Microglia are important cells involved in the regulation of neuropathic pain (NPP) and morphine tolerance. Information on their plasticity and polarity has been elucidated after determining their physiological structure, but there is still much to learn about the role of this type of cell in NPP and morphine tolerance. Microglia mediate multiple functions in health and disease by controlling damage in the central nervous system (CNS) and endogenous immune responses to disease. Microglial activation can result in altered opioid system activity, and NPP is characterized by resistance to morphine. Here we investigate the regulatory mechanisms of microglia and review the potential of microglial inhibitors for modulating NPP and morphine tolerance. Targeted inhibition of glial activation is a clinically promising approach to the treatment of NPP and the prevention of morphine tolerance. Finally, we suggest directions for future research on microglial inhibitors.
Humans ; Calcitonin Gene-Related Peptide/antagonists & inhibitors* ; Drug Tolerance ; Hypoglycemic Agents/pharmacology* ; Microglia/physiology* ; MicroRNAs/physiology* ; Minocycline/pharmacology* ; Morphine/pharmacology* ; Neuralgia/etiology* ; Plant Extracts/pharmacology* ; Signal Transduction/physiology*

OBJECTIVEPrevious studies have clarified that calcitonin gene-related peptide (CGRP) can promote the biologi- cal activity of osteoblasts. To further reveal the role of CGRP in bone repair, we studied its influence on osteogenic differentia- tion of mouse bone marrow stromal cells (BMSCs) and initially explored the effect of the Hippo signaling pathway with this process.

METHODSBMSCs were induced to osteogenic differentiate osteoblasts by different concentrations of CGRP for a screening of the optimal concentration. CGRP was added in BMSCs, then the activity of alkaline phosphatase (ALP) and the number of mineralized nodules were examined by specific ALP kits after 48 hours and alizarin red staining fluid after 7 days, respectively. The protein expression of p-Mst1/2 was measured by Western blot. Verteporfin was used to block the downstream Yap signaling. The mRNA expression of collagen type I (Col I) and runt-related transcription factor 2 (Runx2) were detected by reverse transcription-polymerase chain reaction.

RESULTSCompared to the blank group, different concentrations of CGRP (10⁻⁹, 10⁻⁸, 10⁻⁷ mol · L⁻¹), especially 10⁻⁸ mol · L⁻¹, significantly increased the ALP activity of BMSCs (P < 0.05). Alizarin red staining also showed more mineralized nodules in 10⁻⁸ mol · L⁻¹ group. The expression of p-Mst1/2 increased in the CGRP group (P < 0.05). Verteporfin treatment effectively decreased the mRNA expression of Runx2 and Col I (P < 0.05).

CONCLUSIONThe Hippo signaling pathway plays a role in CGRP-induced osteogenic differentiation in mouse BMSCs.

Alkaline Phosphatase ; Animals ; Calcitonin ; genetics ; metabolism ; Calcitonin Gene-Related Peptide ; metabolism ; Cell Differentiation ; Cells, Cultured ; Collagen Type I ; Core Binding Factor Alpha 1 Subunit ; Mesenchymal Stromal Cells ; physiology ; Mice ; Osteoblasts ; Osteogenesis ; physiology ; Signal Transduction

The calcitonin gene-related peptide (CGRP) family mainly includes CGRPα, CGRPβ, adrenomedullin, calcitonin and amylin. The members of CGRP family and their receptors are widely distributed in the central and peripheral nervous systems. Studies show that members of CGRP family such as CGRP and adrenomedullin play important roles in the transmission of nociceptive information. At spinal level, CGRP promotes the transmission of nociceptive information, spinal morphine tolerance, migraine, inflammatory pain and neuropathic pain. At superspinal level, CGRP suppresses the transmission of nociceptive information. Adrenomedullin is a pain-related neuropeptide which has recently been demonstrated. It facilitates the transmission of nociceptive information and is involved in the development and maintenance of opioid tolerance. The involvement of amylin and calcitonin in pain is not clear yet.
Adrenomedullin ; physiology ; Analgesics, Opioid ; pharmacology ; Animals ; Calcitonin Gene-Related Peptide ; physiology ; Drug Tolerance ; Humans ; Islet Amyloid Polypeptide ; physiology ; Nociception ; Pain ; physiopathology

OBJECTIVETo investigate the vasodilating effect of capsaicin (CAP) on rat mesenteric artery and its mechanism.

METHODSThe third branch of the superior mesenteric artery in male Sprague-Dawley rat (250-350 g) was excised, the periadventitial fat and connective tissue were removed and the mesenteric artery was dissected into 2 mm rings. Each ring was placed in a 5 ml organ bath of DMT 610M system and the tension was recorded.

RESULTSCAP (10(-9)-10(-5) mol/L) relaxed endothelium-intact and endothelium-denuded mesenteric artery pre-constricted by phenylephrine (10(-5) mol/L), and the vasodilation in endothelium-intact mesenteric artery was stronger than that in endothelium-denuded one. Pretreatment with either L-NAME (3 X10(-4) mol/L), an inhibitor of nitric oxide synthase(NOS), or CGRP8-37 (2 X 10(-6) mol/L), an antagonist of calcitonin gene-related peptide (CGRP), for 30 min significantly attenuated the relaxation of endothelium-intact mesenteric artery induced by CAP. CGRP (10(-10)-3 X10(-8) mol/L) relaxed endothelium-intact and endothelium-denuded mesenteric artery pre-constricted by phenylephrine, and the vasodilation in endothelium-intact mesenteric artery was stronger than that in endothelium-denuded one. Substance P did not relax the mesenteric artery pre-constricted by phenylephrine.

CONCLUSIONCAP has partial endothelium-dependent relaxation effect on rat mesenteric artery, which may be mediated by activating the endothelial NOS-NO pathway. The endothelium-independent relaxation in rat mesenteric artery induced by CAP may be mediated by CGRP.

Animals ; Calcitonin Gene-Related Peptide ; metabolism ; Capsaicin ; pharmacology ; In Vitro Techniques ; Male ; Mesenteric Arteries ; drug effects ; physiology ; Peptide Fragments ; metabolism ; Rats ; Rats, Sprague-Dawley ; Vasodilation ; drug effects

The present study investigated the effects of intrathecal (i.t.) application of bovine adrenal medulla 22 (BAM22), an endogenous opioid peptide potently activating opioid receptors and sensory neuron-specific receptor (SNSR), on a model of complete Freund's adjuvant (CFA)-induced inflammatory pain. Unilateral, but not bilateral, inflammatory pain was induced by intraplantar (i.pl.) injection of CFA in one side, as indicated by the shortened paw withdrawal latency and the increased edema of paw. Paw withdrawal latency test, paw edema determination and immunohistochemistry were used in CFA-induced inflammatory pain model after i.t. administration of BAM22 or saline. It was found that administration of BAM22 dose-dependently attenuated CFA-induced hyperalgesia and edema, and resumed antinociceptive effects against thermal stimulation in behavioral test. In 10 nmol BAM22 group, paw withdrawal latency was resumed to 83.2% of normal, and edema increased only by 60% of normal at 48 h. The potency of BAM22 was 33.5% of maximal possible effect (MPE) at 24 h, and the antinociception persisted for at least 1 h. Furthermore, i.t. treatment of 10 nmol BAM22 evidently decreased the expressions of CFA-evoked neuronal nitric oxide synthase (nNOS)-positive cells and calcitonin gene-related peptide (CGRP)-immunoreactivity positive nerve fibers by 25.6% (P<0.01) and 25.2% (P<0.001) compared with saline group, respectively, at L3-L5 segments of the spinal cord. Small and medium CGRP-positive cells were 57.4% and 35.2% in dorsal root ganglion (DRG) in 10 nmol BAM22 group, respectively, which were remarkably lower than those in saline group (P<0.001). The present study suggests that BAM22 relieves CFA-induced thermal hyperalgesia in the early phase and resumes antinociceptive effects through down-regulation of nNOS and CGRP expressions in DRG and spinal cord, which is possibly mediated via SNSR.
Animals ; Calcitonin Gene-Related Peptide ; metabolism ; Enkephalin, Methionine ; analogs & derivatives ; pharmacology ; Freund's Adjuvant ; Hyperalgesia ; etiology ; physiopathology ; Inflammation ; chemically induced ; complications ; Male ; Nitric Oxide Synthase Type I ; metabolism ; Pain ; etiology ; physiopathology ; Pain Measurement ; drug effects ; Protein Precursors ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled ; physiology

Animals ; Calcitonin Gene-Related Peptide ; physiology ; Heart ; physiology ; Male ; Physical Exertion ; physiology ; Rats ; Rats, Sprague-Dawley

BACKGROUNDMost of the basic and clinical studies of osteonecrosis of the femoral head (ONFH) are restricted to bone tissues only, whereas various systems are involved in the onset and development of ONFH, including nervous system. Peptidergic nerve participates in the neuronal regulation of bone metabolism and anabolism, and plays key roles in the growth, repair and reconstruction of bone. Calcitonin gene-related peptide (CGRP), which is secreted by peptidergic nerve, is the main mediator of bone metabolism. It dramatically promotes the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Additionally, it enhances the osteoblast mass and the rate of osteoblast formation, and reduces the bone resorption by acting on osteoblasts and osteoclasts. Hence, we aimed to construct recombinant retrovirus vector pLNCX(2)-hCGRPα and to investigate the proliferation and osteogenic potential of hCGRPα-producing BMSCs (BMSCs/pLNCX(2)-hCGRPα) after virus infection.

METHODSThe constructed recombinant retrovirus vector pLNCX(2)-hCGRPα was transfected into PT67 packaging cells by lipofectamine 2000. Virus was collected for BMSCs infection. The mRNA and protein expression of hCGRPα was examined by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting, respectively. The cell proliferation was determined by methyl thiazoleterazolium (MTT) assay. The osteogenic potential of BMSCs was evaluated by alkaline phosphatase (ALP) activity.

RESULTSBoth mRNA and protein expression of hCGRPα was detected in BMSCs/pLNCX(2)-hCGRPα cells. These cells exhibited significantly elevated proliferation and ALP value as compared with control BMSCs (P < 0.05).

CONCLUSIONBMSCs/pLNCX(2)-hCGRPα cells could stably express hCGRPα and showed promoted proliferation ability and osteogenic potential as compared with control BMSCs.

Alkaline Phosphatase ; genetics ; metabolism ; Animals ; Blotting, Western ; Bone Marrow Cells ; cytology ; Calcitonin Gene-Related Peptide ; genetics ; metabolism ; Cell Differentiation ; genetics ; physiology ; Cell Proliferation ; Cells, Cultured ; Humans ; Mesenchymal Stromal Cells ; cytology ; Osteogenesis ; genetics ; physiology ; Rabbits ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo evaluate the effect of octacostyl alcohol preparation on the motor function, blood free radical metabolism and cardiac endocrine function of rats.

METHODSA rat model of exercise fatigue was used for this study. The rats were made to perform continuous exhaustive exercise, and the total exercise time of the rats till exhaustion was recorded followed by examination of the serum superoxide dismutase (SOD), malonaldehyde (MDA), plasma endothelin (ET), calcitonin gene-related peptide (CGRP), and atrial natriuretic peptide (ANP).

RESULTSCompared with rats without interventions for exercise fatigue, the rats receiving octacostyl alcohol preparation had significant prolonged exercise time till exhaustion (P<0.05), with also significantly enhanced serum SOD activity (P<0.05), significantly decreased MDA level and plasma ET (P<0.05) and increased CGRP and ANP levels (P<0.05). Octacostyl alcohol preparation produced more favorable effect on all the indices measured than pyruvic acid-creatine (P<0.05).

CONCLUSIONThe octacostyl alcohol preparation can promote the motor function, increases blood antioxidase activity, suppressed lipid peroxidation in rats engaged in exhaustive exercise. The preparation also produces favorable effect on cardiac endocrine function for heart protection during exercise.

Animals ; Atrial Natriuretic Factor ; blood ; Calcitonin Gene-Related Peptide ; blood ; Drugs, Chinese Herbal ; pharmacology ; Endocrine System ; drug effects ; physiology ; Endothelins ; blood ; Fatigue ; blood ; physiopathology ; prevention & control ; Fatty Alcohols ; pharmacology ; Free Radicals ; blood ; metabolism ; Heart ; drug effects ; physiology ; Male ; Malondialdehyde ; blood ; Motor Activity ; drug effects ; Physical Conditioning, Animal ; physiology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Superoxide Dismutase ; blood

OBJECTIVEThis study investigates the plasma vasoactive substances and antioxidant enzymes levels in prehypertensive patients.

METHODSPatients were scruited according to JNC-7 and divided into three groups: 74 normotensive subjects (NT group, 38 males, mean age 47.15 +/- 7.77 years old); 51 prehypertensive patients (PH group, 29 males, mean age 47.82 +/- 5.16 years old) and 71 essential hypertensive patients (EH group, 37 males, mean age 48.25 +/- 7.97 years old). Serum lipids and plasma angiotensin II (Ang II), endothelin (ET), vasopressin (AVP), calcitonin gene-related peptide (CGRP), nitric oxide synthase (NOS), superoxide dismutase (SOD) and glutathione peroxidase (GPX) by radioimmunoassay and enzyme linked immunosorbent assay.

RESULTSSerum Lipids (TG, CHO and LDL) were significantly higher in the PH and EH groups compared to NT group (all P < 0.05). Ang II, AVP and ET were significantly increased while CGRP decreased in the EH group than that in NT group (all P < 0.05). SOD was significantly lower while GPX significantly higher. Further more, in the PH and EH groups than those in the NT group (all P < 0.05).

CONCLUSIONSOD was reduced and GPX increased in prehypertensive patients.

Adult ; Angiotensin II ; blood ; Antioxidants ; Blood Pressure ; physiology ; Calcitonin Gene-Related Peptide ; blood ; Case-Control Studies ; Endothelins ; blood ; Female ; Glutathione Peroxidase ; blood ; Humans ; Hypertension ; blood ; Male ; Middle Aged ; Nitric Oxide Synthase ; blood ; Plasma ; metabolism ; Superoxide Dismutase ; blood ; Vasopressins ; blood

OBJECTIVETo study the relationship between substance P (SP) and/or calcitonin gene-related peptide (CGRP) immunoreactive neurons in dorsal root ganglia (DRG) and the transmission of nociception in the penile frenulum of rats.

METHODSThe fluoro-gold (FG) retrograde tracing method was used to trace the origin of nerve terminals in the penile frenulum of rats. And SP and/or CGRP immunofluorescence labeling was employed to detect the distribution of SP and/or CGRP immunoreactive neurons in DRG.

RESULTSFG retrograde tracing showed that the FG retrolabeled neurons were localized in L6-DRG and S1-DRG. SP and/or CGRP immunofluorescence labeling indicated that a large number of DRG neurons were SP- and CGRP-immunoreactive, different in size, bright red and bright green respectively in color, and arranged in rows or spots among nerve bundles. All the FG/SP and FG/CGRP double-labeled neurons were medium or small-sized. One third of the FG-labeled neurons were SP-immunoreactive, and a half of them CGRP-immunoreactive in L6-DRG and S1-DRG respectively. The FG/SP/CGRP-labeled neurons accounted for one fifth of the FG retro labeled neurons.

CONCLUSIONSP- and CGRP-immunoreactive neurons in L6-DRG and SI-DRG of rats may be involved in the transmission of nociception in rat penile frenulum.

Animals ; Calcitonin Gene-Related Peptide ; analysis ; Ganglia, Spinal ; chemistry ; cytology ; Male ; Microscopy, Fluorescence ; Neurons ; chemistry ; physiology ; Neurons, Afferent ; chemistry ; physiology ; Penis ; innervation ; Rats ; Rats, Sprague-Dawley ; Substance P ; analysis