Ghrelin prevents cisplatin-induced mechanical hyperalgesia and cachexia

Extracellular vesicles in cancer cachexia: deciphering pathogenic roles and exploring therapeutic horizons

Cancer cachexia (CC) is a debilitating syndrome that affects 50-80% of cancer patients, varying in incidence by cancer type and significantly diminishing their quality of life. This multifactorial syndrome is characterized by muscle and fat loss, systemic inflammation, and metabolic imbalance. Extracellular vesicles (EVs), including exosomes and microvesicles, play a crucial role in the progression of CC. These vesicles, produced by cancer cells and others within the tumor environment, facilitate intercellular communication by transferring proteins, lipids, and nucleic acids. A comprehensive review of the literature from databases such as PubMed, Scopus, and Web of Science reveals insights into the formation, release, and uptake of EVs in CC, underscoring their potential as diagnostic and prognostic biomarkers. The review also explores therapeutic strategies targeting EVs, which include modifying their release and content, utilizing them for drug delivery, genetically altering their contents, and inhibiting key cachexia pathways. Understanding the role of EVs in CC opens new avenues for diagnostic and therapeutic approaches, potentially mitigating the syndrome's impact on patient survival and quality of life.

Downregulation of PGC-1α during cisplatin-induced muscle atrophy in murine skeletal muscle

This study aimed to investigate the effects of cisplatin on adenosine triphosphate (ATP) levels, expressions of genes related to mitochondrial oxidative phosphorylation (OXPHOS), and the factors related to mitochondrial biosynthesis in skeletal muscle. Systemic cisplatin administration decreased skeletal muscle mass, skeletal muscle strength, and endurance. The mitochondrial DNA /nuclear DNA ratio was also reduced after treatment with cisplatin. Moreover, among the factors related to mitochondrial biogenesis and function, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) was significantly downregulated in the cisplatin-treated group. Downregulation of PGC-1α in the skeletal muscle may contribute to muscle weakness during cisplatin-induced muscle atrophy.

Decoupling FcRn and tumor contributions to elevated immune checkpoint inhibitor clearance in cancer cachexia

High baseline clearance of immune checkpoint inhibitors (ICIs), independent of dose or systemic exposure, is associated with cachexia and poor outcomes in cancer patients. Mechanisms linking ICI clearance, cachexia and ICI therapy failure are unknown. Here, we evaluate in four murine models and across multiple antibodies whether altered baseline catabolic clearance of administered antibody requires a tumor and/or cachexia and whether medical reversal of cachexia phenotype can alleviate altered clearance. Key findings include mild cachexia phenotype and lack of elevated pembrolizumab clearance in the MC38 tumor-bearing model. We also observed severe cachexia and decreased, instead of increased, baseline pembrolizumab clearance in the tumor-free cisplatin-induced cachexia model. Liver Fcgrt expression correlated with altered baseline catabolic clearance, though elevated clearance was still observed with antibodies having no (human IgA) or reduced (human H310Q IgG1) FcRn binding. We conclude cachexia phenotype coincides with altered antibody clearance, though tumor presence is neither sufficient nor necessary for altered clearance in immunocompetent mice. Magnitude and direction of clearance alteration correlated with hepatic Fcgrt, suggesting changes in FcRn expression and/or recycling function may be partially responsible, though factors beyond FcRn also contribute to altered clearance in cachexia.

EXT418, a novel long-acting ghrelin, mitigates Lewis lung carcinoma induced cachexia in mice

BACKGROUND

Ghrelin is a potential therapy for cachexia due to its orexigenic properties and anabolic effects on muscle and fat. However, its clinical use is limited by the short half-life of active (acylated) ghrelin (~11 min in humans). EXT418 is a novel long-acting, constitutively active ghrelin analog created by covalently linking it to a vitamin D derivative. Here, we evaluated the effects and mechanisms of action of EXT418 on Lewis lung carcinoma (LLC)-induced cachexia in mice.

METHODS

Male C57BL/6J mice (5- to 7-month-old) were implanted with 1 × 106 heat-killed (HK) or live LLC cells. When the tumour was palpable, mice were injected with vehicle (T + V) or EXT418 daily (T + 418 Daily, 0.25 mg/kg/day) or every other day (T + 418 EOD, 0.5 mg/kg/EOD) for up to 14 days, whereas HK-treated mice were given vehicle (HK + V). Subsets of T + 418 Daily or EOD-treated mice were pair-fed to the T + V group. Body composition and grip strength were evaluated before tumour implantation and at the end of the experiment. Molecular markers were probed in muscles upon termination.

RESULTS

In tumour-bearing mice, administration of EXT418 daily or EOD partially prevented weight loss (T + V vs. T + 418 Daily, P = 0.030; and vs. T + 418 EOD, P = 0.020). Similar effects were observed in whole body fat and lean body mass. Grip strength in tumour-bearing mice was improved by EXT418 daily (P = 0.010) or EOD (P = 0.008) administration compared with vehicle-treated mice. These effects of EXT418 on weight and grip strength were partially independent of food intake. EXT418 daily administration also improved type IIA (P = 0.015), IIB (P = 0.037) and IIX (P = 0.050) fibre cross-sectional area (CSA) in tibialis anterior (TA) and EXT418 EOD improved CSA of IIB fibres in red gastrocnemius (GAS; P = 0.005). In skeletal muscles, tumour-induced increases in atrogenes Fbxo32 and Trim63 were ameliorated by EXT418 treatments (TA and GAS/plantaris, PL), which were independent of food intake. EXT418 administration decreased expression of the mitophagy marker Bnip3 (GAS/PL; P ≤ 0.010). Similar effects of EXT418 EOD were observed in p62 (GAS/PL; P = 0.039). In addition, EXT418 treatments ameliorated the tumour-induced elevation in muscle Il6 transcript levels (TA and GAS/PL), independently of food intake. Il-6 transcript levels in adipose tissue and circulating IL-10 were elevated in response to the tumour but these increases were not significant with EXT418 administration. Tumour mass was not altered by EXT418.

CONCLUSIONS

EXT418 mitigates LLC-induced cachexia by attenuating skeletal muscle inflammation, proteolysis, and mitophagy, without affecting tumour mass and partially independent of food intake.

Capsaicin alleviates cisplatin-induced muscle loss and atrophy in vitro and in vivo

BACKGROUND

Cisplatin (CP) is a widely used chemotherapeutic drug with subsequent adverse effects on different organs and tissues including skeletal muscle loss and atrophy as the most common clinical symptoms. The molecular mechanism of cisplatin-induced muscle atrophy is not clearly understood. However, recent significant advances indicate that it is related to an imbalance in both the protein status and apoptosis. Capsaicin (CAP) is one of the major ingredients in chilli peppers. It is a valuable pharmacological agent with several therapeutic applications in controlling pain and inflammation with particular therapeutic potential in muscle atrophy. However, the mechanisms underlying its protective effects against cisplatin-induced muscle loss and atrophy remain largely unknown. This study aims to investigate capsaicin's beneficial effects on cisplatin-induced muscle loss and atrophy in vitro and in vivo.

METHODS

The anti-muscle-atrophic effect of capsaicin on cisplatin-induced muscle loss was investigated using in vivo and in vitro studies. By using the pretreatment model, pretreated capsaicin for 24 h and treated with cisplatin for 48 h, we utilized a C₂ C₁₂ myotube formation model where cell viability analysis, immunofluorescence, and protein expression were measured to investigate the effect of capsaicin in hampering cisplatin-induced muscle atrophy. C57BL/6 mice were administered capsaicin (10, 40 mg/kg BW) as a pretreatment for 5 weeks and cisplatin (3 mg/kg BW) for seven consecutively days to assess muscle atrophy in an animal model for protein and oxidative stress examination, and the grip strength was tested to evaluate the muscle strength.

RESULTS

Our study results indicated that cisplatin caused lower cell viability and showed a subset of hallmark signs typically recognized during atrophy, including severe reduction in the myotube diameter, repression of Akt, and mTOR protein expression. However, pretreatment with capsaicin could ameliorate cisplatin-induced muscle atrophy by up-regulating the protein synthesis in skeletal muscle as well as down-regulating the markers of protein degradation. Additionally, capsaicin was able to downregulate the protein expression of apoptosis-related markers, activated TRPV1 and autophagy progress modulation and the recovery of lysosome function. In vivo, capsaicin could relieve oxidative stress and cytokine secretion while modulating autophagy-related lysosome fusion, improving grip strength, and alleviating cisplatin-induced body weight loss and gastrocnemius atrophy.

CONCLUSIONS

These findings suggest that capsaicin can restore cisplatin-induced imbalance between protein synthesis and protein degradation pathways and it may have protective effects against cisplatin-induced muscle atrophy.

Ghrelin level as a biomarker for knee osteoarthritis severity and appearance in HIV + patients

BACKGROUND

Knee Osteoarthritis (KOA) is a multifactorial disease with several mechanisms to promote articular cartilage damage. New molecules, such as ghrelin, have been recently reported to participate in the pathogenesis and progression of KOA. In HIV + patients, arthralgias are the most frequent musculoskeletal manifestations, mainly affecting joints such as the knee. Also, it has been reported that HIV + patients have a reduction of ghrelin even with treatment compared to HIV- patients. However, there is no report in the literature evaluating ghrelin and KOA in the HIV + population. We aimed to evaluate whether serum ghrelin levels can function as a biomarker for OA in HIV + patients.

METHODS

We recruited 40 patients, 20 HIV+, and 20 HIV- controls, and grouped as follows: HIV+/KOA+; HIV+/KOA-; HIV-/KOA+; HIV-/KOA-. Clinical features were obtained during clinical visits. Peripheral blood samples were acquired to measure serum ghrelin levels.

RESULTS

The HIV+/KOA + group significantly reduced serum ghrelin levels when compared with the other groups. Comparing the ghrelin levels with the patients' nadir of CD4⁺ T-cells count, we identified a statistically significant negative correlation in the KOA- group (r = -0.80, P < 0.007). An ROC curve analysis, for the accuracy of ghrelin levels to identified HIV+/KOA + from HIV+/KOA- patients, found an area under the curve of 0.83 (95 % CI 0.65-0.10; P = 0.017), with a cut-off < 4026 pg/mL serum ghrelin levels, with a sensitivity of 0.62 (95 % CI 0.32-0.86), and a specificity of 0.10 (95 % CI 0.59-0.10).

CONCLUSION

This study shows the potential use of ghrelin levels as a biomarker for KOA in the high-risk HIV population that should be further analyzed.

Physical Activity as the Best Supportive Care in Cancer: The Clinician's and the Researcher's Perspectives

Multidisciplinary supportive care, integrating the dimensions of exercise alongside oncological treatments, is now regarded as a new paradigm to improve patient survival and quality of life. Its impact is important on the factors that control tumor development, such as the immune system, inflammation, tissue perfusion, hypoxia, insulin resistance, metabolism, glucocorticoid levels, and cachexia. An increasing amount of research has been published in the last years on the effects of physical activity within the framework of oncology, marking the appearance of a new medical field, commonly known as "exercise oncology". This emerging research field is trying to determine the biological mechanisms by which, aerobic exercise affects the incidence of cancer, the progression and/or the appearance of metastases. We propose an overview of the current state of the art physical exercise interventions in the management of cancer patients, including a pragmatic perspective with tips for routine practice. We then develop the emerging mechanistic views about physical exercise and their potential clinical applications. Moving toward a more personalized, integrated, patient-centered, and multidisciplinary management, by trying to understand the different interactions between the cancer and the host, as well as the impact of the disease and the treatments on the different organs, this seems to be the most promising method to improve the care of cancer patients.

PGC1α overexpression preserves muscle mass and function in cisplatin-induced cachexia

BACKGROUND

Chemotherapy induces a cachectic-like phenotype, accompanied by skeletal muscle wasting, weakness and mitochondrial dysfunction. Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC1α), a regulator of mitochondrial biogenesis, is often reduced in cachectic skeletal muscle. Overexpression of PGC1α has yielded mixed beneficial results in cancer cachexia, yet investigations using such approach in a chemotherapy setting are limited. Utilizing transgenic mice, we assessed whether overexpression of PGC1α could combat the skeletal muscle consequences of cisplatin.

METHODS

Young (2 month) and old (18 month) wild-type (WT) and PGC1α transgenic male and female mice (Tg) were injected with cisplatin (C; 2.5 mg/kg) for 2 weeks, while control animals received saline (n = 5-9/group). Animals were assessed for muscle mass and force, motor unit connectivity, and expression of mitochondrial proteins.

RESULTS

Young WT + C mice displayed reduced gastrocnemius mass (male: -16%, P < 0.0001; female: -11%, P < 0.001), muscle force (-6%, P < 0.05, both sexes), and motor unit number estimation (MUNE; male: -53%, P < 0.01; female: -51%, P < 0.01). Old WT + C male and female mice exhibited gastrocnemius wasting (male: -22%, P < 0.05; female: -27%, P < 0.05), muscle weakness (male: -20%, P < 0.0001; female: -17%, P < 0.01), and loss of MUNE (male: -82%, P < 0.01; female: -62%, P < 0.05), suggesting exacerbated cachexia compared with younger animals. Overexpression of PGC1α had mild protective effects on muscle mass in young Tg + C male only (gastrocnemius: +10%, P < 0.05); however, force and MUNE were unchanged in both young Tg + C male and female, suggesting preservation of neuromuscular function. In older male, protective effects associated with PGC1α overexpression were heighted with Tg + C demonstrating preserved muscle mass (gastrocnemius: +34%, P < 0.001), muscle force (+13%, P < 0.01), and MUNE (+3-fold, P < 0.05). Similarly, old female Tg + C did not exhibit muscle wasting or reductions in MUNE, and had preserved muscle force (+11%, P < 0.05) compared with female WT + C. Follow-up molecular analysis demonstrated that aged WT animals were more susceptible to cisplatin-induced loss of mitochondrial proteins, including PGC1α, OPA1, cytochrome-C, and Cox IV.

CONCLUSIONS

In our study, the negative effects of cisplatin were heighted in aged animals, whereas overexpression of PGC1α was sufficient to combat the neuromuscular dysfunction caused by cisplatin, especially in older animals. Hence, our observations indicate that aged animals may be more susceptible to develop chemotherapy side toxicities and that mitochondria-targeted strategies may serve as a tool to prevent chemotherapy-induced muscle wasting and weakness.

Evaluation of protective effects of methylene blue on cisplatin-induced nephrotoxicity

Cisplatin (CP) is used to treat various types of cancer. However, its usage is limited due to nephrotoxicity. This study aims to examine the applicability of methylene blue (MB) against CP-induced kidney injuries. In this study, twenty-eight male rats were divided into four groups. Following administration of a single dose of CP (5 mg/kg), animals received intraperitoneal injections (IP) of MB (4 mg/kg) for seven days. In the final phase of the experiment, serum was collected from rats, with blood urea nitrogen (BUN) and creatinine (Cr) levels measured. Hematoxylin-Eosin (H&E) and Masson's trichrome staining were performed to examine histological changes. Immuno-histological staining was used to evaluate caspase-3 protein expression. The results showed that the MB (4 mg/kg) + CP treated rats underwent a lesser weight loss compared to the CP group (p < 0.05 and p < 0.001, respectively). The kidney weight decreased significantly in the CP + MB group compared to the CP group (p < 0.05 and p < 001, respectively). BUN and Cr levels that were increased significantly in the serum of the CP group (p < 0.001) compared to the control group showed no significant increase in the MB + CP group compared to the control group (p = 0.842 and p = 0.989, respectively). There was a significant decrease in kidney tissue injuries in the CP + MB compared to the CP group (p < 0.001). The glomerular size was recovered in the CP + MB group compared to the CP (p < 0.05). The significant increase in the capsular space of the CP group compared to the control group (p < 0.001) was attenuated in the CP + MB. MB restored the histological alterations in the kidneys. Treatment with 4 mg/kg of MB reduced the expression levels of Caspase-3. In conclusion, this study provides evidence concerning the anti-apoptotic roles of MB in CP-induced kidney damage. In conclusion, MB has a positive impact on kidney function.

Antagonization of Ghrelin Suppresses Muscle Protein Deposition by Altering Gut Microbiota and Serum Amino Acid Composition in a Pig Model

Simple Summary

This study investigated the effects of the antagonization of ghrelin on muscle protein deposition, eating patterns and gut microbiota in pigs by injecting ghrelin antagonist ([D-Lys3]-GHRP-6) in a short term. We found that the antagonization of ghrelin affected the eating patterns of animals, which resulted in changes in the absorption of amino acids and gut microbiota, and it reduced protein deposition in muscles. We emphasize the important role of ghrelin in promoting muscle protein deposition and provide new clues for future research on improving muscle loss.

Abstract

Ghrelin is an appetite-stimulating hormone that can increase food intake and has been reported to prevent muscle loss; however, the mechanism is not yet fully understood. In this study, [D-Lys3]-GHRP-6 (GHRP) was used to investigate the effects of the antagonization of ghrelin on muscle protein deposition, eating patterns and gut microbiota in a pig model. We found that the growth performance and muscle fiber cross-sectional area of pigs treated with GHRP were significantly reduced compared with the control (CON) group. Moreover, the levels of serum isoleucine, methionine, arginine and tyrosine in the GHRP group were lower than that of the CON group. The abundance of acetate-producing bacteria (Oscillospiraceae UCG-005, Parabacteroides and Oscillospiraceae NK4A214 group) and acetate concentration in the colons of pigs treated with GHRP were significantly reduced. In addition, the injection of GHRP down-regulated the mRNA expression of MCT-1 and mTOR, and it up-regulated the mRNA expression of HDAC1, FOXO1 and Beclin-1. In summary, the antagonization of ghrelin reduced the concentration of important signal molecules (Arg, Met and Ile) that activate the mTOR pathway, concurrently reduce the concentration of HDAC inhibitors (acetate), promote autophagy and finally reduce protein deposition in muscles.

Chemotherapy-induced cachexia and model-informed dosing to preserve lean mass in cancer treatment

Although chemotherapy is a standard treatment for cancer, it comes with significant side effects. In particular, certain agents can induce severe muscle loss, known as cachexia, worsening patient quality of life and treatment outcomes. 5-fluorouracil, an anti-cancer agent used to treat several cancers, has been shown to cause muscle loss. Experimental data indicates a non-linear dose-dependence for muscle loss in mice treated with daily or week-day schedules. We present a mathematical model of chemotherapy-induced muscle wasting that captures this non-linear dose-dependence. Area-under-the-curve metrics are proposed to quantify the treatment’s effects on lean mass and tumour control. Model simulations are used to explore alternate dosing schedules, aging effects, and morphine use in chemotherapy treatment with the aim of better protecting lean mass while actively targeting the tumour, ultimately leading to improved personalization of treatment planning and improved patient quality of life.

In this paper we present a novel mathematical model for muscle loss due to cancer chemotherapy treatment. Loss of muscle mass relates to increased drug toxicity and side-effects, and to decreased patient quality of life and survival rates. With our model, we examine the therapeutic efficacy of various dosing schedules with the aim of controlling a growing tumour while also preserving lean mass. Preservation of body composition, in addition to consideration of inflammation and immune interactions, the gut microbiome, and other systemic health measures, may lead to improved patient-specific treatment plans that improve patient quality of life.

Effects of cisplatin on mitochondrial function and autophagy-related proteins in skeletal muscle of rats

Cisplatin is widely known as an anti-cancer drug. However, the effects of cisplatin on mitochondrial function and autophagy-related proteins levels in the skeletal muscle are unclear. The purpose of this study was to investigate the effect of different doses of cisplatin on mitochondrial function and autophagy-re-lated protein levels in the skeletal muscle of rats. Eight-week-old male Wistar rats (n = 24) were assigned to one of three groups; the first group was administered a saline placebo (CON, n = 10), and the second and third groups were given 0.1 mg/kg body weight (BW) (n = 6), and 0.5 mg/kg BW (n = 8) of cisplatin, respectively. The group that had been administered 0.5 mg cisplatin exhibited a reduced BW, skeletal muscle tissue weight, and mitochondrial function and upregulated levels of autophagy-related proteins, including LC3II, Beclin 1, and BNIP3. Moreover, this group had a high LC3 II/I ratio in the skeletal muscle; i.e., the administration of a high dose of cisplatin decreased the muscle mass and mitochondrial function and increased the levels of autophagy-related proteins. These results, thus, suggest that reducing mitochondrial dysfunction and autophagy pathways may be important for preventing skeletal muscle atrophy following cisplatin administration.

Ghrelin enhances cisplatin sensitivity in HO-8910 PM human ovarian cancer cells

BACKGROUND

Resistance to platinum-based chemotherapy is one of the crucial problems in ovarian cancer treatment. Ghrelin, a widely distributed peptide hormone, participates in a series of cancer progression. The aim of this study is to determine whether ghrelin influences the sensitivity of ovarian cancer to cisplatin, and to demonstrate the underlying mechanism.

METHODS

The anti-tumor effects of ghrelin and cisplatin were evaluated with human ovarian cancer cells HO-8910 PM in vitro or in vivo. Cell apoptosis and cell cycle were analyzed via flow cytometry assay. The signaling pathway and the expression of cell cycle protein were analyzed with Western Blot.

RESULTS

Our results showed that treatment with ghrelin specifically inhibited cell proliferation of HO-8910 PM and sensitized these cells to cisplatin via S phase cell cycle arrest, and enhanced the inhibitory effect of cisplatin on tumor growth of HO-8910 PM derived xenografts in vivo. Treatment with ghrelin inhibited the expression of p-Erk1/2 and p-p38, which was opposite the effect of cisplatin. However, under the treatment of ghrelin, cisplatin treatment exhibited a stronger effect on inhibiting P21 expression, upregulating p-CDK1 and cyclin B1 expression, and blocking cell cycle progression. Mechanistically, ghrelin promoted S phase cell cycle arrest and upregulated p-CDK1 and cyclin B1 expression induced by cisplatin via inhibition of p38.

CONCLUSION

This study revealed a specifically inhibitory effect of ghrelin on platinum-resistance via suppressing p-P38 and subsequently promoting p-CDK1 mediated cell cycle arrest in HO-8910 PM.

Impact of cisplatin administration on cerebellar cortical structure and locomotor activity of infantile and juvenile albino rats: the role of oxidative stress

The central neurotoxicity of cisplatin (CisPt) has always raised questions especially during development, but few studies are available. Hence, this work was designed to assess the CisPt's impacts on the postnatal rat cerebellum via evaluation of locomotor activity, histological and immunohistochemical studies, and to focus on cerebellar oxidative stress-related alterations. Eighty newborn pups were divided into 2 equal experimental groups: the control group was kept without any treatment and CisPt-treated group received a single subcutaneous injection of CisPt (5 μg /g b.w.) in their nape at PD10. Ten rats at PD11, PD17, and PD30 ages were weighed, then deeply anesthetized and sacrificed. For locomotor assessment, 20 pups were divided equally into control and CisPt-treated groups and tested at PD11-13, PD15-17, and PD28-30 ages. CisPt-treated rats suffered from decreased motor activity and showed decreased body and cerebellar weights, reduced levels of enzymatic antioxidants (SOD and CAT), and non-enzymatic antioxidant defense (GSH), and increase of lipid peroxidation marker (MDA). Histopathologically, CisPt sowed deleterious changes within cerebellar cortical layers in the form of vacuolations, decreased thickness, and hemorrhage (in PD17), while Purkinje cells exhibited profound degenerative changes in the form of swelling, disrupted arrangement, distortion, and nuclear shrinkage. In CisPt-treated rats, GFAP demonstrated upregulated, hypertrophied, and branched Bergmann glial fibers and reactive astrogliosis. Immuno-localization of Ki-67-positive cells revealed defective migration associated with decreased proliferation in early ages in addition to glial proliferation in PD30. In conclusion, CisPt causes oxidative stress-related deleterious effects on structure of developing cerebellar cortex and affects locomotor activity.

Ghrelin receptor agonist hexarelin attenuates antinociceptive tolerance to morphine in rats

Ghrelin, a peptide hormone released from the gastric endocrine glands, shows analgesic activity apart from its various physiological effects. Nevertheless, the effects of ghrelin receptor (GHS-R) agonists on morphine analgesia and tolerance have not yet been elucidated. The purpose of this study was to evaluate the effects of the ghrelin receptor agonist hexarelin and antagonist [d-Lys3]-GHRP-6 on morphine antinociception and tolerance in rats. A total of 104 Wistar albino male adult rats (weighing approximately 220-240 g) were used in the experiments. To induce morphine tolerance, a three-day cumulative dose regimen was used in the rats. Then, randomly selected rats were evaluated for morphine tolerance on day 4. The analgesic effects of hexarelin (0.2 mg·kg-1), [d-Lys3]-GHRP-6 (10 mg·kg-1), and morphine (5 mg·kg-1) were measured at 30-min intervals (0, 30, 60, 90, and 120 min) by tail-flick and hot-plate analgesia tests. The findings suggest that hexarelin in combination with morphine attenuates analgesic tolerance to morphine. On the other hand, ghrelin receptor antagonist [d-Lys3]-GHRP-6 has no significant analgesic activity on the morphine tolerance in analgesia tests. Furthermore, co-administration of hexarelin and morphine increases the analgesic effect. In conclusion, these data indicate that administration of GHS-R agonist hexarelin with morphine enhances the antinociception and attenuates morphine tolerance.

Targeting the Activin Receptor Signaling to Counteract the Multi-Systemic Complications of Cancer and Its Treatments

Muscle wasting, i.e., cachexia, frequently occurs in cancer and associates with poor prognosis and increased morbidity and mortality. Anticancer treatments have also been shown to contribute to sustainment or exacerbation of cachexia, thus affecting quality of life and overall survival in cancer patients. Pre-clinical studies have shown that blocking activin receptor type 2 (ACVR2) or its ligands and their downstream signaling can preserve muscle mass in rodents bearing experimental cancers, as well as in chemotherapy-treated animals. In tumor-bearing mice, the prevention of skeletal and respiratory muscle wasting was also associated with improved survival. However, the definitive proof that improved survival directly results from muscle preservation following blockade of ACVR2 signaling is still lacking, especially considering that concurrent beneficial effects in organs other than skeletal muscle have also been described in the presence of cancer or following chemotherapy treatments paired with counteraction of ACVR2 signaling. Hence, here, we aim to provide an up-to-date literature review on the multifaceted anti-cachectic effects of ACVR2 blockade in preclinical models of cancer, as well as in combination with anticancer treatments.

The ameliorative effects of methylene blue on testicular damage induced by cisplatin in rats

Cisplatin, a common chemotherapeutic drug, can induce testicular toxicity. Methylene blue, a potent antioxidant, can inhibit the generation of free radicals. This research aimed to study the protective effect of methylene blue against the cisplatin-induced toxicity of the reproductive system in rats. 35 male Wistar rats were divided into five groups: the control group, the cisplatin group (a single dose of 5 mg/kg cisplatin), the low-dose and high-dose methylene blue + cisplatin (2 and 4 mg/kg of methylene blue, respectively, for 7 days) and the methylene blue group (4 mg/kg of methylene blue, for 7 days). The treatments were applied through intraperitoneal injection. Cisplatin treatment reduced the sperm parameters and serum testosterone levels significantly. Methylene blue treatment increased the sperm count (p < .001), viability (p < .001) and motility (p < .001) compared to the cisplatin group. The methylene blue group showed a significant increase in the levels of testosterone compared to the cisplatin group (p < .001) and reverted histopathological changes in cisplatin-treated groups. Immunohistochemical evaluation of the caspase-3 protein revealed that the treatment with methylene blue has significant anti-apoptotic effects on testicular tissue damage. In conclusion, methylene blue can attenuate the cisplatin-induced histological damages and improve the sperm parameters.

Supplementary Oral Anamorelin Mitigates Anorexia and Skeletal Muscle Atrophy Induced by Gemcitabine Plus Cisplatin Systemic Chemotherapy in a Mouse Model

Chemotherapy-induced adverse effects can reduce the relative dose intensity and quality of life. In this study, we investigated the potential benefit of supplementary anamorelin and 5-aminolevulinic acid (5-ALA) as preventive interventions against a gemcitabine and cisplatin (GC) combination chemotherapy-induced adverse effects in a mouse model. Non-cancer-bearing C3H mice were randomly allocated as follows and treated for 2 weeks—(1) non-treated control, (2) oral anamorelin alone, (3) oral 5-ALA alone, (4) gemcitabine and cisplatin (GC) chemotherapy, (5) GC plus anamorelin, and (6) GC plus 5-ALA. GC chemotherapy significantly decreased body weight, food intake, skeletal muscle mass and induced severe gastric mucositis, which resulted in decreased ghrelin production and blood ghrelin level. The supplementation of oral anamorelin to GC chemotherapy successfully mitigated decrease of food intake during the treatment period and body weight loss at day 8. In addition, analysis of the resected muscles and stomach revealed that anamorelin suppressed chemotherapy-induced skeletal muscle atrophy by mediating the downregulation of forkhead box protein O-1 (FOXO1)/atrogin-1 signaling and gastric damage. Our findings suggest the preventive effect of anamorelin against GC combination chemotherapy, which was selected for patients with some types of advanced malignancies in clinical practice.

Doxorubicin-induced skeletal muscle atrophy: Elucidating the underlying molecular pathways

Aim

Loss of skeletal muscle mass is a common clinical finding in cancer patients. The purpose of this meta‐analysis and systematic review was to quantify the effect of doxorubicin on skeletal muscle and report on the proposed molecular pathways possibly leading to doxorubicin‐induced muscle atrophy in both human and animal models.

Methods

A systematic search of the literature was conducted in PubMed, EMBASE, Web of Science and CENTRAL databases. The internal validity of included studies was assessed using SYRCLE’s risk of bias tool.

Results

Twenty eligible articles were identified. No human studies were identified as being eligible for inclusion. Doxorubicin significantly reduced skeletal muscle weight (ie EDL, TA, gastrocnemius and soleus) by 14% (95% CI: 9.9; 19.3) and muscle fibre cross‐sectional area by 17% (95% CI: 9.0; 26.0) when compared to vehicle controls. Parallel to negative changes in muscle mass, muscle strength was even more decreased in response to doxorubicin administration. This review suggests that mitochondrial dysfunction plays a central role in doxorubicin‐induced skeletal muscle atrophy. The increased production of ROS plays a key role within this process. Furthermore, doxorubicin activated all major proteolytic systems (ie calpains, the ubiquitin‐proteasome pathway and autophagy) in the skeletal muscle. Although each of these proteolytic pathways contributes to doxorubicin‐induced muscle atrophy, the activation of the ubiquitin‐proteasome pathway is hypothesized to play a key role. Finally, a limited number of studies found that doxorubicin decreases protein synthesis by a disruption in the insulin signalling pathway.

Conclusion

The results of the meta‐analysis show that doxorubicin induces skeletal muscle atrophy in preclinical models. This effect may be explained by various interacting molecular pathways. Results from preclinical studies provide a robust setting to investigate a possible dose‐response, separate the effects of doxorubicin from tumour‐induced atrophy and to examine underlying molecular pathways. More research is needed to confirm the proposed signalling pathways in humans, paving the way for potential therapeutic approaches.

Protective Effects of Ghrelin on Fasting-Induced Muscle Atrophy in Aging Mice

Sarcopenia is the aging-associated progressive loss of skeletal muscle; however, the pathogenic mechanism of sarcopenia is not clear. The orexigenic hormone ghrelin stimulates growth hormone secretion, increases food intake, and promotes adiposity. Here we showed that fasting-induced muscle loss was exacerbated in old ghrelin-null (Ghrl-/-) mice, exhibiting decreased expression of myogenic regulator MyoD and increased expression of protein degradation marker MuRF1, as well as altered mitochondrial function. Moreover, acylated ghrelin and unacylated ghrelin treatments significantly increased mitochondrial respiration capacity in muscle C2C12 cells. Consistently, acylated ghrelin and unacylated ghrelin treatments effectively increased myogenic genes and decreased degradation genes in the muscle in fasted old Ghrl-/- mice, possibly by stimulating insulin and adenosine monophosphate-activated protein kinase pathways. Furthermore, Ghrl-/- mice showed a profile of pro-inflammatory gut microbiota, exhibiting reduced butyrate-producing bacteria Roseburia and ClostridiumXIVb. Collectively, our results showed that ghrelin has a major role in the maintenance of aging muscle via both muscle-intrinsic and -extrinsic mechanisms. Acylated ghrelin and unacylated ghrelin enhanced muscle anabolism and exerted protective effects for muscle atrophy. Because unacylated ghrelin is devoid of the obesogenic side effect seen with acylated ghrelin, it represents an attractive therapeutic option for sarcopenia.

Cisplatin-Induced Skeletal Muscle Dysfunction: Mechanisms and Counteracting Therapeutic Strategies

Among the severe side effects induced by cisplatin chemotherapy, muscle wasting is the most relevant one. This effect is a major cause for a clinical decline of cancer patients, since it is a negative predictor of treatment outcome and associated to increased mortality. However, despite its toxicity even at low doses, cisplatin remains the first-line therapy for several types of solid tumors. Thus, effective pharmacological treatments counteracting or minimizing cisplatin-induced muscle wasting are urgently needed. The dissection of the molecular pathways responsible for cisplatin-induced muscle dysfunction gives the possibility to identify novel promising therapeutic targets. In this context, the use of animal model of cisplatin-induced cachexia is very useful. Here, we report an update of the most relevant researches on the mechanisms underlying cisplatin-induced muscle wasting and on the most promising potential therapeutic options to preserve muscle mass and function.

Ghrelin promotes neural differentiation of adipose tissue-derived mesenchymal stem cell via AKT/mTOR and β-catenin signaling pathways

Adipose tissue-derived mesenchymal stem cells (ADSCs) are multipotent cells that can differentiate into various cell types. This study aimed to investigate the effect of ghrelin on the neural differentiation of rat ADSCs and underlying molecular mechanisms. Rat ADSCs were isolated and third-passage ADSCs were used in this study. The isolated ADSCs were characterized by flow cytometry analysis for MSCs' surface expression markers as evidenced by positive for CD90, CD44, and CD29 and negative for CD34, CD45, and CD11b/2f/c. The multilineage differentiation of ADSCs was confirmed by adipogenic, osteogenic, and neural differentiation. After induction of neurogenesis, the differentiated cells were identified by development of neuron-like morphology and expression of neural markers including glial fibrillary acidic protein, Nestin, MAP2, and β-Tubulin III using immunofluorescence and western blot. Ghrelin concentration dependently elevated the proportion of neural-like cells and branching dendrites, as well as upregulated the expression of neural markers. Further, the expression of nuclear β-catenin, p-GSK-3β, p-AKT, and p-mTOR was increased by ghrelin, indicating an activation of β-catenin and AKT/mTOR signaling after the ghrelin treatment. Importantly, inhibition of β-catenin or AKT/mTOR signaling suppressed ghrelin-induced neurogenesis. Therefore, we demonstrate that ghrelin promotes neural differentiation of ADSCs through the activation of β-catenin and AKT/mTOR signaling pathways.

Overview of cisplatin-induced neurotoxicity and ototoxicity, and the protective agents

Cisplatin has dramatically improved the survival rate of cancer patients, but it has also increased the prevalence of hearing and neurological deficits in this population. Cisplatin induces ototoxicity, peripheral (most prevalent) and central (rare) neurotoxicity. This review addresses the ototoxicity and the neurotoxicity associated with cisplatin-based chemotherapy, providing an integrated view of the potential protective agents that have been evaluated in vitro, in vivo and in clinical trials, their targets and mechanisms of protection and their effects on the antitumor activity of cisplatin. So far, the findings are insufficient to support the use of any oto- or neuroprotective agent before, during or after cisplatin chemotherapy. Despite their promising effects in vitro and in animal studies, many agents have not been evaluated in clinical trials. Additionally, the clinical trials have limitations concerning the sample size, controls, measurement, heterogeneous groups, several arms of treatment, short follow-up or no blinding. Besides that, for most agents, the effects on the antitumor activity of cisplatin have not been evaluated in tumor-bearing animals, which discourages clinical trials. Further well-designed randomized controlled clinical trials are necessary to definitely demonstrate the effectiveness of the oto- or neuroprotective agents proposed by animal and in vitro studies.

Gut Microbiota Shapes the Efficiency of Cancer Therapy

Systems biology provides an opportunity to discover the role that gut microbiota play in almost all aspects of human health. Existing evidence supports the hypothesis that gut microbiota is closely related to the pharmacological effects of chemical therapy and novel targeted immunotherapy. Gut microbiota shapes the efficiency of drugs through several key mechanisms: metabolism, immunomodulation, translocation, enzymatic degradation, reduction of diversity, and ecological variability. Therefore, gut microbiota have emerged as a novel target to enhance the efficacy and reduce the toxicity and adverse effects of cancer therapy. There is growing evidence to show that cancer therapy perturbs the host immune response and results in dysbiosis of the immune system, which then influences the efficiency of the therapy. Studies suggest that gut microbes play a significant role in cancer therapy by modulating drug efficacy, abolishing the anticancer effect, and mediating toxicity. In this review, we outline the role of gut microbiota in modulating cancer therapy and the implications for improving the efficacy of chemotherapy and immunotherapy in clinical practice. We also summarize the current limitations of the safety and effectiveness of probiotics in cancer therapies such as personalized cancer therapy.

Mitochondrial dysfunction in the pathogenesis of chemotherapy-induced peripheral neuropathy

Several first-line chemotherapeutic agents, including taxanes, platinum agents and proteasome inhibitors, are associated with the dose-limiting side effect of chemotherapy-induced peripheral neuropathy (CIPN). CIPN predominantly manifests as sensory symptoms, which are likely due to drug accumulation within peripheral nervous tissues rather than the central nervous system. No treatment is currently available to prevent or reverse CIPN. The causal mechanisms underlying CIPN are not yet fully understood. Mitochondrial dysfunction has emerged as a major factor contributing to the development and maintenance of CIPN. This chapter will provide an overview of both clinical and preclinical data supporting this hypothesis. We will review the studies reporting the nature of mitochondrial dysfunction evoked by chemotherapy in terms of changes in mitochondrial morphology, bioenergetics and reactive oxygen species (ROS) generation. Furthermore, we will discuss the in vivo effects of pharmacological interventions that counteract chemotherapy-evoked mitochondrial dysfunction and ameliorate pain-like behavior.

Effects of Intracerebroventricular and Intra-Arcuate Nucleus Injection of Ghrelin on Pain Behavioral Responses and Met-Enkephalin and β-Endorphin Concentrations in the Periaqueductal Gray Area in Rats

Ghrelin is an endogenous ligand for orphan growth hormone secretagogue receptors. Ghrelin receptors have been found in central nervous system (CNS) areas responsible for pain modulation and transmission. This study investigated the effects of intracerebroventricular (ICV) and intra-arcuate nucleus (ARC) injection of ghrelin on pain behavioral responses and levels of β-endorphin (β-EP) and met-enkephalin (MENK) in the periaqueductal gray area (PAG) during the formalin test in rats. Thirty-five male rats were studied in five groups. Ghrelin was injected into the left lateral ventricle (ICV, 5 µL) or into the ARC (1 µL). After 15 min, formalin (2.5%) was subcutaneously injected into the left hind paw. Behavioral nociceptive scores were recorded for 60 min. MENK and β-EP were collected by microdialysis in the PAG and determined by high-performance liquid chromatography (HPLC). ICV and ARC injection of ghrelin significantly reduced pain in all phases of the formalin test (p < 0.001). Dialysate concentrations of MENK and β-EP in the PAG increased in all the phases (p < 0.01). In conclusion, the present study shows that the ARC nucleus and the endogenous opioid system are involved in ghrelin-induced pain modulation.

Cisplatin-Loaded Polybutylcyanoacrylate Nanoparticles with Improved Properties as an Anticancer Agent

This study aims to improve the cytotoxicity and potency of cisplatin-loaded polybutylcyanoacrylate (PBCA) nanoparticles (NPs) for the treatment of lung cancer through the modulation of temperature and polyethylene glycol (PEG) concentration as effective factors affecting the NPs’ properties. The NPs were synthesized using an anionic polymerization method and were characterized in terms of size, drug loading efficiency, drug release profile, cytotoxicity effects, drug efficacy, and drug side effects. In this regard, dynamic light scattering (DLS), scanning electron microscopy (SEM), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) methods, and hematoxylin and eosin (H&E) staining were used. The results showed that the size and the drug loading efficiency of the synthesized spherical NPs were 355–386 nm and 14–19%, respectively. Also, the drug release profile showed a controlled and slow drug release pattern with approximately 10% drug release over 48 h. In addition, the NPs significantly increased the cytotoxicity of the cisplatin in vitro environment by approximately 2 times and enhanced the therapeutic effects of the drug in vivo environment by increasing the survival time of lung-cancer-bearing mice by 20% compared to the standard drug receiver group. Also, the nanoformulation decreased the drug toxicity in an in vivo environment. According to the results, increasing the temperature and PEG concentration improved the properties of the drug loading efficiency, drug release profile, and cytotoxicity effect of drug-loaded NPs. Consequently, the synthesized formulation increased the survival of tumor-bearing mice and simultaneously decreased the cisplatin toxicity effects. In conclusion, the prepared nanoformulation can be considered a promising candidate for further evaluation for possible therapeutic use in the treatment of lung cancer.

Therapeutic strategies against cancer cachexia

Cancer cachexia has two main components: anorexia and metabolic alterations. The main changes associated with the development of this multi-organic syndrome are glucose intolerance, fat depletion and muscle protein hypercatabolism. The aim of this paper is to review the more recent therapeutic approaches designed to counteract the wasting suffered by the cancer patient with cachexia. Among the most promising approaches we can include the use of ghrelin agonists, beta-blockers, beta-adrenergic agonists, androgen receptor agonists and anti-myostatin peptides. The multi-targeted approach seems essential in these treatments, which should include the combination of both nutritional support, drugs and a suitable program of physical exercise, in order to ameliorate both anorexia and the metabolic changes associated with cachexia. In addition, another very important and crucial aspect to be taken into consideration in the design of clinical trials for the treatment of cancer cachexia is to staging cancer patients in relation with the degree of cachexia, in order to start as early as possible this triple approach in the course of the disease, even before the weight loss can be detected.

Systemic growth hormone deficiency causes mechanical and thermal hypersensitivity during early postnatal development

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Systemic GHD causes behavioral hypersensitivity at P7 and P14, but not P21.

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Primary afferent sensitization is observed in GHRHr KOs.

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Knockout of GHRHr changes DRG gene expression that is observed throughout development.

Injury during early postnatal life causes acute alterations in afferent function and DRG gene expression, which in addition to producing short-term sensitivity has the potential to influence nociceptive responses in adulthood. We recently discovered that growth hormone (GH) is a key regulator of afferent sensitization and pain-related behaviors during developmental inflammation of the skin. Peripheral injury caused a significant reduction in cutaneous GH levels, which corresponded with the observed hypersensitivity. However, it has yet to be determined whether GH deficiency (GHD) is sufficient to drive peripheral sensitization in uninjured animals. Here, we found that systemic GHD, induced by knockout of the GH release hormone receptor (GHRHr), was able to induce behavioral and afferent hypersensitivity to peripheral stimuli specifically during early developmental stages. GHD also produced an upregulation of many receptors and channels linked to nociceptive processing in the DRGs at these early postnatal ages (P7 and P14). Surprisingly, P21 GHRHr knockouts also displayed significant alterations in DRG gene expression even though behavioral and afferent hypersensitivity resolved. These data support previous findings that GH is a key modulator of neonatal hypersensitivity. Results may provide insight into whether GH treatment may be a therapeutic strategy for pediatric pain.

A Systematic Review of Growth Hormone in Pain Medicine: From Rodents to Humans

Objective

Growth hormone (GH) and GH-related signaling molecules play an important role in nociception and development of chronic pain. This review aims to examine the potential molecular mechanisms through which GH-related signaling modulates sensory hypersensitivity in rodents, the clinical pharmacology of GH, and the clinical evidence of GH treatment for several common pain syndromes.

Methods

A search was conducted using the PUBMED/MEDLINE database, Scopus, and the Cochrane library for all reports published in English on GH in pain management from inception through May 2018. A critical review was performed on the mechanisms of GH-related signaling and the pharmacology of GH. The levels of clinical evidence and implications for recommendations of all of the included studies were graded.

Results

The search yielded 379 articles, of which 201 articles were deemed irrelevant by reading the titles. There were 53 reports deemed relevant after reading abstracts. All of these 53 articles were retrieved for the analysis and discussion.

Conclusions

Dysfunction of the GH/insulin-like growth factor 1 (IGF-1)/ghrelin axis was linked to hyperalgesia and several common clinical pain syndromes. Low levels of GH and IGF-1 were linked to pain hypersensitivity, whereas ghrelin appeared to provide analgesic effects. Pretreatment of GH reversed mechanical and thermal hypersensitivity in an animal model of inflammatory pain. Clinical trials support GH treatment in a subgroup of patients with fibromyalgia syndrome (level of evidence: 1B+) or chronic lower back pain syndrome (level of evidence: 2C+).

Relationship between mitofusin 2 and cancer

Mitochondria are dynamic organelles whose actions are fundamental for cell viability. Within the cell, the mitochondrial system is incessantly modified via the balance between fusion and fission processes. Among other proteins, mitofusin 2 is a central protagonist in all these mitochondrial events (fusion, trafficking, contacts with other organelles), the balance of which causes the correct mitochondrial action, shape, and distribution within the cell. Here we examine the structural and functional characteristics of mitofusin 2, underlining its essential role in numerous intracellular pathways, as well as in the pathogenesis of cancer.

Preservation of muscle mass as a strategy to reduce the toxic effects of cancer chemotherapy on body composition

PURPOSE OF REVIEW

Cancer patients undergoing chemotherapy often experience very debilitating side effects, including unintentional weight loss, nausea, and vomiting. Changes in body composition, specifically lean body mass (LBM), are known to have important implications for anticancer drug toxicity and cancer prognosis. Currently, chemotherapy dosing is based on calculation of body surface area, although this approximation does not take into consideration the variability in lean and adipose tissue mass.

RECENT FINDINGS

Patients with depletion of muscle mass present higher chemotherapy-related toxicity, whereas patients with larger amounts of LBM show fewer toxicities and better outcomes. Commonly used chemotherapy regimens promote changes in body composition, primarily by affecting skeletal muscle, as well as fat and bone mass. Experimental evidence has shown that pro-atrophy mechanisms, abnormal mitochondrial metabolism, and reduced protein anabolism are primarily implicated in muscle depletion. Muscle-targeted pro-anabolic strategies have proven successful in preserving lean tissue in the occurrence of cancer or following chemotherapy.

SUMMARY

Muscle wasting often occurs as a consequence of anticancer treatments and is indicative of worse outcomes and poor quality of life in cancer patients. Accurate assessment of body composition and preservation of muscle mass may reduce chemotherapy toxicity and improve the overall survival.

Ghrelin agonist HM01 attenuates chemotherapy-induced neurotoxicity in rodent models

Chemotherapy-Induced Peripheral Neurotoxicity (CIPN) is often dose-limiting and impacts life quality and survival of cancer patients. Ghrelin agonists have neuroprotectant effects and may have a role in treating or preventing CIPN. We evaluated the CNS-penetrant ghrelin agonist HM01 in three experimental models of CIPN at doses of 3-30 mg/kg p.o. daily monitoring orexigenic properties, nerve conduction, mechanical allodynia, and intra-epidermal nerve fiber density (IENFD). In a cisplatin-based study, rats were dosed daily for 3 days (0.5 mg/kg i.p.) + HM01. Cisplatin treatment induced mechanical hypersensitivity which was significantly reduced by HM01. In a second study, oxaliplatin was administered to mice (6 mg/kg i.p. 3 times/week for 4 weeks) resulting in significant digital nerve conduction velocity (NCV) deficits and reduction of IENFD. Concurrent HM01 dose dependently prevented the decline in NCV and attenuated the reduction in IENFD. Pharmacokinetic studies showed HM01 accumulation in the dorsal root ganglia and sciatic nerves which reached concentrations > 10 fold that of plasma. In a third model, HM01 was tested in preventive and therapeutic paradigms in a bortezomib-based rat model (0.2 mg/kg i.v., 3 times/week for 8 weeks). In the preventive setting, HM01 blocked bortezomib-induced hyperalgesia and IENFD reduction at all doses tested. In the therapeutic setting, significant effect was observed, but only at the highest dose. Altogether, the robust peripheral nervous system penetration of HM01 and its ability to improve multiple oxaliplatin-, cisplatin-, and bortezomib-induced neurotoxicities suggest that HM01 may be a useful neuroprotective adjuvant for CIPN.

Synthetic peripherally-restricted cannabinoid suppresses chemotherapy-induced peripheral neuropathy pain symptoms by CB1 receptor activation

Chemotherapy-induced peripheral neuropathy (CIPN) is a severe and dose-limiting side effect of cancer treatment that affects millions of cancer survivors throughout the world and current treatment options are extremely limited by their side effects. Cannabinoids are highly effective in suppressing pain symptoms of chemotherapy-induced and other peripheral neuropathies but their widespread use is limited by central nervous system (CNS)-mediated side effects. Here, we tested one compound from a series of recently developed synthetic peripherally restricted cannabinoids (PRCBs) in a rat model of cisplatin-induced peripheral neuropathy. Results show that local or systemic administration of 4-{2-[-(1E)-1[(4-propylnaphthalen-1-yl)methylidene]-1H-inden-3-yl]ethyl}morpholine (PrNMI) dose-dependently suppressed CIPN mechanical and cold allodynia. Orally administered PrNMI also dose-dependently suppressed CIPN allodynia symptoms in both male and female rats without any CNS side effects. Co-administration with selective cannabinoid receptor subtype blockers revealed that PrNMI's anti-allodynic effects are mediated by CB1 receptor (CB1R) activation. Expression of CB2Rs was reduced in dorsal root ganglia from CIPN rats, whereas expression of CB1Rs and various endocannabinoid synthesizing and metabolizing enzymes was unaffected. Daily PrNMI treatment of CIPN rats for two weeks showed a lack of appreciable tolerance to PrNMI's anti-allodynic effects. In an operant task which reflects cerebral processing of pain, PrNMI also dose-dependently suppressed CIPN pain behaviors. Our results demonstrate that PRCBs exemplified by PrNMI may represent a viable option for the treatment of CIPN pain symptoms.

Platinum-induced muscle wasting in cancer chemotherapy: Mechanisms and potential targets for therapeutic intervention

Platinum-based drugs are among the most effective anticancer therapies, integrating the standard of care for numerous human malignancies. However, platinum-based chemotherapy induces severe side-effects in cancer patients, such as cachexia. Weight loss, as well as fatigue and systemic inflammation are characteristics of this syndrome that adversely affects the survival and the quality of life of cancer patients. The signalling pathways involved in chemotherapy-induced cachexia are still to be fully understood, but the activity of several mediators associated with muscle wasting, such as myostatin and pro-inflammatory cytokines are increased by platinum-based drugs like cisplatin. Indeed, the molecular mechanisms behind chemotherapy-induced muscle wasting seem to be similar to the ones promoted by cancer in treatment-naive patients. Although some therapeutic agents are under investigation for treating muscle wasting in cancer patients, no effective treatment is yet available. Herein, we review the molecular mechanisms proposed to be involved in chemotherapy-related muscle wasting with a focus on the typical platinum-based drug cisplatin. Therapeutic strategies presently under investigation are also reviewed, providing an overview of the current efforts to preserve muscle mass and quality of life among cancer patients.

In Vitro and In Vivo Characterization of Novel Stable Peptidic Ghrelin Analogs: Beneficial Effects in the Settings of Lipopolysaccharide-Induced Anorexia in Mice

Ghrelin, the only known orexigenic gut hormone produced primarily in the stomach, has lately gained attention as a potential treatment of anorexia and cachexia. However, its biologic stability is highly limited; therefore, a number of both peptide and nonpeptide ghrelin analogs have been synthesized. In this study, we provide in vitro and in vivo characterization of a series of novel peptide growth hormone secretagogue receptor (GHS-R1a) agonists, both under nonpathologic conditions and in the context of lipopolysaccharide (LPS)-induced anorexia. These analogs were based on our previous series modified by replacing the Ser³ with diaminopropionic acid (Dpr), the N-terminal Gly with sarcosine, and Phe⁴ with various noncoded amino acids. New analogs were further modified by replacing the n-octanoyl bound to Dpr³ with longer or unsaturated fatty acid residues, by incorporation of the second fatty acid residue into the molecule, or by shortening the peptide chain. These modifications preserved the ability of ghrelin analogs to bind to the membranes of cells transfected with GHS-R1a, as well as the GHS-R1a signaling activation. The selected analogs exhibited long-lasting and potent orexigenic effects after a single s.c. administration in mice. The stability of new ghrelin analogs in mice after s.c. administration was significantly higher when compared with ghrelin and [Dpr³]ghrelin, with half-lives of approximately 2 hours. A single s.c. injection of the selected ghrelin analogs in mice with LPS-induced anorexia significantly increased food intake via the activation of orexigenic pathways and normalized blood levels of proinflammatory cytokines, demonstrating the anti-inflammatory potential of the analogs.

Mitigation of cisplatin-induced peripheral neuropathy by canagliflozin in rats

Peripheral nervous system neurotoxicity is the most problematic complication of cisplatin treatment. In this study, we have addressed the possible neuroprotective effect of canagliflozin on cisplatin-induced peripheral neurotoxicity in rats. Rats were randomly allocated into the following: control (vehicle) group, received hydhroxypropyl methyl cellulose; cisplatin group, injected cisplatin 2 mg/kg intraperitoneal, twice a week for 5 consecutive weeks; canagliflozin-cisplatin of received canagliflozin, 10 mg/kg/day by gavage and cisplatin in the same schedule like cisplatin group. Thermal nociception and rotarod performance were assessed. Malondialdehyde (MDA), reduced glutathione (GSH), tumor necrosis factor-α (TNF-α), and caspase 3 were determined in serum. Hematoxylin and eosin (H&E) and immunohistochemical stained sciatic nerve sections were examined. Cisplatin induced thermal hypoalgesia and decreased rotarod performance as well as GSH serum level while increased MDA, TNF-α, and caspase-3 serum levels with atrophy and fragmentation of the nerve fibers with decreased expression of myelin basic protein. Canagliflozin prevented thermal hypoalgesia and improved rotarod performance with increment in GSH serum level while decreased MDA, TNF-α, and caspase-3 levels as well as prevented fragmentation of the nerve fibers and enhanced myelin basic protein expression in relation to cisplatin group. Canagliflozin attenuates the neurotoxic effect of cisplatin through anti-inflammatory and anti-oxidant actions as well as inhibition of apoptosis.

The Homeostatic Force of Ghrelin

Ghrelin, a gastric-derived acylated peptide, regulates energy homeostasis by transmitting information about peripheral nutritional status to the brain, and is essential for protecting organisms against famine. Ghrelin operates brain circuits to regulate homeostatic and hedonic feeding. Recent research advances have shed new light on ghrelin's multifaceted roles in cellular homeostasis, which could maintain the internal environment and overcome metaflammation in metabolic organs. Here, we highlight our current understanding of the regulatory mechanisms of the ghrelin system in energy metabolism and cellular homeostasis and its clinical trials. Future studies of ghrelin will further elucidate how the stomach regulates systemic homeostasis.

Cisplatin-induced gastrointestinal toxicity: An update on possible mechanisms and on available gastroprotective strategies

Cisplatin (cis-diamminedichloroplatinum [II], CP) is most widely prescribed in chemotherapy and efficaciously treats diverse human cancers, with remission rates > 90% in testicular cancers. However, clinical use of CP is associated with numerous untoward side effects, in particular, at the gastrointestinal level that reduces the therapeutic efficacy of CP and often results in withdrawal of its clinical usage in long term cancer chemotherapy. Substantial strides have been made to identify effective protective strategies against CP-induced nephrotoxicity, hepatotoxicity and ototoxicity. Unfortunately, very limited studies have focused on CP-induced gastrointestinal toxicity and advances in developing potent gastroprotective strategies/agents are still lacking. The current article reviews the metabolism and pharmacokinetics of CP, mechanisms underlying CP-induced gastrointestinal toxicity and lastly displays the potential approaches including plant-derived agents (phytochemicals) utilized to counteract CP-induced gastrointestinal dysfunction. Furthermore, the gastroprotective agents described in the experimental literature have shown partial protection against CP-induced intestinal damage. This stresses the need to ascertain new information on the underlying mechanism and to discover novel combinatorial strategies for the abrogation of CP-induced gastrointestinal toxicity.

Ghrelin mediates exercise endurance and the feeding response post-exercise

Objective

Exercise training has several well-established health benefits, including many related to body weight, appetite control, and blood glucose homeostasis. However, the molecular mechanisms and, in particular, the hormonal systems that mediate and integrate these beneficial effects are poorly understood. In the current study, we aimed to investigate the role of the hormone ghrelin and its receptor, the growth hormone secretagogue receptor (GHSR; ghrelin receptor), in mediating the effects of exercise on food intake and blood glucose following exercise as well as in regulating exercise endurance capacity.

Methods

We used two mouse models of treadmill running to characterize the changes in plasma ghrelin with exercise. We also assessed the role of the ghrelin system to influence food intake and blood glucose after exercise, exercise endurance, and parameters potentially linked to responses to exercise. Mice lacking GHSRs (GHSR-null mice) and wild-type littermates were studied.

Results

An acute bout of exercise transiently elevated plasma acyl-ghrelin. Without the action of this increased ghrelin on GHSRs (as in GHSR-null mice), high intensity interval exercise markedly reduced food intake compared to control mice. The effect of exercise to acutely raise blood glucose remained unmodified in GHSR-null mice. Exercise-induced increases in plasma ghrelin positively correlated with endurance capacity, and time to exhaustion was reduced in GHSR-null mice as compared to wild-type littermates. In an effort to mechanistically explain their reduced exercise endurance, exercised GHSR-null mice exhibited an abrogated sympathoadrenal response, lower overall insulin-like growth factor-1 levels, and altered glycogen utilization.

Conclusions

Exercise transiently increases plasma ghrelin. GHSR-null mice exhibit decreased food intake following high intensity interval exercise and decreased endurance when submitted to an exercise endurance protocol. These data suggest that an intact ghrelin system limits the capacity of exercise to restrict food intake following exercise, although it enhances exercise endurance.

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High intensity exercise transiently increases plasma ghrelin.

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Without ghrelin action on its receptors (growth hormone secretagogue receptors), exercise markedly reduces food intake.

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An intact ghrelin system enhances exercise endurance.

Chemotherapy-related cachexia is associated with mitochondrial depletion and the activation of ERK1/2 and p38 MAPKs

Cachexia affects the majority of cancer patients, with currently no effective treatments. Cachexia is defined by increased fatigue and loss of muscle function resulting from muscle and fat depletion. Previous studies suggest that chemotherapy may contribute to cachexia, although the causes responsible for this association are not clear. The purpose of this study was to investigate the mechanism(s) associated with chemotherapy-related effects on body composition and muscle function. Normal mice were administered chemotherapy regimens used for the treatment of colorectal cancer, such as Folfox (5-FU, leucovorin, oxaliplatin) or Folfiri (5-FU, leucovorin, irinotecan) for 5 weeks. The animals that received chemotherapy exhibited concurrent loss of muscle mass and muscle weakness. Consistently with previous findings, muscle wasting was associated with up-regulation of ERK1/2 and p38 MAPKs. No changes in ubiquitin-dependent proteolysis or in the expression of TGFβ-family members were detected. Further, marked decreases in mitochondrial content, associated with abnormalities at the sarcomeric level and with increase in the number of glycolytic fibers were observed in the muscle of mice receiving chemotherapy. Finally, ACVR2B/Fc or PD98059 prevented Folfiri-associated ERK1/2 activation and myofiber atrophy in C2C12 cultures. Our findings demonstrate that chemotherapy promotes MAPK-dependent muscle atrophy as well as mitochondrial depletion and alterations of the sarcomeric units. Therefore, these findings suggest that chemotherapy potentially plays a causative role in the occurrence of muscle loss and weakness. Moreover, the present observations provide a strong rationale for testing ACVR2B/Fc or MEK1 inhibitors in combination with anticancer drugs as novel strategies aimed at preventing chemotherapy-associated muscle atrophy.

Ghrelin attenuated hyperalgesia induced by chronic nitroglycerin: CGRP and TRPV1 as targets for migraine management

Background

According to the neurovascular theory of migraine, activation of the trigeminovascular system contributes to the development of migraine. This study examined the effects of chronic intraperitoneal ghrelin (150 µg/kg) treatment on the development of chronic migraine induced by intermittent injection of nitroglycerin 10 mg/kg.

Methods

Baseline and post-drug (2 h following nitroglycerin injection) mechanical and thermal sensitivity were assessed by von Frey hair and tail immersion tests, respectively on days 1, 3, 5, 7, 9 and 11. Moreover, we investigated the effect of ghrelin treatment on nitroglycerin-induced aversive behavior by using a two-chamber conditioned place aversion paradigm. At the end of behavioral testing, on day 11, animals were sacrificed and plasma concentration of calcitonin gene-related peptide was measured using a rat-specific enzyme-linked immunosorbent assay kit. Also, real time polymerase chain reaction was used to quantify mRNA expression of calcitonin gene-related peptide and transient receptor potential vanilloid 1 in the trigeminal ganglion.

Results

Our results indicated that nitroglycerin activated the trigeminovascular system, which was reflected by mechanical and thermal hypersensitivity and elevation of mRNA expression of calcitonin gene-related peptide and transient receptor potential vanilloid-1, as migraine markers, and plasma calcitonin gene-related peptide levels. Moreover, chronic nitroglycerin injection induced conditioned place aversion and body weight loss. Nevertheless, ghrelin modulated nitroglycerin-triggered changes in transient receptor potential vanilloid-1 and calcitonin gene-related peptide expression, and mitigated nitroglycerin-induced hyperalgesia.

Conclusion

These results provide the first convincing evidence that ghrelin has a modulating effect on central sensitization induced by chronic intermittent nitroglycerin, and its antinociceptive effect may be related to a reduction of these factors in the trigeminal ganglion.

What is next after anamorelin?

PURPOSE OF REVIEW

In spite of its relevance, treatments for the cancer anorexia and cachexia syndrome (CACS) are not available. One of the agents that recently reached phase III clinical trials is anamorelin. Its development, along with that of other agents for this indication, will be reviewed here, with a focus on the gaps in the current knowledge and future directions.

RECENT FINDINGS

In spite of several targets showing promising results in early development, their difficulties obtaining regulatory approval underscore the need to reconsider the current strategies in drug development and the challenges in the field of CACS.

SUMMARY

Further research is needed in order to meet the challenges of developing treatments for CACS. Preclinical studies should expand our understanding about key regulators of appetite, muscle, and energy metabolism in this setting using models that can be translated reliably to humans. Clinical research efforts should focus on validating the entry criteria, endpoints, outcomes, and the potential synergistic effects and interaction between different targets, nutrition, and exercise interventions. Clinical meaningfulness and significance should be taken into account in the design of clinical trials. It is essential that all key stakeholders are included in the design of future strategies.

Ghrelin alleviates paclitaxel-induced peripheral neuropathy by reducing oxidative stress and enhancing mitochondrial anti-oxidant functions in mice

Paclitaxel is an effective chemotherapeutic agent, but has some treatment-limiting adverse effects that markedly decrease patients' quality of life. Peripheral neuropathy is one of these, and no treatment for it has been established yet. Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor, is secreted from the stomach and has widespread effects on multiple systems. We investigated the pharmacological potential of ghrelin in preventing paclitaxel-induced peripheral neuropathy using wild-type mice, ghrelin-null mice, and growth hormone secretagogue receptor-null mice. In wild-type mice, ghrelin administration alleviated mechanical and thermal hypersensitivity, and partially prevented neuronal loss of small unmyelinated intraepidermal nerve fibers but not large myelinated nerve fibers. Moreover, ghrelin administration decreased plasma oxidative and nitrosative stress and increased the expression of uncoupling protein 2 (UCP2) and superoxide dismutase 2 (SOD2) in the dorsal root ganglia, which are mitochondrial antioxidant proteins, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a regulator of mitochondrial number. Both ghrelin-null mice and growth hormone secretagogue receptor-null mice developed more severe nerve injuries than wild-type mice. Our results suggest that ghrelin administration exerts a protective effect against paclitaxel-induced neuropathy by reducing oxidative stress and enhancing mitochondrial anti-oxidant functions, and that endogenous ghrelin has a neuroprotective effect that is mediated by ghrelin/growth hormone secretagogue receptor signaling. Ghrelin could be a promising therapeutic agent for the management of this intractable disease.

JMV2894, a novel growth hormone secretagogue, accelerates body mass recovery in an experimental model of cachexia

Oncologic patients subjected to chemotherapy frequently present aphagia, malnutrition, and cachexia. The purpose of this study was to investigate whether selected growth hormone secretagogues including hexarelin, JMV2894 and JMV2951 could antagonize body weight loss and wasting induced by cisplatin administration in rats. The three growth hormone secretagogues behaved as full agonists of the growth hormone secretagogues receptor both in terms of ability to stimulate calcium mobilization in Chinese hamster ovary cells and stimulation of growth hormone release in neonatal rats. Adult rats were (i) treated with vehicle throughout (controls), or (ii) treated with cisplatin (days 1-3) and a growth hormone secretagogues or vehicle, (days 1-12). Body weight and food consumption were measured daily. Although all growth hormone secretagogues caused initial transient acute increases in food intake, the total amount of food eaten by controls and growth hormone secretagogues treated groups over the 12 experimental days was not significantly different. All groups pre-treated with cisplatin lost up to 5-10 % body weight in the first 4 days; they subsequently gained weight at a rate comparable with controls. Interestingly, rats which received JMV2894 demonstrated a faster gain in body weight than any other growth hormone secretagogues treated group and at the end of the protocol reached a weight similar to that of controls. JMV2894 did not stimulate perirenal and epididymal fat accumulation but reduced MuRF mRNA levels in skeletal muscles. In conclusion, our findings demonstrate that JMV2894 antagonizes cisplatin induced weight loss in rats and may prove useful in antagonizing cachexia associated with cancer and chemotherapy in humans.

Associations between serum ghrelin and knee symptoms, joint structures and cartilage or bone biomarkers in patients with knee osteoarthritis

OBJECTIVE

The roles of ghrelin in knee osteoarthritis (OA) are unclear. This study aimed to examine cross-sectional associations of ghrelin with knee symptoms, joint structures and cartilage or bone biomarkers in patients with knee OA.

METHODS

This study included 146 patients with symptomatic knee OA. Serum levels of ghrelin and cartilage or bone biomarkers including cartilage oligomeric matrix protein (COMP), cross linked C-telopeptide of type I collagen (CTXI), cross linked N-telopeptide of type I collagen (NTXI), N-terminal procollagen III propeptide (PIIINP), and matrix metalloproteinase (MMP)-3, 10, 13 were measured using Enzyme-linked immunosorbent assay (ELISA). Knee symptoms were assessed using the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Infrapatellar fat pad (IPFP) volume, IPFP signal intensity alternation, cartilage defects, bone marrow lesions (BMLs) and effusion-synovitis were assessed using the (MRI). Osteophytes and joint space narrowing (JSN) were assessed using the Osteoarthritis Research Society International atlas.

RESULTS

After adjustment for potential confounders, ghrelin quartiles were positively associated with knee symptoms including pain, stiffness, dysfunction and total score (quartile 4 vs 1: β 24.19, 95% CI 8.13-40.25). Ghrelin quartiles were also significantly associated with increased IPFP signal intensity alteration (quartile 4 vs 1: OR 3.57, 95% CI 1.55-8.25) and NTXI, PIIINP, MMP3 and MMP13. Ghrelin was not significantly associated with other joint structures and biomarkers.

CONCLUSIONS

Serum levels of ghrelin were significantly associated with increased knee symptoms, IPFP signal intensity alteration and serum levels of MMP3, MMP13, NTXI and PIIINP, suggesting that ghrelin may have a role to play in knee OA.