Effects of melanocortins on fetal development

Effects of an herbal adaptogen feed-additive on feeding-related hypothalamic neuropeptides in chronic cyclic heat-stressed chickens

Heat stress (HS) is a global serious issue in the poultry industry with numerous adverse effects, including increased stress, depressed feed intake (FI), poor growth performance and higher mortality. Herbal adaptogens, plant extracts considered as stress response modifiers, are metabolic regulators that improve an organism's ability to adapt to and minimize damage from environmental stresses. Previously, we showed that herbal adaptogen supplementation increased FI and body weight (BW) of broiler (meat-type) chickens reared under HS conditions. Therefore, we hypothesized that these effects may be mediated through modulation of hypothalamic feeding-related neuropeptides. Male Cobb 500 chicks were reared in 12 environmental chambers with three diets: a corn-soybean-based diet (C) and two herbal adaptogen-supplemented diets at 500 g/1000 kg (NR-PHY-500) and 1 kg/1000 kg (NR-PHY-1000). Broilers in 9 chambers were exposed to chronic cyclic HS (35 °C for 8 h/day) from d29 to d42, while 3 chambers were maintained at 24 °C (thermoneutral, TN) for all 42 days. Hypothalamic samples were collected on d42 from each group, both before the onset of HS (Pre-HS) that day and after 3 h of HS (post-HS). Hypothalamic expressions of neuropeptide Y (NPY) receptors Y4 and Y7, Corticotropin-releasing hormone (CRH), orexin receptor 1 (ORXR1), melanocortin receptors (MC1R, MC4R, and MC5R), visfatin and neurosecretory protein GL (NPGL) genes were significantly upregulated by adaptogen supplementation. The hypothalamic expression of MC2R was affect by period, with a significant upregulation during post-HS phase. There was a significant period by treatment interaction for hypothalamic orexin and adiponectin expression. The hypothalamic expression of NPY, Y1, Y2, Y5, Y6, proopiomelanocortin (POMC), cocaine and amphetamine regulated transcript (CART), agouti-related peptide (AgRP), ORXR2, AdipR1/2, MC3R, and ghrelin was not affected by diet supplementation nor by HS exposure. In conclusion, these findings suggest that in-feed supplementation of adaptogen might improve FI and growth via modulation of hypothalamic feeding-related neuropeptides in heat-stressed broilers.

The melanocortin receptor signaling system and its role in neuroprotection against neurodegeneration: Therapeutic insights

The melanocortin signaling system consists of the melanocortin peptides, their distinctive receptors, accessory proteins, and endogenous antagonists. Melanocortin peptides are small peptide hormones that have been studied in a variety of physiological and pathological conditions. There are five types of melanocortin receptors, and they are distributed within the central nervous system and in several tissues of the periphery. The G protein-coupled melanocortin receptors typically signal through adenylyl cyclase and other downstream signaling pathways. Depending on the ligand, surface expression of melanocortin receptor, receptor occupancy period, related proteins, the type of cell, and other parameters, the signaling pathways are complicated and pleiotropic. While it is known that all five melanocortin receptors are coupled to Gs, they can also occasionally couple to Gq or Gi. Both direct and indirect neuroprotection are induced by the melanocortin signaling system. Targeting several of the components of the melanocortin signaling system (ligands, receptors, accessory proteins, signaling effectors, and regulators) may provide therapeutic opportunities. Activation of the melanocortin system improves different functional traits in neurodegenerative diseases. There is a potential for additional melanocortin system interventions by interfering with dimerization or dissociation. This review aims to discuss the melanocortin receptor signaling system and its role in neuroprotection, as well as its therapeutic potential.

LIF-IGF Axis Contributes to the Proliferation of Neural Progenitor Cells in Developing Rat Cerebrum

In rodent models, leukemia inhibitory factor (LIF) is involved in cerebral development via the placenta, and maternal immune activation is linked to psychiatric disorders in the child. However, whether LIF acts directly on neural progenitor cells (NPCs) remains unclear. This study performed DNA microarray analysis and quantitative RT-PCR on the fetal cerebrum after maternal intraperitoneal or fetal intracerebral ventricular injection of LIF at day 14.5 (E14.5) and determined that the expression of insulin-like growth factors (IGF)-1 and -2 was induced by LIF. Physiological IGF-1 and IGF-2 levels in fetal cerebrospinal fluid (CSF) increased from E15.5 to E17.5, following the physiological surge of LIF levels in CSF at E15.5. Immunostaining showed that IGF-1 was expressed in the cerebrum at E15.5 to E19.5 and IGF-2 at E15.5 to E17.5 and that IGF-1 receptor and insulin receptor were co-expressed in NPCs. Further, LIF treatment enhanced cultured NPC proliferation, which was reduced by picropodophyllin, an IGF-1 receptor inhibitor, even under LIF supplementation. Our findings suggest that IGF expression and release from the NPCs of the fetal cerebrum in fetal CSF is induced by LIF, thus supporting the involvement of the LIF-IGF axis in cerebral cortical development in an autocrine/paracrine manner.

Melanocortin-5 Receptor: Pharmacology and Its Regulation of Energy Metabolism

As the most recent melanocortin receptor (MCR) identified, melanocortin-5 receptor (MC5R) has unique tissue expression patterns, pharmacological properties, and physiological functions. Different from the other four MCR subtypes, MC5R is widely distributed in both the central nervous system and peripheral tissues and is associated with multiple functions. MC5R in sebaceous and preputial glands regulates lipid production and sexual behavior, respectively. MC5R expressed in immune cells is involved in immunomodulation. Among the five MCRs, MC5R is the predominant subtype expressed in skeletal muscle and white adipose tissue, tissues critical for energy metabolism. Activated MC5R triggers lipid mobilization in adipocytes and glucose uptake in skeletal muscle. Therefore, MC5R is a potential target for treating patients with obesity and diabetes mellitus. Melanocortin-2 receptor accessory proteins can modulate the cell surface expression, dimerization, and pharmacology of MC5R. This minireview summarizes the molecular and pharmacological properties of MC5R and highlights the progress made on MC5R in energy metabolism. We poInt. out knowledge gaps that need to be explored in the future.

MC5R Contributes to Sensitivity to UVB Waves and Barrier Function in Mouse Epidermis

MC5R is known for its role in the exocrine function of sebaceous glands, but other functions in the epidermis remain unclear. This study focused on the relationship between MC5R and homeostasis in the epidermis and examined the role of MC5R in mice whose skin was irradiated with UVB waves. UVB irradiation-induced skin ulcers and severe inflammation at lower doses in homozygotes of MC5R-deficient (i.e., MC5R -/- ) mice (150 mJ/cm2) than the doses in wild-type mice (500 mJ/cm2). Transepidermal water loss was increased (approximately 10-fold) in adult MC5R -/- mice compared with that in wild-type mice. In neonates, a dye exclusion assay showed no remarkable difference between MC5R -/- and wild-type mice. After UVB irradiation, compared with wild-type mice, MC5R -/- mice showed increased inflammatory cell infiltration in the dermis of the ulcerative region, significantly increased thickness of the epidermis in the nonulcerative region, significantly more prickle cells in the nonulcerative region, and increased serum IL-6 levels but decreased IL-10 levels. Transmission electron microscopy revealed fewer lamellar granules, less lipid secretion, and an expansion of the trans-Golgi network in the epidermis in MC5R -/- mice. This study elucidated the increased sensitivity to UVB irradiation and decreased barrier function in MC5R -/- mice.

Lung-brain axis

The appreciation of human microbiome is gaining strong grounds in biomedical research. In addition to gut-brain axis, is the lung-brain axis, which is hypothesised to link pulmonary microbes to neurodegenerative disorders and behavioural changes. There is a need for analysis based on emerging studies to map out the prospects for lung-brain axis. In this review, relevant English literature and researches in the field of 'lung-brain axis' is reported. We recommend all the highlighted prospective studies to be integrated with an interdisciplinary approach. This might require conceptual research approaches based on physiology and pathophysiology. Multimodal aspects should include experimental animal units, while exploring the research gaps and making reference to the already existing human data. The overall microbiome medicine is gaining more ground. Aetiological paths and experimental recommendations as per prospective studies in this review will be an important guideline to develop effective treatments for any lung induced neurodegenerative diseases. An in-depth knowledge of the bi-directional communication between host and microbiome in the lung could help treatment to respiratory infections, alleviate stress, anxiety and enhanced neurological effects. The timely prevention and treatment of neurodegenerative diseases requires paradigm shift of the aetiology and more innovative experimentation.Impact statementThe overall microbiome medicine is gaining more ground. An in-depth knowledge of the bi-directional communication between host and microbiome in the lung could confer treatment to respiratory infections, alleviate stress, anxiety and enhanced neurological effects. Based on this review, we recommend all the highlighted prospective studies to be integrated and be given an interdisciplinary approach. This might require conceptual research approaches based on physiology and pathophysiology. Multimodal aspects should include experimental animal units; while exploring the research gaps and making reference to the already existing human data.

Zika virus dysregulates the expression of astrocytic genes involved in neurodevelopment

Zika virus (ZIKV) is a kind of flavivirus emerged in French Polynesia and Brazil, and has led to a worldwide public health concern since 2016. ZIKV infection causes various neurological conditions, which are associated with fetus brain development or peripheral and central nervous systems (PNS/CNS) functional problems. To date, no vaccine or any specific antiviral therapy against ZIKV infection are available. It urgently needs efforts to explore the underlying molecular mechanisms of ZIKV-induced neural pathogenesis. ZIKV favorably infects neural and glial cells specifically astrocytes, consequently dysregulating gene expression and pathways with impairment of process neural cells. In this study, we applied a model for ZIKV replication in mouse primary astrocytes (MPAs) and profiled temporal alterations in the host transcriptomes upon ZIKV infection. Among the RNA-sequencing data of 27,812 genes, we examined 710 genes were significantly differentially expressed by ZIKV, which lead to dysregulation of numerous functions including neurons development and migration, glial cells differentiation, myelinations, astrocytes projection, neurogenesis, and brain development, along with multiple pathways including Hippo signaling pathway, tight junction, PI3K-Akt signaling pathway, and focal adhesion. Furthermore, we confirmed the dysregulation of the selected genes in MPAs and human astroglioma U251 cells. We found that PTBP1, LIF, GHR, and PTBP3 were upregulated while EDNRB and MBP were downregulated upon ZIKV infection. The current study highlights the ZIKV-mediated potential genes associated with neurodevelopment or related diseases.

Zika virus (ZIKV) infection causes serious neurological disorders of central and peripheral nervous system, and fetal brain development disorders including microcephaly. There are still uncovered explorations for the underlying molecular mechanism of ZIKV-infected pathogenesis. This study reveals a series of dysregulation of neuropathic genes mRNA and protein expression in mouse and human astrocytes upon ZIKV infection. As an ideal ZIKV infection model in mouse primary astrocytes (MPAs), RNA-seq was performed to profile transcriptome alteration by ZIKV infection. Bioinformatics analysis demonstrated the significant alterations of the 710 genes that were linked to glial cell differentiation and projection, neurogenesis and migration of neurons, myelination, as well as synaptic control. Among the top selected differentially expressed genes, such as PTBP1, LIF, GHR, PTBP3, EDNRB, and MBP, the mRNA and protein expressions were confirmed to identify the dysregulation of the transcriptome in MPAs upon ZIKV infection. Furthermore, ZIKV infection altered the mRNA and protein expression of these astrocytic genes involved in neurodevelopment in U251 cells following the analysis of the transcriptome. In conclusion, the alteration of astrocytic gene functions or associated-pathways suggest a novel clue of a mechanism involved in the ZIKV-induced neurodevelopment disorders.

Melanocortin-4 Receptor Deficiency Attenuates Placental Ischemia-Induced Hypertension in Pregnant Rats

Preeclampsia is a pregnancy-specific disorder of new-onset hypertension linked to placental ischemia. While obesity is a major risk factor for preeclampsia, not all obese pregnant women develop pregnancy-induced hypertension or preeclampsia. Previously, we reported that placental ischemia-induced hypertension is dependent upon intact signaling of the sympathetic nervous system. Moreover, in various models of obesity, blockade of MC4R (melanocortin-4 receptor) signaling protects against the development of hypertension via suppression of the sympathetic nervous system. Less is known about this pathway during obese pregnancy. Although blockade of MC4R may lead to increased body weight during pregnancy, we tested the hypothesis that placental ischemia-induced hypertension is attenuated in obese MC4R-deficient pregnant rats. On gestational day 14, MC4R wild-type or heterozygous-deficient (MC4R-def) rats were subjected to chronic placental ischemia via the reduced uterine perfusion pressure procedure or Sham surgery then examined on gestational day 19. In Sham MC4R-def versus Sham wild-type pregnant rats, there was increased body weight, fat mass, and circulating leptin levels but they had similar fetus weights. Reduced uterine perfusion pressure reduced fetus weights in both strains. Reduced uterine perfusion pressure increased blood pressure in wild-type rats but this response was significantly attenuated in MC4R-def rats, although blood pressure was elevated in Sham MC4R-def over Sham wild-type. These data indicate that while obese MC4R-def pregnant rats have higher blood pressure during pregnancy, placental ischemia-induced hypertension is attenuated in obese MC4R-def pregnant rats. Thus, obese women with abnormal MC4R signaling may be less susceptible to the development of placental ischemia-induced hypertension.

Molecular mechanisms underlying the models of neurodevelopmental disorders in maternal immune activation relevant to the placenta

The rapid rise in the prevalence of autism spectrum disorders (ASD) and other psychiatric disorders displaying similar traits has increased the need to elucidate their molecular mechanisms. Epidemiological studies have shown that maternal infection during mid-pregnancy is associated with increased risk of neurodevelopmental disorders such as ASD in offspring. Using maternal infection models, researchers have gathered evidence relevant to such disorders. A comprehensive summary of the changes in the brain structure, function, and behavior in offspring induced by maternal immune activation (MIA) has been reported. However, the molecular mechanisms underlying the association between MIA and improper brain development, which ultimately lead to neurodevelopmental disorders, have not been fully reviewed. This paper summarizes the currently known molecular mechanisms associated with the MIA model, with a special focus on the role of the placenta in fetal brain development.

Multiple beneficial effects of melanocortin MC4 receptor agonists in experimental neurodegenerative disorders: Therapeutic perspectives

Melanocortin peptides induce neuroprotection in acute and chronic experimental neurodegenerative conditions. Melanocortins likewise counteract systemic responses to brain injuries. Furthermore, they promote neurogenesis by activating critical signaling pathways. Melanocortin-induced long-lasting improvement in synaptic activity and neurological performance, including learning and memory, sensory-motor orientation and coordinated limb use, has been consistently observed in experimental models of acute and chronic neurodegeneration. Evidence indicates that the neuroprotective and neurogenic effects of melanocortins, as well as the protection against systemic responses to a brain injury, are mediated by brain melanocortin 4 (MC₄) receptors, through an involvement of the vagus nerve. Here we discuss the targets and mechanisms underlying the multiple beneficial effects recently observed in animal models of neurodegeneration. We comment on the potential clinical usefulness of melanocortin MC₄ receptor agonists as neuroprotective and neuroregenerative agents in ischemic stroke, subarachnoid hemorrhage, traumatic brain injury, spinal cord injury, and Alzheimer's disease.

The suppression of maternal-fetal leukemia inhibitory factor signal relay pathway by maternal immune activation impairs brain development in mice

Recent studies in rodents suggest that maternal immune activation (MIA) by viral infection is associated with schizophrenia and autism in offspring. Although maternal IL-6 is though t to be a possible mediator relating MIA induced these neuropsychiatric disorders, the mechanism remains to be elucidated. Previously, we reported that the maternal leukemia inhibitory factor (LIF)–placental ACTH–fetal LIF signaling relay pathway (maternal–fetal LIF signal relay) promotes neurogenesis of fetal cerebrum in rats. Here we report that the maternal–fetal LIF signal relay in mice is suppressed by injection of polyriboinosinic-polyribocytidylic acid into dams, which induces MIA at 12.5 days post-coitum. Maternal IL-6 levels and gene expression of placental suppressor of cytokine signaling 3 (Socs3) increased according to the severity of MIA and gene expression of placental Socs3 correlated with maternal IL-6 levels. Furthermore, we show that MIA causes reduction of LIF level in the fetal cerebrospinal fluid, resulting in the decreased neurogenesis in the cerebrum. These findings suggest that maternal IL-6 interferes the maternal–fetal LIF signal relay by inducing SOCS3 in the placenta and leads to decreased neurogenesis.

Melanocortins contribute to sequential differentiation and enucleation of human erythroblasts via melanocortin receptors 1, 2 and 5

In this study, we showed that adrenocorticotropic hormone (ACTH) promoted erythroblast differentiation and increased the enucleation ratio of erythroblasts. Because ACTH was contained in hematopoietic medium as contamination, the ratio decreased by the addition of anti-ACTH antibody (Ab). Addition of neutralizing Abs (nAbs) for melanocortin receptors (MCRs) caused erythroblast accumulation at specific stages, i.e., the addition of anti-MC2R nAb led to erythroblast accumulation at the basophilic stage (baso-E), the addition of anti-MC1R nAb caused accumulation at the polychromatic stage (poly-E), and the addition of anti-MC5R nAb caused accumulation at the orthochromatic stage (ortho-E). During erythroblast differentiation, ERK, STAT5, and AKT were consecutively phosphorylated by erythropoietin (EPO). ERK, STAT5, and AKT phosphorylation was inhibited by blocking MC2R, MC1R, and MC5R, respectively. Finally, the phosphorylation of myosin light chain 2, which is essential for the formation of contractile actomyosin rings, was inhibited by anti-MC5R nAb. Taken together, our study suggests that MC2R and MC1R signals are consecutively required for the regulation of EPO signal transduction in erythroblast differentiation, and that MC5R signal transduction is required to induce enucleation. Thus, melanocortin induces proliferation and differentiation at baso-E, and polarization and formation of an actomyosin contractile ring at ortho-E are required for enucleation.

Maternal and fetal outcome in Swedish women with erythropoietic protoporphyria

BACKGROUND

Painful photosensitivity is characteristic of erythropoietic protoporphyria (EPP). In women, symptoms may be affected by menstrual cycle and pregnancy but very little is known about maternal and fetal outcome.

OBJECTIVES

To investigate the impact of menstruation, pregnancy and breast-feeding on photosensitivity and possible effects of EPP on maternal, fetal and neonatal outcome.

METHODS

Retrospective study screening all 20 Swedish women alive and older than 18 years diagnosed with EPP with a total of 33 deliveries. Data were retrieved for 19 women and 32 deliveries in medical records and completed by a questionnaire sent to the patients.

RESULTS

Photosensitivity worsened in five of 19 (26%) women around menstruation whereas amelioration was reported in 17 of 32 (53%) pregnancies and during 11 of 32 (34%) breast-feeding periods. Fertility rate was normal and there were no maternal or fetal complications apart from minor arterial hypertension in one woman.

CONCLUSIONS

The study confirms changes in photosensitivity during menstruation and pregnancy. Amelioration during breast-feeding is a new finding. Pregnancy appears safe without increased risks of pregnancy complications or adverse effects on fetal or neonatal health.