Peptide-like Immunoreactivity Research Articles

Ureteral relaxation through calcitonin gene-related peptide release from sensory nerve terminals by hypotonic solution.

To evaluate the influence of hypotonic solutions on ureteral relaxation mediated by the release of calcitonin gene-related peptide from intramural sensory nerve endings. Urine osmolarity of Sprague-Dawley rats drinking water low in salt content (Fiuggi water) or a reference water for 7 days was measured. Release of calcitonin gene-related peptide-like immunoreactivity from slices of rat ureter and urinary bladder by hypotonic solutions was assessed by an immunometric assay. The mechanism through which hypotonic solutions inhibit neurokinin A-induced phasic contractions of isolated rat ureters was evaluated by organ bath studies. A 7-day consumption of Fiuggi water in rats reduced urine osmolarity by ~40%. Exposure to hypotonic solutions released calcitonin gene-related peptide-like immunoreactivity from slices of rat ureter. This response was abated in a calcium-free medium, after capsaicin desensitization, and in the presence of the unselective transient receptor potential channel antagonist, ruthenium red. Exposure of isolated rat ureteral preparations to a hypotonic solution inhibited neurokinin A-evoked phasic contraction. This response was attenuated by capsaicin desensitization and in the presence of the calcitonin gene-related peptide receptor antagonist, calcitonin gene-related peptide8-37 . Transient receptor potential vanilloid 1 or transient receptor potential vanilloid 4 antagonists did not affect the neurogenic and calcitonin gene-related peptide-dependent relaxation. Present data show that hypotonic solution evokes calcitonin gene-related peptide release from capsaicin-sensitive intramural sensory nerves, thus inhibiting ureteral contractility, through a transient receptor potential-dependent mechanism. However, this mechanism does not involve transient receptor potential vanilloid 1 or transient receptor potential vanilloid 4. Future studies with appropriate in vivo models should investigate the hypothesis that hypostenuric urine diffusing into the ureteral tissue might favor ureteral relaxation through this novel mechanism.

Neuropeptide levels in Dercum's disease (adiposis dolorosa)

Dercum's disease (adiposis dolorosa) is characterised by adiposity and chronic pain in the adipose tissue. It has been proposed that conditions encompassing chronic pain have altered concentrations of neuropeptides involved in pain transmission. The aim of this investigation was to examine whether patients with Dercum's disease have abnormal concentrations of different neuropeptides. In cerebrospinal fluid (CSF) and in plasma (P) from 53 patients with Dercum's disease substance P-like immunoreactivity (SP-LI), neuropeptide Y-like immunoreactivity (NPY-LI), β-endorphin-like immunoreactivity (β-END-LI), calcitonin gene-related peptidelike immunoreactivity (CGRP-LI), met-enkephalin-like immunoreactivity (m-ENK-LI), vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI), somatostatin (SOM-LI), γ2-melanocyte-stimulating hormone-like immunoreactivity (γ2-MSH-LI), and dynorphin-like immunoreactivity (DYN-LI) were measured. Three of the substances were also measured in a control group. The CSF concentration of SP was statistically significantly lower in the Dercum group than in the control group, whereas NPY-LI and b-END-LI were borderline statistically significantly lower and higher, respectively, in Dercum patients compared to controls. Compared with reference values, CSF-MSH-LI levels were slightly elevated and CSF-NPY-LI levels were slightly lowered in the Dercum group. The other substances in both CSF and plasma were within the reference values with a high degree of statistical significance. In conclusion, altered levels of neuropeptides that have previously been seen in different pain conditions cannot clearly be demonstrated in Dercum's disease.

Exercise-induced increase in plasma concentrations of calcitonin gene-related peptide in patients with coronary heart disease and healthy controls

Calcitonin gene-related peptide is a potent regulator of vascular tone. In the present study the authors investigated plasma levels of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) during maximum bicycle exercise in 8 patients with coronary heart disease (CHD) and in a control group of 11 healthy volunteers. There was no significant difference in CGRP-LI baseline concentrations between patients with CHD and controls. During exercise a significant increase in CGRP-LI was observed in both groups, as compared with baseline values. Although maximum CGRP-LI values did not differ significantly between the two groups, the increase in CGRP-LI was found at a much-lower work load (p=0.0006) in patients with CHD.

Prejunctional control of pH 6-induced bronchoconstriction by NK1, NK2, mu-opioid, alpha2-adrenoceptor and glucocorticoid receptors in guinea-pig isolated perfused lung.

This study investigated the release of calcitonin-gene related peptide-like (CGRP) immunoreactivity and bronchoconstriction induced by pH 6 buffer in guinea-pig isolated perfused lung. Both pH 6-induced CGRP-like immunoreactivity and bronchoconstriction were completely abolished after systemic pretreatment with capsaicin. Pretreatment with the NK2 receptor antagonist SR 48968 (5 x 10(-7)M) completely inhibited bronchoconstriction and significantly reduced the immunoreactivity induced by the pH 6 buffer. The NK1 antagonist SR 140333 (5 x 10(-7)M) and, to a lesser extent the NK1 antagonist CP 96345, morphine (5 x 10(-6)M), the alpha2-adrenoceptor agonist UK 14304 (10(-7)M) and betamethasone (10(-6)M) significantly reduced both pH 6-induced bronchial response and CGRP-like immunoreactivity overflow. The effects of morphine and UK14304 were partially reversed by naloxone (5 x 10(-5)M) and idazoxan (5 x 10(-50M). Therefore, NK1, NK2, mu-opioid, alpha2-adrenoceptor and glucocorticoid receptors seemed to have a prejunctional action on pH 6 buffer-induced CGRP-like immunoreactivity and bronchoconstriction.

Participation of the spinal TRPV1 receptors in formalin-evoked pain transduction: a study using a selective TRPV1 antagonist, iodo-resiniferatoxin

The involvement of spinal transient receptor potential vanilloid 1 (TRPV1) in formalin-evoked pain has remained unclear, because investigation of this kind of pain with selective antagonists has not been conducted. The purpose of this study is to investigate the participation of spinal TRPV1 in formalin-evoked pain with iodo-resiniferatoxin (I-RTX), a potent TRPV1-selective antagonist. I-RTX given intrathecally dose-dependently and significantly decreased the number of flinching responses in the formalin-evoked 1st and 2nd phase with ID50 values (drug dose producing 50% inhibition of response) of 1.0 and 3.8 microg, respectively, and concentration-dependently suppressed capsaicin-evoked calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) release from rat spinal cord slices with an IC50 value (drug concentration producing 50% inhibition of response) of 86 nM. Capsazepine, a classical non-selective TRPV1 antagonist, given intrathecally also inhibited formalin-evoked flinching in both the 1st and 2nd phase with ID50s of 420 and 200 microg, respectively, and CGRP-LI release from rat spinal cord slices with an IC50 of 7.8 microM. Ratios of in-vivo analgesic potencies of I-RTX and capsazepine well reflected their intrinsic in-vitro activity. These findings suggest that spinal TRPV1 participates in the transduction system of formalin-evoked pain.

Modulation of Capsaicin-Sensitive Nerve Activation by Low pH Solutions in Guinea-Pig Lung

We have studied the stimulation of airways sensory nerves by low pH solutions and concomitantly induced bronchoconstriction. The effect of low pH buffer and lactic acid solutions at the same pH (5 and 6) were compared and the influence of low pH on the capsaicin effect was recorded. We have used the isolated guinea-pig perfused lung model taking the insufflation pressure as an indicator of bronchial smooth muscle tone while the calcitonin gene-related peptide-like immunoreactivity measured in the lung perfusate represented sensory nerves activation. Low pH buffer and lactic acid solution (3 and 4.1 mM) at the same pH of 5 and 6 induced pH-dependent bronchoconstriction and peptides release which were completely abolished after systemic pretreatment with capsaicin. Both responses were significantly inhibited after Ca2+-free infusion. Capsazepine (10(-6) M), a selective capsaicin antagonist, significantly reduced the calcitonin gene-related peptide-like immunoreactivity overflow evoked by all the solutions studied. Diclofenac (10(-5) M), a cyclooxygenase blocker, inhibited pH 5, pH 6 and lactic acid 3 mM (pH 6)-evoked peptide release, but not lactic acid 4.1 mM (pH 5). The functional response was not significantly modified after diclofenac while only the lactic acid 3 mM response was significantly reduced by capsazepine. There was a synergistic interaction between capsaicin and low pH buffer on calcitonin gene-related peptide-like immunoreactivity release and an additive effect on bronchoconstriction. It is concluded that in the isolated perfused guinea-pig lung, lactic acid and low pH buffer induced calcitonin gene-related peptide-like immunoreactivity release and bronchoconstriction by stimulation of capsaicin-sensitive C fibres via a pathway partly dependent of extracellular Ca2+. The mechanism of calcitonin gene-related peptide-like immunoreactivity release seems to be the same at pH 6, while differences are evident at pH 5 between low pH buffer and lactic acid. Our results also suggest that proton activity could exert a modulatory role on the capsaicin-sensitive sensory nerves by a mechanism which remains to be clarified.

Reduced orexin levels in the cerebrospinal fluid of suicidal patients with major depressive disorder

Orexins are neuropeptides selectively expressed in a small number of neurons in the lateral–posterior hypothalamus. We measured orexin-A in the cerebrospinal fluid (CSF) of 66 patients with major depressive disorder (MDD), dysthymia and adjustment disorder after a suicide attempt. Blood samples confirmed that the patients were free from antidepressive and neuroleptic medication at the time of the lumbar punctures. CSF levels of orexin-A were significantly lower in patients with MDD than in patients with adjustment disorder and dysthymia. Orexin correlated significantly with CSF levels of somatostatin, delta sleep inducing peptide-like immunoreactivity (DSIP-LI) and corticotrophin releasing factor (CRF), but not with leptin or vasopressin. Plasma levels of thyroid-stimulating hormone (TSH) were not reduced in MDD patients, and did not correlate with CSF-orexin. Our results suggest that suicidal patients with MDD have distinct neurobiological features, involving compromised levels of hypothalamic peptides regulating the state of arousal.

Autonomic Control Network Active inAplysiaDuring Locomotion Includes Neurons That Express Splice Variants of R15-Neuropeptides

Splice-variant products of the R15 neuropeptide gene are differentially expressed within the CNS of Aplysia. The goal of this study was to test whether the neurons in the abdominal ganglion that express the peptides encoded by this gene are part of a common circuit. Expression of R15 peptides had been demonstrated previously in neuron R15. Using a combination of immunocytochemical and analytical methods, this study demonstrated that R15 peptides are also expressed in heart exciter neuron RB(HE), the two L9(G) gill motoneurons, and L40--a newly identified interneuron. Mass spectrometric profiling of individual neurons that exhibit R15 peptide-like immunoreactivity confirmed the mutually exclusive expression of two splice-variant forms of R15 peptides in different neurons. The L9(G) cells were found to co-express pedal peptide in addition to the R15 peptides. The R15 peptide-expressing neurons examined here were shown to be part of an autonomic control circuit that is active during fictive locomotion. Activity in this circuit contributes to implementing a central command that may help to coordinate autonomic activity with escape locomotion. Chronic extracellular nerve recording was used to determine the activity patterns of a subset of neurons of this circuit in vivo. These results demonstrate the potential utility of using shared patterns of neuropeptide expression as a guide for neural circuit identification.

Innervation and functional changes in mesenteric perivascular calcitonin gene-related peptide- and neuropeptide Y-containing nerves following topical phenol treatment

We have previously shown that age-related reduction of innervation and function in mesenteric perivascular calcitonin gene-related peptide-containing vasodilator nerves takes place in spontaneously hypertensive rats. The present study was performed to investigate innervation and functional changes in perivascular calcitonin gene-related peptide- and adrenergic neuropeptide Y-containing nerves after topical treatment with phenol, which damages nerve fibers, around the rat superior mesenteric artery. Under pentobarbital-Na anesthesia, 8-week-old Wistar rats underwent in vivo topical application of phenol (10% phenol in 90% ethanol) or saline (sham rats) to the superior mesenteric artery proximal to the bifurcation of the abdominal aorta. After the treatment, the animals were subjected to immunohistochemistry of the 3rd branch of small arteries proximal to the intestine and to vascular responsiveness testing on day 3 through day 14. The innervation levels of calcitonin gene-related peptide-like immunoreactivity containing fibers and neuropeptide Y-like immunoreactivity containing fibers were markedly reduced on day 3 to day 14 and on day 5 to day 14 after the treatment, compared with those in sham-operated rats, respectively. In perfused mesenteric vascular beds isolated from phenol-treated rats, adrenergic nerve-mediated vasoconstriction and calcitonin gene-related peptide nerve-mediated vasodilation in response to periarterial nerve stimulation (2–12 Hz) were significantly decreased on day 3 and day 7. Neurogenic release of norepinephrine in phenol-treated rats on day 7 was significantly smaller that that in sham-operated rats. Nerve growth factor content in the mesenteric arteries of phenol-treated rats was significantly lower than that in sham-operated rats. Administration of nerve growth factor using osmotic mini-pumps for 7 days after the phenol treatment resulted in greater density of calcitonin gene-related peptide- and neuropeptide Y-like immunoreactivity fibers than in phenol-treated rats and restored decreased vascular responses to periarterial nerve stimulation. These results suggest that topical phenol-treatment of the mesenteric artery effectively induces functional denervation of perivascular nerves, which can be prevented or reversed by nerve growth factor treatment.

Involvement of an increased spinal TRPV1 sensitization through its up-regulation in mechanical allodynia of CCI rats

Vanilloid receptor 1 (TRPV1) antagonists are known to attenuate the neuropathic pain symptoms in peripheral nerve injury models, but the mechanism(s) of their effect remains unclear. At the same time, the role of spinal TRPV1 in pain transduction system has not been fully understood. In this study, the role of spinal TRPV1 in mechanical allodynia in rat chronic constriction injury (CCI) model was investigated. Intrathecal administration of a selective TRPV1 antagonist, N-(4-tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropryazine-1(2H)-carbox-amide (BCTC) significantly attenuated mechanical allodynia in CCI rats at 100 and 300 nmol. In vitro, BCTC inhibited capsaicin (300 nM)-induced releases of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and substance P-like immunoreactivity (SP-LI) from the rat spinal cord slice preparations with IC 50s of 37.0 and 36.0 nM, respectively, confirming that BCTC potently inhibits TRPV1 function in the rat spinal cord. TRPV1 expression levels in the spinal cord following CCI were quantified in by Western blot analysis. TRPV1 protein levels were significantly increased in the ipsilateral side of the lumbar spinal cord at 7 and 14 days following CCI surgery, but not in the contralateral side. Furthermore, capsaicin (300 nM)-evoked release of CGRP-LI was significantly higher in the ipsilateral spinal cord of CCI rats (14 days after surgery) than that of sham-operated rats. These findings suggest that an increased sensitization of the spinal TRPV1 through its up-regulation is involved in the development and/or maintenance of mechanical allodynia in rat CCI model.

Dendroaspis Natriuretic Peptide Induces the Apoptosis of Cardiac Muscle Cells

Early heart failure is characterized by elevated plasma Dendroaspis natriuretic peptide-like immunoreactivity (DNP-LI). However, the direct effects of DNP on heart or the heart-associated cell system are not well known. Therefore, we investigated whether DNP induces the apoptosis of H9c2 cardiac muscle cells. H9c2 cardiac muscle cells and rat neonatal cardiomyocytes were treated with various concentrations of DNP. Cell viability and nuclear morphology change were determined by trypan blue staining and Hoechst 33258 staining, respectively. Caspase-3-like activity was measured using specific fluorogenic substrates. Pro-and antiapoptotic proteins were assayed by Western blotting. DNP induced the apoptosis of H9c2 cardiac muscle cells in a dose-dependent manner. Maximum effects occurred at 100 nM concentration of DNP, with a 7–8-fold increase in apoptotic cells, to reach a maximum apoptotic index of 17%. We also identified that H9c2 cardiac muscle cells expressed Natriuretic peptide reactor -A and -B, which respond to DNP to generate cGMP. The treatment with DNP also markedly reduced levels of Bcl-2, inhibitor of apoptosis protein-1, and inhibitor of apoptosis protein-2 and increased the level of Bax and cytochrome c release into cytoplasm and subsequent caspase-3 activation, which co-occurred with increased apoptosis. DNP-induced apoptosis was mediated by cyclic GMP, and this effect was mimicked by dibutylyl-cGMP (30 µM), a membrane permeable analog of cGMP. Furthermore, DNP-induced apoptosis was observed in rat neonatal cardiomyocytes. These results suggestthat DNP induces the apoptosis of H9c2 cardiac muscle cells and of cardiomyocytes via cGMP and demonstrate that the operative mechanism includes the regulation of Bcl-2 family proteins.

Dendroaspis Natriuretic Peptide Induces the Apoptosis of Cardiac Muscle Cells

Early heart failure is characterized by elevated plasma Dendroaspis natriuretic peptide-like immunoreactivity (DNP-LI). However, the direct effects of DNP on heart or the heart-associated cell system are not well known. Therefore, we investigated whether DNP induces the apoptosis of H9c2 cardiac muscle cells. H9c2 cardiac muscle cells and rat neonatal cardiomyocytes were treated with various concentrations of DNP. Cell viability and nuclear morphology change were determined by trypan blue staining and Hoechst 33258 staining, respectively. Caspase-3-like activity was measured using specific fluorogenic substrates. Pro-and antiapoptotic proteins were assayed by Western blotting. DNP induced the apoptosis of H9c2 cardiac muscle cells in a dose-dependent manner. Maximum effects occurred at 100 nM concentration of DNP, with a 7–8-fold increase in apoptotic cells, to reach a maximum apoptotic index of 17%. We also identified that H9c2 cardiac muscle cells expressed Natriuretic peptide reactor -A and -B, which respond to DNP to generate cGMP. The treatment with DNP also markedly reduced levels of Bcl-2, inhibitor of apoptosis protein-1, and inhibitor of apoptosis protein-2 and increased the level of Bax and cytochrome c release into cytoplasm and subsequent caspase-3 activation, which co-occurred with increased apoptosis. DNP-induced apoptosis was mediated by cyclic GMP, and this effect was mimicked by dibutylyl-cGMP (30 µM), a membrane permeable analog of cGMP. Furthermore, DNP-induced apoptosis was observed in rat neonatal cardiomyocytes. These results suggestthat DNP induces the apoptosis of H9c2 cardiac muscle cells and of cardiomyocytes via cGMP and demonstrate that the operative mechanism includes the regulation of Bcl-2 family proteins.

A model of periodontitis in the rat: effect of lipopolysaccharide on bone resorption, osteoclast activity, and local peptidergic innervation.

To establish and characterise a rat model of periodontitis that reiterates the features of human disease. Periodontal inflammation was induced by a single injection of 10 microg liposaccharide (LPS) (Salmonella typhimurium) in 1 microl saline into rat mandibular gingiva at the buccomesial aspect of the second molar. Animals were killed after 3, 7 and 10 days, mandibles dissected and sectioned for histological and immunocytochemical analysis. LPS injection resulted in a significant gingival and periodontal inflammation with inflammatory infiltrate, apical migration of the junctional epithelium, interdental bone loss, and activation of osteoclasts at the site of injection 7 and 10 days after injection. At 10 days post injection, there was a significant trend for bone loss on both sides of the mandible. Periodontal inflammation was associated with alteration in the levels of calcitonin gene-related peptide-like immunoreactivity in nerve terminals innervating the inflamed gingival papilla. Intragingival injection of LPS in the rat provides an easily induced reproducible experimental model of periodontal inflammation that reiterates features of human disease.

The presence of Drosophila melanogaster sex peptide-like immunoreactivity in the accessory glands of male Helicoverpa armigera

In this study a highly specific polyclonal antibody to DrmSP was produced and used to develop and standardize a sensitive direct ELISA. Structure–activity studies revealed that the antiserum is specific to the N-terminal of DrmSP. This ELISA was used for the detection of DrmSP-like immunoreactivity in the reproductive tissues of male Helicoverpa armigera moths at femtomole levels. Two positive immunoreactive peaks were found in HPLC purified extracts of male accessory glands. The immunoreactive peak, which contained a higher amount of immunoreactivity, was also found to be pheromonostatic in PBAN-injected decapitated females as well as in intact female moths during their peak pheromone production. Lower levels of DrmSP-like immunoreactivity were found in younger males (1–2 day-old) when compared to older males (3–7 day-old).

HCaRG is a novel regulator of renal epithelial cell growth and differentiation causing G2M arrest.

We recently identified a novel calcium-regulated gene, HCaRG, that is highly expressed in the kidney and maps to a chromosomal locus determining kidney weight in rats. The mRNA levels of HCaRG negatively correlate with the proliferative status of the kidney cells. To investigate its role in renal epithelial cellular growth directly, we studied the human embryonic kidney cell line (HEK-293) stably transfected with either plasmid alone or plasmid containing rat HCaRG. [(3)H]thymidine incorporation was significantly lower in HCaRG clones. Although HCaRG clones exhibited some enhanced susceptibility to cell death, this was not the primary mechanism of reduced proliferation. Cell cycle analysis revealed a G(2)M phase accumulation in HCaRG clones that was associated with upregulation of p21(Cip1/WAF1) and downregulation of p27(Kip1). HCaRG clones had a greater protein content, larger cell size, and released 4.5- to 8-fold more of an atrial natriuretic peptide-like immunoreactivity compared with controls. In addition, HCaRG clones demonstrated the presence of differentiated junctions and a lower incidence of mitotic figures. Genistein treatment of wild-type HEK-293 cells mimicked several phenotypic characteristics associated with HCaRG overexpresssion, including increased cell size and increased release of atrial natriuretic peptide. Taken together, our results suggest that HCaRG is a regulator of renal epithelial cell growth and differentiation causing G(2)M cell cycle arrest.

C-fiber modulation of the rat type I slowly adapting mechanoreceptor

Effects of C-fiber activation on type I slowly adapting mechanoreceptor responses were investigated in a rat in vitro nerve–skin preparation using controlled mechanical stimuli. Two changes in behavior were evoked by antidromic C-fiber stimulation: (1) The type I response to mechanical stimuli was modulated in a graded fashion by antidromic C-fiber activation. The average decrease in mechanoresponse from baseline discharge was 53% at 20-Hz, 51% at 5-Hz, and 30% at 1-Hz stimulation rate. The type I response recovered to baseline levels following termination of antidromic electrical stimulation. (2) Antidromic C-fiber activation generated a spontaneous ongoing activity in many skin units; this was independent of mechanical stimulation and outlasted electrical stimulation. The fact that neither antidromic electrical stimulation of the crushed nerve trunk nor selective A-fiber activation elicited these reactions suggests that they were mediated via action potentials of slowly conducting (C-fiber) axons. Immunohistochemical staining revealed both substance P- and calcitonin gene-related peptide-like immunoreactivity in small unmyelinated nerve fibers entering the touch dome. These results support the concepts that (1) the type I slowly adapting mechanoreceptor in rat receives input from nociceptive terminals within the touch dome. (2) The function of type I slowly adapting mechanoreceptors is modulated by axon reflex activation of nociceptor terminals, which may play a role in altering the type I response during states of mechanical allodynia and have paracrine and autocrine influences on maintenance of touch dome structure.

The naris muscles in tiger salamander. II. Innervation as revealed by enzyme histochemistry and immunocytochemistry.

The naris muscles control the aperature of the external naris in tiger salamanders, Ambystoma tigrinum, and may contribute to glandular secretion. Autonomic neurons of the palatine ganglion and possibly neurons associated with the nervus terminalis innervate these muscles. To elucidate the neural control of the naris muscles, neurotransmitters in nerve fibers supplying the naris muscles and in neurons of the palatine ganglion were examined using acetylcholinesterase enzyme histochemistry and immunocytochemistry to visualize possible peptide candidates for muscle innervation. The naris muscles, autonomic neurons, and associated nerve fascicles demonstrated strong acetylcholinesterase labeling, and the muscles were innervated by substance P fibers passing through the palatine ganglion from the trigeminal ganglion. Gonadotropin-releasing hormone and molluscan cardioexcitatory peptide-like immunoreactivities were found in secretory cell bodies and/or fibers in the palatine ganglion, and gonadotropin-releasing hormone was found in fiber projection pathways into the muscles. Vasoactive intestinal peptide was found in cell bodies and fibers of the palatine ganglion but appeared to provide a sparse innervation to the naris dilator muscle only. These findings suggest a typical autonomic cholinergic and sensory innervation of the naris muscles with some variations in peptide innervation. The presence of gonadotropin-releasing hormone in palatine ganglion and naris constrictor muscle suggests a potential modulation of autonomic neurons and perhaps even muscle fibers by this neuropeptide. We hypothesize that this reproductive hormone may modulate the activity of the naris constrictor muscle during reproductively appropriate events in order to provide access of pheromones to the vomeronasal organ.

Dendroaspis natriuretic peptide-like immunoreactivity and its regulation in rat aortic vascular smooth muscle

Dendroaspis natriuretic peptide (DNP) is a recently isolated 38 amino acid peptide that shares structural and functional properties with the other members of the natriuretic peptide family. The present study demonstrates the presence of DNP-like immunoreactivity in sections of rat aorta, carotid artery and renal vasculature and tubules. DNP-like immunoreactivity was detected in culture aortic vascular smooth muscle cells and medium and is regulated by endothelin-1, angiotensin II and sodium nitroprusside but not by transforming growth factor-β. Our observations indicate that DNP elicits a marked inhibitory effect on DNA synthesis in culture rat aortic vascular smooth muscle cells.

Calcitonin gene-related peptide and calcitonin in the CSF of patients with dementia and depression: Possible disease markers

Cerebrospinal fluid (CSF) was obtained from 32 patients with dementia, 19 healthy controls that were age-matched with the dementia patients, and 29 DSM-IV major depression patients and calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and calcitonin-like immunoreactivity (CT-LI) measured by RIA. CGRP-LI was lower in the dementia group compared to both the controls and depressed patients ( P<.01) after covarying out sex and age. CT-LI was decreased in the dementia and depressed patients ( P<.05) compared to the controls. A positive relationship between CGRP-LI and CT-LI was found in dementia. A logistic discriminant analysis with calcitonin gene-related peptide (CGRP) and log calcitonin (CT) predicting diagnosis (three classes) revealed a significant overall fit ( χ 2=18.08, P=.0011), with an effect test showing contributions of both independent variables: CGRP ( χ 2=10.03, P<.007), log CT ( χ 2=8.63, P=.013). In dementia, both CGRP-LI and CT-LI were decreased and their concentration ratio did not differ from that in controls, likely reflecting a general neuronal loss. Alternatively and more speculatively, but theoretically possible, expression of the α-CGRP/CT gene may be affected in dementia. In contrast, in depression, CT-LI but not CGRP-LI was decreased and the CGRP/CT concentration ratio was increased, which is consistent with a possibility of an altered splicing process favoring CGRP mRNA.

Atrial Natriuretic Peptide-like Immunoreactivity in Neurons and Astrocytes of Human Cerebellum and Inferior Olivary Complex

Atrial natriuretic peptide (ANP) has previously been localized in areas of mammalian brain associated with olfaction, cardiovascular function, and fluid/electrolyte homeostasis. Despite the presence of several types of natriuretic peptide receptors in mammalian cerebellum, neither intrinsic nor extrinsic sources of the natriuretic peptides have been described. In this report we describe the immunohistochemical localization of both intrinsic and extrinsic sources for ANP in human cerebellum. ANP-like immunoreactivity (ANP-LIR) was observed in climbing fibers in the cerebellar molecular layer that probably originated from isolated immunopositive neurons of the inferior olivary complex. Intrinsic sources of ANP-LIR included small subpopulations of protoplasmic and fibrous astrocytes and Bergmann glia, as well as Golgi and Lugaro neurons of the granule cell layer. These results suggest that, in addition to its presumptive roles in local vasoregulation, ANP may serve as a modulator of the activity of Purkinje neurons.