Pharmacological characterization of the relaxant effect induced by adrenomedullin in rat cavernosal smooth muscle

The aim of the present study was to determine the mechanisms underlying the relaxant effect of adrenomedullin (AM) in rat cavernosal smooth muscle (CSM) and the expression of AM system components in this tissue. Functional assays using standard muscle bath procedures were performed in CSM isolated from male Wistar rats. Protein and mRNA levels of pre-pro-AM, calcitonin receptor-like receptor (CRLR), and Subtypes 1, 2 and 3 of the receptor activity-modifying protein (RAMP) family were assessed by Western immunoblotting and quantitative real-time polymerase chain reaction, respectively. Nitrate and 6-keto-prostaglandin F1α (6-keto-PGF1α; a stable product of prostacyclin) levels were determined using commercially available kits. Protein and mRNA of AM, CRLR, and RAMP 1, -2, and -3 were detected in rat CSM. Immunohistochemical assays demonstrated that AM and CRLR were expressed in rat CSM. AM relaxed CSM strips in a concentration-dependent manner. AM22-52, a selective antagonist for AM receptors, reduced the relaxation induced by AM. Conversely, CGRP8-37, a selective antagonist for calcitonin gene-related peptide receptors, did not affect AM-induced relaxation. Preincubation of CSM strips with NG-nitro-L-arginine-methyl-ester (L-NAME, nitric oxide synthase inhibitor), 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, quanylyl cyclase inhibitor), Rp-8-Br-PET-cGMPS (cGMP-dependent protein kinase inhibitor), SC560 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethyl pyrazole, selective cyclooxygenase-1 inhibitor], and 4-aminopyridine (voltage-dependent K+ channel blocker) reduced AM-induced relaxation. On the other hand, 7-nitroindazole (selective neuronal nitric oxide synthase inhibitor), wortmannin (phosphatidylinositol 3-kinase inhibitor), H89 (protein kinase A inhibitor), SQ22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine, adenylate cyclase inhibitor], glibenclamide (selective blocker of ATP-sensitive K+ channels), and apamin (Ca2+-activated channel blocker) did not affect AM-induced relaxation. AM increased nitrate levels and 6-keto-PGF1α in rat CSM. The major new contribution of this research is that it demonstrated expression of AM and its receptor in rat CSM. Moreover, we provided evidence that AM-induced relaxation in this tissue is mediated by AM receptors by a mechanism that involves the nitric oxide-cGMP pathway, a vasodilator prostanoid, and the opening of voltage-dependent K+ channels.

Cardiovascular effects of the intracerebroventricular injection of adrenomedullin: roles of the peripheral vasopressin and central cholinergic systems

Our objective was to investigate in conscious Sprague-Dawley (6-8 weeks, 250-300 g) female rats (N = 7 in each group) the effects of intracerebroventricularly (icv) injected adrenomedullin (ADM) on blood pressure and heart rate (HR), and to determine if ADM and calcitonin gene-related peptide (CGRP) receptors, peripheral V1 receptors or the central cholinergic system play roles in these cardiovascular effects. Blood pressure and HR were observed before and for 30 min following drug injections. The following results were obtained: 1) icv ADM (750 ng/10 µL) caused an increase in both blood pressure and HR (DMAP = 11.8 ± 2.3 mmHg and ΔHR = 39.7 ± 4.8 bpm). 2) Pretreatment with a CGRP receptor antagonist (CGRP8-37) and ADM receptor antagonist (ADM22-52) blocked the effect of central ADM on blood pressure and HR. 3) The nicotinic receptor antagonist mecamylamine (25 µg/10 µL, icv) and the muscarinic receptor antagonist atropine (5 µg/10 µL, icv) prevented the stimulating effect of ADM on blood pressure. The effect of ADM on HR was blocked only by atropine (5 µg/10 µL, icv). 4) The V1 receptor antagonist [β-mercapto-β-β-cyclopentamethylenepropionyl¹, O-me-Tyr²,Arg8]-vasopressin (V2255; 10 µg/kg), that was applied intravenously, prevented the effect of ADM on blood pressure and HR. This is the first study reporting the role of specific ADM and CGRP receptors, especially the role of nicotinic and muscarinic central cholinergic receptors and the role of peripheral V1 receptors in the increasing effects of icv ADM on blood pressure and HR.

Papel de la adrenomedulina cerebelosa en la hipertensión arterial / Paper of the adrenomedulina cerebelosa in the arterial hypertension

La adrenomedulina (AM) y el péptido relacionado con el gen de la calcitonina (CGRP) pertenecen a la superfamilia de los péptidos de CGRP. En el SNC, los sitios de unión para la AM y el CGRP se encuentran presentes en áreas hipotalámicas y en la corteza cerebelosa de la rata. La administración central de AM o de CGRP en ratas induce diuresis, natriuresis e incremento de la presión arterial. El papel de la AM en el cerebelo se desconoce. Con el fin de establecer la posible relación de la AM y CGRP cerebelosa y la regulación cardiovascular, en el presente estudio evaluamos la densidad de sitios de unión para la AM y el CGRP en el cerebelo de ratas espontáneamente hipertensas (SHR) y sus controles normotensos Wistar Kyoto (WKY) adultos de 16 semanas, mediante el uso de técnicas autoradiografícas y empleando 125I-hCGRPα y 125I-hAM13-52 como radioligandos. Los cortes coronales de cerebelo fueron incubados con 35 pM de [125I]-hCGRPα o [125I]-hAM13-52, durante 90 y 120 minutos, respectivamente. La unión no específica fue determinada en presencia de 1µM del ligando no marcado. El análisis densitométrico demostró que existe una colocalización de los sitios de unión para el [125I]-hCGRPα y la [125I]-hAM13-52 en la corteza cerebelosa. En el cerebelo la unión de la [125I]-hAM13-52 en las ratas SHR fue significativamente mayor que las WKY, indicando una mayor expresión de los receptores para la AM en el cerebelo de animales hipertensos. En relación a la unión de [125I]-hCGRPα, se observó también un pequeño incremento significativo en las ratas SHR en relación a las WKY. Con el fin de establecer la posible vía de señalización de la AM en la corteza cerebelosa, se evaluó la actividad de la óxido nítrico sintasa inducida por la AM.

Effects of CGRP on LPS-induced MMP-9 secretion by alveolar macrophages / 中国应用生理学杂志

<p><b>AIM</b>To explore the effects of calcitonin-gene-related peptide (CGRP) on LPS-induced MMP-9 secretion by alveolar macrophages (AM) in vitro.</p><p><b>METHODS</b>The supernatant of LPS-induced Wistar rat AM from different intervention groups were collected to measure the activity by gelatin zymography.</p><p><b>RESULTS</b>(Only secreting a small amount of MMP-9 with unstimulated AM, LPS stimulated MMP-9 production in a concentration-dependent manner (p < 0.01). (2) The activity of MMP-9 in CGRP intervention groups at different levels were significantly lower than those in non-intervention group (p < 0.01). (3) The inhibiting effects of CGRP were diminished by H-7 and W-7, an antagonist of protein kinase C (PKC) and calmodulin (CaM) (p < 0.05).</p><p><b>CONCLUSION</b>These data suggested that CGRP involved in the MMP-9 secretion by AM, partly, via PKC and CaM pathway.</p>

Protective effect of verapamil pretreatment against cerebral ischemia-reperfusion injury in gerbils / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the protective effect of verapamil pretreatment against cerebral ischemia-reperfusion injury in gerbils.</p><p><b>METHODS</b>Thirty-three Mongolian gerbils were randomized into the control group (group A, n=6, with sham operation), ischemia group (group B), and 3 verapamil groups (groups C, D, and E, n=7) with intraperitpneal verapamil injection (2 mg/kg) 48, 24 and 12 h before ischemia, respectively. In group A, the bilateral common carotid arteries were only exposed without clamping, and in the other 4 groups, the arteries were clamped for 20 min followed by reperfusion for 50 min. The gerbils were then decapitated and the forebrain cerebral cortex was removed to determine superoxide dismutase (SOD) and glutathione (GSH) activities and measure the contents of malondial dehyde (MDA), endothelin (ET) and calcitonin gene-related peptide (CGRP). The left forebrain cerebral cortex was sampled in each group to observe the ultrastructural changes under electron microscope.</p><p><b>RESULTS</b>In groups C and D, SOD activities were significantly higher than those in group B (P<0.05), and in group E, the SOD activity elevation was not statistically significant (P>0.05). In groups C, D and E, GSH activity was significantly higher than that in group B (P<0.05). MDA content was significantly lower in groups C and D than in group B (P<0.05), but comparable between groups E and B (P>0.05). ET content was also significantly lower in the pretreatment groups (P<0.05), but CGRP content higher (not statistically so, however) than those in group B. The more serious ultrastructural damage of the cerebral tissue was observed in group B, but only mild damage was found in the verapamil groups.</p><p><b>CONCLUSIONS</b>Verapamil given 12-48 h before cerebral ischemia may protect the gerbils from cerebral ischemia-reperfusion injury by enhancing SOD, GSH activities and decreasing ET content.</p>

Expression of Neuropeptides and Their Receptors in Psoriatic Lesions / 대한피부과학회지

BACKGROUND: Neuroimmunocutaneous system alteration can be responsible for the induction and maintenance of the inflammatory process of psoriasis. OBJECTIVE: This study was carried out to examine the expression of Substance P (SP), calcitonin gene-related peptide (CGRP), somatostatin (SOM), neutral endopeptidase (NEP), SP receptor, and CGRP receptor in psoriatic lesions. METHODS: A skin biopsy was obtained from 10 psoriatic patients and 10 normal control subjects. Confocal laser scanning microscopy was performed. RESULTS: The SP and CGRP receptors consistently increased in psoriatic lesions, compared to the normal controls. CONCLUSION: The increased expression of neuropeptides and their receptors may be involved in the pathogenesis of psoriasis.

Regulative effects of ovarian steroids on rat gastric motility and sensitivity / 生理学报

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.

Adrenomedullin reduces intracellular calcium concentration in cultured hippocampal neurons / 生理学报

The effects of adrenomedullin (ADM) on intracellular calcium concentration ([Ca(2+)](i)) were investigated in cultured hippocampal neurons. Changes in [Ca(2+)](i) were detected by laser scanning confocal microscopy using Fluo 3-AM as the calcium fluorescent probe. [Ca(2+)](i) was represented by relative fluorescent intensity. The results showed that: (1) ADM (0.01-1.0 micromol/L) decreased the resting [Ca(2+)](i) in a concentration-dependent manner. (2) Calcitonin gene-related peptide receptor antagonist CGRP(8-37) significantly inhibited the effects of ADM. (3) ADM significantly reduced the increase in [Ca(2+)](i) induced by high K(+). (4) ADM markedly inhibited the inositol 1,4,5-trisphosphate (IP(3))-induced increase in [Ca(2+)](i), while did not influence ryanodine-evoked increase in [Ca(2+)](i). These results suggest that ADM reduces [Ca(2+)](i) in cultured hippocampal neurons through suppressing Ca(2+) release from IP(3)-sensitive stores. Although ADM does not alter resting Ca(2+) influx, it significantly suppresses Ca(2+) influx activated by high K(+). These effects may be partly mediated by CGRP receptors. ADM in the CNS may act as a cytoprotective factor in ischemic/hypoxic conditions.

Peptídeo relacionado ao gene da calcitonina por iontoforese na viabilidade de retalho cutâneo randômico em ratos / Calcitonin gene-related peptide by iontophoresis on the viability of the randon skin flaps in rats

Objetivo: Investigar o efeito da administração tópica do peptídeo relacionado ao gene da calcitonina (CGRP) por iontoforese na viabilidade de retalho cutâneo randômico em ratos. Métodos: Sessenta ratos Wistar EPM-1, adultos e machos foram submetidos a retalho cutâneo randômico. Os animais foram distribuídos aleatoriamente em quatro grupos. Nos animais do grupo 1 (controle, n=15) realizou-se simulação de estímulo elétrico, no grupo 2 (iontoforese placebo, n=15) os animais foram submetidos à corrente contínua, no grupo 3 (controle de absorção, n=15) os animais receberam simulação de estímulo elétrico com CGRP e, por fim os animais do grupo 4 (tratado, n=15) foram tratados com iontoforese de CGRP. Em todos os grupos estes procedimentos foram realizados imediatamente após a técnica operatória e nos dois dias subsequentes. A porcentagem da área de necrose foi avaliada no sétimo dia de pós-operatório. Resultados: A média das porcentagens das áreas de necrose foram: grupo 1- 48 por cento, grupo 2 - 51 por cento, grupo 3 - 46 por cento e, grupo 4 - 28 por cento. A análise estatística, através do teste de Kruskal-Wallis, evidenciou diferença significante (p<0,001). Conclusão: a administração tópica de CGRP por iontoforese é eficaz em aumentar a viabilidade de retalho cutâneo randômico em ratos.

Effect of CGRP receptor antagonist CGRP8-37 on nociceptive response, NOS expression and NO content in the dorsal horn of spinal cord during formalin-induced inflammatory pain in rats / 中国应用生理学杂志

<p><b>AIM</b>To 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.</p><p><b>METHODS</b>Using 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-).</p><p><b>RESULTS</b>spontaneous 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.</p><p><b>CONCLUSION</b>The activation of CGRP receptors enhances NOS expression and NO production in the dorsal horn of the spinal cord during formalin-induced inflammatory pain.</p>

Increased atria expression of receptor activity-modifying proteins in heart failure patients / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>Receptor activity-modifying proteins (RAMPs) determine the ligand specificity of the calcitonin receptor-like receptor (CRLR); co-expression of RAMP1 and CRLR results in a calcitonin gene related peptide (CGRP) receptor, whereas the association of RAMP2 or RAMP3 with CRLR gives an adrenomedullin(ADM) receptor. As CGRP and ADM may play a beneficial role in heart failure, this study aimed at the question whether RAMPs mRNAs are changed in heart failure.</p><p><b>METHODS</b>Semi-quantitative reverse transcription-PCR (RT-PCR) was used to detect and quantify the mRNAs of RAMP1 and RAMP3 in the atria of heart failing patients.</p><p><b>RESULTS</b>It was found that the expressions of RAMP1, RAMP2 and RAMP3 mRNAs increased with the worsening of heart function, but the expressions of RAMP1 and RAMP2 mRNA decreased at level IV of heart failure.</p><p><b>CONCLUSION</b>The above results demonstrated in the atria of heart failure patients an up-regulation of CGRP receptor by an increase of RAMP1 in association with CRLR and an up-regulation of ADM receptor by an increase of RAMP2 expression in association with CRLR, thus suggesting that CGRP and ADM receptors be playing a functional role in compensating the chronic heart failure in human.</p>

Temporal and spatial distribution of VIP, CGRP and their receptors in the development of airway hyperresponsiveness in the lungs / 生理学报

To explore the role of intrapulmonary neuropeptides in the development of airway hyperresponsiveness, we established an animal model of airway hyperresponsiveness (AHR) in rabbits by using ozone exposure. With the model, after test of the mechanics of respiration and bronchoalveolar lavage assay, the levels of vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) in the lungs were determined by radioimmunoassay, and the expression of mRNA coding receptors of these two neuropeptides was evaluated by reverse transcriptional-polymerase chain reaction (RT-PCR). At the same time, the distribution of VIP receptor-1 (VIPR1) and CGRP receptor-1 (CGRPR1) in lung tissues and its time-course were examined by in situ hybridization. The results showed: (1) in ozone-stressing groups, airway resistance increased significantly and typical inflammatory pathological changes were observed in pulmonary tissue slides, including neutrophil and eosinophil infiltration, mucus exudation and bronchial epithelial cells (BECs) shedding; (2) with elongation of ozone exposure, the levels of VIP and CGRP in the lungs increased at first, reaching a peak on d 2 to 4, then decreased slowly, and CGRP peaked somewhat earlier than VIP; (3) mRNA expression of the two neuropeptide receptors in the lungs changed in a similar manner like VIP and CGRP, but the high level of mRNA expression of VIPR1 lasted longer than that of CGRPR1; and (4) in situ hybridization for neuropeptide receptors demonstrated that, in unstressed control, VIPR1 and CGRPR1 positive cells appeared in the airway epithelium, pulmonary interstitial and focal areas of airway and vascular smooth muscles. With the elongation of ozone exposure, hybridization stained deeper and the majority of positive cells were located around the vessels and bronchus except a few in the alveoli. At 8 d, only a small number of positive cells were seen in the lungs. From the results, it is concluded that ozone-stressing can induce the development of AHR, in which VIP and CGRP may play important roles. That implies, through binding to CGRPR1, CGRP stimulates an early inflammation response which contributes in cleaning up of irritants, while VIP exerts a later dampening of pulmonary inflammation response. These two neuropeptides may play sequential and complementary roles in the development of AHR.

Intracerebroventricular administration of adrenomedullin increases the expression of c-fos and activates nitric oxide-producing neurons in rat cardiovascular related brain nuclei / 生理学报

To define the action sites of adrenomedullin (ADM) in the rat brain, and to examine whether neuronal NO may participate in the actions of ADM, the present study was undertaken to examine the effects of i.c.v. administration of ADM on the induction of Fos protein and on nitric oxide-producing neurons in rat brain nuclei involved in cardiovascular regulation, using double immunohistochemical method for Fos and neuronal nitric oxide synthase (nNOS). Following i.c.v. administration of ADM (1 nmol/kg, 3 nmol/kg), Fos-like immunoreactivity neurons were markedly increased in several brain areas of the rat, including the nucleus of the solitary tract (NTS), the area postrema, the locus coeruleus, the parabrachial nucleus and the nucleus paragigantocelluaris laterialis (PGL) in the brainstem, the paraventricular nucleus (PVN), the supraoptic nucleus (SON) and the ventromedial hypothalamic nucleus in the hypothalamus, as well as the central amygdaloid nucleus and the lateral habenular nucleus in the forebrain. Following i.c.v. injection of ADM (1 nmol/kg, 3 nmol/kg), the number of double-labeled neurons for Fos and nNOS was increased in the PVN and SON. Small numbers of double-labeled neurons were also found in the NTS and PGL following i.c.v. injection of ADM (3 nmol/kg), while i.c.v. injection of ADM (1 nmol/kg) did not change the number of double-labeled neurons in the NTS and PGL. Pretreatment with calcitonin gene-related peptide receptor antagonist CGRP(8-37) (30 nmol/kg) significantly reduced the action of ADM (3 nmol/kg) in the brain. These results suggest that centrally administered ADM may increase the expression of c-fos in the forebrain, the hypothalamus and the brainstem and activate nitric oxide-producing neurons in the PVN, SON, NTS and PGL. These effects may be partly mediated by CGRP receptors.

The latest research progress on CGRP and its potential application in forensic medicine / 法医学杂志

Calcitonin gene-related peptide (CGRP) play a key role in some physiological and pathological progresses. The latest studies indicate that CGRP might involve in some disease progress and has a close relation with wound healing. It is significant to further investigate and then apply it to clinical diagnosis and therapy as well as forensic pathology.

The mechanism of gentisic acid-induced relaxation of the guinea pig isolated trachea: the role of potassium channels and vasoactive intestinal peptide receptors

We examined some of the mechanisms by which the aspirin metabolite and the naturally occurring metabolite gentisic acid induced relaxation of the guinea pig trachea in vitro. In preparations with or without epithelium and contracted by histamine, gentisic acid caused concentration-dependent and reproducible relaxation, with mean EC50 values of 18 æM and Emax of 100 percent (N = 10) or 20 æM and Emax of 92 percent (N = 10), respectively. The relaxation caused by gentisic acid was of slow onset in comparison to that caused by norepinephrine, theophylline or vasoactive intestinal peptide (VIP). The relative rank order of potency was: salbutamol 7.9 > VIP 7.0 > gentisic acid 4.7 > theophylline 3.7. Gentisic acid-induced relaxation was markedly reduced (24 + or - 7.0, 43 + or - 3.9 and 78 + or - 5.6 percent) in preparations with elevated potassium concentration in the medium (20, 40 or 80 mM, respectively). Tetraethylammonium (100 æM), a nonselective blocker of the potassium channels, partially inhibited the relaxation response to gentisic acid, while 4-AP (10 æM), a blocker of the voltage potassium channel, inhibited gentisic acid-induced relaxation by 41 + or - 12 percent. Glibenclamide (1 or 3 æM), at a concentration which markedly inhibited the relaxation induced by the opener of ATP-sensitive K+ channels, levcromakalim, had no effect on the relaxation induced by gentisic acid. Charybdotoxin (0.1 or 0.3 æM), a selective blocker of the large-conductance Ca2+-activated K+ channels, caused rightward shifts (6- and 7-fold) of the gentisic acid concentration-relaxation curve. L-N G-nitroarginine (100 æM), a NO synthase inhibitor, had no effect on the relaxant effect of gentisic acid, and caused a slight displacement to the right in the relaxant effect of the gentisic acid curve at 300 æM, while methylene blue (10 or 30 æM) or ODQ (1 æM), the inhibitors of soluble guanylate cyclase, all failed to affect gentisic acid-induced relaxation. D-P-Cl-Phe6,Leu17[VIP] (0.1 æM), a VIP receptor antagonist, significantly inhibited (37 + or - 7 percent) relaxation induced by gentisic acid, whereas CGRP (8-37) (0.1 æM), a CGRP antagonist, only slightly enhanced the action of gentisic acid.

Effect of Antiandrogen on Calcitonin Gene-related Peptide Receptor of the Rat Gubernaculum / 대한비뇨기과학회지

PURPOSE: We attempted to investigate whether calcitonin gene-related peptide binding to receptors in the gubernaculum is different between normal and flutamide-treated rats or pups and whether calcitonin gene-related peptide(CGRP) binding is androgen dependent. MATERIALS AND METHODS: Timed pregnant Sprague Dawley rats were injected with flutamide or vehicle alone once daily on gestational days 15-19. Weight, anogenital distance and distance from testicle to symphisis pubis of pups of gestational day 20 and rats of neonatal day 1 and 7 were measured. Gubernacular sections from rats of neonatal day 7 were incubated with [125I]human CGRP with various concentrations of unlabeled hCGRP, and those from pups of gestational day 20 and rats of neonatal day 1 were incubated only with [125I]human CGRP. After exposure of gubernacular sections to imaging plate (BAS 2500), the images from the plate were quantified by computerized densitometry (TINA). RESULTS: Weight and anogenital distance of flutamide-treated pups or neonatal rats were significantly smaller and shorter than those of normal pups or neonatal rats (P< 0.01). Though the distance from testicle to symphisis pubis was not significantly different between normal and flutamide-treated pups or neonatal 1 day rats, that of flutamide-treated neonatal 7 day rats was significantly longer than that of normal neonatal 7 day rats (P< 0.01). The total binding counts of [125I]human CGRP on gubernacular sections of normal pups, neonatal 1 day rats and neonatal 7 day rats were 56.3 +/- 24.74, 68.2 +/- 24.90, 78.4 +/- 17.25 (dpm/mg polymer), respectively, and those of flutamide- treated pups, neonatal 1 day rats and neonatal 7 day rats were 43.7 +/- 12.54, 35.1 +/- 8.25, 57.5 +/- 16.27, respectively. There were significant differences between normal and flutamide-treated neonatal 1 day and 7 day rats (P< 0.01). The binding in normal rats was consistently increased from gestational day 20 to neonatal day 7, and it showed weak correlation (r = 0.398, P< 0.05). The binding analysis showed that concentrations of CGRP receptors were 20.0+/- 4.78 amol/mg polymer, 13.3 +/- 3.87 amol/mg polymer for normal and flutamide treated neonatal 7 day rats, respectively, and there was significant difference between normal and flutamide-treated rats (P< 0.01). However there was no significant difference in the dissociation constant between 2 models. The images from the plate in flutamide-treated neonatal 7 day rats looked smaller than those in normal 7 day rats. CONCLUSIONS: These results suggest that the inguinoscrotal descent of testicle occurs after the gubernacular eversion, CGRP binding in the gubernaculum is androgen dependent, and androgen may not influence CGRP release from genitofemoral nerve because of down regulation of CGRP receptor by antiandrogen. However, the role of CGRP in testicular descent is still obscure and the mechanism of down regulation of CGRP receptor by antiandrogen needs further investigation

Chronotropic, inotropic and lusitropic effects of capsaicin on isolated rat Atria

This work includes results on chronotropic, inotropic and lusitropic changes induced by capsaicin on isolated rat atria. As regards spontaneous frequency, it was stimulated from 10(-9) M up to 7 x 10(-7) M of capsaicin. A simultaneous depression in developed force (F) showed a signigicant correlation with this positive chronotropic effect up to 7 X 10(-8) M of capsaicin, which is the result of the negative staircase phenomenon in the rat heart. The correlation was lost at 2 and 7 x 10(-7) M of capsaicin since in spite of the sustained increase in atrial rate the decrease in F was reversed and then depressed again at 2 and 7x 10(-6) M of capsaicin without changes in frequency. A concentration of capsaicin that overcome the negative staircase phenomenon, 5 x 10(-7) M, was tested as unique dose resulting in stimulation of the chronotropic, inotropic and lusitropic states of the atria. Percentual differences with respect to control values were maximal after 1-3 minutes for frequency (10+3 per cent), F (29+4 per cent), maximal velocity of force development (+F=50+12 per cent) (in all cases +F and -F,bold indicates +F and -F, respectively) and maximal velocity of relaxation (-F=64+13 per cent); a positive lusitropic effect was significant after 8-10 minutes (+F/-F=-17+7 per cent). Capsaicin did not affect the rat atria in the presence of 10(-6) M of ruthenium red, a blocker of capsaicin activation of sensory nerves, indicating that the stimulatory effects were entirely mediated by the release of neurotransmitters and that this concentration of capsaicin was not deleterous "per se". Capsaicin elicited similar inotropic responses in electrically driven isolated atria (+F=41+9 per cent) but the positive lusitropic effect was lost suggesting that capsaicin-induced increases in -F are limited at a frequency higher than the spontaneous frequency (11+6 vs. 32+4 per cent, respectively). 10(-6) M of CGRP8(-37), an antagonist of CGRP1 receptors, suppress the stimulatory effects of capsaicin on atrial contraction. In summary, atrial rate as compared to atrial contraction is more sensitive to the neurotransmitter released by capsaicin, which results in mechanical effects expressing the negative staircase phenomenon in the rat at low concentrations of capsaicin. The positive chronotropic, inotropic and lusitropic responses elicited by capsaicin are mediated by the reelease of neurotransmitters from sensory fibbers and no deletereous effects...