Organization and ultrastructural identification of the catecholamine nerve terminals in the neural lobe and pars intermedia of the rat pituitary

Summary The central catecholamine innervation of the pituitary neural lobe and pars intermedia of the rat have been identified ultrastructurally and their organization has been investigated in a combined fluorescence histochemical and electron microscopical study. The dopamine analogues, 5-hydroxydopamine and 6-hydroxydopamine, were used to label the catecholamine terminals, and to enable the direct correlation between the fluorescence microscopical and the electron microscopical pictures.The fibre type that was identified as catecholamine-containing was ultrastructurally chiefly characterized by dense-cored vesicles, 500–1200 Å in diameter, intermingled with varying numbers of small empty vesicles. 5-hydroxydopamine was selectively accumulated in these fibres and caused an increased electron density of the granular vesicles as well as of some small normally agranular vesicles, and systemically administered 6-hydroxydopamine caused a selective degeneration of these fibres, most prominently within the neural lobe. The dopaminergic terminals of the neural lobe showed frequent close contacts (80–120 Å), without real membrane thickenings, to neurosecretory axons and to pituicyte processes. It is suggested that these close contacts might signify a direct dopaminergic influence on the neurosecretory axons and/or on the pituicyte processes. The identified central catecholamine fibres were also found to make common synapse-like contacts on the pars intermedia cells, whereas the innervation by neurosecretory fibres was very rare. This suggests that the direct central nervous control of the rat pars intermedia is exerted by the catecholamine neurons. A very special feature of the catecholamine fibres in the pituitary is the occurrence of peculiar, large dopamine-filled droplet-like swellings. Electron microscopically, such large axonal swellings (more than 2 in diameter) were found to contain, in addition to the characteristic vesicles and organelles, strongly osmiophilic lamellated membrane complexes resembling myelin bodies and multivesicular bodies encircling disintegrated vesicles, suggesting that these droplet fibres represent dilated stumps of spontaneously degenerating dopaminergic axons. It is suggested that the dopaminergic neural lobe fibres are undergoing continuous reorganization through degeneration—regeneration cycles, a phenomenon previously suggested for the neurosecretory axons of the neural lobe.Supported by the Deutsche Forschungsgemeinschaft.Supported by Svenska Livförsäkringsbolags Nämnd för Medicinsk Forskning, by The Medical Faculty, University of Lund and by the Ford Foundation.     

Adrenergic innervation of the oesophagus in the cat (Fellis domestica) and rhesus monkey (Macacus rhesus)

Summary The distribution of monoamines in the pharynx and oesophagus of the rhesus monkey (Macacus rhesus) and the cat (Felis domestica) was investigated by means of fluorescence microscopical and chemical methods. Fluorimetric determinations reveal the presence of varying amounts of noradrenaline in the pharynx and oesophagus of the rhesus monkey. The lowest amount (0.05 (g/g) was found in the lower part of the oesophagus, the so-called sphincter-segment. The middle and upper part of the oesophagus contain medium amounts of noradrenaline (0.06–0.09 g) whereas the highest concentration was detected in the pharynx (0.14 (g/g). Neither dopamine nor adrenaline occurred in the tissue pieces analyzed. Fluorescence microscopically noradrenaline was found to be located in varicose intramural nerve fibre plexus which innervate mucous glands and blood vessels in the pharynx of both species. In the rhesus monkey, the lamina muscularis mucosae of all parts of the oesophagus is supplied by a well developed noradrenergic ground-plexus. Preterminal and terminal varicose nerve fibres are distributed in myenteric and submucous ganglia of the oesophagus; the number of such ganglia decreases towards the lower segment. The density of the adrenergic innervation is higher in myenteric when compared to submucous ganglia. The arrangement of the intraganglionic terminals suggests that both axosomatic and axodendritic contacts occur in Auerbach's ganglia whereas axodendritic contacts seem to predominate in Meissner's ganglia. Myenteric ganglia situated close to the submucosa as well as true submucous ganglia may be occasionally seen to be traversed by faintly fluorescent non-varicosed fibres which do not establish any synaptic contacts. The fluorescence intensity of intraganglionic varicosities varies considerably; accordingly the transmitter content of individual varicosities seems to be very variable. The adrenergic innervation of the lamina muscularis is restricted to single contorted fibres being sparsely distributed throughout the longitudinal smooth muscle layer. The circularly arranged smooth musculature of the sphincter-segment lacks an adrenergic nerve supply. The vagus nerve carries sympathetic adrenergic fibres to the lower oesophagus and the cardia. Species differences between the innervation pattern in rhesus monkeys and cats are outlined: No adrenergically innervated ganglia occur in the submucosa of the cat. However, part of the myenteric ganglia in cats exhibit an adrenergic innervation pattern similar to that seen in submucous ganglia of the rhesus monkey. They might therefore be regarded as morphologically equivalent to the plexus submucosus which is, however, present in the whole gut. The density of the noradrenergic ground-plexus in the muscularis mucosae of the cat's oesophagus is less than that of the corresponding plexus in rhesus monkeys.The influence of noradrenaline upon the smooth musculature and the neurons from myenteric as well as submucous ganglia is discussed. From the point of view of the adrenergic innervation there is no structure corresponding to the sphincterlike lower oesophageal segment.Supported by the Deutsche Forschungsgemeinschaft and the Joachim-Jungius-Gesellschaft zur Förderung der Wissenschaften, Hamburg.     

The localization of the β-subtype of protein kinase C (PKC-β) in rat sympathetic neurons

Summary The localization of PKC- was studied in rat sympathetic neurons using a polyclonal antibody specific for the ₁- and ₂-subspecies. The tissues studied included the superior cervical (SCG) and hypogastric (HGG) ganglia and the target tissues of the SCG and HGG neurons: the submandibular gland, iris, prostate and vas deferens. PKC--LI was found in nerve fibers in both ganglia. A proportion of the fibers in the SCG disappeared after decentralization, suggesting that the fibers were of both pre- and postganglionic origin. The somata of the HGG and SCG neurons expressed varying amounts of PKC--LI, the majority of SCG neurons being labelled only after colchicine treatment. In all target tissues there were PKC--immunoreactive nerve fibers in bundles, but the most peripheral branches of the fibers were negatively labelled. The results show that PKC--LI is widely present in sympathetic postganglionic neurons with mainly quantitative differences. The lack of PKC- in the most peripheral branches of nerve fibers might be a general feature of sympathetic postganglionic neurons, suggesting that the participation of PKC- in neurotransmitter release and in other functions in nerve terminals in sympathetic adrenergic neurons is unlikely.     

Extrinsic adrenergic innervation of the extrahepatic biliary duct system in guinea-pigs,cats and rhesus monkeys

Summary The localization of catecholamines has been investigated in the extrahepatic biliary duct system of cats, guinea-pigs and rhesus monkeys. In fluorimetric determinations noradrenaline was found to be the main primary catecholamine present in the biliary tract of rhesus monkeys. There exist regional differences in the noradrenaline content: Fairly low amounts were detected in the lower fundus of the gall-bladder (0.28 g/g). Increasing concentrations were measured in the corpus vesicae felleae (0.35 g/g), reaching a maximum level in the collum vesicae (0.49 g/g) and the ductus cysticus (0.50 g/g). The noradrenaline content of the choledochus and the choledocho-duodenal junction including Oddi's sphincter was much lower: 0,27 and 0,25 g/g respectively. The noradrenaline level in the small intestine of the rhesus monkey amounted to less than half the concentration found in the biliary ducts. Neither dopamine nor adrenaline have been detected. Fluorescence microscopical analysis reveals the presence of adrenergic nerves in the bile ducts which correspond to the measured noradrenaline concentrations: All parts of the biliary duct system in the different species investigated contain an elaborate perivascular adventitial plexus and adrenergic fibres confined to adventitial non-adrenergic ganglia. In guinea-pigs adrenergically innervated ganglia extend into the smooth muscle layer. The smooth muscle layer of the gall-bladder and the terminal choledochus in cats and rhesus monkeys is penetrated by a wide-meshed adrenergic ground plexus. This plexus was absent in guinea-pigs. The smooth musculature of the sphincter Oddi lacks a specialized adrenergic nerve supply in all species investigated. Finally, bound to the arterial vascular bed inside the propria in all parts of the biliary tract from all species investigated a prominent perivascular plexus is present. It is concluded that the smooth musculature of the gall-bladder and the terminal choledochus (the sphincter region excluded) in cats and monkeys receives 1. a direct sympathetic noradrenergic inhibitory innervation and 2. an indirect sympathetic noradrenergic inhibitory innervation which acts on intrinsic excitatory neurons and is present in all species investigated. The functional significance of the direct and indirect inhibitory innervation to the smooth musculature of the gall-bladder is discussed in detail.Dedicated to Professor Bengt Falck.Supported by the Deutsche Forschungsgemeinschaft and Joachim-Jungius-Gesellschaft zur Förderung der Wissenschaften, Hamburg.     

Polarized distribution of γ interferon-stimulated MHC antigens and transferrin receptors in a clonal cell line isolated from Fisher rat thyroid (FRT cells)

Summary The fine structure of single identified muscle fibers and their nerve terminals in the limb closer muscle of the shore crab Eriphia spinifrons was examined, using a previous classification based on histochemical evidence which recognizes a slow (Type-I) fiber and three fast (Type-II, Type-III, Type-IV) fibers. All four fiber types have a fine structure characteristic of crustacean slow muscle, with 10–12 thin filaments surrounding each thick filament and sarcomere lengths of 6–13 m. Type-IV fibers have sarcomere lengths of 6 m while the other three types have substantially longer sarcomeres (10–13 m). Structural features of nerve terminals revealed excitatory innervation in all four fiber types but inhibitory innervation in Type-I, Type-II, and Type-III fibers only. Thus fibers with longer sarcomeres receive the inhibitor axon but those with shorter sarcomeres do not. Amongst the former, synaptic contact from an inhibitory nerve terminal onto an excitatory one, denoting presynaptic inhibition, was seen in Type-I and Type-II fibers but not in Type-III and Type-IV fibers. Inhibitory innervation of the walking leg closer muscle is therefore highly differentiated: some fibers lack inhibitory nerve terminals, some possess postsynaptic inhibition, and some possess both postsynaptic and presynaptic inhibition.     

Dense-core vesicles in motor nerve terminals

Summary Motor nerve terminals on white and intermediate muscle fibers of the Atlantic hagfish (Myxine glutinosa, L.) contain translucent synpatic vesicles and about 1–2% dense-core vesicles. Terminals on red muscle fibers contain up to 40% dense-core vesicles with diameter 800–1100 Å. Examinations for formaldehyde-induced fluorescence indicate yellow fluorescence (5-HT ?) apparently corresponding with terminal axons on red muscle fibers in craniovelar muscles. Possibly red muscle fibers of Myxine receive monoaminergic innervation.The author is indebted to Dr. Finn Walvig, Biological station, University of Oslo, Drøbak, for supply of hagfishes.     

Cholinergic nerves in the human liver

Summary The cholinergic innervation of the human liver was studied. Slices (150–200m thick) of human liver and of the greater hepatic blood vessels (hepatic artery and vein, portal vein) were incubated in a solution of 6-hydroxydopamine (6-HDA) in order to obtain a selective degeneration of adrenergic nerves. Controls were prepared from samples incubated with buffer alone. The slices were cut on a cryostat into 15–20m thick sections and processed for the histochemical detection of cholinesterases.Cholinergic nerve fibres innervate the extra hepatic and the intrahepatic branches of the hepatic artery, the portal vein as well as the hepatic vein. Fewer cholinergic fibres innervate the hepatocytes and the hepatic sinusoids. The 6-HDA treatment does not seem to alter the pattern of the cholinergic innervation of the liver. The findings indicate the presence of a cholinergic parasympathetic innervation in the human liver.     

Consecutive demonstration of catecholamines and dopamine-β-hydroxylase within the same specimen

Summary A combined method was developed for characterization and differentiation of catecholamines in neuron populations containing more than one catecholamine, e.g. dopamine and norepinephrine. Its application to small intensely fluorescent (SIF-) cell clusters in sympathetic ganglia allows the successive demonstration of glyoxylic acid-induced catecholamine fluorescence and dopamine--hydroxylase by indirect immunofluorescence within the same tissue section. Applying this technique to an example, two types of SIF-cells were demonstrated in the guinea pig superior cervical ganglion.Supported by the Deutsche Forschungsgemeinschaft grant He 919/4     

Immunohistochemical and histochemical evidence for the presence of noradrenaline,serotonin and gamma-aminobutyric acid in chief cells of the mouse carotid body

The immunohistochemical study revealed tyrosine hydroxylase (TH), dopamine -hydroxylase (DBH), phenylethanolamine N-methyltransferase (PNMT), serotonin, glutamate decarboxylase (GAD) and -aminobutyric acid (GABA) immunoreactivities in the mouse carotid body. TH and DBH immunoreactivities were found in almost all chief cells and a few ganglion cells, and in relatively numerous varicose nerve fibers of the carotid body. The histofluorescence microscopy showed catecholamine fluorescence in almost all chief cells. However, no PNMT immunoreactivity was observed in the carotid body. Serotonin, GAD and GABA immunoreactivities were also seen in almost all chief cells of the carotid body. From combined immunohistochemistry and fluorescence histochemistry, catecholamine and serotonin or catecholamine and GABA were colocalized in almost all chief cells. Thus, these findings suggest that noradrenaline, serotonin and GABA may be synthesized and co-exist in almost all chief cells of the mouse carotid body and may play roles in chemoreceptive functions.     

Ultrastructure of the new neuromuscular junctions formed during reinnervation of rat soleus muscle by a “foreign” nerve

Summary In rats the fast fibular nerve was transposed to the slow soleus muscle outside the original innervation band. Formation of new neuromuscular junctions was induced by cutting the soleus nerve after different periods of time. The morphological maturation of these junctions was studied by electron microscopy.New neuromuscular junctions do not form when the original innervation is left intact.Three to five days after denervation, vesicle-laden terminal boutons contact muscle fibers with only the basal lamina of the latter intervening. Three weeks after denervation, most boutons are larger and postsynaptic folds are present, although younger stages are also seen. Sixteen weeks after denervation, the neuromuscular junctions appear mature. This corresponds well with electrophysiological findings in the same material.The fully developed neuromuscular junctions sixteen weeks after denervation possess postsynaptic folds similar to those of normal fast muscle fibers. This suggests that the fast fibular nerve rather than the slow soleus muscle fibers determines the morphology of the postsynaptic folds.Possible trophic neuromuscular interactions are discussed.The authors are indebted to Mrs. Jorunn Line Vaaland, Miss Bjørg Riber, and Miss Berit Branil for technical assistance. Dr. T. Lømo and Dr. C. Slater have contributed constructive criticism and advice     

Motor innervation of the cat muscle spindle studied by the cholinesterase technique

Summary Muscle spindles were traced in serial transverse sections of cat tenuissimus muscles. Myofibrillar adenosine triphosphatase staining reaction was used to identify nuclear bag₁, nuclear bag₂ and nuclear chain intrafusal muscle fibers. Typical chain fibers and long chain fibers were distinguished, the latter extending for more than 1,000 m beyond the termination of the spindle capsule. Simple rim and more elaborate plate deposits were demonstrated histochemically along the poles of the typical chain fibers in staining for cholinesterases. They were considered to correspond, respectively, to the trail and plate motor nerve terminals. Most long chain fibers and the majority of nuclear bag fibers had their motor innervation limited to plate-type endings. In addition, faint diffuse cholinesterase staining occurred along the spindle capsule and the surface of some intrafusal fibers. These histochemical observations are discussed with regard to the current concepts concerning the morphological and functional organization of the motor innervation of the cat muscle spindle.     

The relationship between gastrin cells and bombesin-like immunoreactive nerve fibres in the gastric antral mucosa of guinea-pig,rat, dog and man

Summary The relationship between bombesin-like immunoreactive (bombesin-LI) nerve fibres and gastrin-LI G-cells was examined in gastric antral mucosa from guineapig, rat, dog and man using a double-labelling fluorescence immunohistochemical technique. The greatest density of bombesin-LI nerve fibres was found within the basal mucosa in all species and the density of innervation decreased towards the luminal surface. Most G-cells were in a band occupying approximately the middle third of the mucosa. The proportion of G-cells found within a distance of 2 m from bombesin-LI nerve fibres was low in all species (6% in the guinea-pig, 22% in the rat, 14% in the dog, and 9% in the human). It is proposed that the neuropeptide released from bombesin-LI antral mucosal nerve fibres traverses distances of greater than several m to reach the target G-cells. This may be achieved by passage through the mucosal microcirculation.     

Catecholaminergic nerves in the embryonic chick ovary: co-localization with β2-adrenoceptor-bearing steroidogenic cells

Summary The present study investigates the innervation of the embryonic chick ovary with regard to (i) development and compartmentalization of catecholaminergic nerves, and (ii) presence of adrenoceptors on steroidogenic target cells of catecholaminergic nerve terminals. Catecholaminergic nerve fibers visualized by glyoxylic acid-induced histofluorescence first appeared at embryonic day (E) 13. From E15 through E21 the density of fluorescent aminergic nerves increased markedly in parallel with the concentration of catecholamines and numbers of nerve bundles and single axons seen at the electron-microscopic level. Catecholaminergic nerves were confined to the ovarian medulla and closely associated with interstitial cells. Nerve terminals approached interstitial cells up to a distance of 20 nm and, in their majority, exhibited uptake of the false adrenergic transmitter 5-hydroxydopamine. Although adrenaline amounted to 14% of the total catecholamine content at E21, adrenaline immunoreactivity was only detected in adrenal chromaffin cells, but not in nerve fibers or cell bodies within the ovary. Interstitial cells structurally matured between E15 and E21 as documented by an increase of smooth endoplasmic reticulum and tubular mitochondria. Monoclonal antibodies mAB 120 and BRK 2 raised against avian ₁ and mammalian ₂-adrenergic receptors revealed the presence of ₂-adrenoceptor-like immunoreactivity on the surface of interstitial cells, but not on any other cell type.The results are consistent with the notion of a dense adrenergic innervation of the embryonic chick ovarian medulla and its steroidogenic interstitial cells, and suggest the chick ovary as an excellent model for elucidating the functional role of a neural input to steroidogenic cells during development.     

Quantitation of fiber growth in transplanted central monoamine neurons

Summary Nerve fiber production by central noradrenaline (NA), dopamine (DA), and 5-hydroxytryptamine (5-HT) neurons was studied using immature brain tissue containing locus coeruleus, substantia nigra, or ventro-caudal medulla oblongata respectively, homologously grafted to the anterior chambers of rat eyes. A method was developed for quantitation of the fiber growth that occurs on the sympathetically denervated host irides as observed in whole mounts using Falck-Hillarp fluorescence histochemistry and by the uptake of ³H-metaraminol into the irides. Survival and growth in oculo of the three different areas were characterized by direct observations through the cornea in vivo for a number of pre- and postnatal stages of development of the donors, and the findings correlated to the degree of monoamine nerve fiber production on the host irides. The growth of fetal locus coeruleus transplants on irides was quantified using both fluorescence microscopical measurements of innervated areas and uptake of ³H-metaraminol. The uptake was well correlated to the histochemical measurements on individual irides, thus validating the fluorescence microscopical measurements of fiber production. The fiber growth of fetal locus coeruleus grafts on irides was followed for 20 weeks. The nerves increased in number and uptake capacity approximately linearly for 6 weeks whereafter the increase rapidly levelled off. On average, the final amount of nerve production by fetal locus grafts did not cover more than 1/3 of the host iris surface, and the average uptake of ³H-metaraminol by these nerves did not exceed 60% of that found in sympathetically intact control irides. The locus grafts produced a similar amount of fluorescent fibers in the host iris independent of the crown-rump length stage of the donor fetus and the final size of the transplants in oculo.The survival and growth of NA, DA and 5-HT neurons grafted from various postnatal donor rats was also followed by fluorescence microscopy. Locus coeruleus grafts produced markedly more fibers than the two other types of grafts when the donor was one week old or less, and DA grafts produced the least fibers of the three. Even from one month old donors some MA neurons survived grafting. Also, using prenatal donars, the locus coeruleus grafts produced many more fibers on the irides than did the DA grafts. It was concluded that the intraocular transplantation technique is very suitable for quantitative studies of nerve fiber production by immature monoamine neurons, and that it should be possible to study many other neuron systems in similar ways with this technique.Supported by the Swedish Medical Research Council (04X-03185), Magnus Bergvalls Stiftelse and Karolinska Institutets Fonder. The skilful technical assistance of Miss Ingrid Strömberg, Miss Maud Eriksson and Miss Gerd Boëtius is gratefully acknowledged. Thanks are due to Swedish Pfizer for the generous supply of Nialamid^®     

Innervation of the large arteries and heart of the toad (Bufo marinus) by adrenergic and peptide-containing neurons

Summary The innervation of the major arteries and heart of the toad (Bufo marinus) was examined by use of glyoxylic acid-induced catecholamine fluorescence and peptide immunohistochemistry. All arteries possessed a moderate to dense plexus of adrenergic axons, which also showed neuropeptide Y-like immunoreactivity (NPY-LI). Some adrenergic axons in the intracardiac vagal trunks showed NPY-LI, but the varicose adrenergic axons innervating the cardiac muscle of the atria and ventricle, and the coronary blood vessels did not display NPY-LI. About half of the nerve cell bodies in the anterior sympathetic chain ganglia with dopamine--hydroxylase-LI (DBH-LI) also contained NPY-LI. The nerve cell bodies with DBH-LI alone were generally larger (median diameter 30 m) than those with both DBH-LI and NPY-LI (median diameter 20 m). Some cell bodies showing DBH-LI alone were surrounded by boutons with NPY-LI but not DBH-LI. Axons that displayed simultaneously both substance P-LI (SP-LI) and calcitonin gene-related peptide-LI (CGRP-LI) also formed a plexus around all arteries studied, being particularly dense around the mesenteric and pulmonary arteries. These axons are most likely sensory since SP-LI was reduced by capsaicin treatment, and nerve cell bodies with both SP-LI and CGRP-LI were found in dorsal root ganglia and the vagal ganglion. A dense plexus of axons showing somatostatin-LI was located around the pulmonary artery and its main intrapulmonary branches. A few nerves with vasoactive intestinal polypeptide-LI were found around the dorsal aorta and pulmonary artery. No perivascular nerves with enkephalin-LI were observed. Reversed-phase, high-pressure liquid chromatography of acid extracts of the large arteries showed that the major peaks of NPY-LI and SP-LI coeluted with porcine NPY (1–36) and synthetic SP (1–11), respectively. Thus, the location and structure of these peptides in perivascular nerves has been highly conserved during vertebrate evolution.     

The Catalytic Transition State in ATP Synthase

The catalytic transition state of ATP synthase has been characterized and modeled by combined use of (1) Mg-ADP–fluoroaluminate, Mg-ADP–fluoroscandium, and corresponding Mg-IDP–fluorometals as transition-state analogs; (2) fluorescence signals of -Trp331 and -Trp148 as optical probes to assess formation of the transition state; (3) mutations of critical catalytic residues to determine side-chain ligands required to stabilize the transition state. Rate acceleration by positive catalytic site cooperativity is explained as due to mobility of -Arg376, acting as an arginine finger residue, which interacts with nucleotide specifically at the transition state step of catalysis, not with Mg-ATP- or Mg-ADP-bound ground states. We speculate that formation and collapse of the transition state may engender catalytic site / subunit-interface conformational movement, which is linked to -subunit rotation.     

β-Dl-Methylene-aspartate,an inhibitor of aspartate aminotransferase,potently inhibitsl-glutamate uptake into astrocytes

[³H]Glutamate uptake into astrocytes in primary culture was potently inhibited by the aspartate analoguesl- andd-aspartic acid,Dl-threo--hydroxy-aspartic acid,l-aspartic acid--hydroxymate (IC50's: 136, 259, 168, and 560 M, respectively) and by -Dl-methylene-aspartate, a suicide inhibitor of asparate aminotransferase (IC50: 524 M), and by the endogenous sulphur-containing amino acidl-cysteinesulfinic acid (IC50: 114 M). [³H]Glutamate uptake was not significantly affected by either N-methyl-d-aspartate orDl-homocysteine thiolactone. These results demonstrate that other excitatory amino acids including aspartate andl-cysteinesulfinic acid (but excludingl-homocysteic acid) interact with the glutamate transport system of astrocytes. Inhibition of glutamate uptake may significantly increase the level of neuronal excitability.     

Catecholamine innervation of the intestine of flying foxes (Pteropus spp.): a substantial supply from enteric neurons

The distribution of catecholamines in the small and large intestine of flying foxes (Pteropus spp.) was investigated using glyoxylic-acid-induced fluorescence and immunohistochemical staining of tyrosine hydroxylase and dopamine--hydroxylase. Dense networks of varicose axons stained by each of these methods supplied blood vessels, the mucosa and both submucous and myenteric ganglia, but were scarce in the circular and longitudinal muscle. The majority (>90%) of submucous neuronal perikarya contained both enzymes and most of these also exhibited catecholamine fluorescence. Somata of similar staining characteristics were less common in the myenteric plexus, where single cells were found in only the minority of ganglia. All of the stained submucosal somata and mucosal axons contained vasoactive intestinal peptide, whereas catecholamine-containing axons that supplied the ganglia, external muscle and blood vessels did not. It is concluded that (1) there is dense catecholamine innervation of most tissues in the flyingfox intestine, similar to many other mammals, (2) mucosal axons originate from enteric catecholamine neurons, not found in other mammals, and (3) axons supplying the blood vessels and enteric ganglia are probably of sympathetic origin and can be distinguished from the intrinsic catecholamine-containing axons by their lack of vasoactive intestinal peptide. The roles and interactions of these two types of catecholamine innervation in the control of secretion and motility remain to be identified.     

Nervous control of the branchial vascular resistance of the Atlantic cod,Gadus morhua

Summary The effects on branchial vascular resistance of electrical stimulation of the nervous supply to the gills of the Atlantic cod were studied in constant pressure perfused gill preparations.Stimulation of the right sympathetic chain immediately anterior to the coeliac ganglion produces either a -adrenoceptor mediated decrease in branchial vascular resistance of the gill arches on the right side, or an -adrenoceptor mediated increase which is reversed by phentolamine to a -adrenoceptor mediated decrease in branchial vascular resistance.Stimulation of the entire vago-sympathetic nerve trunk to the third isolated gill arch produces an increase in branchial vascular resistance, which in some preparations can be reversed by atropine to a -adrenoceptor mediated decrease. A second type of constrictory innervation of vagal origin (non-adrenergic, non-cholinergic) may be concluded from the lack of blocking capacity of cholinergic and adrenergic antagonists.It is concluded that the branchial vascular bed of the cod is controlled by both sympathetic (dilatory and sometimes also constrictory) and parasympathetic (constrictory) fibres. The site of action of the nerve supply on the various effectors of the complex vasculature of the gills is not known. An autonomic innervation with its direct, rapid and restricted effects may reinforce the more general effects of circulating vaso-active substances.