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PubMed1985

Innervation of teeth: qualitative, quantitative, and developmental assessment.

Anatomical characteristics of tooth innervation provide insights into functional capabilities as well as limitations of this organ. In this review, innervation will be discussed from two major viewpoints. The first part will present distribution of nerve fibers in the tooth; nerve pathways, both autonomic and sensory, will be discussed mostly from a descriptive standpoint. In the second part, quantitation of neural units along key points of the pathways will be presented at milestones in tooth and organism development and aging.

Adrenergic Fibers↗
PubMed1983

Restrictions of developmental capacities in the dorsal root ganglia during the course of development.

By grafting ganglia from embryonic quails into the neural crest migration pathway of 2-day chick embryos, it was previously demonstrated that all type of ganglia possess more developmental potentialities than those normally expressed in the normal course of development. Namely autonomic neurones with catecholamine and adrenomedullary cells can be obtained from grafted spinal ganglia. The latter also yield sensory neurons to the host dorsal root ganglia (DRG) but only if they are taken from the donor before 8 days of incubation. In the present article we show that the capacity to differentiate sensory neurons in back-transplantation experiments can be correlated with the presence in the donor DRG of cycling neuronal precursors. Once all the neurons have been withdrawn from the cell cycle - an event which occurs first in the mediodorsal and then in the lateroventral area of the ganglion - the DRG cell population gives rise exclusively to autonomic ganglion cells in the host. It is concluded that in the conditions of the back-transplantation experiments, the postmitotic neurons contained in the donor ganglion do not survive. Therefore, the neurons and paraganglion cells which differentiate in the host arise from still undifferentiated precursor cells. This indicates that besides sensory neuron precursors the embryonic DRG cell population also contains precursor cells for the autonomic differentiation pathway.

Adrenal Medulla↗
PubMed2005

The role of vagal afferent nerves in chronic obstructive pulmonary disease.

Circumstantial evidence supports the hypothesis that the vagal nervous system is dysregulated in chronic obstructive pulmonary disease. This dysregulation can lead to an increased sensitivity of the cough reflex such that the coughing becomes, at times, "nonproductive" or inappropriate. Vagal dysregulation can also lead to an increase in the activity of the parasympathetic reflex control of the airways, which contributes to greater mucus secretion and bronchial smooth muscle contraction. Indirect evidence indicates that lung disease is accompanied by substantive changes to the entire reflex pathways, including enhanced activity of the primary afferent nerves, increases in synaptic efficacy at secondary nerves in the central nervous system, and changes in the autonomic nerve pathways. Drugs aimed at normalizing neuronal activity may, therefore, be beneficial in chronic obstructive pulmonary disease.

Animals↗
PubMed1998

Anterior-posterior patterning within the Caenorhabditis elegans endoderm.

The endoderm of higher organisms is extensively patterned along the anterior/posterior axis. Although the endoderm (gut or E lineage) of the nematode Caenorhabditis elegans appears to be a simple uniform tube, cells in the anterior gut show several molecular and anatomical differences from cells in the posterior gut. In particular, the gut esterase ges-1 gene, which is normally expressed in all cells of the endoderm, is expressed only in the anterior-most gut cells when certain sequences in the ges-1 promoter are deleted. Using such a deleted ges-1 transgene as a biochemical marker of differentiation, we have investigated the basis of anterior-posterior gut patterning in C. elegans. Although homeotic genes are involved in endoderm patterning in other organisms, we show that anterior gut markers are expressed normally in C. elegans embryos lacking genes of the homeotic cluster. Although signalling from the mesoderm is involved in endoderm patterning in other organisms, we show that ablation of all non-gut blastomeres from the C. elegans embryo does not affect anterior gut marker expression; furthermore, ectopic guts produced by genetic transformation express anterior gut markers generally in the expected location and in the expected number of cells. We conclude that anterior gut fate requires no specific cell-cell contact but rather is produced autonomously within the E lineage. Cytochalasin D blocking experiments fully support this conclusion. Finally, the HMG protein POP-1, a downstream component of the Wnt signalling pathway, has recently been shown to be important in many anterior/posterior fate decisions during C. elegans embryogenesis (Lin, R., Hill, R. J. and Priess, J. R. (1998) Cell 92, 229-239). When RNA-mediated interference is used to eliminate pop-1 function from the embryo, gut is still produced but anterior gut marker expression is abolished. We suggest that the C. elegans endoderm is patterned by elements of the Wnt/pop-1 signalling pathway acting autonomously within the E lineage.

Animals↗
PubMed1997

Orthostatic dysregulation in progressive autonomic failure--a transcranial Doppler sonography monitoring.

Hemodynamic changes associated with orthostatic hypotension in one patient with pure progressive autonomic failure (PAF) were studied by a passive (70 degrees tilt of the upper part of the body) and an active orthostatic tests. Mean blood pressure (MBP), heart rate (HR) and mean blood flow velocity (MFV) during transcranial Doppler sonography monitoring of the right middle cerebral artery (RMCA) were determined after 10 minutes of rest and after 1, 10 and 60 minutes passive 70 degrees tilt or active standing. Simultaneously, plasma norepinephrine (NE) levels during recumbency and after 1 and 10 min of the orthostatic manoeuvres were measured. Stand-up tilting induced slight decrease in MBP and MFV without changes in HR. Changes of systemic hemodynamics occurred during the first minute of passive standing and they increased within the first hour however the cerebral hemodynamics remained relatively stable. Active standing was accompanied by a severe decrease in the MBP and the MFV in RMCA, and an increase in vascular resistance immediately after the upright position. The hemodynamic changes were not followed by a secondary cardiac acceleration; they increased within the first minute of active standing and evoked a syncope. During squatting as a self-selected preventive mechanism in our patient an increase in MBP and MFV in RMCA occurred. Plasma NE levels in recumbency were lower than the reference values; they decreased with 12.1% after 10 min of passive tilting and with 24.8% after the first minute of active standing. These results showed that PAF is accompanied by a severe orthostatic dysregulation during active standing, associated with a progressive peripheral autonomic deficiency and disturbed mechanisms against gravitational pooling of the blood to the lower extremities. The orthostatic autoregulation of the cerebral hemodynamics seems to be preserved.

Afferent Pathways↗
PubMed2003

Differences in the chemical coding of nerve fibres supplying major populations of neurons between the caudal mesenteric ganglion and anterior pelvic ganglion in the male pig.

The present study was designed to investigate and to compare the chemical coding of nerve fibres supplying major populations of neurons in the caudal mesenteric (CaMG) and anterior pelvic (APG) ganglion in juvenile male pigs (n=5) using double-labelling immunofluorescence. The co-existence patterns of some biologically active substances including tyrosine hydroxylase (TH) and vesicular acetylcholine transporter (VAChT) as well as vasoactive intestinal polypeptide (VIP), substance P (SP), calcitonin gene-related peptide (CGRP), Leu5-enkephalin (LENK) and serotonin (5-HT) were analysed under a confocal laser scanning microscope. Profound differences in the neurochemical features of the nerve terminals between the ganglia were observed. Moreover, there were also distinct differences in the chemical coding of nerve fibres associated with the particular populations and subpopulations of neurons within the ganglia. In both ganglia, nearly all adrenergic and cholinergic neurons were supplied with VAChT-positive nerve fibres (putative preganglionic fibres). However, in the CaMG, they were more numerous and, in contrast to the APG, many of them also stained for VIP. In the APG, a great number of nerve terminals expressed immunoreactivity to SP and CGRP (putative collaterals of sensory neurons). Interestingly, they densely supplied almost exclusively adrenergic neurons. SP-positive nerve fibres were moderate in number in the CaMG, but, in addition to VAChT-IR nerve terminals, the most numerous populations of nerve fibres in this ganglion were those expressing highly colocalized immunoreactivities to CGRP and LENK, and those which stained for 5-HT (putative processes of enteric neurons). However, these fibres supplied almost exclusively larger, intensely stained for TH and clustered adrenergic neurons. This diversity of the nerve terminals reflects the complexity of nerve circuits involved in the innervation of structures supplied by neurons in the porcine CaMG and APG. It also demonstrates the importance of nerve inputs for the proper function of autonomic neurons and thus their target tissues.

Animals↗
PubMed1993

Small fibre function in primary autonomic failure.

A case of primary autonomic failure (AF) with uncomplicated Parkinson's disease is presented with clinical and neurophysiological data. Special emphasis is placed on new methods of examining impairment of unmyelinated sympathetic and afferent C-fibres. Sympathetic vasoconstrictor responses in the skin induced by deep inspiration were examined quantitatively with laser Doppler flowmetry. The vasoconstriction was markedly depressed in primary AF compared with healthy controls and similar to secondary forms of AF. Peripheral nociceptive C-fibre function was quantitatively assessed by measurement of axon reflex vasodilatation induced by histamine iontophoresis. The axon reflex vasodilatation was completely intact in primary AF in contrast to patients with secondary peripheral small fibre neuropathy. The results indicate that sympathetic C-fibres are considerably affected by the degenerative disease, whereas the afferent C-fibres seem to be totally preserved. Modern neurophysiological methods of testing sympathetic and afferent small fibre function in combination with other neurophysiological tests, e.g. brain-stem auditory evoked potentials, might help to diagnose and differentiate primary AF in early stages and make it easier to distinguish between secondary autonomic neuropathies of unknown origin that often also involve unmyelinated afferent fibres.

Afferent Pathways↗
PubMed1994

Acetyl-L-carnitine treatment increases choline acetyltransferase activity and NGF levels in the CNS of adult rats following total fimbria-fornix transection.

Transection of the fimbria-fornix in adult rats is a useful model for producing impairments of cholinergic activity in the hippocampus (HIPP) and atrophy of the medial septum cholinergic perikarya, similar to those observed during senescence, that are possibly due to the lack of nerve growth factor (NGF) retrogradely transported from the hippocampus. In our investigation we used choline acetyltransferase (ChAT) as an index of cholinergic activity in HIPP, frontal cortex (FCX), septum and nucleus basalis magnocellularis (NBM) along with measurements of NGF levels in the HIPP. Three-month-old rats with unilateral total fimbria transection received acetyl-L-carnitine (ALCAR) (150 mg/kg/day) in drinking water for 1 week before and 4 weeks after the lesion). ALCAR is a substance known to ameliorate some morphological and functional disturbances in the aging central nervous system (CNS). ChAT activity in septum and FCX, and NGF levels in HIPP were significantly increased in the treated group, compared with untreated control groups, while no changes were found in the NBM. On the other hand, a similar ALCAR treatment in unoperated animals induced an increase in ChAT activity in FCX but not in septum nor in NBM. These data are suggestive of a neurotrophic property of ALCAR exerted on those central cholinergic pathways typically damaged by aging.

Acetylcarnitine↗
PubMedDate not supplied

[Vasoactive intestinal polypeptide: a potential neurotransmitter].

A review of current advances in anatomy, physiology and pharmacology of vasoactive intestinal polypeptide (VIP) is presented. VIP is a basic 28-aminoacid peptide of molecular weight 3300. Nerves immunoreactive to VIP are in the heart, lung, digestive and genitourinary tract, eye, skin, ovaries and thyroid gland. In the central nervous system VIP-ergic neurons are found primarily in telencephalic areas. Here, VIP provokes the excitation, vasodilatation and together with noradrenaline participates in the regulation of cortical energy metabolism. VIP-ergic neurons are mainly present in afferent pathways of the spinal cord with higher density in the sacral segments. Anatomic distribution of VIP-ergic neurons suggests involvement in pain transmission and integration of the sacral autonomic reflex pathways. The biologic effects of VIP in periphery are the vasodilatation, relaxation of smooth muscle and influence on exocrine glands secretion. In the endocrine system VIP stimulates the secretion of different hormones (prolaction, growth hormone, oxytocin, vasopressin, ovarial and thyroid hormones). VIP-ergic innervation is changed in some organs during the diseases of those organs. Practical exploatation of this knowledge is limited at present because effective, non-polypeptide agonists and antagonists are not available yet.

Humans↗
PubMedDate not supplied

Topographical distribution and immunocytochemical features of colonic neurons that project to the cranial mesenteric ganglion in the pig.

Using the retrograde neuronal tracers Fast blue and Fluorogold, the topographical distribution and morphological features of porcine colonic neurons projecting to the cranial (superior) mesenteric ganglion have been investigated. Two to four weeks after injection of the tracer into the cranial mesenteric ganglion of immature pigs, labelled neurons were found throughout the colon. In the myenteric and outer submucous plexuses, they were present in ganglia situated to the side of the mesenteric attachment. The highest density of labelled neurons was observed at the end of the ascending colon, which in the pig represents 78-80% of the total colon length. The viscerofugal neurons had a multidendritic appearance and part of them were immunoreactive for calcitonin gene-related peptide or serotonin. This study has revealed similarities but also significant differences in the colono-sympathico-colonic pathways between the pig and small laboratory animals such as the guinea-pig.

Amidines↗
PubMed1980

Functional changes in autonomic nervous responses with ageing.

The effects of ageing on autonomic nervous responses have been investigated in 29 young adults, 64 healthy elderly in the age range 66 to 86 years, and 20 elderly in-patients with hypothermia, instability of bladder function or marked orthostatic hypotension. In the healthy elderly group, the beat-to-beat variation in response to postural change was significantly diminished, the vasoconstrictor response to cooling reduced and baroreflex sensitivity during lower-body negative pressure was decreased compared with young adults. Patients with an atronic bladder, determined by urodynamic tests, showed an even more marked decrease in baroreflex sensitivity. The multisystem nature of these autonomic disturbances suggests that physiological impairment may occur in autonomic neural pathways with ageing.

Adult↗