Falck-Hillarp Fluorescence Research Articles

DL-5-hydroxytryptophan-induced changes in central monoamine neurons after peripheral decarboxylase inhibition.

Abstract The histochemical effects of 500 and 1000 mg/kg of dl-5-hydroxy-tryptophan (5-HTP), both alone and in combination with a peripheral decarboxylase inhibitor (seryl-trihydroxy benzyl hydrazine; Ro 4–4602) have been examined on central monoamine neurons of rats by the Falck-Hillarp fluorescence technique that demonstrates monoamines and their precursors. 5-HTP alone or together with Ro 4–4602 caused only weak intraneuronal accumulation of 5-HT in the central 5-HT neurons, in spite of an increased entry of 5-HTP into the brain after Ro 4–4602 treatment, as shown by an increase in the specific neuropil fluorescence and a reduction of 5-HT accumulation in the cells of the capillary walls. Ro 4–4602 markedly potentiated the effects of 5-HTP on the central dopamine neurons, many of which became clearly yellow fluorescent. The mechanism of dopamine depletion by 5-HTP is probably therefore mainly one of displacement. The effects on the noradrenaline neurons were also potentiated by Ro 4–4602 pretreatment, the neurons exhibiting a yellow-green fluorescence. This depletion may therefore also be mainly be due to amine displacement. It is concluded that the ability of the 5-HT neurons to take up and accumulate 5-HT in the presence of 5-HTP is relatively low in spite of large amounts of 5-HTP present in the brain neuropil after extracerebral decarboxylase inhibition.

Neuropeptide Y-like immunoreactivity in the cardiovascular nerve plexus of the elasmobranchs Raja erinacea and Raja radiata

The distribution of nerves showing neuropeptide Y (NPY)-like immunoreactivity in the cardiovascular system of elasmobranchs and teleosts has been investigated. Two species of teleosts, the rainbow trout (Salmo gairdneri) and the Atlantic cod (Gadus morhua), and three species of elasmobranchs, the spiny dogfish (Squalus acanthias), the little skate (Raja erinacea) and the starry ray (Raja radiata), were used in this study. An innervation of the cardiovascular system by an NPY-like substance was found only in the two species of Raja. A rich innervation was encountered in these skates, with the highest density of fibres in the wall of the ventricle, the conus arteriosus, the coeliac artery and smaller mesenterial vessels. In the vessels, the fibres formed a plexus at the adventitio-mediol border. Few fibres were found in the walls of the dorsal aorta, the sinus venosus and the atrium, and no fibres were observed in the walls of the ventral aorta. Falck-Hillarp fluorescence histochemistry showed the presence of a rich innervation of arteries and arterioles of the gut by catecholamine-containing nerve fibres.

Fate of intraocular chromaffin cell suspensions: role of initial nerve growth factor support.

Adrenal medullary tissue from adult rats was dissociated into cell suspensions and injected into the anterior chamber of the eye, where the cells were made to attach to the previously sympathectomized irides with the use of fibronectin. Short- and long-term survival of the chromaffin cells was examined in whole mounts of irides using Falck-Hillarp fluorescence histochemistry or indirect immunohistochemistry with antibodies against adrenaline and dopamine-beta-hydroxylase (DBH). After 6 days in oculo all cells were immunoreactive for adrenaline; almost none displayed processes even if beta-nerve growth factor (NGF) was given at grafting. One month after weekly intraocular injections of NGF, many cells were surrounded by nerve fiber networks and all cells were DBH-immunoreactive. Eight months postgrafting and 7 months after the last injection of NGF almost the entire iris was reinnervated and resembled a normal, sympathetically innervated iris. Both at 1 and 8 months, chromaffin cells, ganglion cells and transitional cell forms (chromaffin cells transforming towards ganglion-like cells) were found in irides from the NGF-treated eyes. The number of ganglion cells was remarkably increased with time by NGF, while the number of chromaffin cells decreased compared to controls. A single treatment with NGF at grafting had no marked effects as examined up to 3 months; at this time there was a certain outgrowth of nerve terminals, which, however, was not as pronounced as 1 month after repeated NGF injections. In conclusion, it is shown that some cells in a chromaffin cell suspension attach to the iris, transform to ganglion cells after an induction with exogenous NGF, and reinnervate the sympathetically denervated iris. Such cells remain ganglion-like in character and continue to form processes even after cessation of exogenous NGF treatment.

Cellular localization of ovarian histamine, its cyclic variations, and histaminergic effects on ovulation in the rat ovary perfused in vitro

Mast cells, visualized with toluidine blue staining and the Falck-Hillarp fluorescence technique, were mainly located around large blood vessels in the hilus region of the ovary in adult rats and in immature rats treated with PMSG. Histamine concentration in the rat ovary was significantly reduced after the LH surge in PMSG-treated animals, corresponding to a reduced number of ovarian mast cells. No marked change in the number of mast cells and histamine concentration was found in adult rats during the oestrous cycle. Histamine as well as the H1-agonist, 2-methylhistamine, and the H2-agonist, 4-methylhistamine, induced ovulations in the isolated perfused rat ovary. Ovulation rates were significantly lower than those evoked by LH. The histamine liberator, Compound 48/80, induced ovulations which were blocked by the combined effect of the H1- and H2-histamine receptor antagonists, cimetidine and pyrilamine. The anti-degranulating agent, disodium cromoglycate, did not block ovulations induced by Compound 48/80. The results show that the level of ovarian histamine, which is primarily stored in mast cells, can be influenced by PMSG treatment, and that the amine is able to induce ovulations in gonadotrophin-primed rats by an effect mediated by both H1 and H2 receptors.

Blood-brain barrier leakage and brain edema in stroke-prone spontaneously hypertensive rats. Effect of chronic sympathectomy and low protein/high salt diet.

Brain edema associated with severe chronic hypertension was studied in stroke-prone spontaneously hypertensive rats (SHRSP), 5 to 9 months of age. Blood-brain barrier (BBB) leakage sites and intracerebral spreading pathways for plasma proteins were delineated by an intravenously (i.v.) injected exogenous dye tracer (Evans blue), known to form a complex with albumin in blood, and by immunohistochemical visualization of extravasated endogenous plasma proteins. The tissue content of edema fluid was estimated by measuring the specific gravity of selected brain regions, stained or unstained by the tracer dye, on a bromobenzene-kerosene gradient column. Multifocal BBB leakage sites were macroscopically detected within the cerebral cortex and the deep gray matter after i.v. circulation of Evans blue-albumin for 30 min. After 24 h of i.v. circulation the dye tracer had spread not only locally in the gray matter but also into the adjacent white matter, where it was widely distributed. Immunohistochemically visualized plasma proteins showed similar distribution. Unilateral superior cervical ganglionectomy performed at 4 weeks of age neither increased the incidence of major BBB opening to Evans blue-albumin nor altered the specific gravity of the ipsilateral cerebral hemisphere in grown-up SHRSP, furthermore, the blood pressure remained unchanged. The lack of significant effect on BBB function may possibly be attributed to the extensive reinnervation of the cerebral arteries, verified in the grown-up SHRSP using the Falck-Hillarp fluorescence method for visualization of catecholaminergic nerve fibers. In SHRSP raised on a low-protein and high-salt diet the mean arterial blood pressure was 212 mm Hg compared to 195 mm Hg in controls (P less than 0.05) and the incidence of BBB opening was 72% compared to 25% in controls (P less than 0.05). After 24 h of i.v. circulation of Evans blue-albumin, brain regions stained by the dye tracer showed significantly reduced specific gravity (P less than 0.001), while unstained regions had normal values. Thus the brain edema fluid spread, as revealed by specific gravity measurements, corresponded to the intracerebral distribution of extravasated plasma proteins.

Adrenergic Innervation of the Eustachian Tube

The presence of adrenergic nerves in the Eustachian tubes of guinea pigs was observed using the Falck-Hillarp fluorescence method. Abundant adrenergic nerve are forming networks around blood vessels in all tubal regions. Adrenergic fibers also surround the tubal glands. The precise locations of adrenergic nerve terminals in the tube were demonstrated by electron microscopy following application of a false transmitter. Adrenergic nerve terminals were found in abundance just beneath the smooth muscle layer of the arteries in each part of the tube and close to the myoepithelial cells of the tubal gland.

Autonomic nervous control of the circulatory system in the air-breathing fish Channa argus

1. The control of the cardiovascular system with particular emphasis on the regulation of blood distribution in the gills and air-breathing organ was studied in the air-breathing teleost Channa argus. Perfused head preparations were used in addition to experiments with isolated strip preparations of arteries and heart chambers. 2. The distribution of adrenergic nerves was investigated using Falck-Hillarp fluorescence histochemistry. 3. This preliminary study shows an adrenergic control system composed of chromaffin cells and adrenergic nerves similar to that found in other teleosts investigated, although the systemic arteries (coeliac artery, dorsal aorta and the vasculature of the air-breathing organ) appear to lack an adrenergic innervation. 4. The reactions of isolated artery strip preparations to acetylcholine and adrenaline resemble those seen in other teleosts, and there is a prominent inhibitory effect of L-isoprenaline suggestive of arterial β-adrenoceptors. 5. The general vascular resistance of the gill apparatus-air-breathing organ increases in response to acetylcholine or adrenaline, and there is a redistribution of perfusion flow from the air-breathing organ circuit (anterior venous outflow from the first and second pair of gills and the air-breathing organ) to the general systemic circuit (dorsal aortic outflow from the third and fourth pair of gills). 6. Stimulation of the vagal branch entering the air-breathing organ mimics the effects of acetylcholine or adrenaline. 7. This innervation is probably non-adrenergic since no adrenergic nerve fibres could be demonstrated in the vasculature of the air-breathing organ using the histochemical technique. 8. An adrenergic control of the vasculature of the air-breathing organ is not likely, since the concentration of adrenaline needed to affect the vasculature is not reached in the plasma even during “stress”.

Chronic implants of chromaffin tissue into the dopamine-denervated striatum. Effects of NGF on graft survival, fiber growth and rotational behavior

Adult rat chromaffin tissue was transplanted into striatum of adult rat recipients whose nigrostriatal dopamine pathway had been lesioned on the grafted side by 6-hydroxydopamine. Long-term survival of the intrastriatal chromaffin grafts and the effects of treatment with nerve growth factor (NGF) was studied histochemically using Falck-Hillarp fluorescence histochemistry and functionally using rotational behavior induced by apomorphine. Small, cortex-free adrenal chromaffin tissue grafts survived permanently in striatum. The number of surviving cells was significantly increased by NGF. NGF treatment also caused transformation of many cells towards a more neuronal phenotype and greatly enhanced the adrenergic nerve fiber outgrowth into host brain tissue. NGF was either injected stereotaxically into the site of transplantation or infused continuously using implantable osmotic minipumps and a stereotaxically placed chronic indwelling dialysis fiber through striatum. The latter arrangement permitted continuous infusion of NGF for 14-28 days and caused a vigorous adrenergic nerve growth response by the grafts directed towards the source of NGF in the brain. There was a clearcut correlation between morphological signs of taking and rotational behavior. Grafts, and in particular grafts treated with NGF, were able to significantly and permanently counteract the rotational behavior induced by apomorphine. There seemed to be a dose relationship between NGF treatments and amount of reduction of asymmetric behavior. NGF treatment probably decreased the relative importance of diffuse release of catecholamines from chromaffin cells in the graft and increased the importance of adrenergic innervation of host striatum by cells in the graft. Immunofluorescence using antibodies against glial fibrillary acidic protein did not reveal any marked gliosis around the grafts nor were there any marked gliotic reactions around chronic indwelling dialysis fibers. We conclude that implantation of chromaffin tissue into striatum in conjunction with NGF treatments is an effective means of counteracting some of the symptoms of experimentally induced unilateral parkinsonism in rats.

Combined grafts of the ventral tegmental area and nucleus accumbens in oculo. Histochemical and electrophysiological characterization

Dissection techniques and optimal donor stages have been established for constructing an isolated intraocular model of the ventral tegmental area (VTA)-accumbens system using intraocular sequential grafting. Single grafts including accumbens and VTA respectively survived and developed many organotypic features when taken from 15-17 day fetuses. Falck-Hillarp fluorescence histochemistry showed dopamine neurons and terminals in single VTA grafts, no or almost no catecholamine fibers in single accumbens grafts, and a well-developed VTA-accumbens dopamine pathway in combined grafts where cell bodies in the VTA part provided the accumbens part with a rich terminal network. A similar distribution was found using immunohistochemistry with antibodies directed against tyrosine hydroxylase. CCK-like immunoreactivity had a distribution that mimicked that of the catecholamine-containing system. Enkephalin-like immunoreactivity was found both in single VTA and in single accumbens pieces as well as in both parts of the double grafts. Cells with long-duration action potentials typical of dopamine neurons discharged at approximately 8 Hz in single VTA grafts and below 1 Hz in the VTA part of VTA-accumbens double grafts. Cells in the accumbens portion of double grafts had shorter action potential durations and fired at 10-20 Hz. Haloperidol increased discharge frequency in VTA neurons with long action potential durations while apomorphine reduced discharge markedly. Antidromic activation of putative dopamine neurons in the VTA part was obtained by electrical stimulation of the accumbens part. The indirect dopamine agonist + 3-methyl-phencyclidine slowed firing rates of neurons in the accumbens part of double grafts. Taken together, the histochemical and the electrophysiological data show that the intraocular VTA-accumbens system retains several of its normal structural and functional characteristics. It is proposed that the isolated VTA-accumbens projection can be used as a model to study the cellular mechanism of action of stimulant and opiate drugs of abuse.

Neurotransmitters in the intestine of the atlantic cod, Gadus morhua

The effects of the putative neurotransmitters acetylcholine, adrenaline, adenosine, ATP, bombesin, 5-hydroxytryptamine, met-enkephalin, neurotensin, somatostatin, substance P and VIP have been investigated in the perfused intestine of the cod, Gadus morhua. The presence and distribution of the different types of nerves was investigated with immunohistochemistry and Falck-Hillarp fluorescence histochemistry. A spontaneous rhythmic activity of the perfused preparations usually occurred within a few minutes from the start of the experiment. This activity was diminished or abolished by addition of atropine, methysergide or tetrodotoxin to the perfusion fluid. Acetylcholine, 5-hydroxytryptamine or substance P caused a contraction of the intestinal wall. The response to acetylcholine was blocked by atropine but not by tetrodotoxin, while the response to 5-hydroxytryptamine was blocked by methysergide and usually also by tetrodotoxin. This indicates that the effect of acetylcholine is direct on the muscle cells, while the effect of 5-hydroxytryptamine may be at least partly via a second neuron. All adrenergic agonists (adrenaline, isoprenaline and phenylephrine) had a dominating inhibitory effect on the intestine. Experiments with antagonists showed that the inhibition is due to stimulation of both α-adrenoceptors and β-adrenoceptors. ATP, adenosine and somatostatin also caused a relaxation of the intestinal wall, often followed by a contraction. Met-enkephalin produced variable responses, either a relaxation, a contraction or both. Bombesin caused a weak inhibition, if anything. Neurotensin and VIP did not visibly affect the intestinal motility. 5-HT-, substance P- and VIP-like immunoreactivity and catecholamine fluorescence were observed in the myenteric plexus, submucosa and muscle layers in all parts of the intestine. The physiological and histochemical results in combination indicate that adrenergic nerves, serotonergic nerves and nerves containing a substance P-like peptide are involved in the control of intestinal motility of the cod. Acetylcholine, ATP/adenosine, a somatostatin-like peptide, an enkephalin-like peptide and maybe a VIP-like peptide may affect the intestine either via a nervous or via a hormonal pathway.

Adrenal medullary implants in the dopamine-denervated rat striatum. I. Acute catecholamine levels in grafts and host caudate as determined by HPLC-electrochemistry and fluorescence histochemical image analysis

Rats with unilateral 6-hydroxydopamine-induced degeneration of the left nigrostriatal dopamine system were given intrastriatal implants of one cortex-free adrenal medulla divided into 4 pieces. Two pieces were placed in the center of the anterior part of the denervated caudate and two pieces in a more posterior position in lateral caudate. The distribution of catecholamines (CA) in grafts and host brain was studied 2, 100 and 400 min after grafting by HPLC-electrochemistry and Falck-Hillarp fluorescence histochemistry combined with computer-aided image analysis. Two minutes after implantation the chromaffin tissue grafts contained large amounts of adrenaline (A) and noradrenaline (NA) and small amounts of dopamine (DA). The chromaffin cells had a relatively normal fluorescence histochemical appearance. From the grafts, CA had spread into the surrounding host brain tissue where high levels of A and NA and low levels of DA were now found in the denervated host striatum. Fluorescence histochemistry and image analysis showed the CA to have spread 1–1.5 mm in all directions from the grafts. The CA concentrations decreased almost linearly with increasing distance from the grafts. At 100 min after implantation approximately a third of the chromaffin cells were still strongly fluorescent while the rest of the cells were very weakly fluorescent or non-fluorescent. The amounts of A, NA and DA in the host brain had decreased considerably, while the size of the fluorescent halo around the grafts had not diminished. At 400 min after grafting, only scattered cells in the chromaffin implants were strongly fluorescent and the surrounding host striatum contained low amounts of CA. It is concluded that intrastriatal adrenal medullary implants acutely release or leak large amounts of CA into surrounding host brain tissue. Taken together with results from the accompanying paper 24 these data show that the grafts can maintain CA levels in host striatum high enough to elicit strong rotational responses during approximately 200 min.

Chlorhexidine-induced degeneration of adrenergic nerves.

Possible toxic effects of chlorhexidine (CHX) on the sympathetic adrenergic ground plexus were studied in whole mounts of albino rat irides using Falck-Hillarp fluorescence histochemistry. CHX dissolved in an isotone , buffered sodium-acetate solution or in 70% alcohol was injected into the anterior chamber of eye. CHX caused a marked and dose-dependent degeneration of adrenergic nerves. Two days after the lowest dose, 0,25 micrograms (5 microliters of a 0.05% CHX solution), approximately 30% of the nerves had disappeared. Almost complete degeneration was observed after the same time with higher doses (2.5 micrograms, 5.0 micrograms, and 7.5 micrograms corresponding to 0.5, 1.0, and 1.5% CHX respectively). Two weeks after the lowest dose, the nerves had regenerated almost completely. With the highest dose used, only some 40% of the normal adrenergic nerve plexus had reformed after 51 days. Alcohol as a solvent did not have an additive effect on the neurotoxic action caused by CHX. The results demonstrate yet another aspect of chlorhexidine neurotoxicity, degeneration of peripheral adrenergic nerve terminals. This suggests that neurotoxic actions on thin unmyelinated fiber systems should be looked for also in the central nervous system (CNS).

耳管におけるアドレナリン作働神経分布に関する組織化学的研究

There is much clinical evidence of a close relationship between the eustachian tube and the autonomic nervous system, especially in otitis media with effusion. However, the anatomical distribution of the autonomic nerves is not known.Superficial and topographical adrenergic innervation of the tube was demonstrated by the glyoxylic acid method. The nerve fibers were most abundant in the pharyngeal area, sparser in the middle, and even fewer in the tympanic part. The fibers were arranged in an essentially longitudinal manner in all specimens. In the pharyngeal area, the adrenergic plexus formed a loose network of varicose fibers.The cellular location of adrenergic nerves in the tube was then observed in freeze-dried sections by the Falck-Hillarp fluorescence method. Abundant adrenergic nerve fibers forming a network were observed around blood vessels, especially arteries of all the tubal regions. In the lamina propria of the tube, some varicose adrenergic nerve fibers ran separate from blood vessels, and they were abundant in the pharyngeal area. Adrenergic fibers were also seen around the tubal glands.The superior cervical ganglion was transsected to investigate the adrenergic nerve pathways and their origin.No adrenergic nerve was seen in the perivascular region or around the glands after transsection of this ganglion.These studies show that the adrenergic nerve arises from the superior cervical ganglion and reaches the eustachian tube through the tympanic plexus and along the vessels supplying the tube from the external carotid artery.The adrenergic nerve seems to affect the patency of the eustachian tube by controlling vasoconstriction. It is also speculated that patency of the tube is controlled by the adrenergic nervous system through the mucociliary system and the glands in the pharyngeal area.

Identification of Metastatic Neuroblastoma Cells in Bone Marrow by Falck‐Hillarp's Fluorescence Method

Pediatrics InternationalVolume 25, Issue 4 p. 420-421 Identification of Metastatic Neuroblastoma Cells in Bone Marrow by Falck-Hillarp's Fluorescence Method K. Mizukawa, K. Mizukawa Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this authorS. Imashuku, S. Imashuku Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this authorT. Sawada, T. Sawada Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this authorT. Kusunoki, T. Kusunoki Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this authorY. Takeuchi, Y. Takeuchi Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this author K. Mizukawa, K. Mizukawa Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this authorS. Imashuku, S. Imashuku Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this authorT. Sawada, T. Sawada Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this authorT. Kusunoki, T. Kusunoki Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this authorY. Takeuchi, Y. Takeuchi Department of Pediatrics, Kyoto Prefectural Medical CollegeSearch for more papers by this author First published: December 1983 https://doi.org/10.1111/j.1442-200X.1983.tb01727.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume25, Issue4December 1983Pages 420-421 RelatedInformation

Bombesin-, gastrin/CCK-, 5-hydroxytryptamine-, neurotensin-, somatostatin-, and VIP-like immunoreactivity and catecholamine fluorescence in the gut of the elasmobranch, Squalus acanthias.

The presence of peptides and 5-hydroxytryptamine (5-HT) in neurons and endocrine cells in the gastrointestinal tract of the spiny dogfish, Squalus acanthias, was investigated by means of immunohistochemistry, and the distribution of catecholamines by use of the Falck-Hillarp fluorescence-histochemical technique. Bombesin-like immunoreactivity was present in numerous nerves in all layers and all parts of the gut, and also in endocrine cells in the mucosa throughout the stomach, rectum and intestine. VIP-like immunoreactivity occurred in an abundance of nerve fibres and in nerve cell bodies in all parts of the gut except the oesophagus, while 5-HT-like immunoreactivity was found sparsely in nerve fibres and more frequently in endocrine cells throughout the gut. Gastrin/CCK-like immunoreactivity was present in numerous nerve fibres in the rectum, but only in scattered fibres in the other parts of the gut. Endocrine cells showing gastrin/CCK-like immunoreactivity were present in the intestine only. Somatostatin-like immunoreactivity occurred in both nerve fibres and endocrine cells of the stomach and intestine, but only in nerves in the rectum. Neurotensin-like immunoreactivity was confined to endocrine cells of the intestine. Falck-Hillarp fluorescence histochemistry revealed 5-HT in endocrine cells and catecholamines in nerve fibres (and possibly also in endocrine cells) throughout the gut. Bombesin-, VIP-, gastrin/CCK- and somatostatin-like immunoreactivities and catecholamine fluorescence were present in nerve fibres of the rectal gland and, with the exception of gastrin/CCK-like immunoreactivity, also in nerve bundles in the walls of the coeliac and mesenteric arteries. The findings of the present study form an anatomical basis for the assumption that several of the neuropeptides and amines could function as neurotransmitters or neuromodulators in the gut of Squalus.

Hexachlorophene-induced degeneration of adrenergic nerves: application of quantitative image analysis to Falck-Hillarp fluorescence histochemistry.

Possible toxic effects of hexachlorophene (HCP) on sympathetic adrenergic nerves were studied using Falck-Hillarp fluorescence histochemistry on whole-mounts of albino rat irides. HCP dissolved in 5 microliters DMSO, or DMSO alone, was injected into the anterior chamber of the eye. HCP caused a dose-dependent degeneration of adrenergic nerves, first observable after 7 micrograms and profound after 21 micrograms. One and 3 days after 35 micrograms of HCP there was an almost total loss of adrenergic nerves. Regeneration from remaining non-terminal axons led to an almost complete reformation of the adrenergic nerve plexus after 18 days. The results demonstrate a new aspect of hexachlorophene neurotoxicity, degeneration of peripheral adrenergic nerve terminals and suggest that neurotoxic actions on thin unmyelinated fiber systems should be looked for also in the central nervous system (CNS).

Supra-ependymal serotoninergic nerves in mammalian brain: Morphological, pharmacological and functional studies

Supra-ependymal nerves in mammals (mainly rats) have been shown to contain serotonin (5-hydroxytryptamine, 5-HT) by combined Falck-Hillarp fluorescence histochemistry, ultrastructural monoamine cytochemistry and pharmacology as well as by immunohistochemistry and autoradiography. Supra-ependymal 5-HT cells do not occur. At least in rats, virtually all supra-ependymal nerves contain 5-HT and in our opinion the occasionally described non-5-HT supra-ependymal nerve cells and their processes contribute little to the supra-ependymal nerve plexus (with the possible exception of those cells above the median eminence). The cells of origin of the supra-ependymal 5-HT nerves are situated in raphe nuclei. The axons and terminals (varicosities) contain small and large dense core vesicles in both of which 5-HT is stored. A co-transmitter has not been found among the candidates investigated so far (leu- and met-enkephalin, substance P and γ-aminobutyric acid (GABA)). The nerves possess uptake mechanisms specific for 5-HT and possibly GABA. Occasionally desmosome-like junctions are observed between 5-HT nerve terminals and ependymal cells but no true synapses. The function of these nerves is not known. They do not appear to regulate ciliary movement, but might influence the shape of ependymal cells.

Adrenergic nerves and receptors in the liver

The finding of an adrenergic innervation of the liver parenchyma in many mammalian species, using the Falck-Hillarp fluorescence method, together with the electron microscopy documentation of synaptoid contacts between adrenergic nerve terminals and hepatocytes, constitute an important morphological basis for the possibility of a direct role of the sympathetic nervous system on the liver function. The results from the morphological studies are in accordance with physiological experiments, carried out in many laboratories, showing that direct electrical stimulation of the hepatic nerves in vivo leads to an increased release of glucose from the hepatocytes. These findings have augmented the demand for detailed studies of the receptor systems mediating the effects of catecholamines on liver metabolism. Our pharmacological studies on liver tissue in vitro have revealed a predominant role for adrenergic betareceptors mediating glucose output in man.

Distribution and numbers of indoleamine cell bodies in the cat brainstem determined with Falck-Hillarp fluorescence histochemistry

Using the Falck-Hillarp method, the cat brainstem was found to contain approximately 60,000 indoleamine (IA) cells. Most of these (46,000 or 77%) are located within the raphe nuclei. Nissl-stained material demonstrated both medium- and small-sized perikarya in the raphe nuclei, and quantitation revealed that the IA cells comprise only part of the medium-sized cells. Thus, the raphe dorsalis holds about 24,000 IA cells representing some 70% of its medium-sized cells. Corresponding values were for raphe pallidus 8,000 IA cells (55%), raphe centralis superior 7,400 (35%), raphe magnus 2,400 (15%), raphe obscurus 2,300 (33%), linearis intermedius 2,100 (23%), and raphe pontis 280 (9%). A considerable number of IA cells (13,600, representing 23% of the total) were found in locations outside the raphe nuclei: in ventral brainstem as lateral extensions from the raphe, among the bundles of fasciculus longitudinalis medialis, in periventricular gray and adjacent tegmentum, mixing with the noradrenergic cells of the locus coeruleus complex, among the mesencephalic dopamine cells, and in the nucleus interpeduncularis.

Fluorescence histochemical observations on the adrenergic innervation of the cardiovascular system in the aged rat

The Falck-Hillarp fluorescence technique was applied to tissue samples of the heart and certain vessels of both 4 and 24 month Wistar rats. It appeared that with increasing age, the density and fluorescence intensity of the cardiac sympathetic innervation was maintained at a level comparable to the young adult (4 month) in the atria, left ventricle and in the region of the sino-atrial node. Similarly the adrenergic innervation of the coronary vasculature, particularly in the atrium was maintained into old age. In contrast the adrenergic innervation of the common and internal carotid arteries and abdominal aorta was very sparse in the 24 month rat compared to the young adult in which these vessels were surrounded by dense fluorescent plexuses. Peripheral arteriolar innervation in the pancreas was apparently similar in both age-groups. The present study suggests that the density of adrenergic innervation varies within the constituents of the cardiovascular system in aged rats.