenance of thermal homeostasis in cold environments.

Direct Immunofluorescence as a Helpful Tool for the Differential Diagnosis of Oral Lichen Planus and Oral Lichenoid Lesions.

A great number of lichenoid lesions have overlapping clinicopathological features, so the use of adjunct tests to establish definitive diagnosis is recommended for correct management and prognosis of the lesions. In this context, direct immunofluorescence (DIF) can be a useful tool. Thus, this study aimed to characterize the clinical, histopathological, and DIF pattern in patients with oral lichen planus (OLP) and patients with oral lichenoid lesions (OLLs). Patients with OLP and patients with OLL were characterized and compared with patients with mucous membrane pemphigoid, pemphigus vulgaris, and fibrous hyperplasia through a cross-sectional study. Patients with OLP (n = 30) and patients with OLL (n = 26) were mostly white women in the fifth decade of age, with reticular lesions mainly on the buccal mucosa. All patients with OLP and half of the patients with OLL showed liquefaction degeneration at the basal cell layer and a band-like lymphocytic infiltrate in the subepithelial tissue. Twenty-two patients with OLP (73.3%), 10 with OLL (38.4%), 25 with mucous membrane pemphigoid (96.1%), and all with pemphigus vulgaris (100%) had positive DIF. There was no positive DIF in patients with fibrous hyperplasia. The most frequent DIF pattern in patients with OLP and patients with OLL was linear fibrinogen at the basement membrane zone, and a logistic regression model for positive DIF found statistically significant difference in OLP versus OLL (odds ratio, 3.73; confidence interval, 1.23-11.38). Although clinical and histopathological features are sufficient for diagnosing most of the patients with OLP and OLL, DIF is a key tool in differentiating some lichenoid lesions and could improve the diagnosis of OLP and OLL, especially in lesions showing typical clinical and histological features of OLP.

12th World Congress on Neurohypophysial Hormones Mangaratiba, Rio de Janeiro, Brazil - July 26th-29th, 2017.

This Special Issue of Journal of Neuroendocrinology comprises six reviews and eight original research articles describing recent advances in the field of Vasopressin and Oxytocin hormone research based on presentations given at the 12th World Congress on Neurohypophysial Hormones held in July 2017, in Brazil. We, the Chair of the Local Organising Committee and Guest Editor (Maria José A. Rocha) and Guest/Senior Editors for this issue (Celia Sladek and Mike Ludwig), would like to thank the contributors for their excellent reviews and original research articles, the colleagues who reviewed these articles and the Editorial Board of Journal of Neuroendocrinology for their enthusiastic support of the Special Issue. This article is protected by copyright. All rights reserved.

Interleukin-1 Receptor Antagonist Decreases Hypothalamic Oxidative Stress During Experimental Sepsis.

In our previous work, we demonstrated that the intracerebroventricular (i.c.v.) injection of an interleukin-1 receptor antagonist (IL-1ra) prevented the impairment in vasopressin secretion and increased survival rate in septic rats. Additionally, we saw a reduction in nitric oxide (NO) levels in cerebroventricular spinal fluid (CSF), suggesting that the IL-1ra prevents apoptosis that seems to occur in vasopressinergic neurons. Here, we investigated the effect of IL-1ra pre-treatment on the sepsis-induced increase in oxidative stress markers in the hypothalamus of rats. The animals were pre-treated by an i.c.v. injection of IL-1ra (9 nmol) or vehicle (0.01 M PBS) before being subjected to cecal ligation and puncture (CLP) or left as control (sham-operation or naive). After 4, 6, and 24 h, the animals were decapitated (n = 9/group) and the brain removed for hypothalamic tissue collection. Transcript and protein levels of IL-1, inducible nitric oxide synthase (iNOS), caspase-3, and hypoxia-inducible factor 1-alpha (HIF-1α) were measured by quantitative polymerase chain reaction (qPCR) and western blot, respectively. Hypothalamic mRNA levels of all these genes were significantly (P < 0.005) increased at 4, 6, and 24 h CLP, as compared to sham-operated animals. IL-1ra pre-treatment in these CLP animals significantly decreased IL-1 gene expression at all time points and also of iNOS, caspase-3, and HIF-1α at 24 h when compared to vehicle-treated CLP animals. The effect of the pre-treatment on protein expression was most clearly seen for IL-1ß and iNOS at 24 h. Our results showed that blocking the IL-1-IL-1r signaling pathway by central administration of an IL-1ra decreases hypothalamic oxidative stress markers during sepsis.

Interleukin-1 receptor antagonist decreases cerebrospinal fluid nitric oxide levels and increases vasopressin secretion in the late phase of sepsis in rats.

The aim of this study was to analyze the effect of IL-1ra (an Interleukin-1 receptor antagonist) on sepsis-induced alterations in vasopressin (AVP) and nitric oxide (NO) levels. In addition, IL-1ra effect on the hypothalamic nitric oxide synthase (NOS) activities and survival rate was also analyzed. After Wistar rats were intracerebroventricular injected with IL-1ra (9 pmol) or vehicle (PBS 0.01 M), sepsis was induced by cecal-ligation and puncture (CLP). Blood, CSF, and hypothalamic samples were collected from different groups of rats (n = 8/group) after 4, 6, and 24 h. AVP and NO levels were greatly increased in CLP. Both total NOS and inducible NOS (iNOS) activities were also greatly increased in CLP rats. These changes in AVP, NO, and NOS were not observed in sham-operated control rats. IL-1ra administration did not alter plasma AVP levels after 4 and 6 h as compared to vehicle in CLP animals but after 24 h were significantly (P < 0.01) higher in IL-1ra-treated animals. IL-1ra administration significantly (P < 0.01) decreased NO concentration in CSF but not in plasma. Both total NOS and iNOS activities were also significantly decreased by IL-1ra at 24 h in CLP animals. Moreover, the 24 h survival rate of IL-1ra-treated rats increased by 38 % in comparison to vehicle administered animals. The central administration of IL-1ra increased AVP secretion in the late phase of sepsis which was beneficial for survival. We believe that one of the mechanisms for this effect of IL-1ra is through reduction of NO concentration in CSF and hence lower hypothalamic iNOS activities in the septic rats.

Alterations in the central vasopressin and oxytocin axis after lesion of a brain osmotic sensory region.

The anteroventral region of the third ventricle (AV3V) is critical in mediating osmotic sensitivity. AV3V lesions increase plasma osmolality and block osmotic-induced vasopressin (VP) and oxytocin (OT) secretion. The aim was to evaluate the effects of AV3V lesions on neurosecretion under control/water replete conditions and after 48 h dehydration. The focus was on central peptidergic changes with measurement of OT and VP content in the hypothalamic paraventricular (PVN) and supraoptic (OT) regions and the posterior pituitary. AV3V-lesioned rats exhibited an elevated plasma osmolality and higher OT content in SON and PVN. There was an increase in VP content in PVN, but no change in SON. As predicted, the plasma peptide response to dehydration was absent in lesioned animals. However, dehydration produced depletion in posterior pituitary VP in lesioned animals with no change in OT. No changes in nuclear VP and OT levels were seen after dehydration. These results demonstrate that AV3V lesions alter the VP and OT neurosecretory system, seen as a blockade of osmotic-induced release and an increase in basal nuclear peptide content. The data indicate that interruption of the osmotic sensory system affects the central neurosecretory axis, resulting in a backup in content and likely changes in synthesis and processing.

Cellular bioenergetics changes in magnocellular neurons may affect copeptin expression in the late phase of sepsis.

We investigated whether inflammatory mediators during cecal ligation and puncture (CLP)-induced sepsis may diminish copeptin expression in magnocellular neurons, thus affecting arginine-vasopressin (AVP) synthesis. The transcript abundance of IL-1ß, IL-1R1, iNOS and HIF-1α was continuously elevated. IL-1ß, iNOS and cytochrome c protein levels progressively increased until 24h. Immunostaining for these proteins was higher at 6 and 24h, as also seen in the annexin-V assay, while copeptin was continuously decreased. This suggests that increased IL-1ß and NO levels may cause significant bioenergetics changes in magnocellular neurons, affecting copeptin expression and compromising AVP synthesis and secretion in the late phase of sepsis.

Time course of c-fos, vasopressin and oxytocin mRNA expression in the hypothalamus following long-term dehydration.

1. This study presents a time course analysis of the messenger RNA (mRNA) levels of c-fos, vasopressin (VP), and oxytocin (OT) in the paraventricular (PVN) and supraoptic nucleus (SON), following acute and chronic dehydration by water deprivation. 2. Male Wistar rats were separated into five groups: nondehydrated (control group) and dehydrated for 6, 24, 48 and 72 h. Following water deprivation, animals were decapitated, their blood was collected for hematocrit, osmolality, and plasma sodium measurements, and brains were removed for dissection of both PVN and SON. 3. As expected, the hematocrit, osmolality, plasma sodium, and weight loss were increased after water deprivation. In SON, a significant increase in both VP and OT mRNA expression was observed 6 h after dehydration reaching a peak at 24 h and returning to basal levels of expression at 72 h. In the PVN, an increase in both VP and OTmRNA expression occurred 24 h after dehydration. At 72 h the VP and OT mRNA expression levels had decreased but they were still at higher levels than those detected in control animals. 4. These results suggest that SON is the first nucleus to respond to the dehydration stimulus. Additionally, we also observed an increase in c-fos mRNA expression in both PVN and SON 6 h after water deprivation, which progressively decreased 24, 48, and 72 h after the onset of water deprivation. Therefore, it is possible that c-fos may be involved in the modulation of VP and OT genes, regulating the mRNA expression levels on a temporally distinct basis within the PVN and SON.