Adrenergic signaling in human oral keratinocytes and wound repair

β2-Adrenoceptor Activation Favor Acquisition of Tumorigenic Properties in Non-Tumorigenic MCF-10A Breast Epithelial Cells

Noradrenaline and adrenaline, and their cognate receptors, are currently accepted to participate in cancer progression. They may also participate in cancer initiation, although their role in this phase is much less explored. The aim of this work was to study the influence of adrenergic stimulation in several processes related to breast cancer carcinogenesis, using several adrenergic agonists in the MCF-10A non-tumorigenic breast cells. Activation of the β-adrenoceptors promoted an epithelial phenotype in MCF-10A cells, revealed by an increased expression of the epithelial marker E-cadherin and a decrease in the mesenchymal markers, N-cadherin and vimentin. MCF-10A cell motility and migration were also impaired after the β-adrenoceptors activation. Concomitant with this effect, β-adrenoceptors decrease cell protrusions (lamellipodia and filopodia) while increasing cell adhesion. Activation of the β-adrenoceptors also decreases MCF-10A cell proliferation. When the MCF-10A cells were cultured under low attachment conditions, activation the of β- (likely β2) or of α2-adrenoceptors had protective effects against cell death, suggesting a pro-survival role of these adrenoceptors. Overall, our results showed that, in breast cells, adrenoceptor activation (mainly through β-adrenoceptors) may be a risk factor in breast cancer by inducing some cancer hallmarks, providing a mechanistic explanation for the increase in breast cancer incidences that may be associated with conditions that cause massive adrenergic stimulation, such as stress.

Mechanism and application of β-adrenoceptor blockers in soft tissue wound healing

Soft tissue damage stimulates sympathetic nerves to release large amounts of catecholamine hormones which bind to β-adrenergic receptors (β-ARs) on the cell membrane surface. It activates the downstream effector molecules and impairs soft tissue wound healing. β-blockers specifically inhibit β-ARs activation in acute/chronic skin lesions and ulcerative hemangiomas. They also accelerate soft tissue wound healing by shortening the duration of inflammation, speeding keratinocyte migration and reepithelialization, promoting wound contraction and angiogenesis, and inhibiting bacterial virulence effects. In addition, β-blockers shorten wound healing periods in patients with severe thermal damage by reducing the hypermetabolic response. While β-blockers promote/inhibit corneal epithelial cell regeneration and restores limbal stem/progenitor cells function, it could well accelerate/delay corneal wound healing. Given these meaningful effects, a growing number of studies are focused on examining the efficacy and safety of β-blockers in soft tissue wound repair, including acute and chronic wounds, severe thermal damage, ulcerated infantile hemangioma, corneal wounds, and other soft tissue disorders. However, an intensive investigation on their acting mechanisms is imperatively needed. The purpose of this article is to summerize the roles of β-blockers in soft tissue wound healing and explore their clinical applications.

Biodiversity of Skin Microbiota as an Important Biomarker for Wound Healing

Cutaneous wound healing is a natural and complex repair process that is implicated within four stages. However, microorganisms (e.g., bacteria) can easily penetrate through the skin tissue from the wound bed, which may lead to disbalance in the skin microbiota. Although commensal and pathogenic bacteria are in equilibrium in normal skin, their imbalance in the wound area can cause the delay or impairment of cutaneous wounds. Moreover, skin microbiota is in constant crosstalk with the immune system and epithelial cells, which has significance for the healing of a wound. Therefore, understanding the major bacteria species in the cutaneous wound as well as their communication with the immune system has gained prominence in a way that allows for the emergence of a new perspective for wound healing. In this review, the major bacteria isolated from skin wounds, the role of the crosstalk between the cutaneous microbiome and immune system to heal wounds, the identification techniques of these bacteria populations, and the applied therapies to manipulate the skin microbiota are investigated.

Functional drug-delivery hydrogels for oral and maxillofacial wound healing

The repair process for oral and maxillofacial injuries involves hemostasis, inflammation, proliferation, and remodeling. Injury repair involves a variety of cells, including platelets, immune cells, fibroblasts, and various cytokines. Rapid and adequate healing of oral and maxillofacial trauma is a major concern to patients. Functional drug-delivery hydrogels play an active role in promoting wound healing and have shown unique advantages in wound dressings. Functional hydrogels promote wound healing through their adhesive, anti-inflammatory, antioxidant, antibacterial, hemostatic, angiogenic, and re-epithelialization-promoting properties, effectively sealing wounds and reducing inflammation. In addition, functional hydrogels can respond to changes in temperature, light, magnetic fields, pH, and reactive oxygen species to release drugs, enabling precise treatment. Furthermore, hydrogels can deliver various cargos that promote healing, including nucleic acids, cytokines, small-molecule drugs, stem cells, exosomes, and nanomaterials. Therefore, functional drug-delivery hydrogels have a positive impact on the healing of oral and maxillofacial injuries. This review describes the oral mucosal structure and healing process and summarizes the currently available responsive hydrogels used to promote wound healing.

Kahweol, a natural diterpene from coffee, induces peripheral antinociception by endocannabinoid system activation

Kahweol is a compound derived from coffee with reported antinociceptive effects. Based on the few reports that exist in the literature regarding the mechanisms involved in kahweol-induced peripheral antinociceptive action, this study proposed to investigate the contribution of the endocannabinoid system to the peripheral antinociception induced in rats by kahweol. Hyperalgesia was induced by intraplantar injection of prostaglandin E₂(PGE₂) and was measured with the paw pressure test. Kahweol and the drugs to test the cannabinoid system were administered locally into the right hind paw. The endocannabinoids were purified by open-bed chromatography on silica and measured by LC-MS. Kahweol (80 µg/paw) induced peripheral antinociception against PGE₂-induced hyperalgesia. This effect was reversed by the intraplantar injection of the CB₁ cannabinoid receptor antagonist AM251 (20, 40, and 80 μg/paw), but not by the CB₂ cannabinoid receptor antagonist AM630 (100 μg/paw). Treatment with the endocannabinoid reuptake inhibitor VDM11 (2.5 μg/paw) intensified the peripheral antinociceptive effect induced by low-dose kahweol (40 μg/paw). The monoacylglycerol lipase (MAGL) inhibitor, JZL184 (4 μg/paw), and the dual MAGL/fatty acid amide hydrolase (FAAH) inhibitor, MAFP (0.5 μg/paw), potentiated the peripheral antinociceptive effect of low-dose kahweol. Furthermore, kahweol increased the levels of the endocannabinoid anandamide, but not of the other endocannabinoid 2-arachidonoylglycerol nor of anandamide-related N-acylethanolamines, in the plantar surface of the rat paw. Our results suggested that kahweol induced peripheral antinociception via anandamide release and activation of CB₁ cannabinoid receptors and this compound could be used to develop new drugs for pain relief.

Alpha and beta adrenergic receptors modulate keratinocyte migration

Keratinocyte migration into skin wounds is the step of the healing process that correlates with the wound closure rate. Keratinocyte migration, and wound epithelialization are decreased when beta 2-adrenergic receptors (B2AR) are activated by 1 μM epinephrine/adrenaline, resulting in delayed wound healing in human and mouse skin. In the present study, we found paradoxically, that in a subset of keratinocyte strains exposure to low concentrations of epinephrine (0.1 nM) increased, rather than decreased, their migratory rate. We find that both the alpha- and the beta-adrenergic receptors are expressed in human keratinocytes, and expression of alpha-2 AR subtypes demonstrated for the first time. Therefore, we tested if the alpha-AR could be modulating the increased migratory response observed in these cell strains. By using specific inhibitors to alpha-AR, we demonstrated that blocking A2B-AR could reverse the rapid cell migration induced by the 0.1 nM epinephrine. Phosphorylation of ERK was elevated after 1-10 minutes of the low epinephrine treatment and the A2B-AR inhibitor blocked the ERK phosphorylation. The results suggest that both the A2B-AR and B2AR mediate keratinocyte migration, in which with a low level of epinephrine treatment, A2B-AR could alter the B2AR signals and regulate the migration rate.

Response of the periodontal tissues to β-adrenergic stimulation

AIMS

Stimulation of β-adrenergic receptors (βAR) in osteoblasts by isoproterenol (ISO) was shown to induce Vascular Endothelial Growth Factor (VEGF) and angiogenesis in long bones. We thus aimed to determine the vascular response of mandibular tissues to βAR stimulation regarding blood vessel formation.

MAIN METHODS

Six-week-old wild-type C57BL6 female mice received daily intraperitoneal injections of ISO or phosphate buffered saline (PBS) for 1 month. Hemimandibles and tibias were collected for immunolocalization of endomucin, tyrosine hydroxylase (TH), neuropeptide Y (NPY) and norepinephrine transporter (NET). Moreover, Vegfa, Il-1 β, Il-6, Adrb2 and Rankl mRNA expression was assessed in mandibles and tibias 2 h after PBS or ISO treatment.

KEY FINDINGS

Despite similar sympathetic innervation and Adrb2 expression between mandibular tissues and tibias, with TH and NPY+ nerve fibers distributed around blood vessels, ISO treatment did not increase endomucin+ vessel area or the total number of endomucin+ vessels in any of the regions investigated (alveolar bone, periodontal ligament, and dental pulp). Consistent with these results, the expression of Vegfα, Il-6, Il-1β, and Rankl in the mandibular molar region did not change following ISO administration. We detected high expression of NET by immunofluorescence in mandible alveolar osteoblasts, osteocytes, and periodontal ligament fibroblasts, in addition to significantly higher Net expression by qPCR compared to the tibia from the same animals.

SIGNIFICANCE

These findings indicate a differential response to βAR agonists between mandibular and tibial tissues, since the angiogenic potential of sympathetic outflow observed in long bones is absent in periodontal tissues.

The Ambivalent Role of Skin Microbiota and Adrenaline in Wound Healing and the Interplay between Them

After skin injury, wound healing sets into motion a dynamic process to repair and replace devitalized tissues. The healing process can be divided into four overlapping phases: hemostasis, inflammation, proliferation, and maturation. Skin microbiota has been reported to participate in orchestrating the wound healing both in negative and positive ways. Many studies reported that skin microbiota can impose negative and positive effects on the wound. Recent findings have shown that many bacterial species on human skin are able to convert aromatic amino acids into so-called trace amines (TAs) and convert corresponding precursors into dopamine and serotonin, which are all released into the environment. As a stress reaction, wounded epithelial cells release the hormone adrenaline (epinephrine), which activates the β2-adrenergic receptor (β2-AR), impairing the migration ability of keratinocytes and thus re-epithelization. This is where TAs come into play, as they act as antagonists of β2-AR and thus attenuate the effects of adrenaline. The result is that not only TAs but also TA-producing skin bacteria accelerate wound healing. Adrenergic receptors (ARs) play a key role in many physiological and disease-related processes and are expressed in numerous cell types. In this review, we describe the role of ARs in relation to wound healing in keratinocytes, immune cells, fibroblasts, and blood vessels and the possible role of the skin microbiota in wound healing.

Beta adrenergic receptor activation inhibits oral cancer migration and invasiveness

OBJECTIVE

The aim of this study was to verify β2-AR expression in oral squamous cell carcinoma cell lines (SCC-9 and SCC-25), and to investigate the role of this receptor in migration and invasion of these neoplastic cells.

DESIGN

SCC-9 and SCC-25 cells were investigated for gene and protein expression of β2-AR. Cell migration and invasion were analyzed by wound healing assay and transwell invasion camera system. Different concentrations (0.1, 1 and 10 μM) of norepinephrine were used to stimulate, and 1 μM propranolol was used to block the beta-adrenergic receptors on cancer cells. Differences in median values of SCC-9 and SCC-25 and β2-AR protein expression were analyzed by Friedman test and in case of significant differences; pairwise comparisons were performed using Bonferroni correction.

RESULTS

The results showed that the β2-AR gene and protein expression were observed in both oral cancer cell lines. The concentration of 10 μM of norepinephrine significantly inhibited (p ≤ 0.05) migration of SCC-9 and SCC-25 cell lines. Furthermore, there was a significant reduction (p ≤ 0.05) in the effect of norepinephrine on cell migration when the β2-AR was inhibited by propranolol. The blockade by propranolol showed a tendency to reverse the effect of norepinephrine on the invasiveness of SCC-9 and SCC-25.

CONCLUSIONS

The use of beta-adrenergic receptor agonists could become an adjuvant therapeutic target in the treatment of this malignancy.

Trace amines produced by skin bacteria accelerate wound healing in mice

Certain skin bacteria are able to convert aromatic amino acids (AAA) into trace amines (TA) that act as neuromodulators. Since the human skin and sweat contain a comparatively high content of AAA one can expect that such bacteria are able to produce TA on our skin. Here we show that TA-producing Staphylococcus epidermidis strains expressing SadA are predominant on human skin and that TA accelerate wound healing. In wounded skin, keratinocytes produce epinephrine (EPI) that leads to cell motility inhibition by β2-adrenergic receptor (β2-AR) activation thus delay wound healing. As β2-AR antagonists, TA and dopamine (DOP) abrogate the effect of EPI thus accelerating wound healing both in vitro and in a mouse model. In the mouse model, the S. epidermidis wild type strain accelerates wound healing compared to its ΔsadA mutant. Our study demonstrates that TA-producing S. epidermidis strains present on our skin might be beneficial for wound healing.

α2-Adrenoceptor agonist induces peripheral antinociception via the endocannabinoid system

BACKGROUND

Xylazine is an α₂ adrenoceptor agonist that is extensively used in veterinary medicine and animal experimentation procedures to produce analgesia, sedation and muscle relaxation without causing general anesthesia. Considering the lack of knowledge of the mechanisms involved in peripheral antinociception induced by xylazine and the potential interactions between the adrenergic and endocannabinoid systems, the present study investigated the contribution of the latter system in the mechanism of xylazine.

METHODS

The rat paw pressure test, in which hyperalgesia was induced by the intraplantar injection of prostaglandin E₂, was performed.

RESULTS

Xylazine administered via an intraplantar injection (25, 50 and 100 μg) induced a peripheral antinociceptive effect against prostaglandin E₂ (2 μg)-induced hyperalgesia. This effect was blocked by treatment with the selective CB₁ cannabinoid antagonist AM251 (20, 40 and 80 μg) but not by the selective CB₂ cannabinoid antagonist AM630 (100 μg). The anandamide reuptake inhibitor VDM11 (2.5 μg) intensified the peripheral antinociceptive effect of a submaximal dose of xylazine (25 μg), and the inhibitor of endocannabinoid enzymatic hydrolysis, MAFP (0.5 μg), showed a tendency towards this same effect. In addition, liquid-chromatography mass spectrometric analysis indicated that xylazine (100 μg) treatment was associated with an increase in anandamide levels in the rat paws treated with PGE₂.

CONCLUSIONS

The present results provides evidence that the peripheral antinociceptive effect of the α₂ adrenoceptor agonist xylazine probably results from anandamide release and subsequent CB₁ cannabinoid receptor activation.

Differential Response of Dopamine Mediated by β-Adrenergic Receptors in Human Keratinocytes and Macrophages: Potential Implication in Wound Healing

OBJECTIVE

Dopamine is an immunomodulatory neurotransmitter. In the skin, keratinocytes and macrophages produce proinflammatory cytokines and metalloproteinases (MMPs) which participate in wound healing. These cells have a catecholaminergic system that modulates skin pathophysiologic processes. We have demonstrated that dopamine modulates cytokine production in keratinocytes via dopaminergic and adrenergic receptors (ARs). The aim of this study was to evaluate the effect of dopamine and its interaction with β-ARs in human HaCaT keratinocytes and THP-1 macrophages. We evaluated the production of inflammatory mediators implicated in wound healing.

METHODS

Cells were stimulated with dopamine in the absence or presence of the β-adrenergic antagonist propranolol. Wound closure, MMP activity, and the production of IL-8, IL-1β, and IκB/NFκB pathway activation were determined in stimulated cells.

RESULTS

Dopamine did not affect the wound closure in human keratinocytes, but diminished the propranolol stimulatory effect, thus delaying cell migration. Similarly, dopamine significantly decreased MMP-9 activity and the propranolol-induced MMP activity. Dopamine significantly increased the p65-NFκB subunit levels in the nuclear extracts, which were reduced in the presence of propranolol in keratinocytes. On the other hand, dopamine significantly increased MMP-9 activity in THP-1 macrophages, but did not modify the propranolol-increased enzymatic activity. Dopamine significantly increased IL-8 production in human macrophages, an effect that was partially reduced by propranolol. Dopamine did not modify the p65-NFκB levels in the nuclear extracts in THP-1 macrophages.

CONCLUSION

We suggest that the effect of dopamine via β-ARs depends on the physiological condition and the cell type involved, thus contributing to either improve or interfere with the healing process.

Correlation of Beta-2 Adrenergic Receptor Expression in Tumor-Free Surgical Margin and at the Invasive Front of Oral Squamous Cell Carcinoma

Background. The beta-2 adrenergic receptor is expressed by neoplastic cells and is correlated with a wide spectrum of tumor cell mechanisms including proliferation, apoptosis, angiogenesis, migration, and metastasis. Objectives. The present study aimed to analyze the expression of the beta-2 adrenergic receptor (β2-AR) in tumor-free surgical margins of oral squamous cell carcinomas (OSCC) and at the invasive front. Sixty-two patients diagnosed with OSCC, confirmed by biopsy, were selected for the study. The clinicopathological data and clinical follow-up were obtained from medical records and their association with β2-AR expression was verified by the chi-square test or Fischer's exact test. To verify the correlation of β2-AR expression in tumor-free surgical margins and at the invasive front of OSCCs, Pearson's correlation coefficient test was applied. Results. The expression of β2-AR presented a statistically significant correlation between the tumor-free surgical margins and the invasive front of OSCC (r = 0.383; p = 0.002). The immunohistochemical distribution of β2-AR at the invasive front of OSCC was also statistically significant associated with alcohol (p = 0.038), simultaneous alcohol and tobacco consumption (p = 0.010), and T stage (p = 0.014). Conclusions. The correlation of β2-AR expression in OSCC and tumor-free surgical margins suggests a role of this receptor in tumor progression and its expression in normal oral epithelium seems to be constitutive.

Agonist binding to β-adrenergic receptors on human airway epithelial cells inhibits migration and wound repair

Human airway epithelial cells express β-adrenergic receptors (β-ARs), which regulate mucociliary clearance by stimulating transepithelial anion transport and ciliary beat frequency. Previous studies using airway epithelial cells showed that stimulation with isoproterenol increased cell migration and wound repair by a cAMP-dependent mechanism. In the present study, impedance-sensing arrays were used to measure cell migration and epithelial restitution following wounding of confluent normal human bronchial epithelial (NHBE) and Calu-3 cells by electroporation. Stimulation with epinephrine or the β2-AR-selective agonist salbutamol significantly delayed wound closure and reduced the mean surface area of lamellipodia protruding into the wound. Treatment with the β-AR bias agonist carvedilol or isoetharine also produced a delay in epithelial restitution similar in magnitude to epinephrine and salbutamol. Measurements of extracellular signal-regulated kinase phosphorylation following salbutamol or carvedilol stimulation showed no significant change in the level of phosphorylation compared with untreated control cells. However, inhibition of protein phosphatase 2A activity completely blocked the delay in wound closure produced by β-AR agonists. In Calu-3 cells, where CFTR expression was inhibited by RNAi, salbutamol did not inhibit wound repair, suggesting that β-AR agonist stimulation and loss of CFTR function share a common pathway leading to inhibition of epithelial repair. Confocal images of the basal membrane of Calu-3 cells labeled with anti-β1-integrin (clone HUTS-4) antibody showed that treatment with epinephrine or carvedilol reduced the level of activated integrin in the membrane. These findings suggest that treatment with β-AR agonists delays airway epithelial repair by a G protein- and cAMP-independent mechanism involving protein phosphatase 2A and a reduction in β1-integrin activation in the basal membrane.

Activation of β2-adrenergic receptor by (R,R')-4'-methoxy-1-naphthylfenoterol inhibits proliferation and motility of melanoma cells

(R,R')-4'-methoxy-1-naphthylfenoterol [(R,R')-MNF] is a highly-selective β2 adrenergic receptor (β2-AR) agonist. Incubation of a panel of human-derived melanoma cell lines with (R,R')-MNF resulted in a dose- and time-dependent inhibition of motility as assessed by in vitro wound healing and xCELLigence migration and invasion assays. Activity of (R,R')-MNF positively correlated with the β2-AR expression levels across tested cell lines. The anti-motility activity of (R,R')-MNF was inhibited by the β2-AR antagonist ICI-118,551 and the protein kinase A inhibitor H-89. The adenylyl cyclase activator forskolin and the phosphodiesterase 4 inhibitor Ro 20-1724 mimicked the ability of (R,R')-MNF to inhibit migration of melanoma cell lines in culture, highlighting the importance of cAMP for this phenomenon. (R,R')-MNF caused significant inhibition of cell growth in β2-AR-expressing cells as monitored by radiolabeled thymidine incorporation and xCELLigence system. The MEK/ERK cascade functions in cellular proliferation, and constitutive phosphorylation of MEK and ERK at their active sites was significantly reduced upon β2-AR activation with (R,R')-MNF. Protein synthesis was inhibited concomitantly both with increased eEF2 phosphorylation and lower expression of tumor cell regulators, EGF receptors, cyclin A and MMP-9. Taken together, these results identified β2-AR as a novel potential target for melanoma management, and (R,R')-MNF as an efficient trigger of anti-tumorigenic cAMP/PKA-dependent signaling in β2-AR-expressing lesions.

Crosstalk between adrenergic and toll-like receptors in human mesenchymal stem cells and keratinocytes: a recipe for impaired wound healing

Previous studies demonstrate that skin wounds generate epinephrine (EPI) that can activate local adrenergic receptors (ARs), impairing healing. Bacterially derived activators of Toll-like receptors (TLRs) within the wound initiate inflammatory responses and can also impair healing. In this study, we examined the hypothesis that these two pathways crosstalk to one another, using EPI and macrophage-activating lipopeptide-2 (MALP2) to activate ARs and TLR2, respectively, in human bone marrow-derived mesenchymal stem cells (BM-MSCs) and neonatal keratinocytes (NHKs). BM-MSCs exposed to EPI significantly (p < .05) increased TLR2 message (sevenfold BM-MSCs), TLR2 protein (twofold), and myeloid differentiation factor 88 (MyD88) (fourfold). Conversely, activation of TLR2 by MALP2 in these cells increased β2-AR message (twofold in BM-MSCs, 2.7-fold in NHKs), β2-AR protein (2.5-fold), phosphorylation of β-AR-activated kinase (p-BARK, twofold), and induced release of EPI from both cell types (twofold). Treating cells with EPI and MALP2 together, as would be encountered in a wound, increased β2-AR and p-BARK protein expression (sixfold), impaired cell migration (BM-MSCs- 21%↓ and NHKs- 60%↓, p < .002), and resulted in a 10-fold (BM-MSCs) and 51-fold (NHKs) increase in release of IL-6 (p < .001) responses that were remarkably reduced by pretreatment with β2-AR antagonists. In vivo, EPI-stressed animals exhibited impaired healing, with elevated levels of TLR2, MyD88, and IL-6 in the wounds (p < .05) relative to nonstressed controls. Thus, our data describe a recipe for decreasing cell migration and exacerbating inflammation via novel crosstalk between the adrenergic and Toll-like receptor pathways in BM-MSCs and NHKs.

Novel antioxidants are not toxic to normal tissues but effectively kill cancer cells

Free radicals are formed as a result of cellular processes and play a key role in predisposition to and development of numerous diseases and of premature aging. Recently, we reported the syntheses of a number of novel phenolic antioxidants for possible application in food industry. In the present study, analyses of the cellular processes and molecular gene expression effects of some of the novel antioxidants in normal human tissues and in cancer cells were undertaken. Results indicated that whereas the examined antioxidants showed no effects on morphology and gene expression of normal human oral and gingival epithelial tissues, they exerted a profound cell killing effect on breast cancer cells, including on chemotherapy-resistant breast cancer cells and on oral squamous carcinoma cells. Among the tested antioxidants, N-decyl-N-(3-methoxy-4-hydroxybenzyl)-3-(3,4-dihydroxyphenyl) propanamide and N-decyl-N-(3,5-dimethoxy-4-hydroxybenzyl)-3-(3,4-dihydroxyphenyl) propanamide were the most promising, with excellent potential for cancer treatment. Moreover, our gene expression databases can be used as a roadmap for future analysis of mechanisms of antioxidant action.

CB1 and CB2 cannabinoid receptor agonists induce peripheral antinociception by activation of the endogenous noradrenergic system

BACKGROUND

Cannabinoid agonists induce norepinephrine release in central, spinal, and peripheral sites. Previous studies suggest an interaction between the cannabinoid and adrenergic systems on antinociception. In this study, we sought to verify whether the CB1 and CB2 cannabinoid receptor agonists anandamide and N-palmitoyl-ethanolamine (PEA), respectively, are able to induce peripheral antinociception via an adrenergic mechanism.

METHODS

All drugs were administered locally into the right hindpaw of male Wistar rats. The rat paw pressure test was used, with hyperalgesia induced by intraplantar injection of prostaglandin E2 (2 μg).

RESULTS

Anandamide, 12.5 ng/paw, 25 ng/paw, and 50 ng/paw elicited a local peripheral antinociceptive effect that was antagonized by CB1 cannabinoid receptor antagonist AM251, 20 µg/paw, 40 µg/paw, and 80 µg/paw, but not by CB2 cannabinoid receptor antagonist AM630, 100 µg/paw. PEA, 5 µg/paw, 10 µg/paw, and 20 µg/paw, elicited a local peripheral antinociceptive effect that was antagonized by AM630, 25 µg/paw, 50 µg/paw, and 100 µg/paw, but not by AM251, 80 µg/paw. Antinociception induced by anandamide or PEA was antagonized by the nonselective α2 adrenoceptor antagonist yohimbine, 05 µg/paw, 10 µg/paw, and 20 µg/paw, and by the selective α2C adrenoceptor antagonist rauwolscine, 10 µg/paw, 15 µg/paw, and 20 µg/paw, but not by the selective antagonists for α2A, α2B, and α2D adrenoceptor subtypes, 20 μg/paw. The antinociceptive effect of the cannabinoids was also antagonized by the nonselective α1 adrenoceptor antagonist prazosin, 0.5 µg/paw, 1 µg/paw, and 2 µg/paw, and by the nonselective β adrenoceptor antagonist propranolol, 150 ng/paw, 300 ng/paw, and 600 ng/paw. Guanethidine, which depletes peripheral sympathomimetic amines (30 mg/kg/animal, once a day for 3 days), restored approximately 70% the anandamide-induced and PEA-induced peripheral antinociception. Furthermore, acute injection of the norepinephrine reuptake inhibitor reboxetine, 30 µg/paw, intensified the antinociceptive effects of low-dose anandamide, 12.5 ng/paw, and PEA, 5 µg/paw.

CONCLUSIONS

This study provides evidence that anandamide and PEA induce peripheral antinociception activating CB1 and CB2 cannabinoid receptors, respectively, stimulating an endogenous norepinephrine release that activates peripheral adrenoceptors inducing antinociception.

The psychology of wound healing

PURPOSE OF REVIEW

Research into the effects of psychological factors on wound healing represents an ideal research model for psychoneuroimmunology, as both the impact on clinically relevant health outcomes and the underlying biological mechanisms can be examined. Mounting interest in this topic from biological scientists, psychologists, and medical specialists has resulted in new findings that are discussed in this review.

RECENT FINDINGS

Known psychological influences on wound healing include stress as well as coping styles, positive affect, environmental enrichment, and social support. Research has highlighted the roles of oxytocin, vasopressin, epinephrine, cortisol, and leukocyte redistribution in wound healing. Clinical significance has been demonstrated by a growing number of studies in patient populations. Furthermore, pragmatic interventions with clinical samples have demonstrated clear benefits of psychological interventions on wound healing.

SUMMARY

Recent studies add to growing evidence that psychology impacts wound repair, and highlight in particular the positive role of social support on modulating the negative effects of stress. The first few studies to demonstrate that psychological interventions can improve healing in clinical populations are exciting developments. New knowledge of psychobiological mechanisms provides opportunities to develop further interventions to improve health outcomes.

Stress-Induced Hormones Cortisol and Epinephrine Impair Wound Epithelization

BACKGROUND

Stress-induced disruption of hormonal balance in animals and humans has a detrimental effect on wound healing.

THE PROBLEM

After the injury, keratinocytes migrate over the wound bed to repair a wound. However, their nonmigratory phenotype plays a role in pathogenesis of chronic wounds. Despite many therapeutic approaches, there is a dearth of treatments targeting the molecular mechanisms mediated by stress that prevent epithelization.

BASIC/CLINICAL SCIENCE ADVANCES

Recent studies show that epidermal keratinocytes synthesize stress hormones. During acute wound healing, cortisol synthesis in the epidermis is tightly controlled. Further, a key intermediate molecule in the cholesterol synthesis pathway, farnesyl pyrophosphate (FPP), can bind glucocorticoid receptor (GR) and activate GR. Additionally, keratinocytes express beta-2-adrenergic-receptor (β2AR), a receptor for the stress hormone epinephrine. Importantly, migratory rates of keratinocytes are reduced by cortisol, FPP, epinephrine, and other β2AR agonists, thus indicating their role in the inhibition of epithelization. Topical inhibition of local glucocorticoid and FPP synthesis, as well as treatment with β2AR antagonists promotes wound epithelization.

CLINICAL CARE RELEVANCE

Modulation of local stress hormone production may represent an important therapeutic target for wound healing disorders. Topical administration of inhibitors of cortisol synthesis, statins, β2AR antagonists, and systemic beta-blockers can decrease cortisol synthesis, FPP, and epinephrine levels, respectively, thus restoring keratinocyte migration capacity. These treatment modalities could represent a novel therapeutic approach for wound healing disorders.

CONCLUSION

Attenuation of the local stress-induced hormonal imbalance in epidermis may advance therapeutic modalities, thereby leading to enhanced epithelization and improved wound healing.

Zilpaterol hydrochloride alters abundance of β-adrenergic receptors in bovine muscle cells but has little effect on de novo fatty acid biosynthesis in bovine subcutaneous adipose tissue explants

We predicted that zilpaterol hydrochloride (ZH), a β-adrenergic receptor (AR) agonist, would depress mRNA and protein abundance of β-AR in bovine satellite cells. We also predicted that ZH would decrease total lipid synthesis in bovine adipose tissue. Bovine satellite cells isolated from the semimembranosus muscle were plated on tissue culture plates coated with reduced growth factor matrigel or collagen. Real-time quantitative PCR was used to measure specific gene expression after 48 h of ZH exposure in proliferating satellite cells and fused myoblasts. There was no effect of ZH dose on [(3)H]thymidine incorporation into DNA in proliferating myoblasts. Zilpaterol hydrochloride at 1 µM decreased (P < 0.05) β1-AR mRNA, and 0.01 and 1 µM ZH decreased (P < 0.05) β2-AR and β3-AR mRNA in myoblasts. The expression of IGF-I mRNA tended to increase (P = 0.07) with 1 µM ZH. There was no effect (P > 0.10) of ZH on the β-AR or IGF-I gene expression in fused myotube cultures at 192 h or on fusion percentage. The β2-AR antagonist ICI-118, 551 at 0.1 µM attenuated (P < 0.05) the effect of 0.1 µM ZH to reduce expression of β1- and β2-AR mRNA. The combination of 0.01 µM ZH and 0.1 µM ICI-118, 551 caused an increase (P < 0.05) in β1-AR gene expression. There was no effect (P > 0.10) of ICI-118, 551 or ZH on β3-AR or IGF-I. Western blot analysis revealed that the protein content of β2-AR in ZH-treated myotube cultures decreased (P < 0.05) relative to control. Total lipid synthesis from acetate was increased by ZH in bovine subcutaneous adipose tissue explants in the absence of theophylline but was decreased by ZH when theophylline was included in the incubation medium. These data indicate that ZH alters mRNA and protein concentrations of β-AR in satellite cell cultures, which in turn could affect responsiveness of cells to prolonged ZH exposure in vivo. Similar to other β-adrenergic agonists, ZH had only modest effects on lipid metabolism in adipose tissue explants.