Chemogenetic activation of endogenous arginine vasopressin exerts anorexigenic effects via central nesfatin-1/NucB2 pathway.

We examined whether the chemogenetic activation of endogenous arginine vasopressin (AVP) affects central nesfatin-1/NucB2 neurons, using a transgenic rat line that was previously generated. Saline (1 mL/kg) or clozapine-N-oxide (CNO, 1 mg/mL/kg), an agonist for hM3Dq, was subcutaneously administered in adult male AVP-hM3Dq-mCherry transgenic rats (300-370 g). Food and water intake were significantly suppressed after subcutaneous (s.c.) injection of CNO, with aberrant circadian rhythmicity. The percentages of Fos expression in nesfatin-1/NucB2-immunoreactive neurons were significantly increased in the hypothalamus and brainstem at 120 min after s.c. injection of CNO. Suppressed food intake that was induced by chemogenetic activation of endogenous AVP was ablated after intracerebroventricularly administered nesfatin-1/NucB2-neutralizing antibody in comparison with vehicle, without any alteration of water intake nor circadian rhythmicity. These results suggest that chemogenetic activation of endogenous AVP affects, at least in part, central nesfatin-1/NucB2 neurons and may exert anorexigenic effects in the transgenic rats.

Restraint stress affects circulating NUCB2/nesfatin-1 and phoenixin levels in male rats.

The two peptides phoenixin and nesfatin-1 are colocalized in hypothalamic nuclei involved in the mediation of food intake and behavior. Phoenixin stimulates food intake and is anxiolytic, while nesfatin-1 is an anorexigenic peptide shown to increase anxiety and anhedonia. Interestingly, central activation of both peptides can be stimulated by restraint stress giving rise to a role in the mediation of stress. Thus, the aim of the study was to test whether also peripheral circulating levels of NUCB2/nesfatin-1 and phoenixin are altered by restraint stress. Male ad libitum fed Sprague Dawley rats equipped with a chronic intravenous catheter were subjected to restraint stress and plasma levels of NUCB2/nesfatin-1, phoenixin and cortisol were measured over a period of 240 min and compared to levels of freely moving rats. Peripheral cortisol levels were significantly increased in restrained rats at 30, 60, 120 and 240 min compared to controls (p < 0.05). In contrast, restraint stress decreased plasma phoenixin levels at 15 min compared to unstressed conditions (0.8-fold, p < 0.05). Circulating NUCB2/nesfatin-1 levels were increased only at 240 min in restrained rats compared to those in unstressed controls (1.3-fold, p < 0.05). In addition, circulating NUCB2/nesfatin-1 levels correlated positively with phoenixin levels (r = 0.378, p < 0.001), while neither phoenixin nor nesfatin-1 were associated with cortisol levels (r = 0.0275, and r=-0.143, p> 0.05). These data suggest that both peptides, NUCB2/nesfatin-1 and phoenixin, are affected by restraint stress, although less pronounced than circulating cortisol.

Colocalized neurotransmitters in the hindbrain cooperate in adaptation to chronic hypernatremia.

Chronic hypernatremia activates the central osmoregulatory mechanisms and inhibits the function of the hypothalamic-pituitary-adrenal (HPA) axis. Noradrenaline (NE) release into the periventricular anteroventral third ventricle region (AV3V), the supraoptic (SON) and hypothalamic paraventricular nuclei (PVN) from efferents of the caudal ventrolateral (cVLM) and dorsomedial (cDMM) medulla has been shown to be essential for the hypernatremia-evoked responses and for the HPA response to acute restraint. Notably, the medullary NE cell groups highly coexpress prolactin-releasing peptide (PrRP) and nesfatin-1/NUCB2 (nesfatin), therefore, we assumed they contributed to the reactions to chronic hypernatremia. To investigate this, we compared two models: homozygous Brattleboro rats with hereditary diabetes insipidus (DI) and Wistar rats subjected to chronic high salt solution (HS) intake. HS rats had higher plasma osmolality than DI rats. PrRP and nesfatin mRNA levels were higher in both models, in both medullary regions compared to controls. Elevated basal tyrosine hydroxylase (TH) expression and impaired restraint-induced TH, PrRP and nesfatin expression elevations in the cVLM were, however, detected only in HS, but not in DI rats. Simultaneously, only HS rats exhibited classical signs of chronic stress and severely blunted hormonal reactions to acute restraint. Data suggest that HPA axis responsiveness to restraint depends on the type of hypernatremia, and on NE capacity in the cVLM. Additionally, NE and PrRP signalization primarily of medullary origin is increased in the SON, PVN and AV3V in HS rats. This suggests a cooperative action in the adaptation responses and designates the AV3V as a new site for PrRP's action in hypernatremia.

Genetic analyses uncover pleiotropic compensatory roles for Drosophila Nucleobindin-1 in inositol trisphosphate-mediated intracellular calcium homeostasis.

Nucleobindin-1 is an EF-hand calcium-binding protein with a distinctive profile, predominantly localized to the Golgi in insect and wide-ranging vertebrate cell types, alike. Its putative involvements in intracellular calcium (Ca2+) homeostasis have never been phenotypically characterized in any model organism. We have analyzed an adult-viable mutant that completely disrupts the G protein α-subunit binding and activating (GBA) motif of Drosophila Nucleobindin-1 (dmNUCB1). Such disruption does not manifest any obvious fitness-related, morphological/developmental, or behavioral abnormalities. A single copy of this mutation or the knockdown of dmnucb1 in restricted sets of cells variously rescues pleiotropic mutant phenotypes arising from impaired inositol 1,4,5-trisphosphate receptor (IP3R) activity (in turn depleting cytoplasmic Ca2+ levels across diverse tissue types). Additionally, altered dmNUCB1 expression or function considerably reverses lifespan and mobility improvements effected by IP3R mutants, in a Drosophila model of amyotrophic lateral sclerosis. Homology modeling-based analyses further predict a high degree of conformational conservation in Drosophila, of biochemically validated structural determinants in the GBA motif that specify in vertebrates, the unconventional Ca2+-regulated interaction of NUCB1 with Gαi subunits. The broad implications of our findings are hypothetically discussed, regarding potential roles for NUCB1 in GBA-mediated, Golgi-associated Ca2+ signaling, in health and disease.

Contingent role of phoenixin and nesfatin-1 on secretions of the male reproductive hormones.

Phoenixin (PNX) and nesfatin-1 are localised in the hypothalamus and the pituitary gland. Moreover, the most of the PNX-expressing neurons in the hypothalamus also co-express nesfatin-1. These outcomes may suggest that there is an interaction between PNX and nesfatin-1, at least in terms of neuroendocrine-mediated regulations. Hence, the study was planned to find out the effects of centrally delivered PNX and nesfatin-1 on male sex hormones or to show the interactive association of intracerebroventricularly (ICV) injected PNX+nesfatin-1 combination on the release of male hormones. PNX and nesfatin-1, single or together, were delivered ICV to different male Wistar Albino rat groups. Both PNX and nesfatin-1 induced a significant enhancement in plasma FSH, LH and testosterone without inducing any alteration in plasma GnRH in the rats. The central combinatorial treatment of both the neuropeptides produced a more potent rise in male plasma hormone levels than treating with single neuropeptide. In summary, our preliminary data show that centrally delivered PNX and nesfatin-1 can affect plasma male hormone levels. Moreover, that the combinatorial treatment with both the neuropeptides in male rats leading to a more potent effect on the plasma male hormone levels might suggest that both these neuropeptides act synergistically in terms of regulation of male HPGA.

Interaction between nesfatin-1 and oxytocin in the modulation of the swallowing reflex.

Nesfatin-1, an 82-amino acid peptide encoded by the secreted precursor nucleobinin-2 (NUCB2), exerts potent anorexigenic action independently of leptin signaling. This propensity has propelled this peptide and its analogues as potential anti-obesity drug candidates. However, a more extensive comprehension of its biological actions is needed prior to envisaging its potential use in the treatment of metabolic diseases. Swallowing is an essential motor component of ingestive behavior, which induces the propulsion of the alimentary bolus from the mouth to the esophagus. The dorsal swallowing group (DSG) which constitutes a part of the central pattern generator of swallowing (SwCPG) is located within the solitary tract nucleus (STN), a region reported to contain nesfatin-1/NUCB2 expressing neurons. In this context, we investigate here the possible effects of nesfatin-1 on swallowing discharge. Nesfatin-1 dose-dependently inhibited swallowing reflex and activated neurons located in the DSG region. In addition, we provide evidences that strongly suggest that this nesfatin-1 inhibitory effect involved an oxytocinergic relay. Indeed, oxytocin (OT) injection at the brainstem level inhibited swallowing reflex and OT receptor antagonist prevented nesfatin-1 inhibitory action. Altogether, these data constitute the first demonstration that nesfatin-1 modulates swallowing reflex by acting at the brainstem level via an oxytocinergic relay.

Role of nesfatin-1 in anxiety, depression and the response to stress.

Nesfatin-1 has been discovered a decade ago and since then drawn a lot of attention. The initially proposed anorexigenic effect was followed by the description of several other involvements such as a role in gastrointestinal motility, glucose homeostasis, cardiovascular functions and thermoregulation giving rise to a pleiotropic action of this peptide. The recent years witnessed mounting evidence on the involvement of nesfatin-1 in emotional processes as well. The present review will describe the peptide's relations to anxiety, depressiveness and stress in animal models and humans and also discuss existing gaps in knowledge in order to stimulate further research.