Effects of neuropeptides on growth of cultivated rat molar pulp fibroblasts

The effect of the neuropeptides substance P (SP), neurokinin A (NKA), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) on DNA synthesis of dental pulp cells was investigated in cells grown from molar tooth bud explants from 4–6 days old rat pups. A concentration response-assay of the proliferative response of pulpal cells was performed with SP, NPY, NKA, CGRP and VIP (0.01 to 1 nM) in the presence of EGF (10 ng/ml), hydrocortisone (0.4 μg/ml) and 3% FCS, using [³H]thymidine incorporation. The results showed that SP, NKA and CGRP, but not NPY and VIP, increased the cell number in a concentration-dependent manner, with maxima at 10⁻¹⁰ – 10⁻⁹ M (SP, NKA) and 10⁻⁷ M (CGRP). No potentiating effect was noted when cells are simultaneously stimulated with SP and CGRP. The finding that SP, NKA and CGRP have growth regulatory properties on pulpal cells in vitro suggests that sensory neuropeptides may be involved during pulpal development or in wound healing after pulpal injury.     

Monosodium glutamate exposure in the neonate alters hypothalamic and pituitary neuropeptide levels in the adult

Administration of monosodium glutamate (MSG) during the neonatal period in rats produced differential effects on the contents of various neuropeptides in the hypothalamus: beta-endorphin (beta-E) level was reduced by 70% while substance P (SP), neurotensin (NT) and Met5-enkephalin (ME) levels were not significantly changed (ME content of male rats was slightly reduced). The contents of ME, SP and NT in striatum and hippocampus were also unaffected by the same treatment. Male rats contain higher pituitary content of beta-endorphin-like immunoreactivity (beta-ELI) than female rats. MSG treatment reduced the pituitary content of beta-ELI and abolished the sex difference in beta-ELI level seen in the control rats. MSG treatment in the neonates by eliminating beta-E neurons while sparing ME neurons in the brain may be a useful tool for studying the different functions of these two separate opioid peptides.     

Progesterone and norethisterone have different effects on tachykinin-like immunoreactivity in rat cortex and striatum

OBJECTIVE: The purpose of this study was to investigate the effects of progesterone and the most commonly prescribed synthetic progestogen, norethisterone, on regional immune-like reactivity of neuropeptide Y (NPY), substance P (SP), neurokinin A (NKA) and neurotensin (NT) in brains of female ovariectomized estradiol-substituted rats. Results: Norethisterone+estradiol-treated rats had 44% lower SP levels compared with estradiol-only-treated in frontal cortex and 20% lower NKA levels in comparison with progesterone+estradiol-treated in frontal cortex. Progesterone+estradiol-treated rats had 66% lower SP levels in striatum in comparison with both estradiol-only-treated and norethisterone+estradiol-treated. No significant results were found for NPY and NT. CONCLUSION: Progesterone and the synthetic progestogen, norethisterone, have different effects on SP- and NKA-like immunoreactivity in rat cortex and striatum.The effects of NET on SP- and NKA-like immunoreactivity in frontal cortex may contribute to the mood effects ascribed to this progestogen in clinical usage.     

Distribution of immunoreactive neuropeptides in the pancreas of the bullfrog,Rana catesbeiana,demonstrated by immunofluorescence

Indirect double immunofluorescence labelling for eight neuropeptides in the pancreas of the bullfrog, Rana catesbeiana, demonstrated the occurrence, distribution, and coexistence of certain neuropeptides in the exocrine and endocrine pancreas. Immunoreactivity of substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), FMRFamide (FMRF), and galanin (GAL) was localized in nerve fibers distributed between the acini and around the duct system and vasculature of the exocrine pancreas. In these regions, CGRP-immunoreactive fibers were more numerous than those containing the other five peptides. Almost all SP fibers showed coexistence of SP with CGRP, and about one third of fibers also showed coexistence of SP with VIP, NPY, FMRF, and GAL. In the endocrine pancreas, SP, CGRP, VIP, and GAL were recognized in the nerve fibers around and within the islets of Langerhans, and VIP and GAL fibers were more numerous than SP and CGRP fibers. All CGRP fibers, and about half of the VIP and GAL fibers were immunoreactive for SP. NPY- and FMRF-immunoreactive cells were found at the periphery of the islets. These findings suggest that the exocrine and endocrine pancreatic functions of the bullfrog are under the control of peptidergic innervation.     

大鼠鼻粘膜肽能神经末梢分布的研究

用免疫组化技术（ＡＢＣ法）系统研究了大鼠鼻粘膜９种肽能神经末梢分布的特征,这９种神经肽分别是Ｐ物质（ｓｕｂｓｔａｎｃｅＰ,ＳＰ）,神经激肽Ａ（ｎｅｕｒｏｋｉｎｉｎＡ,ＮＫＡ）,神经激肽Ｂ（ｎｅｕｒｏｋｉｎｉｎＢ,ＮＫＢ）,降钙素基因相关肽（ｃａｌｃｉｔｏｎｉｎｇｅｎｅ－ｒｅｌａｔｅｄｐｅｐｔｉｄｅ,ＣＧＲＰ）,血管活性肠多肽（ｖａｓｏａｃｔｉｖｅｉｎｔｅｓｔｉｎａｌｐｏｌｙｐｅｐｔｉｄｅ,ＶＩＰ）,神经肽Ｙ（ｎｅｕｒｏｐｅｐｔｉｄｅＹ,ＮＰＹ）,甘丙肽（ｇａｌａｎｉｎ,ＧＡＬ）,生长抑素（ｓｏｍａｔｏｓｔａｔｉｎ,ＳＯＭ）及神经降压素（ｎｅｕｒｏｔｅｎｓｉｎ,ＮＴ）,同时选择与鼻粘膜神经肽（ＮＰ）作用密切相关的三叉神经节（ＴＧ）细胞进行上述ＮＰ的定位。用重组ＰＳＰ６５质粒（４００ＳＯＭｃＤＮＡ）制备ＳＯＭｍＲＮＡ单链探针,以地高辛精标记,在鼻粘膜及ＴＧ细胞进行ＳＯＭｍＲＮＡ的原位杂交组化研究。结果提示大鼠鼻粘膜有丰富的肽能神经末梢;ＴＧ细胞含有多种ＮＰ并且可以合成ＳＯＭ。该研究结果对重新认识鼻粘膜神经分布规律有一定意义。     

Effect of sensory neuropeptides on canine bronchial and pulmonary vessels in vitro

Sensory neuropeptides may be important in the noncholinergic component of parasympathetic vasodilation in the tracheobronchial circulation. We studied the effects of substance P (SP), neurokinin A (NKA), neurokinin B (NKB) and calcitonin gene-related peptide (CGRP) on the isolated canine bronchial artery and used pulmonary artery and vein of similar size for comparison. CGRP (10pM-300nM) was a potent relaxant of the bronchial and pulmonary arteries, and the pulmonary vein with equal potency in all vessels. SP in low concentrations (10pM-100nM) caused vasodilation of the precontracted bronchial artery and in high concentration (10-100 microM) contracted the vessel from resting tone. SP also relaxed the pulmonary artery and vein. NKA and NKB caused relaxation in all three vessels. All of the vascular effects of the sensory neuropeptides were concentration-dependent. The order of potency of the neuropeptides in the bronchial and pulmonary artery was SP greater than NKA greater than CGRP greater than NKB. In the pulmonary vein NKB caused a much larger relaxation than SP and NKA but it was less potent than either NKA or CGRP. Capsaicin (1 microM) caused a large contraction of the bronchial artery, similar in magnitude to the contraction caused by high dose of SP. Neuropeptide Y was also studied and found to cause no consistent constriction of any of the vessels studied. In conclusion, CGRP is a universal dilator of the bronchial and pulmonary blood vessels. SP and NKA exert their main effect on arterial vasomotor tone, whereas NKB is the only tachykinin producing marked dilation of the pulmonary vein.     

Refeeding after 72 hour fasting alters neuropeptide Y and monoamines in various cerebral areas in the rat

• 1.1. Monoamine turnover and neuropeptide Y (NPY) levels were evaluated in the CNS of adult male rats either after fasting (72 hr) or refeeding.
• 2.2. In the fasted group, an overall increase in NPY levels was observed except in the striatum where it was decreased. The serotoninergic turnover was decreased in the hippocampus, striatum and cortex.
• 3.3. After refeeding, NPY decreased in the hypothalamus and cortex but was further increased in the hippocampus and decreased in the striatum. The serotoninergic turnover was still decreased in the hippocampus and cortex. The norepinephrine levels and the dopaminergic turnover increased in the hippocampus and cortex.
• 4.4. No relationship appeared between NPY and monoamine changes suggesting that NPY can act independently in feeding behavior, and play, in different brain areas, an important role in its regulation.

     

Calcitonin gene-related peptide, neurokinin A and substance P: effects on nociception and neurogenic inflammation in human skin and temporal muscle.

Calcitonin gene-related peptide (CGRP) was injected alone and in combination with substance P (SP) or neurokinin A (NKA) into the forearm skin and temporal muscle of human volunteers. In the skin, 50 pmol of CGRP induced a wheal response and a delayed erythema. No pain was recorded. No interaction between CGRP and SP or NKA was observed. In the temporal muscle, 200 pmol of CGRP alone did not induce pain or tenderness but, in combination with SP or NKA, CGRP elicited a significant pain sensation. It is concluded that CGRP may be involved in neurogenic inflammation and that only SP, of the three peptides present in nociceptive C fibers, seems to be of major importance in relation to cutaneous nociception. Simultaneous neurogenic release of CGRP and other neuropeptides in skeletal muscle may induce myofascial pain.     

Effects of neurokinin A and calcitonin gene-related peptide on mucociliary activity in rabbit maxillary sinus

Substance P (SP) released from sensory C-fibers in the airways increases the mucociliary (m.c.) activity in the rabbit maxillary sinus. The purpose of the present study was to investigate the m.c. effects of two other neuropeptides, coexisting with SP in sensory neurones, neurokinin A (NKA) and calcitonin gene-related peptide (CGRP). NKA increased the m.c. activity dose-dependently (dose range 0.1-10.0 micrograms/kg, 88 pmol to 8.8 nmol/kg), the maximum increase being 41.9 +/- 2.6%. The effect was inhibited by pretreatment with the tachykinin antagonist (D-Pro2,D-Trp7,9)SP, but not with atropine or hexamethonium. Thus NKA released from sensory C-fibers may contribute to the non-cholinergic increase of m.c. activity observed after C-fiber stimulation. In contrast CGRP did not influence the m.c. activity. Neither did it influence the responses to NKA or SP. It is concluded that CGRP is unlikely to be involved in the control of m.c. function.     

Neuropeptides of the primary sensory neurones in rat skin: an ontogenic study.

Cutaneous primary sensory neurones contain a number of biologically-active peptides, including substance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (CGRP). However, little information is available on ontogenic changes in the tissue concentrations of these neuropeptides. In this study, the concentrations of these neuropeptides have been assessed in dorsal and ventral abdominal rat skin at various stages of development from foetal, early neonatal, late neonatal, weaner to adult, using sensitive and specific radioimmunoassays. In addition, the levels of peptide histidine isoleucine (PHI), a peptide found in non-sensory cutaneous nerves, were assessed to control the study. The levels of PHI and NKA immunoreactivity did not change significantly at any stage of development. However, the levels of SP and CGRP immunoreactivity were significantly elevated in the early neonate with CGRP remaining elevated in the late neonate. The levels of both SP and CGRP were not significantly different between other developmental groups. Significant elevations in cutaneous SP and CGRP concentrations in early neonatal life in the rat, at a time when the pups are blind and naked, may be related to control of cutaneous sensitivity, which during this period of development, has positive survival value for the pups.     

Galanin-, neuropeptide Y- and enkephalin-like immunoreactivities in catecholamine-storing paraganglia of the fetal guinea pig and newborn pig

Summary The occurrence and distribution of several neuropeptides and transmitter enzymes have been investigated by means of indirect immunofluorescence histochemistry in preaortal and carotid body-like paraganglia of the fetal guinea pig and the newborn pig. Preaortal paraganglia from the celiac and inferior mesenteric ganglion regions in fetal guinea pigs showed cell bodies immunoreactive (IR) for tyrosine hydroxylase (TH), dopamine -hydroxylase (DBH), neuropeptide Y (NPY), galanin (GAL) and metenkephalin (ENK). Almost all cells were IR for TH and DBH, whereas NPY-like immunoreactivity (-LI), GAL-LI and ENK-LI occurred less frequently. Direct double-labeling revealed the coexistence of NPY/GAL, NPY/ENK and GAL/ENK in paraganglion cells from the celiac and inferior mesenteric region. Nerve fibers and terminals were IR for ENK; fibers IR for calcitonin-gene-related peptide (CGRP) were present in the inferior mesenteric ganglion region. Preaortal paraganglia cells from the newborn pig showed TH-LI, DBH-LI, GAL-LI and ENK-LI, the distribution pattern being similar to that seen in the guinea pig; however, NPY-LI was absent. Carotid-body-like paraganglia from the newborn pig showed cell bodies IR to TH, GAL and ENK. Few cells were seen with DBH-LI. A rich supply of nerve fibers with CGRP-LI was present; some fibers exhibited ENK-LI and CCK-LI. In the adjacent superior cervical ganglion, ganglion cell bodies showed immunoreactivity to TH, DBH and NPY. A small number of cells were positive for GAL, CGRP and vasoactive intestinal polypeptide (VIP). Physiological activation of the paraganglia, leading to release or increase in catecholamines, may also change the content of the neuropeptides present in the paraganglia.     

Neuropeptide-containing nerve fibres in the human parotid gland: a semiquantitative analysis using an antibody against protein gene product 9.5

The occurrence and distribution of neuropeptide-containing fibres in the human parotid gland were examined by the peroxidase--antiperoxidase method with attention to the quality of fixation and the condition of patients. Many fibres immunoreactive for neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) and a moderate number of galanin- positive (GAL) fibres were distributed around the acini. A moderate number of NPY and VIP fibres were distributed around the intercalated ducts. The semiquantitative mean densities (_SD) of periacinar NPY, VIP and GAL fibres expressed as a percentage of the total protein gene product (PGP) 9.5 immunoreactive fibres were 75.62 _ 7.25%, 70.52 _ 9.33% and 41.76 _ 5.45%, respectively, whereas those of substance P (SP), calcitonin gene-related peptide (CGRP) and FMRF amide (FMRF) fibres were below 10%. The mean densities of NPY and VIP fibres around the intercalated ducts expressed as the percentage of PGP 9.5 fibres associated with these ducts were 52.37 _ 6.19% and 59.62 _ 7.02% respectively. Those of SP, CGRP, GAL, and FMRF fibres were below 10%. The densities of NPY, VIP, SP, CGRP, GAL and FMRF fibres around the striated and excretory ducts were also below 10%. In the vasculature, NPY fibres were the most prominent. Similarly, the mean density of perivascular NPY fibres was 93.76 _ 2.03%. No somatostatin or leucine or methionine enkephalin immunoreactivity was detected around the acini, duct system or blood vessels. These findings suggest that, in this gland, the periacinar NPY, VIP and GAL fibres may participate in regulating the synthesis of saliva and its secretion and that perivascular peptidergic fibres, especially NPY fibres, may be involved in controlling local blood flow This revised version was published online in November 2006 with corrections to the Cover Date.     

Age differences in neurokinin A and substance P from the hypothalamus,pituitary, pineal gland,and striatum of the rat. Effect of exogenous melatonin

Previous data showed that aging of the central nervous system (CNS) is associated with widespread changes in tachykinin gene expression. However, there are no data about the possible role of exogenous melatonin in modulating the tachykinergic system during aging. The aim of this work was to analyze the age-dependent changes on neurokinin A (NKA) and substance P (SP) levels in hypothalamus, pituitary, pineal gland and striatum and the role of exogenous melatonin on these changes. We studied female rats at three different ages: 5-month-old (cyclic), 15-month-old (preacyclic) and 25-month-old (acyclic). Hypothalamic tachykinin levels increase when female rats reached acyclicity, this increase was blunted in acyclic-melatonin-treated rats. However, melatonin treatment in young cyclic rats resulted in significantly increased values as compared to controls. Pituitary NKA concentrations did no show age-dependent changes in control rats, however, in both, preacyclic and acyclic-melatonin-treated rats significantly increased values of pituitary NKA were found compared to controls. In the pineal gland, a marked decrease of NKA levels was observed in acyclic-control rats. Melatonin treatment did not alter this decrease. In the striatum, NKA and SP concentrations were significantly reduced in preacyclic- and acyclic-control rats compared to young cyclic rats, melatonin had no effect on striatal tachykinins. Our results indicate that melatonin may regulate tachykinin stores during aging mainly on structures of the neuroendocrine-reproductive axis.     

Effects of Electroconvulsive Stimuli and MK-801 on Neuropeptide Y,Neurokinin A,and Calcitonin Gene-Related Peptide in Rat Brain

Rats were pretreated with 0.9% NaCl, or 0.1 or 1.0 mg/kg MK-801, an anticonvulsant and a psychotomimetic drug, and 60 minutes later given ECS or sham ECS. After six sessions the animals were sacrificed and neuropeptide Y (NPY-), neurokinin A (NKA-), and calcitonin gene-related peptide (CGRP-) like immunoreactivity (-LI) measured with radioimmunoassays. ECS increased NPY-LI in frontal cortex, striatum, occipital cortex and hippocampus, and NKA-LI in occipital cortex and hippocampus. MK-801 increased CGRP in a dose-response manner in frontal cortex, and NKA-LI in occipital cortex. Although the higher MK-801 dose reduced seizure duration by 50%, the ECS induced NPY-LI increase in striatum, occipital cortex and hippocampus, and NKA-LI in occipital cortex was not diminished. In contrast, there was a parallel decrease in seizures and NPY-LI and NKA-LI changes in frontal cortex and hippocampus, respectively. Investigation of neuropeptides in brain may contribute to understanding of the mechanisms of action of antide-pressive and antipsychotic treatments and of psychotomimetic drugs.     

Sex and hormonal cycle differences in rat brain levels of pain-related cannabimimetic lipid mediators

One important function of endocannabinoids and related lipid mediators in mammalian central nervous system is modulation of pain. Evidence obtained during the last decade shows that altered levels of these compounds in the brain accompany decreases in pain sensitivity. Such changes, if sexually dimorphic, could account for sex differences in pain and differences that occur during different phases of the hormonal cycle in females. To examine this possibility, we measured the levels of the pain-modulatory lipids anandamide, 2-arachidonoyl glycerol, N-arachidonoyl glycine, N-arachidonoyl gamma amino butyric acid, and N-arachidonoyl dopamine in seven different brain areas (pituitary, hypothalamus, thalamus, striatum, midbrain, hippocampus, and cerebellum) in male rats, and in female rats at five different points in the estrous cycle. The cerebellum did not demonstrate a change in endocannabinoid production across the estrous cycle, whereas all other areas tested showed significant differences in at least one of the compounds measured. These changes in levels occurred predominantly within the 36-h time period surrounding ovulation and behavioral estrus. Differences between males and females were measured as either estrous cycle-independent (all estrous cycles combined) or cycle-dependent (comparisons of males to each estrous cycle). In cycle-independent analyses, small sex differences were observed in the pituitary, hypothalamus, cerebellum, and striatum, whereas no differences were observed in the thalamus, midbrain, and hippocampus. In cycle-dependent analyses, the hypothalamus and pituitary showed largest sex differences followed by the striatum, midbrain, and hippocampus, whereas no sex differences were measured in thalamus and cerebellum. These data provide a basis for investigations into how differences in sex and hormonal status play a role in mechanisms regulating endocannabinoid production and pain.     

Introduction of lipidization–cationization motifs affords systemically bioavailable neuropeptide Y and neurotensin analogs with anticonvulsant activities

The neuropeptides galanin (GAL), neuropeptide Y (NPY) or neurotensin (NT) exhibit anticonvulsant activities mediated by their respective receptors in the brain. To transform these peptides into potential neurotherapeutics, their systemic bioavailability and metabolic stability must be improved. Our recent studies with GAL analogs suggested that an introduction of lipoamino acids in the context of oligo‐Lys residues (lipidization–cationization motif) significantly increases their penetration into the brain, yielding potent antiepileptic compounds. Here, we describe an extension of this strategy to NPY and NT. Rationally designed analogs of NPY and NT containing the lipidization–cationization motif were chemically synthesized and their physicochemical and pharmacological properties were characterized. The analogs NPY‐BBB2 and NT‐BBB1 exhibited increased serum stability, possessed log D > 1.1, retained high affinities toward their native receptors and produced potent antiseizure activities in animal models of epilepsy following intraperitoneal administration. Our results suggest that the combination of lipidization and cationization may be an effective strategy for improving systemic bioavailability and metabolic stability of various neuroactive peptides. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Sensory innervation of the ear drum and middle-ear mucosa: Retrograde tracing and immunocytochemistry

Summary The distribution and origin of nerve fibers of presumed sensory nature in the ear drum and middle-ear mucosa of the rat were studied by a retrograde tracing technique in combination with immunocytochemistry.Application of True Blue (TB) on the ear drum or on the middle-ear mucosa labeled nerve cell bodies in the jugular, trigeminal, geniculate and cervical dorsal root ganglia (C₂–C₄). Judging from the number of TB-labeled nerve cell bodies the jugular and trigeminal ganglia contributed the major component to the sensory innervation of the ear drum and the middle-ear mucosa, while the contribution from the geniculate and cervical dorsal root ganglia was relatively minor.The majority of the TB-labeled nerve cell bodies contained calcitonin gene-related peptide (CGRP), whereas minor populations stored substance P (SP) and neurokinin A (NKA). Nerve fibers containing SP, NKA and CGRP were moderate in number in the middle-ear mucosa and few in the ear drum. Double immunostaining revealed that SP invariably coexisted with NKA in nerve cell bodies in the ganglia examined. The SP/NKA-containing nerve cell bodies constituted a subpopulation of those storing CGRP.The findings indicate that several ganglia project to the ear drum and middle-ear mucosa and that many neuropeptides are involved in the mediation of middle-ear sensitivity.     

Bone and joint neuropathy in rats with type-2 diabetes

We have previously demonstrated that Goto-Kakizaki (GK) rats with spontaneous type-2 diabetes and peripheral neuropathy exhibit regional osteopathic changes. In the present study on 18 GK rats and 21 control Wistar rats, the occurrence of the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP), and the autonomic neuropeptide Y (NPY) was analysed in bone and joints, dorsal root ganglia and lumbar spinal cord by immunohistochemistry and radioimmunoassay (RIA). Immunohistochemistry disclosed a predominance of immunoreactivities in vessel-related nerve fibers, although some were also seen in free terminals. While SP, CGRP and NPY in periosteum, cortical bone and synovium was confined to neuronal tissue, the bone marrow in addition exhibited an abundance of NPY-positive megakaryocytes. Apart from this cellular source of NPY, the observations suggest that the three neuropeptides analysed in bone and joints are of neuronal origin. Quantification by RIA showed a significant decrease of NPY in cortical bone (-36%), bone marrow (-66%) and ankle (-29%) of GK rats. CGRP was decreased in the spinal cord (-19%) and dorsal root ganglia (-26%) but was unchanged in bone and joints, as with SP. Given the suggested anabolic role of NPY and CGRP on bone, neuropeptidergic deficit in diabetes may prove to be an important factor underlying the development of regional osteopenia.     

Innervation of lower airways and neuropeptide effects on bronchial and vascular tone in the pig

Summary The occurrence and distribution of peptide-containing nerve fibres [substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), neuropeptide Y (NPY)] and noradrenergic nerve fibres [tyrosine hydroxylase (TH)- and dopamine beta hydroxylase (DBH)-positive] in the airways of the pig were studied by means of immunohistochemistry. SP- and CGRP-immunoreactive (-IR) nerve fibres were present close to and within the lining respiratory epithelium, around blood vessels, within the tracheobronchial smooth muscle layer and around local tracheobronchial ganglion cells. The content of CGRP- and neurokinin A (NKA)-like immunoreactivity (-LI) measured by radioimmunoassay (RIA) was twice as high in the trachea compared to that in the peripheral bronchi. SP was a more potent constrictor agent than NKA on pig bronchi in vitro. CGRP had a relaxant effect on precontracted pig bronchi. On blood vessels CGRP exerted a relaxant effect that was more pronounced on pulmonary arteries than on bronchial arteries. VIP/PHI-IR fibres were seen in association with exocrine glands and in the tracheobronchial smooth muscle layer. VIP-positive nerve fibres were abundant around blood vessels in the trachea but sparse or absent around blood vessels in the peripheral bronchi. This histological finding was supported by RIA; it was shown that the content of peptides displaying VIP-like immunoreactivity (-LI) was 18 times higher in the trachea compared to peripheral bronchi. VIP was equally potent as CGRP in relaxing precontracted pig bronchi in vitro. Both bronchial and pulmonary arteries were relaxed by VIP. NPY was colocalized with VIP in tracheal periglandular nerve fibres and in nerve fibres within the tracheobronchial smooth muscle layer. NPY was also present in noradrenergic (DBH-positive) vascular nerve fibres. The content of NPY was much higher (15-fold) in the trachea compared to small bronchi. NPY caused a contraction of both pulmonary and bronchial arteries. The bronchial smooth muscle contraction to field stimulation in vitro was purely cholinergic. A non-cholinergic relaxatory effect following field stimulation was observed after bronchial precontraction. Capsaicin had no effect on pig bronchi in vitro.     

Neuropeptide Y administration acutely increases hypothalamic corticotropin-releasing factor immunoreactivity: lack of effect in other rat brain regions

The effect of acute central administration of Neuropeptide Y (NPY) to adult male rats on the brain content of corticotropin-releasing factor immunoreactivity (CRF-ir) was investigated. The brain regions studied included frontal cortex, hippocampus, medulla-pons, midbrain-thalamus, cerebellum, neurointermediate lobe of pituitary, median eminence and the remaining hypothalamus. CRF-ir was determined in each of these regions using a radioimmunoassay specific for rat CRF. CRF-ir was found to be significantly increased in the major site of CRF localization in the brain, the hypothalamus, in NPY-treated rats as compared to vehicle-treated controls either 15 minutes (p less than 0.025) or 45 minutes (p less than 0.005) post-injection. This increase was localized to the median eminence (p less than 0.05 after 15 minutes, p less than 0.01 after 45 minutes). No statistically significant differences were noted in any of the other brain regions assessed. Plasma adrenocorticotropin levels were also found to increase following NPY treatment, an effect which became significant after 45 minutes (p less than 0.05). These data show that NPY can alter the content of hypothalamic CRF and may play a role in its regulation.