Neuropeptide Y-like Immunoreactive Nerve Research Articles

Occurrence of adrenergic nerve fibers in human thymus during immune response

The adrenergic nerve fibers (ANF), the neuropeptide Y-like immunoreactive nerve fibers (NPY-NF) and the noradrenaline (NA) amount were studied in the human thymus in subjects previously treated or not treated with interferon therapy with the aim to identify the changes due to the interferon therapy. This therapy has been used in patients affected by multiple sclerosis (MS). Biochemical and morphological methods were used associated with quantitative analysis of images. The whole thymuses were removed during autopsies in young and adult patients not treated with interferon. Moreover, samples of thymus were removed from patients, either young or adult who had previously been treated with interferon therapy, and subjected, for diagnostic reasons, to thymic biopsy. All samples of thymus were weighed, measured and dissected. Thymic slices were stained with Eosin-orange for detection of the microanatomical details, or with Bodian's reaction for recognition of nervous structures. Histofluorescence microscopy was used for detection of ANF, and immunofluorescence microscopy for recognition of NPY-like immunoreactive structures. All morphological results were subjected to quantitative analysis of images. Noradrenaline contained in thymic structures was measured by biochemical methods. Our results only concerned the effects of the therapy and suggested that treatment with interferon therapy induces many changes in the thymic structures: (1) The protein content of thymus is significantly increased; (2) the NA content in the thymus is also significantly increased; (3) NPY-like immunoreactive structures in the thymus are significantly increased; (4) occurrence of NPY-like immunoreactivity is particularly and significantly increased both in thymic microenvironment and in structures resembling nerve fibers; (5) ANF are significantly increased in the same thymic structures in which NPY-like immunoreactivity is also increased (i.e. thymic microenvironment and structures resembling nerve fibers). The morphological and biochemical changes observed can also explain the immunological changes induced in the thymus after immunostimulating therapy.

Postnatal development of substance P-, calcitonin gene-related peptide- and neuropeptide Y-like immunoreactive nerve fibres in the synovial membrane of the rat temporomandibular joint

The postnatal (0–24 days) development of substance P (SP)-, calcitonin gene-related peptide (CGRP)- and neuropeptide Y(NPY)-like immunoreactive (LI) nerves in the rat temporomandibular joint (TMJ) was investigated immunohistochemically. Immediately after birth, SP- or CGRP-LI nerves were observed in most disc attachments. A few NPY-LI nerves were observed around the large blood vessels in the joint capsule. From days 3 to 6, the SP- or CGRP-LI nerves were first found close to the anterior, lateral, medial (third day) or posterior (sixth day) peripheral portion of the disc. The synovial cells (type A and B) first appeared at the anterior peripheral portion of the disc (sixth day), and then at the posterior, lateral and medial portions (seventh day). NPY-LI nerves were found around the blood vessels at the disc attachment on the sixth day, and then entered into the peripheral portion of the disc from days 10 to 14. At 14 days a few NPY-LI nerves were first found close to the blood vessels in the sublining layer of the synovial membrane. From days 18 to 24, a few NPY-LI nerves were located in the superficial layer of the synovial membrane. The central portion of the disc did not contain any nerves from days 0 to 24. Thus SP- or CGRP-LI sensory nerves are shown to innervate the rat TMJ at an earlier age than NPY-LI sympathetic nerves, which may modulate the regulation of blood flow in the joint capsule, disc and synovial membrane. However, it is considered that the disc itself does not contribute to the transportation of the afferent sensory information. Furthermore, from the fact that SP- or CGRP-LI nerves were found earlier than the appearance of the synovial cells, it is suggested that these nerves may be associated with the growth and proliferation of synovial cells.

Regional Differences in the Innervation of the Human Ureterovesical Junction by Tyrosine Hydroxylase-, Vasoactive Intestinal Peptide- and Neuropeptide Y-Like Immunoreactive Nerves

Regional Differences in the Innervation of the Human Ureterovesical Junction by Tyrosine Hydroxylase-, Vasoactive Intestinal Peptide- and Neuropeptide Y-Like Immunoreactive Nerves

Regional Differences in the Innervation of the Human Ureterovesical Junction by Tyrosine Hydroxylase-, Vasoactive Intestinal Peptide- and Neuropeptide Y-Like Immunoreactive Nerves

We have used double-label immunohistochemistry to examine the presence and pattern of colocalization of vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), tyrosine hydroxylase (TH) and protein gene product (PGP) in nerve fibers supplying the human ureterovesical junction (UVJ). Several populations of nerve fibers within the UVJ region were identified according to their expression of potential transmitter substances. Presumptive noradrenergic axons containing TH- and NPY-like immunoreactivity (LIR) and non-noradrenergic fibers containing VIP-and NPY-LIR accounted for most of the total (PGP-LIR) innervation and supplied all regions of the UVJ. The distal ureter, Waldeyer's sheath and the trigone were supplied by predominantly noradrenergic TH/NPY-LIR nerve fibers, whereas the majority of fibers supplying the detrusor muscle were non-noradrenergic VIP/NPY-LIR axons. The similarity in innervation of Waldeyer's sheath, ureter and trigone is consistent with the notion that these structures are all derived from a common mesodermal origin. Regional differences in innervation were also noted within the musculature of the distal ureter: TH/NPY-LIR fibers were localized to the outer part of the ureter, while VIP/NPY-LIR fibers supplied the inner part. This finding suggests that the different layers of the ureter may be independently controlled by different populations of nerves. The findings of this study support the view that noradrenergic nerves are important in maintaining the tone of the UVJ, but indicate that other neurotransmitters or neuromodulators may also be involved in the control of this region.

Enhancement of serotonergic immunoreactivity in sympathetic cerebrovascular nerve fibers after experimental embolic stroke

We examined 5-hydroxytryptamine-like immunoreactive cerebrovascular nerve fibers in rats after experimental thromboembolic stroke. Although there were no visible 5-hydroxytryptamine-like immunoreactive nerve fibers in normal animals, we found many of these fibers near the clot emboli 30 min after the stroke, and the number of fibers increased slightly with time. In immunohistochemical double staining, these fibers corresponded to neuropeptide Y-like immunoreactive nerve fibers. And they were not observed in animals after superior cervical ganglionectomy. These findings suggest that the sympathetic nerves take up serotonin released from intraluminal aggregating platelets.

Diminished neuropeptide Y and dopamine beta-hydroxylase immunoreactivity in a guinea pig model of left ventricular hypertrophy.

The aims of the study were to determine the effect of chronic pressure overload of the left ventricle on the density and distribution of neuropeptide-Y-like immunoreactive (NPY-LI) nerve fibres in heart and to compare any changes to those observed in adrenergic nerve fibres, identified by dopamine beta-hydroxylase immunoreactivity. Pressure overload was produced in female adult guinea pigs by constriction of the abdominal aorta, using a modified Weck haemoclip. The same operation was performed on a separate group of animals except that no clip was placed around the aorta. Five weeks after surgery, animals were anaesthetised, and the hearts were fixed by perfusion for immunohistochemistry. Cryostat sections were stained, using an indirect peroxidase/antiperoxidase method, for NPY or dopamine beta-hydroxylase. Aortic stenosis caused a 45% increase in left ventricular weight and a 58% increase in left atrial weight at 5 weeks postsurgery. Pulmonary oedema, a sign of cardiac failure, was evident in most of the animals with aortic stenosis. Immunohistochemical studies showed that in atria and right ventricles from animals with abdominal aortic stenosis the distribution and density of NPY-LI nerve fibres were similar to those in the sham operated guinea pigs. However, the left ventricles obtained from the animals with aortic stenosis were nearly devoid of NPY-LI nerve fibres. The density of dopamine beta-hydroxylase-LI nerve fibres was also substantially reduced in the hypertrophied left ventricles. Aortic stenosis resulting in left ventricular hypertrophy caused a nearly complete loss of NPY-LI and dopamine beta-hydroxylase-LI nerve fibres from the left ventricle. The parallel reduction in both neuropeptide Y and dopamine beta-hydroxylase is in accordance with the association of neuropeptide Y with sympathetic (adrenergic) nerve fibres in the left ventricle and suggests that chronic left ventricular hypertrophy causes a severe degeneration of sympathetic axons supplying this chamber and/or reduces the ability of these sympathetic neurones to maintain normal levels of neurotransmitter related enzymes and neuropeptides.

The role of platelets in the development of cerebral vasospasm

A possible role of platelet-derived 5-HT was examined concerning the pathogenesis of cerebral vasospasm. Intracisternal injection of 5 ml of platelet-rich plasma (PRP; approximately 7.5 × 10 8 platelets) induced not only acute (1 h) but also chronic (7 days) angiographically evident cerebral vasospasm in dogs. Sympathetic perivascular nerves on cerebral arteries showed no remarkable change following repeated injections of PRP, as the dense distribution of catecholamine-fluorescence and neuropeptide Y-like immunoreactive nerve fibers on Day 7 was comparable to findings in the preinjection controls. While there were no 5-HT-immunoreactive fibers in the cerebral arteries of control animals, numerous 5-HT-immunoreactive fibers were present in the PRP-injected animals. These results suggest that 5-HT, presumably released from extravasated platelets, may be taken up by nerve endings and act as a vasoconstrictor transmitter in the pathogenesis of chronic vasospasm.

Nerve growth factor receptor-like immunoreactivity in primary and permanent canine tooth pulps of the cat.

The distribution of nerve growth factor receptor (NGF receptor)-like immunoreactivity in pulps of developing primary and mature permanent cat canine teeth was examined, by use of a monoclonal antibody against NGF receptor detected by fluorescence immunohistochemistry and pre-embedding immunocytochemical light- and electron microscopy. Both primary and permanent pulps contained a vast number of NGF receptor-like immunoreactive nerves. Immunolabelling appeared to be localized both to axons and Schwann cells. In addition, many blood vessel walls in immature primary tooth pulps showed NGF receptor-like immunoreactivity, in contrast to permanent pulps where blood vessels rarely were NGF receptor-immunoreactive. Double-labelling immunofluorescence experiments revealed that in the permanent pulp a majority of the NGF receptor-positive nerves also showed calcitonin gene-related peptide (CGRP)-like immunoreactivity, and many showed substance P-like immunoreactivity. However, nerve fibers with neuropeptide Y-like immunoreactivity lacked NGF receptor-like immunoreactivity. In developing primary tooth pulps fewer NGF receptor-positive nerves were CGRP-like immunoreactive or substance P-like immunoreactive, as compared to the permanent pulp. Neuropeptide Y-like immunoreactive nerve fibers were not detected in the primary tooth pulp. The results suggest a role for nerve growth factor in both developing and mature sensory nerves of the tooth pulp.

Changes in adrenergic and peptidergic nerves in the submucous plexus of streptozocin-diabetic rat ileum

The effect of streptozocin diabetes on the distribution of adrenergic and peptidergic nerves in the submucous plexus of rat ileum was investigated and compared with the changes in the myenteric plexus of the same region of ileum. There was an increase in the intensity of immunoreactivity in vasoactive intestinal polypeptide- and neuropeptide Y-like immunoreactive nerve fibers and neurons and a decrease in calcitonin gene-related peptide-like immunoreactivity but no change in substance P- and dopamine β-hydroxylase-like immunoreactivity in the nerve fibers and neurons of the submucous plexus of both 8- and 16-wk streptozocin-diabetic rat ileum. However, in the myenteric plexus of the diabetic rat ileum, there was enlargement of varicosities and an increase followed by a slight decrease in the intensity of immunoreactivity of vasoactive intestinal polypeptide- and dopamine β-hydroxylase-like immunoreactive nerve fibers and neurons, increased substance P-like immunoreactivity in diabetes at 16 wk, and an initial decrease (at 8 wk) followed by a recovery of calcitonin gene-related peptide-like immunoreactivity at 16 wk, but no change in neuropeptide Y-like immunoreactivity. The markedly different changes in peptidergic and adrenergic nerves between the two enteric plexuses show that diabetic neuropathy induced by streptozocin is not selective and involves factors other than neurotransmitter types.

Long-term chemical sympathectomy leads to an increase of neuropeptide Y immunoreactivity in cerebrovascular nerves and iris of the developing rat

Short-term (surgical) and long-term (chemical) sympathectomy have revealed the presence of a population of neuropeptide Y-like immunoreactive nerve fibres which do not degenerate in parallel with noradrenaline-containing nerves supplying cerebral vessels and the iris of the rat. Two days after bilateral removal of the superior and middle cervical ganglia of 7-week-old rats, noradrenaline-containing nerves could not be detected along any of the arteries of the rat circle of Willis or of the iris, but 18–32% of neuropeptide Y-like immunoreactive nerves remained. Long-term treatment (6 weeks) with guanethidine commencing in developing 1-week-old rats caused degeneration of the sympathetic neurons in cervical ganglia and disappearance of 5-hydroxydopamine-labelled nerves (that showed dense-cored vesicles at the electron microscope level) from rat cerebral vessels, but did not significantly change the density of neuropeptide Y-like immunoreactive axons on the vessels. Furthermore, whilst in control rats neuropeptide Y-like immunoreactivity was localized largely within 5-hydroxydopamine-labelled cerebrovascular nerves, after long-term sympathectomy with guanethidine, neuropeptide Y-like immunoreactivity was seen only in nerves lacking small dense-cored vesicles. A small number of catecholamine-containing nerves appeared along the internal carotid and anterior cerebral arteries after long-term sympathectomy; these may arise from neurons of central origin. These results suggest that as a consequence of long-term sympathectomy with guanethidine, compensatory changes occur, involving an increase in the expression of neuropeptide Y-like immunoreactivity in non-sympathetic axons in cerebrovascular nerves and iris of the rat. In contrast, the neuropeptide Y-like immunoreactive nerves in the dura mater appear to be entirely sympathetic, since none were present after short-term sympathectomy and none appeared after long-term sympathectomy.

Light and electron microscopic demonstration of neuropeptide Y-like immunoreactive nerves in human cardiac muscle.

Neuropeptide Y (NPY)-like immunoreactive nerves were demonstrated in human cardiac muscle. The atrial specimens were obtained from open-heart surgery. The PAP method was applied for immunocytochemistry for light and electron microscopy. A dense, extensive network of NPY-like immunoreactive nerve fibres was seen between cardiac muscle cells and around blood vessels. In electron microscope PAP precipitates were localized in large dense-cored vesicles of 80-120 nm in size in separate nerve terminals or in the terminals situated in the nerve bundles. Close contacts were observed between NPY nerves and muscle cells and blood vessels. The possible functional role of NPY innervation in the human heart is discussed.

Neuropeptide Y and the innervation of the human eye

Using the indirect immunohistochemical technique, neuropeptide Y was found in human ocular nerves. While limbal blood vessels were innervated and a few nerves were seen in the trabecular meshwork, the cornea proper contained no immunoreactive nerve fibers. Neuropeptide Y-like immunoreactive nerves supplied the iris dilator muscle and, to a lesser extent, the iris sphincter. Immunoreactive nerve fibers were present within the ciliary muscle and the ciliary processes. Neuropeptide Y-like immunoreactive choroidal nerve fibers were frequently associated with blood vessels. The apposition of immunoreactive nerve fibers and melanocytes occurred throughout the uvea. The distribution of neuropeptide Y-like immunoreactive nerves in the eye closely parallels the adrenergic innervation. Evidence linking neuropeptide Y to the ocular sympathetic innervation is discussed.

Neuropeptide Y and the ocular innervation of rat, guinea pig, cat and monkey

By the immunohistofluorescence technique, peripheral nerves of the rat, guinea pig, cat and monkey eye contain a neuropeptide Y-like immunoreactive peptide. A broad distribution of immunoreactive nerve fibers is present in all four animals, innervating tissues of the aqueous humor outflow apparatus, the limbal blood vessels, and uveal blood vessels. A dense plexus of neuropeptide Y-like immunoreactive nerve fibers is present to the ciliary processes. A rich innervation exists to the iris dilator muscle, but that to the iris sphincter is modest. Throughout all regions of the uvea, neuropeptide Y-like immunoreactive nerves are associated closely with melanocytes. When acid extracts of anterior uvea and choroid from rat and guinea pig are analyzed by radioimmunoassay and reverse phase high performance liquid chromatography, the immunoreactive ocular peptide occurs in a single molecular form indistinguishable from porcine neuropeptide Y. The present findings indicate that neuropeptide Y is present in ocular nerves of rat, guinea pig, cat, and monkey. Their distribution, with a few small exceptions, closely parallels that of ocular adrenergic nerves as revealed by histofluorometric techniques. While no ocular effects of neuropeptide Y have been reported to date, its other known biological effects imply potential functions in the eye.

The distribution of sympathetic adrenergic, tyrosine hydroxylase- and neuropeptide Y-immunoreactive nerves in human axillary sweat glands.

The innervation of human axillary sweat glands was studied by using the specific SPG (sucrose-potassium phosphate-glyoxylic acid) catecholamine histofluorescence method and the peroxidase-antiperoxidase (PAP) immunocytochemical method. The present results demonstrated that human sweat glands are surrounded by nerves containing a weak tyrosine hydroxylase activity. Nerves showing catecholamine histofluorescence could be visualized around the sweat glands only in the presence of exogenous catecholamine (adrenaline in the local anestheticum). In all tissue specimens studied fluorescent adrenergic nerves could be seen around arteries and arterioles corresponding to the distribution of neuropeptide Y-like immunoreactive nerves.