Neuropeptides of the human magnocellular hypothalamus.

Hypothalamic magnocellular nuclei with their large secretory neurons are unique and phylogenetically conserved brain structures involved in the continual regulation of important homeostatic and autonomous functions in vertebrate species. Both canonical and newly identified neuropeptides have a broad spectrum of physiological activity at the hypothalamic neuronal circuit level located within the supraoptic (SON) and paraventricular (PVN) nuclei. Magnocellular neurons express a variety of receptors for neuropeptides and neurotransmitters and therefore receive numerous excitatory and inhibitory inputs from important subcortical neural areas such as limbic and brainstem populations. These unique cells are also densely innervated by axons from other hypothalamic nuclei. The vast majority of neurochemical maps pertain to animal models, mainly the rodent hypothalamus, however accumulating preliminary anatomical structural studies have revealed the presence and distribution of several neuropeptides in the human magnocellular nuclei. This review presents a novel and comprehensive evidence based evaluation of neuropeptide expression in the human SON and PVN. Collectively this review aims to cast a new, medically oriented light on hypothalamic neuroanatomy and contribute to a better understanding of the mechanisms responsible for neuropeptide-related physiology and the nature of possible neuroendocrinal interactions between local regulatory pathways.

Spexin-expressing neurons in the magnocellular nuclei of the human hypothalamus.

Neuropeptides are involved in numerous brain activities being responsible for a wide spectrum of higher mental functions. The purpose of this concise, structural and qualitative investigation was to map the possible immunoreactivity of the novel neuropeptide spexin (SPX) within the human magnocellular hypothalamus. SPX is a newly identified peptide, a natural ligand for the galanin receptors (GALR) 2/3, with no molecular structure similarities to currently known regulatory factors. SPX seems to have multiple physiological functions, with an involvement in reproduction and food-intake regulation recently revealed in animal studies. For the first time we describe SPX expressing neurons in the supraoptic (SON) and paraventricular (PVN) nuclei of the human hypothalamus using immunohistochemical and fluorescent methods, key regions involved in the mechanisms of osmotic homeostasis, energy expenditure, consummatory behaviour, reproductive processes, social recognition and stress responses. The vast majority of neurons located in both examined neurosecretory nuclei show abundant SPX expression and this may indirectly implicate a potential contribution of SPX signalling to the hypothalamic physiology in the human brain.

The potential role of the novel hypothalamic neuropeptides nesfatin-1, phoenixin, spexin and kisspeptin in the pathogenesis of anxiety and anorexia nervosa.

Due to the dynamic development of molecular neurobiology and bioinformatic methods several novel brain neuropeptides have been identified and characterized in recent years. Contemporary techniques of selective molecular detection e.g. in situ Real-Time PCR, microdiffusion and some bioinformatics strategies that base on searching for single structural features common to diverse neuropeptides such as hidden Markov model (HMM) have been successfully introduced. A convincing majority of neuropeptides have unique properties as well as a broad spectrum of physiological activity in numerous neuronal pathways including the hypothalamus and limbic system. The newly discovered but uncharacterized regulatory factors nesfatin-1, phoenixin, spexin and kisspeptin have the potential to be unique modulators of stress responses and eating behaviour. Accumulating basic studies revelaed an intriguing role of these neuropeptides in the brain pathways involved in the pathogenesis of anxiety behaviour. Nesfatin-1, phoenixin, spexin and kisspeptin may also distinctly affect the energy homeostasis and modulate food intake not only at the level of hypothalamic centres. Moreover, in patients suffered from anxiety and anorexia nervosa a significant, sex-related changes in the plasma neuropeptide levels occurred. It should be therefore taken into account that the targeted pharmacomodulation of central peptidergic signaling may be potentially helpful in the future treatment of certain neuropsychiatric and metabolic disorders. This article reviews recent evidence dealing with the hypothetical role of these new factors in the anxiety-related circuits and pathophysiology of anorexia nervosa.

The novel neuropeptide phoenixin is highly co-expressed with nesfatin-1 in the rat hypothalamus, an immunohistochemical study.

The hypothalamus regulates a number of autonomic functions essential for homeostasis; therefore, investigations concerning hypothalamic neuropeptides and their functions and distribution are of great importance in contemporary neuroscience. Recently, novel regulatory factors expressed in the hypothalamus have been discovered, of which nesfatin-1 and phoenixin (PNX), show intriguing similarities in their brain distributions. There are currently few studies characterizing PNX expression, so it is imperative to accurately trace its localization, with particular attention to the hypothalamic nuclei and nesfatin-1 co-expression. Using fluorescence and classical immunohistochemical stainings on adult rat brain, we visualized the potential co-expression of nesfatin-1 and PNX immunoreactive cells. We have demonstrated a distinct PNX-immunoreactivity in 21-32% of cells in the arcuate nucleus, paraventricular nucleus, ventromedial and lateral hypothalamus. Nesfatin-1 expression reached 45-68% of all neurons in the same sites, while co-expression was strikingly seen in the vast majority (70-86%) of PNX-immunoreactive neurons in the rat hypothalamic nuclei. Our results demonstrate for the first time, a wide distribution of PNX in the hypothalamus which could implicate a potential functional relationship with nesfatin-1, possibly in the regulation of the hypothalamic-pituitary-gonadal axis or other autonomic functions, which require further study.

Randomized controlled trial of mindfulness meditation for generalized anxiety disorder: effects on anxiety and stress reactivity.

OBJECTIVE: Mindfulness meditation has met increasing interest as a therapeutic strategy for anxiety disorders, but prior studies have been limited by methodological concerns, including a lack of an active comparison group. This is the first randomized, controlled trial comparing the manualized Mindfulness-Based Stress Reduction (MBSR) program with an active control for generalized anxiety disorder (GAD), a disorder characterized by chronic worry and physiologic hyperarousal symptoms. METHOD: Ninety-three individuals with DSM-IV-diagnosed GAD were randomly assigned to an 8-week group intervention with MBSR or to an attention control, Stress Management Education (SME), between 2009 and 2011. Anxiety symptoms were measured with the Hamilton Anxiety Rating Scale (HAMA; primary outcome measure), the Clinical Global Impressions-Severity of Illness and -Improvement scales (CGI-S and CGI-I), and the Beck Anxiety Inventory (BAI). Stress reactivity was assessed by comparing anxiety and distress during pretreatment and posttreatment administration of the Trier Social Stress Test (TSST). RESULTS: A modified intent-to-treat analysis including participants who completed at least 1 session of MBSR (n = 48) or SME (n = 41) showed that both interventions led to significant (P < .0001) reductions in HAMA scores at endpoint, but did not significantly differ. MBSR, however, was associated with a significantly greater reduction in anxiety as measured by the CGI-S, the CGI-I, and the BAI (all P values < .05). MBSR was also associated with greater reductions than SME in anxiety and distress ratings in response to the TSST stress challenge (P < .05) and a greater increase in positive self-statements (P = .004). CONCLUSIONS: These results suggest that MBSR may have a beneficial effect on anxiety symptoms in GAD and may also improve stress reactivity and coping as measured in a laboratory stress challenge. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01033851.

Effect of acute posttrauma propranolol on PTSD outcome and physiological responses during script-driven imagery.

INTRODUCTION: Animal and human research suggests that the development of posttraumatic stress disorder (PTSD) may involve the overconsolidation of memories of a traumatic experience. Previous studies have attempted to use pharmaceutical agents, especially the ß-adrenergic blocker propranolol, to reduce this overconsolidation. AIMS: In this randomized, placebo-controlled study of the efficacy of propranolol in reducing the development of PTSD, we optimized dosages and conducted both psychophysiological and clinical assessments 1 and 3 months after the traumatic event. Forty-one emergency department patients who had experienced a qualifying acute psychological trauma were randomized to receive up to 240 mg/day of propranolol or placebo for 19 days. At 4 and 12 weeks post-trauma, PTSD symptoms were assessed. One week later, participants engaged in script-driven imagery of their traumatic event while psychophysiological responses were measured. RESULTS: Physiological reactivity during script-driven traumatic imagery, severity of PTSD symptoms, and the rate of the PTSD diagnostic outcome were not significantly different between the two groups. However, post hoc subgroup analyses showed that in participants with high drug adherence, at the 5-week posttrauma assessment, physiological reactivity was significantly lower during script-driven imagery in the propranolol than in the placebo subjects. CONCLUSIONS: The physiological results provide some limited support for a model of PTSD in which a traumatic conditioned response is reduced by posttrauma propranolol. However, the clinical results from this study do not support the preventive use of propranolol in the acute aftermath of a traumatic event.

Efficacy of CBT for benzodiazepine discontinuation in patients with panic disorder: Further evaluation.

Despite its acute efficacy for the treatment of panic disorder, benzodiazepines (BZs) are associated with a withdrawal syndrome that closely mimics anxiety sensations, leading to difficulty with treatment discontinuation and often disorder relapse. An exposure-based cognitive-behavioral treatment for BZ discontinuation, Panic Control Treatment for BZ Discontinuation (CBT) targets the fear of these sensations and has demonstrated efficacy in preventing disorder relapse and facilitating successful BZ discontinuation among patients with panic disorder. In this randomized controlled trial, CBT was compared to taper alone and a taper plus a relaxation condition to control for the effect of therapist contact and support among 47 patients with panic disorder seeking taper from BZs. Based on the primary outcome of successful discontinuation of BZ use, results indicate that adjunctive CBT provided additive benefits above both taper alone and taper plus relaxation, with consistently medium and large effect sizes over time that reached significance at the six month follow-up evaluation. The efficacy of CBT relative to either of the other taper conditions reflected very large and significant effect sizes at that time. These findings suggest that CBT provides specific efficacy for the successful discontinuation from BZs, even when controlling for therapist contact and relaxation training.