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Biomedical subjects

A Dahlström

Publications and source records attributed to A Dahlström.

At least 19 recordsLinked to original sources
PubMed1992

Influence of spinal cord transection on the presence and axonal transport of CGRP-, chromogranin A-, VIP-, synapsin I-, and synaptophysin-like immunoreactivities in rat motor nerve.

Using immunofluorescence and cytofluorimetric scanning (CFS), we investigated the short-term (1-7 days) influence of lower thoracic spinal cord transection on lumbar motor neurons. The content of calcitonin gene-related peptide- (CGRP) like immunoreactivity (LI), chromogranin A (Chr A)-LI, vasoactive intestinal polypeptide (VIP)-LI, Syn I-LI, and synaptophysin (p38)-LI in motor perikarya, and the anterograde and retrograde axonal transport of these substances in the sciatic nerve, were studied in nerve crush (6 h) experiments. During the week after transection, CGRP-LI in perikarya decreased, whereas Chr A-LI increased. VIP-LI, co-localized with Chr A-LI in motor perikarya, did not change after transection. The antero- and retrograde transport of CGRP-LI in the sciatic nerve, occurring in both motor and sensory axons, appeared unchanged in cytofluorimetric scanning (CFS) graphs, but the microscopical picture clearly showed that large motor axons had a decreased content of CGRP-LI at 3 and 7 days posttransection, whereas thinner axons were unchanged in fluorescence intensity. The anterograde transport of Chr A-LI, present in both motor and postganglionic adrenergic axons, was decreased 1 and 3 days after lesion, but returned to control by day 7. There was a marked decrease in anterograde transport of VIP-LI, present mainly in postganglionic sympathetic axons, at day 3, but at 7 days transport was normal. The amounts of transported p38, the synaptic vesicle marker, were in the normal range during the whole period. Syn I-LI accumulation anterogradely was somewhat decreased at 3 and 7 days posttransection, and at 1 day the retrograde accumulation was significantly increased. The results suggest that removal of supraspinal input to intact lower motor neurons causes alterations in metabolism and axonal transport of organelle-associated substances, partly probably related to the complex pattern of transmitter leakage from degenerating, descending nerve terminals. These alterations appear to take place also in postganglionic sympathetic neurons in the sciatic nerve, that originate in the lumbar sympathetic chain.

Acetylcholinesterase↗
PubMed1992

Possible regulatory role of dynorphin A in the urinary bladder.

UNLABELLED: Muscle strips from rat and human detrusor were studied using indirect immunofluorescence and electrical nerve stimulation in an organ bath. Immunoreactivity towards dynorphin was observed in varicose nerve fibres in the detrusor muscle and around immunonegative nerve cell bodies in the prevesical ganglia of the rat. In vitro, dynorphin A (1-13) (10(-13)-10(-6) M) strongly facilitated detrusor contraction induced by electrical field stimulation (EFS). This facilitation was counteracted by morphine (10(-10) and 10(-8) M) and naloxone (10(-10) and 10(-8) M) in a competitive manner. The facilitation could also be counteracted by the addition of the kappa-receptor antagonist M(r) 2266 (10(-7) M). Muscarinic blockade, achieved with atropine (10(-6) M), did not alter the effect of dynorphin A (1-13). Addition of phentolamine mesylate (10(-6) M), and propranolol (10(-6) M) per se facilitated the EFS-induced contractions. Both adrenergic blockade as well as the addition of the substance P blocker spantide, counteracted the facilitating effect of dynorphin A (1-13). IN CONCLUSION: Dynorphin A immunoreactive material was found to be present in nerves in the rat detrusor and in prevesical ganglia. Dynorphin A (1-13) facilitated the detrusor contraction, possibly via actions on kappa-opioid receptors and interaction with non-cholinergic nerves.

Analgesics↗
PubMed1992

Effect of substance P on detrusor muscle in rats with diabetic cystopathy.

Diabetic cystopathy (DCP) is a well known complication in diabetes mellitus (DM). In the present experimental study, DM was induced in rats by streptozotocin and DCP was confirmed on cystometry. In vitro studies on detrusor strips from diabetic rats showed an increased contractile response to substance P (SP) compared with controls, indicating denervation supersensitivity. A decreased response to capsaicin in diabetic detrusor strips indicated a decreased neuronal content of SP or a diminished number of SP-containing sensory nerves. This suggests that DM induces alterations in nerves containing SP which may be at least partly responsible for sensory loss and the development of DCP.

Animals↗
PubMed1979

The intra-axonal transport of acetylcholine and cholinergic enzymes in rat sciatic nerve during regeneration after various types of axonal trauma.

The proximo-distal intra-axonal transport of acetylcholine (ACh) and cholinergic enzymes (choline acetyltransferase, CAT, and ACh-esterase, AChE) in rat regenerating sciatic nerve was studied by accumulation technique. Four types of axonal trauma were performed: freezing with solid CO2, crushing, ligating the nerve with remaining tight silk ligature, and cutting the nerve. Normal and sham-operated rats were used as controls. One to twenty-nine days later, the nerves were crushed about 15 mm proximal to the trauma. The nerve segment proximal to this crush was dissected out 12 hr later and assayed for ACh-content and enzyme activities. The increase in this segment 12 hr after crushing was taken as an indication of proximo-distal transport in the regenerating nerves. ACh transport did not seem to vary during regeneration as compared to controls. In contrast, the transport of both CAT and AChE was initially markedly depressed. Towards the end of the observation period (29 days), a recovery of CAT-transport occurred in all groups. Recovery of AChE-transport was marked in the freeze and crush groups. In the cut group no recovery was seen and in the ligated group only a small recovery occurred. Thus, in the nerves where regeneration was facilitated by the presence of intact connective tissue sheaths (freezing and crushing) recovery of transport occurred earlier than in cut or ligated nerves.

Acetylcholine↗
PubMed1979

The effects of splanchnic nerve stimulation on the plasma levels of serotonin and substance P in the portal vein of the cat.

The blood levels of serotonin (5-HT) and substance P (SP) in the portal vein were studied after splanchnic nerve stimulation in the cat. The portal levels of both substances were studied before, during and after splanchnic nerve stimulation. There was a twofold increase in 5-HT during stimulation whilst the SP concentration remained unchanged. These results suggest that the nervous control of the amine release into the portal stream and the mechanism that regulates the release of the polypeptide is not the same.

Animals↗
PubMed1979

The effect of transmural field stimulation on the serotonin content in rat duodenal enterochromaffin cells--in vitro.

The effect of transmural field stimulation (TFS)--in vitro--on the sertonin (5-HT) content in enterochromafffin cells (EC) in rat duodenum was studied with a cytofluorimetric method. TFS caused a significant 25% decrease of 5-HT in EC. The presence of tetrodotoxin or d,1-propranolol in the stimulation bath antagonized the effect of TFS. In biopsies from rats pretreated with 6-OH-dopamine TFS had no effect of the 5-HT content in EC. The results of the present study strongly suggest, that the TFS induced decrease in 5-HT content is due to a direct neural, probably beta-adrenoceptor mediated, influence on the EC.

Adrenergic Fibers↗
PubMed1979

The effect of propranolol on the serotonin concentration in the portal plasma after vagal nerve stimulation in the cat.

Efferent cervical vagal nerve stimulation in the cat caused a marked increase of the portal plasma 5-HT concentration. This increase was more than two-fold within 15 min of stimulation. After cessation of stimulation portal plasma 5-HT returned to basal levels within 10 min. Treatment with the beta-adrenoceptor antagonist propranolol, in various doses (0.1-2 mg/kg b.wt.), did not abolish but significantly reduced the response to vagal stimulation, particularly during the final part of the stimulation period. The results confirm the existence of a beta-adrenoceptor-mediated release of 5-HT, but also suggest that other mechanisms for 5-HT release may be involved in the response on vagal nerve stimulation.

Adrenergic beta-Antagonists↗
PubMed1979

Substance P-, VIP-, and enkephalin-like immunoreactivity in the human vagus nerve.

The human vagus nerve has been investigated for the presence of substance P (SP), vasoactive intestinal polypeptide (VIP), and enkephalin (ENK) using immunohistochemistry. After 0.5-4 hr of nerve ligation during surgical operations two right thoracic main truncs, two anterior subdiaphragmal trunks, and four anterior nerves of Latarjet were found to contain accumulation of immunoreactive material in nerve fibers above the ligation. Very high numbers of SP-, medium numbers of ENK-, and low number of VIP-immunoreactive fibers were seen. The relative proportions were similar at all levels studied. These data thus indicate the presence and axonal transport of SP-, ENK-, and VIP-like peptides in the human vagus nerve. Our observations in humans correlate well with results obtained from other species. Thus gastrointestinal vagal sensory mechanisms may be mediated by SP (and possibly VIP) and some motor mechanisms by ENK.

Endorphins↗
PubMed1978

The adrenergic innervation of the urinary bladder in the cat and man in the normal state and after parasympathetic denervation.

The adrenergic innervation of the feline and human urinary bladder was studied with the histochemical fluorescence method of Hillarp and Falck. In the normal bladder of both species the trigone area was densely innervated by thick and strongly green-fluorescent adrenergic terminals while the detrusor muscle contained a sparse innervation of very thin and weakly fluorescent nerve terminals. After parasympathetic denervation (lower motor neuron lesion in patients) the adrenergic innervation of the detrusor muscle was altered. In the cat, the first signs of altered adrenergic innervation were observed 6 weeks after parasympathetic denervation, when thick, strongly fluorescent adrenergic fibres appeared between and in the smooth muscle bundles. These fibres had the characteristics of growth cones and indicated an outgrowth of new adrenergic fibres into the detrusor muscle. Later on, the muscle bundles were densely innervated by thick and strongly fluorescent terminals, reminiscent of trigone terminals. In the patients with lower motor neuron lesions, thick, strongly fluorescent adrenergic terminals were seen in the detrusor. In both cat and man the appearance of this "new" type of adrenergic nerve terminal in the detrusor muscle coincided with the presence of alpha-adrenoceptor function (rather than the normal beta-adrenoceptor activity of the feline and human detrusor).

Adrenergic Fibers↗
PubMed1978

The release of serotonin from rat duodenal enterochromaffin cells by adrenoceptor agonists studied in vitro.

The serotonin (5-HT) content of enterochromaffin cells (EC) was studied by a cytofluorimetric method in biopsies from rat duodenal mucosa after in vitro incubation with different adrenoceptor agonists and antagonists and acetylcholine (ACh). Noradrenaline (NA), Adrenaline (A) and Isoprenaline (IP) caused a decrease of 5-HT in EC down to 40--60% and for NA and A this effect was concentration-dependent. The effect was antagonized by d,1-propranolol but not by d-propranolol, metoprolol, phentolamine or phenoxybenzamine indicating that the 5-HT release from EC is probably mediated via a true beta-adrenoceptor mechanism possibly of the beta2 type. ACh also decreased the 5-HT content of EC but was much less potent than the adrenergic substances. Dopamine (DA) had no effect.

Acetylcholine↗
PubMed1978

The influence of supraspinal impulse activity on the intra-axonal transport of acetylcholine, choline acetyltransferase and acetylcholinesterase in rat motor neurons.

The effect of supraspinal impulse activity upon the intra-axonal transport of acetylcholine (ACh), ACh esterase (AChE) and cholineacetyltransferase (CAT) in rat sciatic nerve has been studied. A decreased inpulse activity was obtained by spinal cord transsection (SCT) in the thoracic region 18 h, 6 days or 20 days before killing the rats. An increased neuronal activity was obtained by exercising the rats in a commercial rodent treadmill a couple of hours per day for 14 days. The amounts of substances which had accumulated in the sciatic nerve segments relative to a nerve crush performed 12 or 18 h. earlier were used to calculate the intra-axonal transport. The amounts of proximo-distal transported ACh decreased markedly with time after the SCT, while the proximo-distal transport of AChE-activity increased. Physical exercise appeared to increase ACh-transport. Thus, input to motor pericarya from supraspinal centers may regulate intra-axonal transport from the cell body of motor neurons into their axons.

Acetylcholine↗
PubMed1978

Ultrastructural evidence for an innervation of epithelial enterochromaffine cells in the guinea pig duodenum.

The innervation of the duodenal enterochromaffine cells (E.C.) of the guinea pig was studied at the electronmicroscopic level. Pretreatment with 5-OH-dopamine was performed to visualize catecholaminergic (CA) nervous elements. Near the basement membrane of all examined E.C. in the crypts, bundles of unmyelinated nerve processes were observed, only partly ensheathed in a Schwann cell cover. At least 4 types of processes could be observed. 1) Boutons containing only small clear vesicles, probably cholinergic fibres; 2) boutons with small clear vesicles, and in addition large (greater than 200 nm) granules with a dense matrix (P-type-fibres); 3) boutons with small electron-dense vesicles, probably CA-fibres; and 4) processes with few vesicles but having the appearance of dendrites. No typical synaptic arrangements were observed, but the minimal distance between the E.C. and the nerve bundles was 150 to 250 nm, thus well within the functional limits of the "autonomic gap". Thus epithelial E.C. may be influenced by several types of nervous elements, including CA-fibres.

Adrenergic Fibers↗
PubMed1978

Efferent innervation of the small intestine by adrenergic neurons from the cervical sympathetic and stellate ganglia, studied by retrograde transport of peroxidase.

The nervous pathways between the small intestine of cat and guinea pig and various sympathetic ganglia were investigated by the retrograde horse-radish peroxidase (HRP) technique. HRP was injected at multiple sites in the wall of the duodenum and the first third of the jejunum. At 1--5 days after the injections, the HRP reaction product was searched for in various sympathetic ganglia. Not only the coeliac and nodose ganglia, but also the superior cervical, medial cervical, stellate and thoracic ganglia contained HRP-positive nerve cells. Crushing the cervical vagal nerve prevented the occurrence of HRP-reaction in the cervical ganglia, indicating that the HRP was transported from the gut to the cervical ganglia via axons in the vagal nerve. The results demonstrate that the sympathetic ganglia in the neck (sup, and med. cerv. ganglia and stellate ggl.) send efferent fibres to the small intestine.

Animals↗