AIMTo study the effect of CGRP receptor antagonist CGRP8-37 on nociceptive response and expression of nitric oxide synthase (NOS) and content of nitric oxide (NO) in the dorsal horn of the spinal cord of rats during formalin-induced inflammatory pain.

METHODSUsing formalin injection into right hind paw induced inflammatory pain. Counting the times of flinching reflex was used to observe the degree of spontaneous pain. NADPH-d histochemistry was used to observe the changes of NOS expression. The content of NO was observed by measuring the contents of nitrate/nitrite (NO3- / NO2-).

RESULTSspontaneous pain behavioral was elicited by formalin injection. The NOS expression and NO content significantly increased in the spinal cord at 24 h after formalin injection. Intrathecal injection of CGRP8-37 could significantly inhibit the response of spontaneous pain and the increases of NOS expression and NO content induced by formalin injection.

CONCLUSIONThe activation of CGRP receptors enhances NOS expression and NO production in the dorsal horn of the spinal cord during formalin-induced inflammatory pain.

Animals ; Calcitonin Gene-Related Peptide ; pharmacology ; Formaldehyde ; adverse effects ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase ; metabolism ; Pain ; chemically induced ; metabolism ; Peptide Fragments ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Calcitonin Gene-Related Peptide ; antagonists & inhibitors ; Spinal Cord ; drug effects ; metabolism

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

Women often complain gut symptoms during pregnancy and the luteal phase of the menstrual cycle. To investigate the relationship between ovarian steroids and the abnormal gut motility and sensitivity, the expressions of cholecystokinin (CCK), calcitonin gene-related peptide (CGRP) and their receptors in stomach were studied in ovariectomized rats. Blood samples were collected for estradiol (E(2)), progesterone (P(4)), CCK and CGRP radioimmunoassay. Expression of CCK(A) receptor in fundus was assessed by Western blot and CGRP receptor was determined by (125)I-CGRP radioligand binding assay (RBA). The replacement therapy with estradiol benzoate (EB) could dose-dependently increase the plasma CCK level and the expression of gastric CCK(A) receptor (P<0.05 respectively). P(4) replacement therapy could stimulate the release of CGRP and increase the binding sites of CGRP receptors in stomach (P<0.05 respectively). The combined effect of EB and P(4) was to stimulate the release of CCK and CGRP, and to increase the expressions of gastric CCK(A) and CGRP receptors. These results indicate that EB could inhibit gastric emptying by increasing CCK secretion and CCK(A) receptor expression in ovariectomized rats. P(4) could increase gut sensitivity by up-regulating the release of CGRP and the activity of CGRP receptor. It could be deduced from these observations that CCK(A) and CGRP receptor antagonists could be used for female patients who suffer from gastrointestinal dysfunction closely related with the menstrual cycle, such as distension, satiety, bloating and abdominal pain.
Animals ; Calcitonin Gene-Related Peptide ; blood ; Cholecystokinin ; blood ; Estradiol ; analogs & derivatives ; pharmacology ; physiology ; Female ; Gastric Emptying ; drug effects ; physiology ; Ovariectomy ; Progesterone ; pharmacology ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, Calcitonin Gene-Related Peptide ; metabolism ; Receptors, Cholecystokinin ; metabolism ; Stomach ; metabolism ; physiology

OBJECTIVETo investigate the pathogenesis of gastrointestinal motility dysfunction as a result of scald and lipopolysaccharide (LPS) challenge in guinea pigs.

METHODSThirty guinea pigs were enrolled in the study and were randomly divided into 3 groups:i. e. control (n = 10, with intraperitoneal injection of isotonic saline), scald (n = 10, with 30% TBSA deep partial thickness burn) and LPS (n = 10, with intraperitoneal injection of LPS) groups. Thirty minutes after treatment, all animals were gavaged with carbolic ink. The propelled distance of the ink within the gastrointestinal tract was measured. The intestinal tissue was harvested and homogenized, and the contents of CGRP, Na+-K+-ATP enzyme, Mg2+-ATP enzyme, Ca2+-ATP enzyme, Ca2+-Mg2+-ATP enzyme were determined, and the delta phim of haustra coli smooth muscular cell mitochondria was assessed.

RESULTSThe propelled distance of the ink in the gastrointestinal tract in scald (53 +/- 9 cm) and LPS (91 +/- 10 cm) groups was obviously shorter than that in control group (142 +/- 11 cm, P < 0.01). Furthermore, the distance in scald group was shorter than that in LPS group (P < 0.01). The CGRP content in scald and LPS groups [52.0 +/- 39.0 microg/L and 20.0 +/- 23.0 microg/L] was obviously higher than that in control group (0.8 +/-2.0 microg/L, P <0.05 or 0.01), especially in scald group ( P < 0.05). The Na+-K+-ATP enzyme, Mg2+-ATP enzyme, Ca2+-ATP enzyme, Ca2+-Mg2+-ATP enzyme and the delta phim in scald and LPS groups were remarkably lower than those in control group (P <0.005), but there was no difference between scald and LPS groups (P > 0.05).

CONCLUSIONThe gastrointestinal motility of guinea pigs could obviously be inhibited by scald and LPS, especially by scald. LPS might be the key factor to produce change in the membrane potential of mitochondria of intestinal smooth muscle after severe scald.

Animals ; Burns ; pathology ; physiopathology ; Calcitonin Gene-Related Peptide ; metabolism ; Disease Models, Animal ; Gastrointestinal Motility ; drug effects ; Guinea Pigs ; Lipopolysaccharides ; adverse effects ; Myoelectric Complex, Migrating ; drug effects

The purpose of this study was to investigate the effects of calcitonin gene-related peptide (CGRP) on the repolarization process in isolated guinea-pig atrial cells and to determine the contribution of K(+) channels to the CGRP-induced changes in action potential using conventional microelectrode method at the physiological temperature. We found that: (1) CGRP (16 nmol/L) antagonized the influences of potassium channel blockers, 4-AP and BaCl2, on action potential; (2) CGRP (16 nmol/L) increased the amplitude and maximum depolarizing velocity of slow action potential and shortened the conducting time in guinea pig atrial myocardium at extracellular K(+) concentration of 18.5 mmol/L; (3) CGRP (16 nmol/L) alleviated triggered activity induced by superfusion with solution containing CsCl and no potassium ion; and (4) the effects of CGRP on the configuration of action potential were temperature-dependent. At the temperature of 36.5+/-0.5 degrees C, CGRP (5, 16, and 50 nmol/L) increased the amplitude of the action potential and shortened APD(20), APD(50) and APD(90). The CGRP effects on APD(20) and APD(50) were dose-dependent and reversible. On the contrary, CGRP prolonged APD(20), APD(50) and APD(90) at the temperature of 25.5+/-2.1 degrees C. The present study suggests that CGRP possesses multiple effects on various ionic channels. Among them the effects on potassium currents are major determinants in the changes in action potential induced by CGRP under physiological temperature. It is necessary to further study the influences of CGRP on different types of potassium channels.
Action Potentials ; drug effects ; physiology ; Animals ; Body Temperature ; Calcitonin Gene-Related Peptide ; pharmacology ; Cells, Cultured ; Female ; Guinea Pigs ; Heart Atria ; cytology ; drug effects ; Male ; Potassium Channels ; physiology

The purpose of this study was to explore the effects of calcitonin gene-related peptide (CGRP) on the long-term depression (LTD) of hippocampus in mice. Sixty C57BL/6J mice (30 days old) were randomly divided into control group, three CGRP (50, 100, and 200 nmol/L) groups, CGRP + CGRP group and CGRP + APV group (10 mice for each group). The effects of exogenous application of different concentrations of CGRP on synaptic plasticity and LTD in hippocampus of mice were detected by in vitro recording of local field potential. The results showed that higher doses (100 and 200 nmol/L) of CGRP significantly enhanced the induction of LTD in the hippocampus. Moreover, CGRP increased the magnitude of N-methyl-D-aspartate (NMDA) receptor-mediated excitatory postsynaptic currents. The above-mentioned effects of CGRP were blocked by either CGRP selective antagonist CGRP or NMDA receptor antagonist APV. These results suggest that CGRP can dose-dependently enhance the induction of LTD in hippocampus of mice, and the underlying mechanism involves the mediation of NMDA receptor function.
Animals ; Calcitonin Gene-Related Peptide ; pharmacology ; Hippocampus ; drug effects ; Long-Term Synaptic Depression ; drug effects ; Mice ; Mice, Inbred C57BL ; Random Allocation

OBJECTIVETo discuss the effect of calcitonin gene-related peptides (CGRP) on epithelial cadherin (E-cd) expression in human bronchial epithelial cells (HBECs) in vitro.

METHODSThe effect of CGRP on E-cd protein and mRNA expression in both normal and O3-challenged HBECs were determined by immunocytochemistry and RT-PCR. The signal transduction pathways of CGRP were observed by using protein kinase C(PKC) inhibitor (H-7), calmodulin(CaM) inhibitor (W-7) and PKA inhibitor (H-89).

RESULTSCGRP increased E-cd mRNA and protein expressions of normal and O3-challenged HBECs in a dose-dependent manner. CGRP had no effect on cytoplasm E-cd expression. Pre-treatment with H-89, H-7 and W-7, the up-regulatory effect of CGRP on E-cd expression was partly abolished.

CONCLUSIONCGRP increased in cytomembrane E-cd expression of normal and O3-challenged HBECs in a dose-dependent manner. E-cd expression on HBECs was strengthened by CGRP via PKA, PKC and CaM pathways.

Bronchi ; cytology ; Cadherins ; metabolism ; Calcitonin Gene-Related Peptide ; administration & dosage ; pharmacology ; Cell Line ; Epithelial Cells ; drug effects ; metabolism ; Humans ; Ozone ; RNA, Messenger ; genetics

The testicular gubernaculum plays an important role in testicular descent and development. Its differentiation and development are affected by many factors. Androgens, calcitonin gene-related peptide (CGRP), insulin-like factor 3 (INSL3), Müllerian inhibiting substance (MIS), epidermal growth factor (EGF) and environmental estrogens (EEs) are involved in gubernacular development. The effect of CGRP, INSL3 and especially EEs on genital system has been attracted more attention.
Animals ; Calcitonin Gene-Related Peptide ; physiology ; Estrogens ; pharmacology ; Humans ; Insulin ; physiology ; Male ; Mice ; Proteins ; physiology ; Rats ; Testis ; drug effects ; embryology ; physiology

OBJECTIVE: To examine the expression of matrix metalloproteinase-9 (MMP-9) in human bronchial epithelial cells treated with calcitonin-gene-related peptide (CGRP). METHODS: RT-PCR and gelatin zymography were performed to examine the dynamic expression and activity of MMP-9 in human bronchial epithelial cells at different doses (10(-10), 10(-9), 10(-8), 10(-7), and 10(-6)mol/L) and different time points (6,12,18,24,36, and 48h) after the stimulation of CGRP. RESULTS: The unstimulated human bronchial epithelial cells only secreted a small amount of MMP-9. After the CGRP stimulation, the expression of MMP-9 presented in a concentration-dependent (10(-10), 10(-9), 10(-8), 10(-7), and 10(-6) mol/L) and time-dependent (6,12,18,24,36, and 48 h) manners (P<0.01) in human bronchial epithelial cells. The effect of CGRP could be diminished by H-7 and W-7, an antagonist of protein kinase C (PKC) and calmodulin (CaM) (P<0.05). CONCLUSION CGRP can stimulate the secretion and expression of MMP-9 in human bronchial epithelial cells, and the signal transduction is partly via the PKC and CaM pathway.
Bronchi ; cytology ; Calcitonin Gene-Related Peptide ; pharmacology ; Calmodulin ; metabolism ; Cells, Cultured ; Epithelial Cells ; drug effects ; metabolism ; Humans ; Matrix Metalloproteinase 9 ; metabolism ; Protein Kinase C ; metabolism ; Signal Transduction

OBJECTIVE: To explore the effect of calcitonin gene-related peptide (CGRP) on murine oocyte maturation. METHODS: After injection of pregnant mare serum gonadotropin (PMSG, 10 U, i.p.) for 48 h, 6-week old female Kunming mice were killed, and the cumulus oocyte complexes (COCs) were collected from ovaries and inoculated in the culture plate by 30-40/hole. The COCs were treated with 4 concentrations of CGRP (0, 10(-10), 10(-9), and 10(-8) mol/L), and the germinal vesicle breakdown (GVBD) and polar body I (PBI) were examined. Human granulosa cells were also cultured with CGRP (0, 10(-10), 10(-9), 10(-8) mol/L) and levels of intracellular cyclic adenosine monophosphate (cAMP) were measured. RESULTS: Exogenous CGRP caused a decrease in GVBD and PBI in COCs, and an increase in cAMP levels in human granulosa cells in a concentration-dependent manner. CONCLUSION CGRP can inhibit the oocyte maturation, which may be related to the increased content of cAMP in granulosa cells.
Animals ; Calcitonin Gene-Related Peptide ; pharmacology ; Cyclic AMP ; metabolism ; Female ; Granulosa Cells ; cytology ; Humans ; In Vitro Techniques ; Mice ; Oocytes ; cytology ; drug effects