Potential of Intranasal Neuropeptide Y (NPY) and/or Melanocortin 4 Receptor (MC4R) Antagonists for Preventing or Treating PTSD.

There is a great need for effective treatment options for post-traumatic stress disorder (PTSD). Neuropeptide Y (NPY) is associated with resilience to traumatic stress. MC4R antagonists, such as HS014, also reduce response to stress. Both regulate stress-responsive systems - the hypothalamic-pituitary-axis (HPA) and the noradrenergic nervous system and their associated behaviors. Therefore, we examined if their intranasal delivery to brain could attenuate development of PTSD-related symptoms in single prolonged stress (SPS) rodent PTSD model. Three regimens were used: (1) prophylactic treatment 30 min before SPS stressors, (2) early intervention right after SPS stressors, (3) therapeutic treatment when PTSD behaviors are manifested 1 wk or more after the traumatic stress. NPY delivered by regimen 1 or 2 prevented SPS-triggered elevation in anxiety, depressive-like behavior, and hyperarousal and reduced dysregulation of HPA axis. Hypothalamic CRH mRNA and GR in ventral hippocampus were significantly induced in vehicle- but not NPY-treated group. NPY also prevented hypersensitivity of LC/NE system to novel mild stressor and induction of CRH in amygdala. Some of these impairments were also reduced with HS014, alone or together with NPY. When given after symptoms were manifested (regiment 3), NPY attenuated anxiety and depressive behaviors. This demonstrates strong preclinical proof of concept for intranasal NPY, and perhaps MC4R antagonists, for non-invasive early pharmacological interventions for PTSD and comorbid disorders and possibly also as therapeutic strategy.

[THE THYROID STATUS OF RATS IMMUNIZED WITH PEPTIDES DERIVED FROM THE EXTRACELLULAR REGIONS OF THE TYPES 3 AND 4 MELANOCORTIN RECEPTORS AND THE 1B-SUBTYPE 5-HYDROXYTRYPTAMINE RECEPTOR].

The activity of the hypothalamic-pituitary-thyroid (HPT) axis is controlled by the brain neurotransmitter systems, including the melanocortin signaling system. Pharmacological inhibition of type 4 melanocortin receptor (M4R) leads to disruption of the functioning of HPT axis and to reduction of the level of thyroid hormones. At the same time, the data on how prolonged inhibition of M4R affects this axis and on its role in regulation of M3R are absent. The relationship between the thyroid status and the activity of 1B-subtype 5-hydroxytryptamine receptor (5-HT1BR) is scarcely explored. The aim of this work to study the effects of chronic inhibition of M3R, M4R and 5-HT1BR induced by immunization of rats with BSA-conjugated peptide derived from the extracellular regions of these receptors on the thyroid status and the activity of thyroid stimulating hormone (TSH)-sensitive adenylyl cyclase signaling system (ACSS) in the thyroid glarid (TG) of the immunized animals. In rats immunized with the peptides K-[TSLHL WNRSSHGLHG11-25]-A of M4R, A[PTNPYCICTTAH269-280]-A of M3R and. [QAKAEE-EVSEC(Acm)-VVNTDH189-205]-A of 5-HT1BR levels of thyroid hormones such as fT4, tT4 and tT3 were significantly reduced. In rats immunized with M4R and M3R peptides, an increase of TSH was detected whereas in the animals immunized with 5-HT1BR peptide the level of TSH, on the contrary, was reduced. In the TG of rats immunized with M4R and M3R peptides, the stimulatory effects of hormones (TSH, PA-CAP-3 8) and GppNHp on adenylyl cyclase activity were attenuated, and the changes were most pronounced in the case M4R peptide immunization. After immunization with 5-HT1BR peptide the stimulatory effects of TSH, PACAP-38 and GppNHp were retained. Thus, the main cause of thyroid hormones deficit in rats immunized with M4R and M3R peptides was the decreased sensitivity of ACSS thyrocytes to TSH, whereas in rats iimunized with 5-HT1BR peptide the deficit of thyroid hormones was associated with decreased level of TSH. Our data on the negative impact of long-term immunization of rats with BSA-conjugated peptides derived from the extracellular regions of M4R, M3R.and 5-HT1BR on their thyroid status is a strong argument in favor of participation of these receptors and intracellular signaling pathways associated with them in the regulation of HPT axis.

Prevalence, spectrum, and functional characterization of melanocortin-4 receptor gene mutations in a representative population-based sample and obese adults from Germany.

CONTEXT: Autosomal dominant inheritance of mutations in the melanocortin-4 receptor gene (MC4R) is currently regarded as the most relevant genetic cause for extreme obesity and affects 2-4% of extremely obese individuals. OBJECTIVE: Our objective was to assess the relevance of MC4R mutations in a German population-based sample. DESIGN AND SETTING: We conducted a mutation screen of the MC4R gene by capillary electrophoresis-based single-strand conformation polymorphism analysis and denaturing HPLC. PARTICIPANTS: Subjects included 4068 individuals of a German population-based study group [Kooperative Gesundheitsforschung im Raum Augsburg, Survey 4 (KORA-S4); i.e. Cooperative Health Research in the Region of Augsburg] and 1003 German obese adults (body mass index >or= 30 kg/m(2)). MAIN OUTCOME MEASURES: Samples with aberrant capillary electrophoresis-based single-strand conformation polymorphism analysis/denaturing HPLC patterns were resequenced. Functional studies including agonistic receptor stimulation (Nle-D-Phe-alpha-, alpha-, and beta-MSH) and cell surface expression assays were performed. RESULTS: Sixteen (six novel) coding nonsynonymous mutations were detected in 27 heterozygous individuals of KORA-S4. Four of the mutation alleles led to impaired receptor function in vitro; however, none of these six heterozygous mutation carriers was obese (body mass index >or= 30 kg/m(2)). In the obese adults, six coding nonsynonymous and a nonsense mutation were detected in 13 individuals. Only the nonsense mutation allele entailed impaired receptor function. CONCLUSIONS: Our study depicts prevalence, spectrum, and functional characterization of MC4R mutations in the German population-based sample KORA-S4. In this epidemiological study group, individuals heterozygous for nonsynonymous MC4R mutation alleles entailing impaired function were not obese. Furthermore, nonsynonymous MC4R mutations causing impaired receptor function were rare in German obese adults (two in 1003 = 0.2%).

Involvement of proopiomenalocortin-derived peptides in endogenous central histamine-induced reversal of critical haemorrhagic hypotension in rats.

An increase in endogenous central histamine concentrations, after loading with histamine precursor L-histidine or inhibition of histamine N-methyltransferase (HNMT) activity, produces the reversal of critical hypotension with improvement in survival of haemorrhage-shocked rats. In the present study, the involvement of proopiomelanocortin (POMC)-derived peptides in central histamine-induced resuscitating action was examined in male anaesthetised Wistar rats subjected to a haemorrhagic hypotension of 20-25 mmHg resulting in the death of all control animals within 30 min. HNMT inhibitor metoprine (20 microg) administered intracerebroventricularly (i.c.v.) at 5 min of critical hypotension produced a long-lasting pressor effect with a 100% survival rate at 2 h. The action was accompanied by 34.5% and 28.9% higher plasma concentrations of ACTH and alpha-MSH, respectively, in comparison to concentrations in the saline-injected group as measured 20 min after treatment. Melanocortin type 4 (MC(4)) receptor antagonist HS014 (5 microg; i.c.v.) inhibited metoprine-induced increase in mean arterial pressure, which resulted from decreased regional vascular resistance, however, it did not affect the heart rate and the survival at 2 h. On the other hand, glucocorticoid type II receptor blocker mifepristone (30 mg/kg; sc) had no effect. In conclusion, POMC-derived peptides, acting centrally via MC(4) receptors, participate in endogenous central histamine-induced resuscitating effect in rats.