Vagal afferent innervation in regenerated rat liver

Summary The possible presence of neural sprouting in the afferent neurons of regenerated rat liver after hepatectomy was investigated bu retrograde transport of horesradish peroxidase. This experiment was carried out to see if the increase in hepatic parenchyma could provide an adequate stimulus for the sprouting precess. The study was limited to the vagal afferents, particularly the left ones, because they are the principal contributors to hepatic afferent innervation in the rat. The results show that neural sprouting does not occur in regenerated rat liver after 3 weeks In fact, the number of intensely labeled neurons in the left nodose ganglia of hepatectomized rats was significantly smaller than in controls. This could be due to a lessened availability of horseradish peroxidase to nerve terminals in hepatectomized and control animals. This could be a consequence of their possible distribution in hepatic areas not involved in the regenerative process.     

Vagal afferent innervation of the pylorus and the upper small intestine studied in the rat with the horseradish peroxidase technique

The neuronal tracer horseradish peroxidase was injected into different segments of the gastrointestinal in the rat, in order to study the vagal afferent innervation. In the nodose ganglia the extent of labeling was greater in the experiments on the gastric antrum and pylorus than in the experiments on the first part of the small intestine. Vagal afferents are scarce in the upper duodenum and originate mainly from the left nodose ganglion.     

Vagal afferent innervation of the pylorus and the uper small intestine studied in the rat with the horseradish peroxidase technique

Summary The neuronal tracer horseradish peroxidase was injected into different segments of the gastrointestinal in the rat, in order to study the vagal afferent innervation. In the nodose ganglia the extent of labeling was greater in the experiments on the gastric antrum and pylorus than in the experiments on the first part of the small intestine. Vagal afferents are scarce in the upper doudenum and originate mainly from the left nodose ganglion.     

Quantitative histological study of spinal afferent innervation on the ventral surface of the cat stomach by horseradish peroxidase (HRP) method

Summary Retrograde axonal transport of horseradish peroxidase (HRP) was applied to the ventral surface of the cat stomach. We investigated the number, size and distribution of HRP-positive cells in spinal ganglia. The unexpected finding was the wide distribution of these cells from T3 down to L3. This would result in a diffuse pattern of referred pain.     

Quantitative histological study of spinal afferent innervation on the ventral surface of the cat stomach by horseradish peroxidase (HRP) method.

Retrograde axonal transport of horseradish peroxidase (HRP) was applied to the ventral surface of the cat stomach. We investigated the number, size and distribution of HRP-positive cells in spinal ganglia. The unexpected finding was the wide distribution of these cells from T3 down to L3. This would result in a diffuse pattern of referred pain.     

The size of motor units in laryngeal muscles of the rat

Summary The size of motor units in rat laryngeal muscles was determined by correlating the number of neurons labeled by i.m. injections of horseradish peroxidase with the number of motor end plates stained for acetylcholinesterase. The cricothyroid has a motor unit size of 8 muscle fibers per motor neuron and the posterior cricoarytenoid 4–5 muscle fibers per motor neuron.     

Hypnotic effect of serotonin administered in the vago-aortic afferent pathway

A minute amount of serotonin injected in the nodose ganglion circulation area develops abrupt myosis and general electrocortical synchronization activity in "encéphale isolé" Cat preparation. This hypnogenic effect of serotonin can still be reproduced after transection of vago-aortic nerves caudally to the nodose ganglia. The same injections become ineffective after rostral transection of the same pathway. These results suggest that serotonin may trigger some signs of sleep through peripheric nervous elements in which are probably localized in the nodose ganglia.     

Neuropeptides in pelvic afferent pathways

Summary Neurochemical and pharmacological experiments have raised the possibility that several neuropeptides including, vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine amide (PHI), substance P, calcitonin gene-related peptide (CGRP), neurokinin A, cholecystokinin (CCK) and opioid peptides may be transmitters in afferent pathways to the pelvic viscera. These substances are widely distributed in: 1) nerve fibers in the pelvic organs, 2) visceral afferent neurons in the lumbosacral dorsal root ganglia and 3) at sites of afferent termination in the spinal cord. Double, staining immunocytochemical techniques have shown that more than one peptide can be localized in individual visceral afferent neurons and that neuronal excitatory (VIP, substance P, CCK) and inhibitory peptides (leucine enkephalin) can coexist in the same afferent cell. Studies with the neurotoxin, capsaicin, indicate that peptidergic afferent pathways are, involved in the initiation of central autonomic reflexes as well as peripheral axon reflexes which modulate smooth muscle activity, facilitate transmission in automatic ganglia and trigger local inflammatory responses.     

Neuropeptides in pelvic afferent pathways

Neurochemical and pharmacological experiments have raised the possibility that several neuropeptides including, vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine amide (PHI), substance P, calcitonin gene-related peptide (CGRP), neurokinin A, cholecystokinin (CCK) and opioid peptides may be transmitters in afferent pathways to the pelvic viscera. These substances are widely distributed in: 1) nerve fibers in the pelvic organs, 2) visceral afferent neurons in the lumbosacral dorsal root ganglia and 3) at sites of afferent termination in the spinal cord. Double staining immunocytochemical techniques have shown that more than one peptide can be localized in individual visceral afferent neurons and that neuronal excitatory (VIP, substance P, CCK) and inhibitory peptides (leucine enkephalin) can coexist in the same afferent cell. Studies with the neurotoxin, capsaicin, indicate that peptidergic afferent pathways are involved in the initiation of central autonomic reflexes as well as peripheral axon reflexes which modulate smooth muscle activity, facilitate transmission in automatic ganglia and trigger local inflammatory responses.     

Role of extracardiac factors in heart development

Many factors extrinsic to the developing heart play important roles in determining its final form. The neural crest has been shown to provide ectomesenchyme to the pharyngeal apparatus and outflow tract, as well as the postganglionic innervation of the heart. Ablation of the neural crest providing ectomesenchyme to the outflow tract results in various cardiac malformations. These malformations have in common either outflow and/or inflow tract malalignment. Although the reason for this malalignment is not understood, it is thought that hemodynamic parameters during early cardiac morphogenesis may be disrupted causing cardiac dysmorphogenesis. The most likely area for this alteration to occur is in the pharyngeal apparatus which houses the aortic arch arteries. Various possibilities are discussed. The innervation of the heart by neural crest-derived autonomic neurons and nodose placode-derived sensory neurons is outlined, and the interactions between the two progenitive sites is discussed.     

Application to the study of connections in the CNS of the retrograde axonal transport of an iron-dextran complex]

The retrograde axonal transport of an iron-dextran complex was observed in neurons of the substantia nigra and of the intralaminar nuclei of the thalamus, after previous injection into the striatum. The histochemical demonstration of iron is simple and rapid, and can be combined with that of horseradish peroxidase, under precise conditions in the sequence of reactions. The iron-dextran complex revealed to be a valuable material for neuronal connectivity studies in the central nervous system.     

Immunohistochemical localization of glutamine synthetase in human liver

Glutamine synthetase (GS) of human liver was recognized with a polyclonal antibody to pig brain GS, but failed to stain with an antibody against rat liver GS. Using the latter antibody GS of human liver was shown to be localized within small rings of 1 to 3 hepatocytes surrounding the terminal hepatic venules. This pattern was analogous to that seen in rat and mouse liver.     

Histofluorescence of catecholamines and visualization of retrograde transported peroxidase in the same tissue section and in the same neuron]

The demonstration of fluorescent catecholamines and horseradish peroxidase (HRP) in the same neuron has been achieved in the Rat in two ways: by submitting vibratome sections to a modified glyoxylic acid fluorescence method followed by the usual procedure to reveal HRP; or by combining the last procedure with the cryostat technique of Chiba et coll. After HRP injection into the striatum or the nucleus accumbens of the Rat, non-fluorescent HRP labelled neurons were observed in the substantia nigra and the ventral tegmental area respectively, in addition to the HRP labelled fluorescent dopaminergic neurons.     

Immunohistochemical localization of glutamine synthetase in human liver

Glutamine synthetase (GS) of human liver was recognized with a polyclonal antibody to pig brain GS, but failed to stain with an antibody against rat liver GS. Using the latter antibody GS of human liver was shown to be localized within small rings of 1 to 3 hepatocytes surrounding the terminal hepatic venules. This pattern was analogous to that seen in rat and mouse liver.     

Uptake of exogenous protein by supraependymal cells of the feline area postrema.

Supraependymal cells occurring on the surface of the feline area postrema were examined for phagocytic ability. It was shown that they could ingest exogenous horseradish peroxidase that was experimentally introduced into the brain ventricular system. The cells thus bear functional as well as ultrastructural attributes of macrophages, similar to those found in the third ventricle and subarachnoid space.     

Age-dependent increase of thermal stability of in situ chromatin of rat liver and its reversal after hepatectomy

Summary An age-dependent increase of thermal stability of DNA in situ has been demonstrated in rat liver by means of microfluorimetry, which was reversed to a great extent in old regenerated liver.These authors are guests for collaboration at Ancona (Italy) till July, 1976. Their permanent address: Biological Research Institute of the Hungarian Academy of Sciences, Tihany, Hungary.     

Mechanisms of glial-guided neuronal migration in vitro and in vivo

Summary Our laboratory has developed an in vitro model system in which glial-guided neuronal migration can be observed in real time. Cerebellar granule neurons migrate on astroglial fibers by apposing their cell soma against the glial arm, forming a specialized migration junction, and extending a motile leading process in the direction of migration. In vitro assays indicate that the neuronal antigen astrotactin functions as a neuron-glia ligand, and is likely to play a role in the movement of neurons along glial fibers. In heterotypic recombinations of neurons and glia from mouse cerebellum and rat hippocampus, neurons migrate on heterotypic glial processes with a cytology, speed and mode of movement identical to that of neuronal migration on homotypic glial fibers, suggesting that glial fibers provide a permissive pathway for neuronal migration in developing brain. In vivo analyses of developing cerebellum demonstrate a close coordination of afferent axon ingrowth relative to target cell migration. These studies indicate that climbing fibers contact immature Purkinje neurons during the migration and settling of Purkinje cells, implicating a role for afferents in the termination of migration.     

Mechanisms of glial-guided neuronal migration in vitro and in vivo

Our laboratory has developed an in vitro model system in which glial-guided neuronal migration can be observed in real time. Cerebellar granule neurons migrate on astroglial fibers by apposing their cell soma against the glial arm, forming a specialized migration junction, and extending a motile leading process in the direction of migration. In vitro assays indicate that the neuronal antigen astrotactin functions as a neuron-glia ligand, and is likely to play a role in the movement of neurons along glial fibers. In heterotypic recombinations of neurons and glia from mouse cerebellum and rat hippocampus, neurons migrate on heterotypic glial processes with a cytology, speed and mode of movement identical to that of neuronal migration on homotypic glial fibers, suggesting that glial fibers provide a permissive pathway for neuronal migration in developing brain. In vivo analyses of developing cerebellum demonstrate a close coordination of afferent axon ingrowth relative to target cell migration. These studies indicate that climbing fibers contact immature Purkinje neurons during the migration and settling of Purkinje cells, implicating a role for afferents in the termination of migration.     

Endocrine control of lysosomal alterations in rat liver during the perinatal period

Within hours of birth, some physical properties of liver lysosomes are modified. These alterations, which may be related to the autophagic vacuoles formation known to occur during this period, were inhibited by insulin administration. Glucagon, a potent inducer of autophagy in adult rat liver, did not anticipate this process in fetal liver. Our results suggest that the decrease of plasma insulin immediately after birth is an important factor in the development of hepatic autophagy.