Anders Änggård

Co-existence of peptide HI (PHI) and VIP in nerves regulating blood flow and bronchial smooth muscle tone in various mammals including man

By immunohistochemistry it was found that PHI- and VIP-like immunoreactivity (-IR) occurred in the same autonomic neurons in the upper respiratory tract, tongue and salivary glands with associated ganglia in rat, guinea-pig, cat, pig and man. VIP- and PHI-like immunoreactivity was also found in similar locations in the human heart. The N-terminally directed, but not the C-terminally directed, PHI antiserum or the VIP antiserum stained endocrine cells in the pig duodenum. This suggests the existence of an additional PHI-like peptide. Ligation of nerves acutely caused marked overlapping axonal accumulations of PHI- and VIP-IR central to the lesion. Two weeks after transection of the nerves, both types of immunoreactivities were still observed in accumulations both in the axons as well as in the corresponding cell bodies. The levels of PHI- and VIP-IR in normal tissues from the cat were around 10-50 pmol/g with a molar ratio of about 1 to 2. Systemic administrations of PHI and VIP induced hypotension, probably due to peripheral vasodilation in both guinea-pig and cat. Furthermore, both PHI and VIP caused an inhibition of the vagally induced increase in respiratory insufflation pressure in guinea-pig. PHI and VIP relaxed the guinea-pig trachea in vitro, suggesting a direct action on tracheobronchial smooth muscle. VIP was about 5-10 times more potent than PHI with regard to hypotensive effects and 2-3-fold, considering respiratory smooth muscle-relaxant effects in the guinea-pig. PHI was about 50-fold less potent to induce hypotension in the cat than in the guinea-pig. Although species differences seem to exist as regards biological potency, PHI should also be considered when examining the role of VIP as an autonomic neurotransmitter.

Guanethidine-sensitive release of neuropeptide Y-like immunoreactivity in the cat spleen by sympathetic nerve stimulation

Splenic nerve stimulation (10 Hz for 2 min) caused a perfusion-pressure increase, a volume reduction and an increase in the output of neuropeptide Y-like immunoreactivity (NPY-LI) from the isolated blood-perfused cat spleen. Gel-filtration HPLC analysis revealed that plasma NPY-LI collected during nerve stimulation was similar to the NPY-LI in the spleen and synthetic porcine NPY. Combined propranolol and phenoxybenzamine pretreatment enhanced NPY output upon nerve stimulation by about 60%. Forty percent of the perfusion-pressure increase and 25% of the volume reduction seen during control stimulations remained after adrenoceptor blockade. Guanethidine abolished the release of NPY-LI, the perfusion-pressure increase and the volume reduction normally seen upon splenic nerve stimulation. Infusion of synthetic porcine NPY caused a long-lasting increase in perfusion pressure and a relatively moderate volume reduction. Noradrenaline (NA) both increased perfusion pressure and induced a marked volume reduction. The NPY effects were resistant to adrenoceptor antagonists in doses which abolished the NA response. In conclusion, the present data show that NPY-LI is released upon sympathetic nerve stimulation by a guanethidine-sensitive mechanism. Furthermore, the sympathetic response is partially resistant to adrenoceptor antagonists and NPY has powerful vasoconstrictor effects. This provides further evidence for a role of NPY in sympathetic vascular control.

Origin and Distribution of Capsaicin-Sensitive Substance P-Immunoreactive Nerves in the Nasal Mucosa

In immunohistochemical studies, substance P-immunoreactivity (SP-IR) was found in a population of trigeminal ganglion cells in guinea pig, rat and cat. SP-IR nerve endings were found in the spinal trigeminal nucleus, around sphenopalatine ganglion cells, around blood vessels, as well as under and within the epithelium of the nasal mucosa. Ligation and denervation experiments in the cat indicated that the SP-IR nerves in the sphenopalatine ganglion and the nasal mucosa are of trigeminal origin. Capsaicin pretreatment of guinea pigs and rats resulted in a selective loss of the SP-IR nerves in the nasal mucosa and sphenopalatine ganglion, while the parasympathetic and sympathetic nerves were still present.

Increased Vascular Permeability in Rat Nasal Mucosa Induced by Substance P And Stimulation of Capsaicin-Sensitive Trigeminal Neurons

Electrical stimulation of the maxillary branches of the trigeminal nerve induced an increase in vascular permeability to macromolecules and an interstitial edema in the nasal mucosa of the rat, as indicated by extravasation of Evans blue. In animals that had been treated neonatally with capsaicin, the effect of trigeminal nerve stimulation was abolished. Local application of capsaicin or substance P (SP) also induced a significant Evans blue extravasation in the nasal mucosa. In capsaicin-pretreated animals the effect of SP was still present, while the permeability increase induced by capsaicin was abolished. In conclusion, chemogenic irritation of the nasal mucosa by capsaicin induces edema probably via a local axon reflex inducing release of SP. Capsaicin-sensitive SP-containing afferents in the nasal mucosa may also be involved in the pathogenesis of nasal congestion seen in various types of rhinitis.

Capsaicin and nicotine-sensitive afferent neurones and nasal secretion in healthy human volunteers and in patients with vasomotor rhinitis.

1 Applications of capsaicin, nicotine and methacholine were made locally onto the nasal mucosa in human controls and patients suffering from hyperreactive nasal disorders. Perception of sensation was registered as a sympton score and secretion quantified. The sensory reaction (irritation ‐pain) to capsaicin was similar in the three groups studied, i.e. controls, a group of patients with the diagnosis of vasomotor rhinitis and a group of patients with increased nasal secretion as the main symptom of the hyperreactive disorder. Nicotine induced only a mild itching sensation in the three groups. However, capsaicin and nicotine challenge caused a significantly larger secretory response in the last group than in the unselected vasomotor rhinitis group and in the control group. 2 Pretreatment with muscarinic receptor antagonists almost completely abolished the secretory response to both capsaicin and nicotine, and blocked methacholine‐induced secretion. Furthermore, pretreatment with a combination of local anaesthetic and vasoconstrictor agent abolished the capsaicin‐induced irritation, as well as the capsaicin‐ and nicotine‐induced secretion on both the ipsilateral and the contralateral side. Therefore, no clearcut contribution seems to be exerted by locally released peptides from sensory neurones as direct trigger substances for the secretory response to capsaicin. 3 In conclusion, the nasal secretory response, in man, to both capsaicin and nicotine, seems to be mediated via cholinergic parasympathetic reflexes. In patients with hyperreactive non‐allergic disorders of the nasal mucosa with rhinorrhea as the main complaint, the enhanced secretion may be due to a hyperreactive efferent cholinergic mechanism rather than hypersensitive irritant receptors on capsaicin‐ and nicotine‐sensitive sensory neurones. Challenge with irritant agents seems a useful test for the evaluation of both afferent and efferent reflexogenic responses in hyperreactive disorders of the nasal mucosa.

Neuropeptide Y-, substance P- and VIP-immunoreactive nerves in cat spleen in relation to autonomic vascular and volume control

SummaryNeuropeptide Y (NPY)-immunoreactive (IR) nerve fibres were found around both arteries and veins and in smooth muscle trabeculae of the cat spleen with the highest density on the arterial side. Considerably more tyrosine hydroxylase (TH)- and dopamine-β-hydroxylase (DBH)-positive than NPY-IR nerves were seen in the trabeculae and splenic capsule. The NPY-IR nerves in the spleen most likely originated in the coeliac ganglion, since (1) splanchnic nerve sectioning did not change the splenic NPY-IR nerves, (2) most neurones in the coeliac ganglion were NPY-IR, as well as DBH- and TH-positive, and (3) NPY-IR was transported axonally from the coeliac ganglion towards the spleen via the splenic nerve. Local NPY infusion in the isolated, blood-perfused cat spleen caused a marked increase in splenic vascular resistance and a small volume reduction. NA caused a comparatively larger reduction in splenic volume than NPY in addition to vasoconstriction. VIP-IR cell bodies in the coeliac ganglion were NPY- and TH-negative. VIP-IR nerves were seen both around the splenic artery and vein as well as around arterioles and within venous trabeculae of the spleen. VIP infusion caused reduction of splenic perfusion pressure (i.e. vasodilation) as well as an increase in splenic volume. Substance P-IR nerves, most likely of splanchnic afferent origin, were present in the coeliac ganglion around the splenic artery and arterioles of the spleen. Infusion of substance P induced marked reduction in perfusion pressure and a reduction in splenic volume. Enkephalin-immunoreactive nerves of splanchnic origin surrounded some TH- and NPY-positive, coeliac ganglion cells.It is concluded that several vasoactive peptides are located in splenic nerves. NPY is present in noradrenergic neurones and causes mainly increased vascular resistance. VIP occurs in non-adrenergic neurones of sympathetic origin and induces vasodilation and relaxation of the capsule. Finally, substance P is present in peripheral branches of spinal afferent nerves and causes vasodilation and capsule contraction. Stimulation of the splenic nerves may thus release several vasoactive substances in addition to noradrenaline, exerting a variety of actions.

Tachykinins and calcitonin gene-related peptide: co-existence in sensory nerves of the nasal mucosa and effects on blood flow.

SummaryThe presence and co-existence of calcitonin generelated peptide (CGRP)- and substance P (SP)-like immunoreactivity (-LI) in sensory neurons of the nasal mucosa and trigeminal ganglion in several vertebrate species, including man, were established using immunohistochemistry. In the nasal mucosa the CGRP- and SP-immunoreactive (IR) nerve fibers were localized within the epithelium, around arteries, arterioles, venules, venous sinusoids and close to exocrine elements, mainly ducts. Double-staining experiments revealed that the CGRP-LI-containing nerve profiles and cell bodies also contained SP-LI. In the pig, CGRP- and SP-IR fibers were also detected in the maxillary portion of the trigeminal nerve and around the sphenopalatine artery and vein, as well as around the nasal dorsal vein. The nasal mucosal content of CGRP-LI, as determined by radioimmunoassay, was almost 5-fold higher in the pig and guinea pig compared to man. The nasal CGRP-IR nerves disappeared after capsaicin pretreatment in the guinea pig. In the cat, local intra-arterial infusions of capsaicin, SP, neurokinin A (NKA), neuropeptide K (NPK) and CGRP caused a concentration-dependent increase in nasal blood flow. CGRP caused a longer-lasting vasodilatation than the tachykinins. In conclusion, the morphological findings of co-localization of CGRP-LI and SP-LI in capsaicin-sensitive nerve fibers of the nasal mucosa and trigeminal ganglia of different species including man, coupled with the in vivo description of the high vasodilator potency of CGRP and tachykinins, imply co-release of several vasoactive agents upon activation of the nasal sensory nerves. Furthermore, the similarity of the morphological findings among the different species indicates that experimental data from animals may reflect the existence of similar mechanisms in humans.

Subcellular fractionation of cat submandibular gland: Comparative studies on the distribution of acetylcholine and vasoactive intestinal polypeptide (VIP)

Abstract In previous studies, evidence has been obtained for the presence of vasoactive intestinal polypeptide (VIP) in presumptive cholinergic neurons innervating the exocrine glands in the cat. In the present study, an attempt was made to define the storage sites of these two compounds in the cat submandibular gland using subcellular fractionation techniques. Particulate VIP was preferentially found in dense fractions (0.78–0.97 M sucrose) of a density gradient. Particle-bound acetylcholine showed a bimodal distribution in the gradient with relative enrichment in a dense fraction (0.87 M sucrose) but mainly in lighter fractions (0.28–0.44 M sucrose). More than 50% of all acetylcholine was recovered in a soluble form. For comparison, noradrenaline was also analysed and found in paniculate form in fractions ranging between 0.44–0.78 M sucrose. The electron microscopic analysis revealed presence of i.a. small clear vesicles in the lighter fractions, whereas the fractions rich in VIP contained i.a. many larger vesicles, sometimes with an electron-dense core. In agreement with earlier ultrastructural immunocytochemical studies on intact tissue, the present results support the view that VIP is present in large dense-cored vesicles. Most of the particulate acetylcholine seems to be localized in small clear vesicles, although a small proportion could be associated with large vesicles. Whether acetylcholine and VIP coexist in such large vesicles or whether separate populations of large vesicles exist, remains to be elucidated.

Lipoxin formation in human nasal polyps and bronchial tissue

Chopped human nasal polyps and bronchial tissue produced lipoxin A4 and isomers of lipoxins A4 and B4, but not lipoxin B4, after incubation with exogenous leukotriene A4. In addition, these tissues transformed arachidonic acid to 15‐hydroxyeicosatetraenoic acid. The capacity per gram of tissue to produce lipoxins and 15‐hydroxyeicosatetraenoic acid was 3–5‐times higher in the nasal polyps. Neither tissue produced detectable levels of lipoxins or leukotrienes after incubation with ionophore A23187 and arachidonic acid. Co‐incubation of nasal polyps and polymorphonuclear granulocytes with ionophore A23187 led to the formation of lipoxins, including lipoxins A4 and B4. The results indicate the involvement of an epithelial 15‐lipoxygenase in lipoxin formation in human airways.

Neuropeptide Y: presence in sympathetic and parasympathetic innervation of the nasal mucosa

SummaryThe occurrence of neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI) in the sympathetic and parasympathetic innervation of the nasal mucosa was studied in various species including man. A dense network of NPY-immunoreactive (IR) fibres was present around arteries and arterioles in the nasal mucosa of all species studied. NPY was also located in nerves around seromucous glands in pig and guinea-pig, but not in rat, cat and man. The NPY-IR glandular innervation corresponded to about 20% of the NPY content of the nasal mucosa as revealed by remaining NPY content determined by radioimmunoassay after sympathectomy. These periglandular NPY-positive fibres had a distribution similar to the VIP-IR and PHI-IR nerves but not to the noradrenergic markers tyrosine hydroxylase (TH) or dopamine-β-hydroxylase (DBH). The NPY nerves around glands and some perivascular fibres were not influenced by sympathectomy and probably originated in the sphenopalatine ganglion where NPY-IR and VIP-IR ganglion cells were present. The venous sinusoids were innervated by NPY-positive fibres in all species except the cat. Dense NPY and DBH-positive innervation was seen around thick-walled vessels in the pig nasal mucosa; the latter may represent arterio-venous shunts. Double-labelling experiments using TH and DBH, and surgical sympathectomy revealed that the majority of NPY-IR fibres around blood vessels were probably noradrenergic. The NPY-positive perivascular nerves that remained after sympathectomy in the pig nasal mucosa also contained VIP/PHI-IR. The major nasal blood vessels, i.e. sphenopalatine artery and vein, were also densely innervated by NPY-IR fibres of sympathetic origin. Perivascular VIP-IR fibres were present around small arteries, arterioles, venous sinusoids and arterio-venous shunt vessels of the nasal mucosa whereas major nasal vessels received only single VIP-positive nerves. The trigeminal ganglion of the species studied contained only single TH-IR or VIP-IR but no NPY-positive ganglion cells. It is concluded that NPY in the nasal mucosa is mainly present in perivascular nerves of sympathetic origin. In some species, such as pig, glandular and perivascular parasympathetic nerves, probably of VIP/PHI nature, also contain NPY.