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The two-faced effects of nerves and neuropeptides in corneal diseases.
Prog Retin Eye Res
Romina Mayra Lasagni Vitar, Paolo Rama, Giulio Ferrari
Corneal nerves are instrumental to maintain cornea integrity through regulation of key physiological functions such as tear secretion, blink reflex, and neuropeptide turnover. Corneal nerve injury/stimulation can follow many insults including mechanical/chemical trauma, infections and surgeries. Nerve disruption initiates a process named neurogenic inflammation which leads to edema, pain, and recruitment and activation of leukocytes. Interestingly, leukocyte influx in the cornea can further damage nerves by releasing inflammatory mediators-including neuropeptides. The clinical outcome of neuroinflammation can be beneficial or detrimental to corneal integrity. On one side, it ensures prompt wound healing and prevents infections. On the other, prolonged and/or deranged neuroinflammation can permanently disrupt corneal integrity and impair vision. The cornea is an ideal site to study peripheral neuroinflammation and neurogenic inflammation since it receives the highest density of sensory nerves of the entire body. We will review the corneal nerve anatomy and neurochemistry, discuss the beneficial and detrimental effects of neurogenic inflammation in corneal wound healing, inflammatory processes, and pain. We will also examine the emerging remote impact of corneal nerve disruption on the trigeminal ganglion and the brain, highlighting the key role of neuropeptide Substance P. Finally, we will discuss the clinical relevance of such neuroinflammatory network in the context of severe and highly prevalent ocular diseases, including potential treatments.
Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank.
J Clin Pharmacol
Cassandra R Doyno, C Michael White
There are many nonopioid central nervous system depressant substances that share a gamma-aminobutyric acid (GABA) receptor-related mechanism of action. These sedatives-hypnotics can be indicated to treat anxiety, seizures, depression, and insomnia but are also used as substances of abuse and used to facilitate sexual assault. Barbiturates, methaqualone, and glutethimide were among the first type A GABA receptor-mediated sedative-hypnotics. Their clinical use was limited for most indications by serious adverse events and strong abuse potential but continue to be used illicitly around the world. The benzodiazepines supplanted barbiturates for most indications because they were less likely to cause severe adverse events in monotherapy. Flunitrazepam is a newer benzodiazepine that is preferentially used recreationally and to facilitate sexual assault. Flunitrazepam has greater potency and higher affinity for the type A GABA receptor than most benzodiazepines. Gamma-hydroxybutyric acid is sought illicitly for its hypnotic, euphoric and anabolic effects as well as to facilitate sexual assault. When any of these GABAergic drugs are used in high doses or with other sedative hypnotic agents, respiratory depression, coma, and death have occurred. Chronic use of these GABAergic drugs can lead to significant withdrawal syndromes. Phenibut and selank are poorly studied Russian drugs with GABAergic mechanisms that are inexplicably sold to US consumers as dietary supplements. Poison control center calls regarding phenibut have increased substantially over the past 5 years. Desired euphoriant effects account for the recreational and illicit use of many GABA-modulating agents. However, illicit use can lead to significant toxicities related to abuse, dependence, and subsequent withdrawal syndromes. Significant evaluation of developing agents with GABA properties should be conducted to determine abuse potential before public access ensues.
Effect of metformin treatment on memory and hippocampal neurogenesis decline correlated with oxidative stress induced by methotrexate in rats.
Biomed Pharmacother
Nataya Sritawan, Kornrawee Suwannakot, Salinee Naewla +6 more
Metformin is currently used as a first-line drug to treat patients with type 2 diabetes. Previous studies have demonstrated that metformin has antioxidant properties and reduces neuroinflammation and hippocampal neuronal cell loss, which eventually improves memory. Methotrexate (MTX) is an antimetabolite chemotherapeutic agent reported to activate cognitive impairment found in many patients. Moreover, MTX negatively affects the spatial working memory, related to neurogenesis reduction in animal models. Therefore, the present study aimed to investigate the antioxidant effect of metformin on the reduction of memory and neurogenesis caused by MTX. Male Sprague-Dawley rats were divided into four groups: control, MTX, metformin, and MTX+metformin. MTX (75 mg/kg, i.v.) was administered on days 7 and 14. Rats were administered metformin (200 mg/kg, i.p.) for 14 days. Memory was determined using novel object location (NOL) and novel object recognition (NOR) tests. Furthermore, cell cycle arrest was quantified by p21 immunostaining. Levels of neuronal protein expression, scavenging enzymes activity, and malondialdehyde (MDA) level changes in the hippocampus and prefrontal cortex were investigated. Rats receiving only MTX showed memory impairment. Decreases in scavenging enzyme activity and BDNF, DCX, and Nrf2 protein expressions levels were detected in the MTX-treated rats. In addition, MTX significantly increased p21-positive cell numbers and MDA levels. However, these adverse MTX effects were counteracted by co-administration with metformin. These results demonstrate that metformin can improve memory impairments, increase BDNF, DCX and Nrf2 protein expressions and antioxidant capacities, and decrease MDA levels in MTX-treated rats.
Effects of growth hormone-releasing hormone agonistic analog MR-409 on insulin-secreting cells under cyclopiazonic acid-induced endoplasmic reticulum stress.
Mol Cell Endocrinol
Karina Rodrigues-Dos-Santos, Gabriela M Soares, Dimitrius S P S F Guimarães +9 more
The endoplasmic reticulum (ER) stress is one of the mechanisms related to decreased insulin secretion and beta cell death, contributing to the progress of type 2 diabetes mellitus (T2D). Thus, investigating agents that can influence this process would help prevent the development of T2D. Recently, the growth-hormone-releasing hormone (GHRH) action has been demonstrated in INS-1E cells, in which it increases cell proliferation and insulin secretion. As the effects of GHRH and its agonists have not been fully elucidated in the beta cell, we proposed to investigate them by evaluating the role of the GHRH agonist, MR-409, in cells under ER stress. Our results show that the agonist was unable to ameliorate or prevent ER stress. However, cells exposed to the agonist showed less oxidative stress and greater survival even under ER stress. The mechanisms by which GHRH agonist, MR-409, leads to these outcomes require further investigation.
Protection effect of thymosin β4 on ethanol injury in corneal stromal keratocyte.
BMC Ophthalmol
Jinghua Liu, Chen Guo, Peng Hao +4 more
To investigate the protective effects of thymosin β4 (Tβ4) on ethanol injured human corneal keratocytes (HCKs).
Review of Kyotorphin Research: A Mysterious Opioid Analgesic Dipeptide and Its Molecular, Physiological, and Pharmacological Characteristics.
Front Med Technol
Hiroshi Ueda
Tyrosine-arginine (kyotorphin), an opioid analgesic dipeptide, was discovered more than 40 years ago in 1979. The evidence accumulated during this period has established the physiological significance of kyotorphin as a neuromodulating peptide, and pharmacological applications. Some of the following important findings have been discussed in this review: (1) kyotorphin is unevenly distributed in the brain; it is found in high concentrations in the pain pathway, which involves the regions associated with morphine analgesia; (2) kyotorphin is subcellularly localized in the synaptosome fraction or nerve-ending particles; (3) a specific synthetase generates kyotorphin from tyrosine and arginine; (4) kyotorphin may be also processed from calpastatin by a novel calcium-activated neutral protease or calpain; (5) kyotorphin preloaded into the synaptosome is released by high K+ depolarization in a Ca2+-dependent manner; (6) kyotorphin has a specific G protein coupled receptor, which mediates the activation of phospholipase C (PLC) and inhibition of adenylyl cyclase through Gi; (7) leucine-arginine works as a specific kyotorphin receptor antagonist; 8) membrane-bound aminopeptidase or excretion through a peptide transporter, PEPT2, may contribute to the inactivation of kyotorphin; and (9) kyotorphin causes increased Met-enkephalin release from brain and spinal slices. It is also known that the opening of plasma membrane Ca2+ channels through a conformational coupling of the InsP3 receptor with the transient receptor potential C1, which is downstream of the kyotorphin receptor-mediated activation of Gi and PLC, could be a potential underlying mechanism of Met-enkephalin release. Considering these findings, translational research is an exciting domain that can be explored in the future. As kyotorphin is a small molecule, we could design function-added kyotorphin derivatives. These studies would include not only the brain-permeable kyotorphin derivatives but also hybrid kyotorphin derivatives conjugated with small compounds that have additional pharmacological actions. Further, since there are reports of kyotorphin being involved in either the etiology or treatment of Alzheimer's disease, epilepsy, inflammation, and chronic pain, studies on the beneficial effects of kyotorphin derivatives should also be expected in the future.
[Multimodal therapeutic strategies in the treatment of cerebrovascular disease].
Zh Nevrol Psikhiatr Im S S Korsakova
A I Fedin, E N Saverskaya, K R Badalyan
The review presents the scientific substantiation of the relationship between age-related cerebrovascular changes and dysregulation of cerebral perfusion, blood-brain barrier (BBB) function and neurovascular units. The ischemic cascade in cerebrovascular disease (CVD) is considered, the main links of which are glutamate excitoxicosis, oxidative stress and neuroinflammation. Endothelial dysfunction and increased BBB permeability play an important role in the development of neuroinflammation. The use of multifunctional drugs aimed at various pathological targets of acute and chronic cerebral ischemia for the purpose of neuroprotection has been substantiated. These drugs include the peptide Cortexin (cattle cerebral cortex polypeptides). Experimental data on the study of its molecular partners in the brain are presented. The clinical efficacy of Cortexin as a neuroprotective drug in CVD has been established in many studies.
Improvement of cardiac and systemic function in old mice by agonist of growth hormone-releasing hormone.
J Cell Physiol
Pingping Xiang, Wangwei Jing, Yinuo Lin +9 more
Age-related diseases such as cardiovascular diseases portend disability, increase health expenditures, and cause late-life mortality. Synthetic agonists of growth hormone-releasing hormone (GHRH) exhibit several favorable effects on heart function and remodeling. Here we assessed whether GHRH agonist MR409 can modulate heart function and systemic parameters in old mice. Starting at the age of 15 months, mice were injected subcutaneously with MR409 (10 µg/day, n = 8) or vehicle (n = 7) daily for 6 months. Mice treated with MR409 showed improvements in exercise activity, cardiac function, survival rate, immune function, and hair growth in comparison with the controls. More stem cell colonies were grown out of the bone marrow recovered from the MR409-treated mice. Mitochondrial functions of cardiomyocytes (CMs) from the MR409-treated mice were also significantly improved with more mitochondrial fusion. Fewer β-gal positive cells were observed in endothelial cells after 10 passages with MR409. In Doxorubicin-treated H9C2 cardiomyocytes, cell senescence marker p21 and reactive oxygen species were significantly reduced after cultured with MR409. MR409 also improved cellular ATP production and oxygen consumption rate in Doxorubicin-treated H9C2 cells. Mitochondrial protein OPA1 long isoform was significantly increased after treatment with MR409. The effects of MR409 were mediated by GHRH receptor and protein kinase A (PKA). In short, GHRH agonist MR409 reversed the aging-associated changes with respect of heart function, mobility, hair growth, cellular energy production, and senescence biomarkers. The improvement of heart function may be related to a better mitochondrial functions through GHRH receptor/cAMP/PKA/OPA1 signaling pathway and relieved cardiac inflammation.
The role of humanin in the regulation of reproduction.
Biochim Biophys Acta Gen Subj
Hui Lei, Meng Rao
Humanin, a mitochondria-derived peptide, has been found to exert variously protective function in many tissues, especially in the nervous tissues. However, relatively limited studies have focused on the role of humanin in the regulation of reproduction. Current observations indicate that humanin plays an important role in regulating the response of the cell to oxidative stress and apoptosis in ovaries and testes via the modulation of several signaling pathways, especially when the body is in an abnormal state. Even so, the detailed mechanism of humanin function needs to be explored urgently. In this passage, we demonstrate how humanin exerts its protective role in female and male reproduction and raise several questions that need further investigations. Given humanin's new frontier for the design of novel therapeutic approaches for male infertility, male contraception, female infertility, and glucose metabolism in polycystic ovary syndrome, it is worthy of further study on its protective effects and clinical applications in reproductive function.
Severe Pulmonary Arterial Hypertension Is Characterized by Increased Neutrophil Elastase and Relative Elafin Deficiency.
Chest
Andrew J Sweatt, Kazuya Miyagawa, Christopher J Rhodes +14 more
Preclinical evidence implicates neutrophil elastase (NE) in pulmonary arterial hypertension (PAH) pathogenesis, and the NE inhibitor elafin is under early therapeutic investigation.
Adjunctive Thymosin Beta-4 Treatment Influences PMN Effector Cell Function during Pseudomonas aeruginosa-Induced Corneal Infection.
Cells
Yuxin Wang, Thomas W Carion, Abdul Shukkur Ebrahim +2 more
Previous work examining the therapeutic efficacy of adjunct thymosin beta 4 (Tβ4) to ciprofloxacin for ocular infectious disease has revealed markedly reduced inflammation (inflammatory mediators and innate immune cells) with increased activation of wound healing pathways. Understanding the therapeutic mechanisms of action have further revealed a synergistic effect with ciprofloxacin to enhance bacterial killing along with a regulatory influence over macrophage effector cell function. As a natural extension of the aforementioned work, the current study uses an experimental model of P. aeruginosa-induced keratitis to examine the influence of Tβ4 regarding polymorphonuclear leukocyte (PMN/neutrophil) cellular function, contributing to improved disease response. Flow cytometry was utilized to phenotypically profile infiltrating PMNs after infection. The generation of reactive oxygen species (ROS), neutrophil extracellular traps (NETs), and PMN apoptosis were investigated to assess the functional activities of PMNs in response to Tβ4 therapy. In vitro work using peritoneal-derived PMNs was similarly carried out to verify and extend our in vivo findings. The results indicate that the numbers of infiltrated PMNs into infected corneas were significantly reduced with adjunctive Tβ4 treatment. This was paired with the downregulated expression of proinflammatory markers on these cells, as well. Data generated from PMN functional studies suggested that the corneas of adjunctive Tβ4 treated B6 mice exhibit a well-regulated production of ROS, NETs, and limited PMN apoptosis. In addition to confirming the in vivo results, the in vitro findings also demonstrated that neutrophil elastase (NE) was unnecessary for NETosis. Collectively, these data provide additional evidence that adjunctive Tβ4 + ciprofloxacin treatment is a promising option for bacterial keratitis that addresses both the infectious pathogen and cellular-mediated immune response, as revealed by the current study.
Effects of hormonal changes on sarcopenia in chronic kidney disease: where are we now and what can we do?
J Cachexia Sarcopenia Muscle
Ozkan Gungor, Sena Ulu, Nuri Baris Hasbal +2 more
Sarcopenia or muscle wasting is a progressive and generalized skeletal muscle disorder involving the accelerated loss of muscle mass and function, often associated with muscle weakness (dynapenia) and frailty. Whereas primary sarcopenia is related to ageing, secondary sarcopenia happens independent of age in the context of chronic disease states such as chronic kidney disease (CKD). Sarcopenia has become a major focus of research and public policy debate due to its impact on patient's health-related quality of life, health-care expenditure, morbidity, and mortality. The development of sarcopenia in patients with CKD is multifactorial and it may occur independently of weight loss or cachexia including under obese sarcopenia. Hormonal imbalances can facilitate the development of sarcopenia in the general population and is a common finding in CKD. Hormones that may influence the development of sarcopenia are testosterone, growth hormone, insulin, thyroid hormones, and vitamin D. Although the relationship between free testosterone level that is low in uraemic patients and sarcopenia in CKD is not well-defined, functional improvement may be seen. Unlike testosterone, it is known that vitamin D is associated with muscle strength, muscle size, and physical performance in patients with CKD. Outcomes after vitamin D replacement therapy are still controversial. The half-life of growth hormone (GH) is prolonged in patients with CKD. Besides, IGF-1 levels are normal in patients with Stage 4 CKD-a minimal reduction is seen in the end-stage renal disease. Unresponsiveness or resistance of IGF-1 and changes in the GH/IGF-1 axis are the main causes of sarcopenia in CKD. Low serum T3 level is frequent in CKD, but the net effect on sarcopenia is not well-studied. CKD patients develop insulin resistance (IR) from the earliest period even before GFR decline begins. IR reduces glucose utilization as an energy source by hepatic gluconeogenesis, decreasing muscle glucose uptake, impairing intracellular glucose metabolism. This cascade results in muscle protein breakdown. IR and sarcopenia might also be a new pathway for targeting. Ghrelin, oestrogen, cortisol, and dehydroepiandrosterone may be other players in the setting of sarcopenia. In this review, we mainly examine the effects of hormonal changes on the occurrence of sarcopenia in patients with CKD via the available data.
PACAP and NAP: Effect of Two Functionally Related Peptides in Diabetic Retinopathy.
J Mol Neurosci
Agata Grazia D'Amico, Grazia Maugeri, Giuseppe Musumeci +2 more
Pituitary adenylate cyclase-activating polypeptide (PACAP) is a peptide involved in physio-pathological processes of the eye. It exerts multiple effects directly through activation of its related receptors and indirectly through increases in the synthesis of activity-dependent neuroprotective protein (ADNP). To study the role of ADNP and protect against ADNP deficiencies, a small peptide called NAP was synthetized. It includes an eight amino acid active site sequence of ADNP. In this review, we summarize the knowledge regarding the neuroprotective function played by PACAP and NAP in retinal tissue and provide an overview of the correlation between PACAP and ADNP in the context of diabetic retinopathy.
Adjunctive Thymosin Beta-4 Treatment Influences MΦ Effector Cell Function to Improve Disease Outcome in Pseudomonas aeruginosa-Induced Keratitis.
Int J Mol Sci
Yuxin Wang, Thomas W Carion, Abdul Shukkur Ebrahim +2 more
Our previous work has shown that topical thymosin beta 4 (Tβ4) as an adjunct to ciprofloxacin treatment reduces inflammatory mediators and inflammatory cell infiltrates (neutrophils/PMN and macrophages/MΦ) while enhancing bacterial killing and wound healing pathway activation in an experimental model of P. aeruginosa-induced keratitis. This study aimed to mechanistically examine how Tβ4 influences MΦ function in particular, leading to reduced inflammation and enhanced host defense following P. aeruginosa-induced infection of the cornea. Flow cytometry was conducted to profile the phenotype of infiltrating MΦ after infection, while generation of reactive nitrogen species and markers of efferocytosis were detected to assess functional activity. In vitro studies were performed utilizing RAW 264.7 cells to verify and extend the in vivo findings. Tβ4 treatment decreases MΦ infiltration and regulates the activation state in response to infected corneas. MΦ functional data demonstrated that the adjunctive Tβ4 treatment group significantly downregulated reactive nitrogen species (RNS) production and efferocytotic activity. In addition, the in vitro studies showed that both Tβ4 alone and adjunctive Tβ4 treatment influenced MΦ cellular function following LPS stimulation. Collectively, these data provide further evidence that adjunctive Tβ4 + ciprofloxacin treatment offers a more efficacious option for treating bacterial keratitis. Not only does the adjunctive therapy address both the infectious pathogen and corneal wound healing response, but it also influences MΦ infiltration, activation, and function, as revealed by the current study.
Circular RNA PIP5K1A (circPIP5K1A) accelerates endometriosis progression by regulating the miR-153-3p/Thymosin Beta-4 X-Linked (TMSB4X) pathway.
Bioengineered
Lin Sun, Yan Wei, Junli Wang
As a common gynecologic disease, endometriosis (EM) poses a threat to the reproductive health of about 10% women globally. Recent studies have revealed that circular RNAs (circRNAs) are deeply implicated in EM pathogenesis. However, the functions of circPIP5K1A in EM have not been studied yet. Our study intended to uncover the molecular mechanism of circPIP5K1A in EM. In this work, gene and protein expressions were determined by RT-qPCR or Western blotting. CCK-8, wound healing, transwell, and flow cytometry assays were conducted to analyze cell viability, migration, invasion, cell cycle, and apoptosis. Additionally, bioinformatics analysis, dual-luciferase reporter assay, as well as RIP assay were performed to investigate the combination between miR-153-3p and circPIP5K1A or TMSB4X. Herein, we found remarkable high circPIP5K1A expression in EM tissues and cells. Silencing of circPIP5K1A suppressed proliferation, restrained cell cycle, increased cell apoptosis, and decreased migration and invasion in EM cells. In addition, miR-153-3p inhibition could abrogate the impacts of circPIP5K1A knockdown on EM progression in vitro. Also, we found that circPIP5K1A regulated TMSB4X level via interaction with miR-153-3p in EM cells. Besides, circPIP5K1A promoted EM progression via TMSB4X. Moreover, TMSB4X could activate the TGF-β signaling in hEM15A cells. To sum up, our study elucidated that circPIP5K1A accelerated EM progression in vitro by activating the TGF-β signaling pathway via the miR-153-3p/TMSB4X axis, providing a potential clinical target for EM treatment.
Neural correlates of mating system diversity: oxytocin and vasopressin receptor distributions in monogamous and non-monogamous Eulemur.
Sci Rep
Nicholas M Grebe, Annika Sharma, Sara M Freeman +4 more
Contemporary theory that emphasizes the roles of oxytocin and vasopressin in mammalian sociality has been shaped by seminal vole research that revealed interspecific variation in neuroendocrine circuitry by mating system. However, substantial challenges exist in interpreting and translating these rodent findings to other mammalian groups, including humans, making research on nonhuman primates crucial. Both monogamous and non-monogamous species exist within Eulemur, a genus of strepsirrhine primate, offering a rare opportunity to broaden a comparative perspective on oxytocin and vasopressin neurocircuitry with increased evolutionary relevance to humans. We performed oxytocin and arginine vasopressin 1a receptor autoradiography on 12 Eulemur brains from seven closely related species to (1) characterize receptor distributions across the genus, and (2) examine differences between monogamous and non-monogamous species in regions part of putative "pair-bonding circuits". We find some binding patterns across Eulemur reminiscent of olfactory-guided rodents, but others congruent with more visually oriented anthropoids, consistent with lemurs occupying an 'intermediary' evolutionary niche between haplorhine primates and other mammalian groups. We find little evidence of a "pair-bonding circuit" in Eulemur akin to those proposed in previous rodent or primate research. Mapping neuropeptide receptors in these nontraditional species questions existing assumptions and informs proposed evolutionary explanations about the biological bases of monogamy.
E2F transcription factor 1 (E2F1) promotes the transforming growth factor TGF-β1 induced human cardiac fibroblasts differentiation through promoting the transcription of CCNE2 gene.
Bioengineered
Rongheng Liao, Bo Xie, Jun Cui +3 more
The differentiation of cardiac fibroblast to myofibroblast is the key process of cardiac fibrosis. In the study, we aimed to determine the function of E2F Transcription Factor 1 (E2F1) in human cardiac fibroblasts (HCFs) differentiation, search for its downstream genes and elucidate the function of them in HCFs differentiation. As a result, we found that E2F1 was up-regulated in TGF-β1-induced HCFs differentiation. Silencing the expression of E2F1 by siRNA in HCFs, we found that the expression of differentiation-related genes (Collagen-1, α-Smooth muscle actin, and Fibronectin-1) was significantly suppressed, combining with proliferation and migration assay, we determined that HCFs differentiation was decreased. Luciferase report assay and immunoprecipitation proved that the oncogene CCNE2 was a direct target gene of E2F1, overexpression of CCNE2 was found in differentiated HCFs, silencing the expression of CCNE2 by siRNA decreased HCFs differentiation. Our research suggested that E2F1 and its downstream target gene CCNE2 play a vital role in TGF-β1-induced HCFs differentiation, thus E2F1 and CCNE2 may be a potential therapeutic target for cardiac fibrosis.
GDF15: emerging biology and therapeutic applications for obesity and cardiometabolic disease.
Nat Rev Endocrinol
Dongdong Wang, Emily A Day, Logan K Townsend +3 more
Growth differentiation factor 15 (GDF15) is a member of the TGFβ superfamily whose expression is increased in response to cellular stress and disease as well as by metformin. Elevations in GDF15 reduce food intake and body mass in animal models through binding to glial cell-derived neurotrophic factor family receptor alpha-like (GFRAL) and the recruitment of the receptor tyrosine kinase RET in the hindbrain. This effect is largely independent of other appetite-regulating hormones (for example, leptin, ghrelin or glucagon-like peptide 1). Consistent with an important role for the GDF15-GFRAL signalling axis, some human genetic studies support an interrelationship with human obesity. Furthermore, findings in both mice and humans have shown that metformin and exercise increase circulating levels of GDF15. GDF15 might also exert anti-inflammatory effects through mechanisms that are not fully understood. These unique and distinct mechanisms for suppressing food intake and inflammation makes GDF15 an appealing candidate to treat many metabolic diseases, including obesity, type 2 diabetes mellitus, non-alcoholic fatty liver disease, cardiovascular disease and cancer cachexia. Here, we review the mechanisms regulating GDF15 production and secretion, GDF15 signalling in different cell types, and how GDF15-targeted pharmaceutical approaches might be effective in the treatment of metabolic diseases.
Hypoactive Sexual Desire Disorder in Women: Physiology, Assessment, Diagnosis, and Treatment.
J Midwifery Womens Health
Jessica A Pettigrew, Andrew M Novick
Nearly half of women in the United States report problems with sexual function. Many health care providers do not ask about sexual concerns during routine clinical encounters because of personal discomfort, lack of familiarity with treatment, or the belief that they lack adequate time to address this complex issue. This may be especially true for hypoactive sexual desire disorder (HSDD), the most commonly identified sexual problem among women. HSDD is characterized by a deficiency of sexual thoughts, feelings, or receptiveness to sexual stimulation that has been present for at least 6 months, causes personal distress, and is not due to another medical condition. This is an up-to-date overview of HSDD for clinicians, discussing its physiology, assessment, diagnosis, and treatment strategies. Although a definitive physiology of HSDD is still unknown, multiple hormones and neurotransmitters likely participate in a dual-control model to balance excitation and inhibition of sexual desire. For assessment and diagnosis, validated screening tools are discussed, and the importance of a biopsychosocial assessment is emphasized, with guidance on how this can be implemented in clinical encounters. The 2 recently approved medications for HSDD, flibanserin and bremelanotide, are reviewed as well as off-label treatments. Overall, HSDD represents a common yet likely underrecognized disorder that midwives and other health care providers who care for women across the life span are in a unique position to address.
The Effectiveness in Activating M-Type K+ Current Produced by Solifenacin ([(3R)-1-azabicyclo[2.2.2]octan-3-yl] (1S)-1-phenyl-3,4-dihydro-1H-isoquinoline-2-carboxylate): Independent of Its Antimuscarinic Action.
Int J Mol Sci
Hsin-Yen Cho, Tzu-Hsien Chuang, Sheng-Nan Wu
Solifenacin (Vesicare®, SOL), known to be a member of isoquinolines, is a muscarinic antagonist that has anticholinergic effect, and it has been beneficial in treating urinary incontinence and neurogenic detrusor overactivity. However, the information regarding the effects of SOL on membrane ionic currents is largely uncertain, despite its clinically wide use in patients with those disorders. In this study, the whole-cell current recordings revealed that upon membrane depolarization in pituitary GH3 cells, the exposure to SOL concentration-dependently increased the amplitude of M-type K+ current (IK(M)) with effective EC50 value of 0.34 μM. The activation time constant of IK(M) was concurrently shortened in the SOL presence, hence yielding the KD value of 0.55 μM based on minimal reaction scheme. As cells were exposed to SOL, the steady-state activation curve of IK(M) was shifted along the voltage axis to the left with no change in the gating charge of the current. Upon an isosceles-triangular ramp pulse, the hysteretic area of IK(M) was increased by adding SOL. As cells were continually exposed to SOL, further application of acetylcholine (1 μM) failed to modify SOL-stimulated IK(M); however, subsequent addition of thyrotropin releasing hormone (TRH, 1 μM) was able to counteract SOL-induced increase in IK(M) amplitude. In cell-attached single-channel current recordings, bath addition of SOL led to an increase in the activity of M-type K+ (KM) channels with no change in the single channel conductance; the mean open time of the channel became lengthened. In whole-cell current-clamp recordings, the SOL application reduced the firing of action potentials (APs) in GH3 cells; however, either subsequent addition of TRH or linopirdine was able to reverse SOL-mediated decrease in AP firing. In hippocampal mHippoE-14 neurons, the IK(M) was also stimulated by adding SOL. Altogether, findings from this study disclosed for the first time the effectiveness of SOL in interacting with KM channels and hence in stimulating IK(M) in electrically excitable cells, and this noticeable action appears to be independent of its antagonistic activity on the canonical binding to muscarinic receptors expressed in GH3 or mHippoE-14 cells.