Supply Of Fibers Research Articles

Origin of small primary afferent substance P-immunoreactive nerve fibers in the guinea-pig

Primary afferent and substance P (SP)-immunoreactive nerve fibers of the guinea pig and rat heart were investigated by physiological and immunohistochemical methods. Immunohistochemistry revealed abundant SP-positive fibers in the guinea pig atria, with fewer in the ventricles. Only an occasional fiber was seen in the rat atrium or ventricle. Sectioning the vagus nerve did not noticeably influence the supply of SP-immunoreactive nerve fibers in the guinea pig heart. When the atria or ventricles were stimulated, afferent nerve fiber activity was recorded from the second and third thoracic dorsal roots. In guinea pig atria 3 types of fibers were identified on the basis of conduction velocities: A δ 1, A δ 2 and C fibers. Only Aδ fibers were identified in the ventricle. By vagal recordings, Aδ fibers were demonstrated but a C fiber response could not be shown in this nerve. SP-immunoreactivity in primary afferent fibers was depleted by the neurotoxin capsaicin. Capsaicin treatment also caused a reduction in the conduction velocity of small diameter myelinated A δ 2 (by 29%) and unmyelinated C fibers (by 46%). In the rat heart, evidence for A δ 2 or C fibers was not found. These results indicate that primary afferent and SP-immunoreactive fibers are numerous in guinea pig heart, but few in the rat. It is concluded that most of these fibers have their cell bodies of origin in the dorsal root ganglia.

Capillary Distribution in the Lateral Muscle of Axolotl (Ambystoma mexicanum Shaw)

AbstractThe vascular supply of red, intermediate and white fibres in the axial muscle of axolotl (Ambystoma mexicanum Shaw) was visualized with Indian ink‐injections and quantified with morphometrical methods on semithin sections.Red fibres were surrounded by 1.4 ± 0.6 capillaries (mean + SD), the intermediate fibres by 1.2 ± 0.9 capillaries and white fibres by 0.3 ± 0.6 capillaries. The mean vascularized surface area per unit volume of fibre was 0.0159, and 0.0068 and 0.0007 (μm2/μm3) for red, intermediate and white fibres, respectively. A unit volume of mitochondria within each type of fibre was supplied by 0.15, 0.17 and 0.08 μm2 vascularized surface for red, intermediate and white fibres, respectively. This indicates that there exist a good balance between oxygen demand represented by mitochondrial content and oxygen supply represented by the vascularized surface.

Neuropeptide Y: immunocytochemical localization to and effect upon feline pial arteries and veins in vitro and in situ.

Plexuses of nerve fibres containing neuropeptide Y (NPY)-like immunoreactivity invest pial arteries belonging to the circle of Willis, pial arterioles, occasionally penetrating arterioles and large veins. A more sparse supply of NPY-like fibres were observed around pial veins and venules. The NPY-immunoreactive fibres are located within the adventitia or at the adventitia-media border. Only occasional fibres are present in cerebral vessels of animals in which the superior cervical ganglion has been removed one week previously. Administration of NPY resulted in strong, concentration-dependent contractions of isolated feline middle cerebral arteries whereas administration of avian pancreatic polypeptide (APP) elicited weak contractions. In chloraloseanaesthetized cats, perivascular microapplication of NPY in situ resulted in marked concentration-dependent contractions of cerebral pial arterioles (34.7 +/- 6.6%; maximum decrease in calibre with NPY. Perivascular administration of NPY resulted in the constriction of pial veins but the magnitude of the venous calibre reductions was smaller than the response of arterioles at each reductions was smaller than the response of arterioles at each concentration examined. APP did not elicit contraction of pial arterioles or veins during in situ conditions. The pharmacological and immunocytochemical results strongly indicate the existence of a novel perivascular neuronal system containing NPY, which mediates contraction of cerebral blood vessels and NPY is colocalized with NA in sympathetic nerves.

The nerves of the juxtaglomerular apparatus of man and other mammals contain the potent peptide NPY.

The juxtaglomerular apparatus, a neuroendocrine unit located in the vascular pole of the glomerulus and influencing blood pressure by the secretion of renin, is known to have a rich supply of monoaminergic nerve fibres. Neuropeptide Tyrosine (NPY), a newly discovered, potent, vasoconstrictor peptide of 36 amino acids, has been found by immunocytochemistry to be present in a dense plexus of fibres around the juxtaglomerular apparatus of man, monkey, mouse, hamster, rat and guinea pig. NPY-immunoreactivity was markedly depleted after chemical sympathectomy by 6-hydroxydopamine. The concentration of NPY within the whole mouse kidney was 29.6 +/- 6.8 pmol/g and fractionation of the extracts demonstrated that the NPY-like immunoreactivity co-eluted from the column in the same position as the porcine NPY standard. The role of this peptide in renal physiology and pathology now needs urgent investigation.

Occurrence and distribution of GRP-immunoreactive nerve fibres in the respiratory tract.

The occurrence and distribution of nerve fibres containing gastrin-releasing peptide (GRP) were investigated in the respiratory tract of several mammals using immunocytochemistry. A moderate supply of nerve fibres displaying GRP immunoreactivity was seen in the middle ear mucosa, the nasal mucosa and the tracheobronchial wall. Generally, the fibres were distributed around blood vessels and seromucous glands. In addition, scattered GRP fibres were seen in the smooth muscle of the tracheal wall. The distribution of GRP fibres in the respiratory tract suggests multiple functions of GRP such as regulation of local blood flow, glandular secretion and smooth muscle activity.

Innervation of the rat urinary bladder. I. The morphological changes of intrinsic nerves of the urinary bladder after pelvic ganglionectomy

The dual autonomic innervation of the urinary bladder of the female rat was studied using histochemical and light and electron microscopic methods. The bladder body in the normal state had a rich supply of cholinergic nerve fibers with a uniformly reticular pattern, but it was sparsely supplied with adrenergic nerves mainly associated with the blood vessels rather than the detrusor muscles. Seven days after the unilateral extirpation of the pelvic ganglion, most cholinergic and adrenergic fibers on the ipsilateral side of the bladder body disappeared markedly with the use of enzymatic and fluorescent histochemical techniques. The acetylcholinesterase activity of cholinergic fibers and the intensity of fluorescence of adrenergic fibers were somewhat restored 14 days after the operation. Seventy days postoperatively, it was found that the former had recovered in the relatively fine nerve fibers, while the latter had been almost completely restored, compared with the normal adrenergic innervation of the bladder body.

Localization of vasoactive intestinal polypeptide in penile erectile tissue and in the major pelvic ganglion of the rat

Vasoactive intestinal polypeptide was localized by immunocytochemical techniques in the major pelvic ganglion and penile erectile tissue of the rat. Vasoactive intestinal polypeptide fibers were concentrated in penile crura with the density of innervation decreasing distally. The helicine arteries were very densely innervated while fewer fibers surrounded the deep artery of the penis. Intrinsic smooth muscle of the cavernous bodies received a moderate supply of vasoactive intestinal polypeptide immunoreactive fibers. Dorsal vascular structures, including the deep dorsal vein were innervated by vasoactive intestinal polypeptide fibers. Vasoactive intestinal polypeptide immunoreactive cell bodies were found in the major pelvic ganglion, concentrated on one end of the ganglion. Rectrograde studies with a dye injected into the penile crura indicated that neurons in major pelvic ganglion projected to the penis. Combined dye and immunofluorescent studies showed that all the dye-labeled neurons were immunoreactive for vasoactive intestinal polypeptide. It is concluded that all vascular beds in the penis of the rat are innervated by vasoactive intestinal polypeptide fibers and that the extent of the innervation is related to the occurrence of smooth muscle. Neurons in the major pelvic ganglion probably are the main source of vasoactive intestinal polypeptide fibers to the penis.

Neuropeptide Y in the female reproductive tract of the rat. Distribution of nerve fibres and motor effects

Fluorescence immunochemistry revealed the presence of extensive systems of nerve fibres containing neuropeptide Y (NPY) in the rat's ovary, fallopian tube, uterine horns and cervix. The most prominent supply of NPY fibres was found in the cervix, where they were associated with both vascular and non-vascular smooth musculature. Smooth muscle effect of NPY was studied in an in vitro model using circular cervix preparations from estrogen-treated spayed rats. NPY inhibited in a dose-dependent way neurally evoked (tetrodotoxin-sensitive) contractions, but had no effect on resting tension. The nerve-induced contractions were blocked by atropine, the experiments thus suggest prejunctional actions of NPY on cholinergic nerves in the uterine cervix.

Vasoactive intestinal polypeptide immunoreactive nerve fibres in the human eye.

Immunohistochemistry applied to whole-mount preparations was used to investigate the presence and distribution of vasoactive intestinal polypeptide (VIP) immunoreactive nerves in the non-retinal part of the human eye. The choroid has a dense perivascular supply of VIP immunoreactive nerve fibers, and some free nerve endings within the stroma. These nerves enter the choroid in ciliary nerves and also as perivascular networks around the ciliary arteries. Occasional choroidal VIP immunoreactive nerve cell bodies are seen. The ciliary body stroma, close to the iris root has a dense circumferential plexus of VIP immunoreactive nerve fibers that occur both singly and in bundles. The iris root has a circumferential arrangement of bundles from which VIP immunoreactive nerve fibres travel radially in the stroma. They supply the pupillary region with numerous free nerve endings; the sphincter pupillae is not supplied by these nerves. The cornea is devoid of VIP immunoreactive nerves. These findings, together with existing knowledge of the physiological actions of VIP, indicate that VIP immunoreactive nerves are likely to be involved in the functioning of several ocular tissues.

Vasoactive intestinal peptide-like immunoreactivity in nerves associated with the cardiovascular system of guinea-pigs

The distribution of nerves with vasoactive intestinal peptide (VIP)-like immunoreactivity has been examined in the heart and vascular system of guinea-pigs. There was a very sparse supply of fibres to the heart. No immunoreactive cell bodies were found in the intrinsic cardiac ganglia; however, positive nerve cell bodies were seen along the superior vena cava near the right atrium. There were immunoreactive fibres with most arteries; these fibres were located at the media-adventitia junction. The supply to major distributing arteries, such as the aorta, subclavian, carotid and femoral arteries as well as to the pulmonary arteries, was sparse. Of the individual vascular beds, the most densely supplied arteries were the mesenteric and uterine (or in the male deferential) arteries. Arteries running to other organs or tissues, such as skeletal muscle, kidney, pancreas, spleen and heart were less densely supplied. There were clear differences in the innervation of different cerebral vessels. The greatest density was associated with the anterior and middle cerebral arteries. Fewer nerves accompanied the posterior cerebral, cerebellar and meningeal arteries. There was a sparse innervation of the rostral part of the basilar artery. Throughout the body, veins were sparsely supplied. The distribution of nerves with VIP-like immunoreactivity was not changed when noradrenergic nerves were degenerated by 6-hydroxydopamine or when substance P nerves were disrupted by capsaicin. It is concluded that VIP containing nerves innervating the heart and blood vessels form a population distinct from the substance P-containing and the noradrenergic nerves. It is suggested that the VIP fibres might be efferent vasodilator nerves to the blood vessels.

Nerve fibers in the gut and pancreas of the rat displaying neuropeptide-Y immunoreactivity. Intrinsic and extrinsic origin.

Immunoreactive neuropeptide Y (NPY) was demonstrated in neuronal elements in the gut and pancreas of the rat. Immunoreactive endocrine cells could not be detected. The occurrence of NPY-containing nerve-cell bodies in the submucosal and myenteric ganglia indicates an intrinsic origin of the NPY fibers. However, an additional extrinsic supply of NPY fibers is suggested by the finding that abdominal sympathectomy caused the disappearance of some NPY fibers, notably those around blood vessels. The distribution of NPY fibers in all layers of the gut wall suggests multiple functions of NPY, including a role in the regulation of intramural neuronal activities, smooth muscle tone, and local blood flow.

Comparative and scaling aspects of heart and body weights with reference to blood supply of cardiac fibers

1.1. Relative heart weight (RHW) differs in vertebrates with the ratio 1:20 between extremes (bottom bound fishes—Pleuronectidae—and birds). When plotting heart weight (HW) against body weight (BW) one obtains channels which contain not only vertebrates of the same classes (poikilotherms, small and big mammals and birds) but also animals belonging to different classes: tuna fish data are located in the “small mammalian channel” together with data of large tropical snakes while large mammals (upwards 4000g) belong to the “bird channel”. Reasons for such groupings are not clear and physical activity seems not to be the only reason. When comparing active and non active vertebrates one finds that the RHW is as a rule greater in physically more active poikilotherms and homoiotherms. The RHW is also higher in wild than in domesticated forms the differences appearing after weaning (wild vs laboratory rat).2.2. In spongy type of myocardium the growth of cardiac fibers results in restriction of the blood flow through lacunae and the contact between endothelial cells lining growing strands of musculature probably provokes formation of capillaries.3.3. The appearance of mixed type of myocardium (outer compact and inner spongy compartments) is not bound to the water to land transition since it occurs also in some fishes; it does not occur or is rare in amphibia and is frequent in reptiles. The compact outer layer comprises a different proportion of the cardiac wall volume (5–73%). Metabolic differences were described between cardiac cells in compact and spongy compartments. The occurrence of a compact layer does not seem to be correlated with the size of the animal; it occurs in physically active species (fishes) and an autonomous development was observed during the individual development of a single fish species (salmon). Blood flow through the compact layer (coronary flow) is low, being 1% of the cardiac output (fish).4.4. Compact myocardium supplied by capillaries occurs in homoiotherms. When plotting density of capillaries (C), size of cardiac fibers (F), and fiber to capillary ratio (F/C) in animals of different BW (field vole to elephant), the F/C ratio is slightly inclining with the mean value one. The density of capillaries decreases and the size of cardiac fibers increases with the BW. Generally, the cardiac capillary density is directly proportional to the beat frequency and inversely proportional to the stroke volume, whereas the volume (diameter) of myofibers is proportional to the stroke volume and inversely proportional to the heart beat frequency.5.5. It follows that the wall of the “high speed pump” in small mammals is constructed of small units supplied by a high density capillary network in contrast to the “low speed pump” wall which contains larger fibers with a lesser number of capillaries. An identical difference in construction of the ventricular wall was found in hearts of physically very active (wild or flying) and non active (domesticated) mammals. Since ion transport pumps are situated in the cardiac cell membranes, this construction pattern of myocardial fibers and their blood supply favours the exchange of substances around cardiac cells under high rate cycle in small mammals and during high physical activity.

Structure of the glomic arteries.

The structure of the arteries which supply blood tp the carotid bodies was examined in five cases in which the weights of the cardiac ventricles were normal and in which hypoxaemia due to emphysema or systemic hypertension were absent. The right glomic arteries were studied by light microscopy, and the left by electron microscopy. A sixth case, also free from myocardial hypertrophy, was used solely for an examination of the common carotid artery, the carotid sinus and the internal carotid artery by light and electron microscopy. The glomic arteries resembled the carotid sinus in being highly elastic with a rich supply of non-myelinated nerve fibres and thus had a structure consistent with having a baroreceptor function.

Adrenergic and peptidergic innervation of cochlear blood vessels.

Guinea pig cochlear blood vessels were investigated with regard to their supply of adrenergic and peptidergic nerve fibers. Using the glyoxylic acid histofluorescence technique, numerous adrenergic fibers were seen around the labyrinthine artery, whereas the spiral modiolar artery contained only few such fibers. Immunocytochemistry revealed nerve fibers containing immunoreactive avian pancreatic polypeptide, vasoactive intestinal peptide, substance P, or gastrin-releasing peptide around the labyrinthine and spiral modiolar arteries. Adrenergic or peptidergic nerve fibers were not seen around the blood vessels of the stria vascularis. Upon removal of the superior cervical ganglion, adrenergic fibers disappeared and fibers displaying avian pancreatic polypeptide immunoreactivity were reduced in number. These data suggest co-occurrence of catecholamines and immunoreactive avian pancreatic polypeptide in a population of adrenergic nerves.

Immunohistochemical demonstration of APP (Avian Pancreatic Polypeptide)-immunoreactive nerve fibres around cerebral blood vessels

Nerve fibres containing immunoreactive avian pancreatic polypeptide (APP) were demonstrated in the wall of cerebral blood vessels from several species. Pial arteries of chicken, mouse, rat, guinea-pig, cat and dog had a dense supply of APP fibres while APP fibres were less numerous in rabbit, cow and monkey. The APPimr unoreactive fibres were more numerous in the rostral part of the circle of Willis than around more caudally located pial vessels. Immunoreactive fibres were also seen in the wall of pial vessels of the spinal cord, as shown in the cat. Extirpation of the superior cervical sympathetic ganglion was followed by a marked reduction in the number of APP-containing fibres on the ipsilateral side of the brain.

Capillary supply and cross-sectional area of slow and fast twitch muscle fibres in man.

The muscles triceps brachii, quadriceps femoris (part vastus lateralis) and soleus were analysed in 6 men and 6 women for fibre composition (% slow twitch, ST-fibres and % fast twitch, FT-fibres), fibre cross sectional areas, and capillarization. Also the fraction of fibres enclosed by their own fibre type was analysed together with the capillary supply of these fibres. Fibre composition was 39(19-60)% ST in m. triceps brachii, 60(29-78)% ST in m. vastus lateralis and 73(49-88)% ST in m. soleus. Fibre areas ranged from 2,320 to 16,667 microns2 being smallest in m. triceps brachii and largest in m. soleus (p less than 0.05) and with ST fibres being significantly smaller than FT fibres in some of the muscles. In all muscles the shape of the fibres was elliptical with the larger diameter being about twice the smaller diameter. Capillary density per cross sectional muscle area was not related to the fibre composition and was 379(302-500) cap/mm2 in m. triceps brachii, 404(284-529) cap/mm2 in m. vastus lateralis and 417(333-592) cap/mm2 in m. soleus. However, capillary supply expressed as fibre type area per capillary was up to 40% larger for FT-fibres than for ST-fibres within the same muscle (p less than 0.05). The capillary supply of enclosed fibres was not different from that of fibres surrounded also by the other fibre type. The results demonstrate that the difference in capillary supply to ST and FT-fibres is less distinct in humans than in other mammals, which is consistent with the metabolic potentials also being more alike.

Adrenergic, cholinergic and peptidergic nerve fibres in dura mater--involvement in headache?

Nerve fibres containing noradrenaline, acetylcholinesterase, vasoactive intestinal polypeptide and substance P were demonstrated in the dura mater of guinea-pigs using histochemical and immunohistochemical methods. These fibres accompanied blood vessels of all size, indicating a vasomotor role. In addition, some nerve fibres were observed without any obvious relation to the blood vessels. The rich supply of nerve fibres to the various parts of the dura mater may possibly be of importance in the pathogenesis of some types of headache.

Evidence for exclusive adrenergic innervation of feather muscles (mm. pennati) in the chicken. Histochemical studies and experiments with 5-hydroxydopamine.

Feather follicles in the avian skin are interconnected by well-defined bundles of smooth muscle cells, which are responsible for the erection and depression of feathers and thus play an important role in thermoregulation. The depressing and erecting muscle bundles were found to receive a very dense supply of unmyelinated nerve fibres that displayed ultrastructural and histochemical characteristics of noradrenergic axons (formaldehyde- and glyoxylic acid-induced catecholamine fluorescence; uptake to 5-hydroxydopamine). No nerve fibres were encountered showing histochemical acetylcholinesterase activity. There was no indication of the presence of peptidergic or purinergic nerve endings. The neuromuscular space usually ranged from 40-60 nm in width and contained a basal lamina. Occasionally, this space was reduced to approximately 20 nm. At such close neuromuscular contacts a basal lamina was lacking, and focal densities beneath the pre- and postsynaptic plasma membrane were observed. Since no gap junctions between muscle cells were detected, the dense supply with noradrenergic nerve fibres indicates a high amount of directly innervated smooth muscle cells. An additional finding of the present study was the observation that high local concentrations of 5-hydroxydopamine led to degeneration of noradrenergic nerve endings.

Role of adrenergic nerves in blood-induced cerebral vasospasm.

Cerebral arteries have an abundant supply of adrenergic nerve fibers which are believed to release vasoactive substances responsible for the induction of cerebral vasospasm. To assess the importance of adrenergic nerves in this phenomenon, high doses (600 microgram/ml) of 6-hydroxydopamine (6-OHDA) were used to produce in vitro chemical sympathectomy in bovine middle cerebral artery. 6-OHDA reduced catecholamine fluorescence to undectable limits. H3-norepinephrine re-uptake was reduced to 1.5% of intact controls. Arterial norepinephrine content was reduced by 92%. Contractile responses to norepinephrine, serotonin, and fresh human whole blood were modestly reduced after denervation. This reduction was probably due to alpha receptor inactivation by 6-OHDA, because after protection of the alpha receptors with phentolamine the vessel response was the same as in untreated controls. Contractions in response to aged human whole blood were not affected by denervation. The results suggest that the endogenous release of catecholamines does not play a major role in the initiation or spread of blood-induced vasospasm in large cerebral arteries.

Distribution of gastrin and CCK-like peptides in rat brain

The distribution of gastrin and CCK-like peptides in the rat brain was studied by immunocytochemistry using an antiserum reacting equally well with both groups of peptides. Immunoreactive nerve cell bodies were detected in all cortical areas, in the hippocampus where they were particularly numerous, in the mesencephalic central gray and in the medulla oblongata. After colchicine treatment immunoreactive material appeared also in cell bodies of the magnocellular hypothalamic system. Immunoreactive nerve fibers were widely distributed in the brain. Particularly dense accumulations were seen in the hippocampus near the ventral surface of the brain, in the caudate nucleus, in the interpeduncular nucleus, the parabrachial nucleus, the dorsal part of the medulla oblongata and in the dorsal horn of the spinal cord. In the hypothalamus immunoreactive nerve fibers were observed in all nuclei, being most frequent in the ventromedial, dorsal and lateral hypothalamic nuclei. A rich supply of nerve fibers was seen in the outer zone of the median eminence and in the neurohypophysis. From previous immunochemical analysis it appears that the peptide demonstrated in most parts of the brain is identical with CCK-8. In the neurosecretory cell bodies of the hypothalamus, the median eminence and the neurohypophysis, however, the immunoreactive material is probably identical with gastrin.