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PubMed2003

Reduced number of intrinsic pulmonary nitrergic neurons in Fawn-Hooded rats as compared to control rat strains.

The Fawn-Hooded rat (FHR) strain reveals a congenital predisposition to primary (idiopathic) pulmonary hypertension (PPH), and can therefore be regarded as an animal model in which to study possible mechanisms underlying an inherited susceptibility to pulmonary hypertension. Pulmonary hypertension can be induced in FHRs after a short exposure to mild hypoxia, presumably because of an altered peripheral oxygen sensitivity. Given the presence of pulmonary nitrergic neurons in rat lungs, the observed link between airway hypoxia and the expression of pulmonary neuronal nitric oxide synthase (nNOS), and the fact that nNOS appears to be involved in peripheral chemoreceptor sensitivity, we examined the intrinsic pulmonary nitrergic innervation in the FHR. In the present study the number of intrapulmonary nitrergic nerve cell bodies, detected by NADPH diaphorase (NADPHd) histochemistry, was quantified in the FHR and three control rat strains. Compared to the control rat strains, the FHR lungs revealed a highly significantly lower number of intrinsic nitrergic neurons, while no apparent differences were found in the number of enteric nitrergic neurons in the esophagus. In conclusion, the possible links between neuronal NO, hypersensitivity to airway hypoxia, and the development of PPH clearly deserve further investigation.

Animals↗
PubMed2003

Access of autonomic nerves through the optic canal, and their orbital distribution in man.

The notion that autonomic nerves from the internal carotid plexus are transmitted to the orbit with the ophthalmic artery through the optic canal has been variously assumed, disregarded, or denied, but never demonstrated. The objective of this study was to examine the contents of the canal, identify any autonomic nerves, and follow their passage within the orbit. The soft tissues of the optic canal, and the apical tissues of the orbit were removed and examined histologically using 10 cadaver preparations. Additionally, tissues from an orbital exenteration and 10 ocular enucleation or donor specimens were prepared. Some of the latter material was examined with an electron microscope. Numerous autonomic nerves (four to 25, ranging in diameter from 23 to 130 microm) entered the orbit from the internal carotid plexus in the periosteum of the optic canal, the optic nerve dura mater, or the adventitia of the ophthalmic artery. In the orbit they advanced in the loose connective tissue covering the optic nerve dura and joined ciliary nerves close to the eye or entered the eye directly. None were observed to penetrate the dura, apart from a nerve accompanying the central retinal artery. Others were distributed with the ophthalmic artery and its branches. It is concluded that the optic canal is a regular, and often major, route for autonomic nerve distribution to the eye and orbit.

Autonomic Pathways↗
PubMed1994

Angiographic changes in the hepatic artery after skeletonization resection for biliary tract cancer.

Using preoperative and postoperative arteriography, angiographic changes in the hepatic artery were studied after skeletonization of the hepatoduodenal ligament and hepatic resection for biliary tract carcinoma. Of 52 patients evaluated (32 with carcinoma of the bile duct, 20 with gallbladder cancer), no angiographic changes were apparent after operation in 30 (58 per cent) and there were pathological findings in 22 (42 per cent; smooth stenosis in five patients, irregular stenosis in seven, a beaded appearance in four, dilatation in two, obstruction in four). Based on angiographic findings, patients were classified into three subgroups (no change, 30 patients; irregular form, 18; obstructed, four). Postoperative liver function was also evaluated. No definite correlation was evident between angiographic findings and the incidence of hepatic failure or liver dysfunction in the first month after operation. Given that connective tissue and lymph node dissection in the hepatoduodenal ligament is essential for curative resection of biliary tract carcinoma, these findings suggest that skeletonization is an acceptable operative procedure.

Adolescent↗
PubMed2005

Major urinary dysfunction after mesorectal excision for rectal carcinoma.

BACKGROUND: Urinary dysfunction may occur after mesorectal excision and pelvic autonomic nerve preservation (PANP) in patients with rectal carcinoma. The aim of this prospective study was to identify factors predictive of long-term urinary catheterization. METHODS: Two hundred and ten patients without significant urological problems underwent resection of rectal cancer with mesorectal excision. The number of patients with complete, partial or no identification of the nerves was documented and correlated with possible predictive factors for postoperative major urinary dysfunction. RESULTS: Eight patients (3.8 per cent) required long-term urinary catheterization: two after complete PANP (two of 168) and six in whom PANP was incomplete (six of 42) (P = 0.001). Multiple regression analysis identified incomplete PANP (odds ratio 13.8 (95 per cent confidence interval 2.7 to 71.3); P = 0.002) as a predictive factor for major urinary dysfunction. CONCLUSION: Major urinary dysfunction after mesorectal excision for rectal cancer is associated with an incomplete nerve-sparing technique.

Adult↗
PubMed2005

Feasibility of autonomic nerve-preserving surgery for advanced rectal cancer based on analysis of micrometastases.

BACKGROUND: Autonomic nerve preservation has been advocated as a means of preserving urinary and sexual function after surgery for rectal cancer, but may compromise tumour clearance. The aim of this study was to determine the incidence of micrometastasis in the connective tissues surrounding the pelvic plexus. METHODS: The study included 20 consecutive patients who underwent rectal surgery with bilateral lymph node dissection for advanced cancer. A total of 78 connective tissues medial and lateral to the pelvic plexus and 387 lymph nodes were sampled during surgery. All connective tissue samples and 260 lymph nodes were examined for micrometastases by reverse transcriptase-polymerase chain reaction (RT-PCR) after operation. All patients were followed prospectively for a median of 36.0 months. RESULTS: Of 245 histologically negative lymph nodes, 38 (15.5 per cent) were shown by RT-PCR to harbour micrometastases. However, micrometastases to tissues surrounding the pelvic plexus were detected in only two (3 per cent) of 78 tissues, that is in two of 20 patients. Clinical follow-up showed that the two patients had a poor prognosis owing to distant metastases. CONCLUSION: Autonomic nerve-preserving surgery may be feasible for advanced rectal cancer, but study of more patients positive for micrometastases is required.

Adult↗
PubMed2003

Autonomic and motor neuron death is progressive and parallel in a lumbosacral ventral root avulsion model of cauda equina injury.

Injuries to the cauda equina of the spinal cord result in autonomic and motor neuron dysfunction. We developed a rodent lumbosacral ventral root avulsion injury model of cauda equina injury to investigate the lesion effect in the spinal cord. We studied the retrograde effects of a unilateral L5-S2 ventral root avulsion on efferent preganglionic parasympathetic neurons (PPNs) and pelvic motoneurons in the L6 and S1 segments at 1, 2, 4, and 6 weeks postoperatively in the adult male rat. We used Fluoro-Gold-prelabeling techniques, immunohistochemistry, and quantitative stereologic analysis to show an injury-induced progressive and parallel death of PPNs and motoneurons. At 6 weeks after injury, only 22% of PPNs and 16% of motoneurons remained. Furthermore, of the neurons that survived at 6 weeks, the soma volume was reduced by 25% in PPNs and 50% in motoneurons. Choline acetyltransferase (ChAT) protein was expressed in only 30% of PPNs, but 80% of motoneurons remaining at 1 week postoperatively, suggesting early differential effects between these two neuronal types. However, all remaining PPNs and motoneurons were ChAT positive at 4 weeks postoperatively. Nuclear condensation and cleaved caspase-3 were detected in axotomized PPNs and motoneurons, suggesting apoptosis as a contributing mechanism of the neural death. We conclude that lumbosacral ventral root avulsions progressively deplete autonomic and motor neurons. The findings suggest that early neuroprotection will be an important consideration in future attempts of treating acute cauda equina injuries.

Animals↗
PubMed2004

Dual viral transneuronal tracing of central autonomic circuits involved in the innervation of the two kidneys in rat.

The neural control of renal function is exerted by the central nervous system via sympathetic innervation of the kidneys. To determine the extent to which the control of the two kidneys is provided by the same brain neurons, the central circuitry involved in the innervation of both kidneys was characterized in individual rats by dual viral transneuronal tracing using isogenic recombinant strains (PRV-152 and BaBlu) of pseudorabies virus. Prior to dual tracing, the neuroinvasive properties of PRV-152 and BaBlu were characterized by conducting parametric studies, using the two kidneys as an anatomical model, and comparing the pattern of infection with that obtained following injection of the parental strain, PRV-Bartha, into the left kidney. Once the optimal concentrations of virus required to obtain equivalent infection were established, PRV-152 and BaBlu were injected into the left and right kidney, respectively, in the same rats. Immunocytochemical localization of viral reporter proteins at different postinoculation times allowed us to determine the sequence of infection in the brain, as well as to quantify dual- and single-labeled neurons in each infected area. Neurons that influence autonomic outflow to one or both kidneys coexist in all brain areas involved in the control of the sympathetic outflow to the kidneys at every hierarchical level of the circuit. The proportions of dual-infected neurons with respect to the number of total infected neurons varied across regions, but they were maintained at different survival times. The pattern of infection suggests that the activity of each kidney is controlled independently by organ-specific neurons, whereas the functional coordination of the two kidneys results from neurons that collaterize to modulate the sympathetic outflow to both organs. The advantages of using an anatomical symmetrical system, such as the two kidneys, as an experimental approach to characterize PRV recombinants in general are also discussed.

Animals↗
PubMed2004

Metastasis-associated S100A4 (Mts1) protein is expressed in subpopulations of sensory and autonomic neurons and in Schwann cells of the adult rat.

S100A4 (Mts1) is a member of a family of calcium-binding proteins of the EF-hand type, which are widely expressed in the nervous system, where they appear to be involved in the regulation of neuron survival, plasticity, and response to injury or disease. S100A4 has previously been demonstrated in astrocytes of the white matter and rostral migratory stream of the adult rat. After injury, S100A4 is markedly up-regulated in affected central nervous white matter areas as well as in the periventricular area and rostral migratory stream. Here, we show that S100A4 is expressed in a subpopulation of dorsal root, trigeminal, geniculate, and nodose ganglion cells; in a subpopulation of postganglionic sympathetic and parasympathetic neurons; in chromaffin cells of the adrenal medulla; and in satellite and Schwann cells. In dorsal root ganglia, S100A4-positive cells appear to constitute a subpopulation of small ganglion neurons, a few of which coexpressed calcitonin gene-related peptide (CGRP) and Griffonia simplicifolia agglutinin (GSA) isolectin B4 (B4). S100A4 protein appears to be transported from dorsal root ganglia to the spinal cord, where it is deposited in the tract of Lissauer. After peripheral nerve or dorsal root injury, a few S100A4-positive cells coexpress CGRP, GSA, or galanin. Peripheral nerve or dorsal root injury induces a marked up-regulation of S100A4 expression in satellite cells in the ganglion and in Schwann cells at the injury site and in the distal stump. This pattern of distribution partially overlaps that of the previously studied S100B and S100A6 proteins, indicating a possible functional cooperation between these proteins. The presence of S100A4 in sensory neurons, including their processes in the central nervous system, suggests that S100A4 is involved in propagation of sensory impulses in specific fiber types.

Animals↗
PubMed2006

Relationship of presympathetic-premotor neurons to the serotonergic transmitter system in the rat brainstem.

Numerous physiological conditions and emotionally motivated behaviors require concomitant activation of somatomotor and sympathetic efferents. Using a virally mediated retrograde transsynaptic tract-tracing approach, we have previously determined locations of presympathetic-premotor neurons (PSPMNs) in the rat brainstem. These putative dual-function neurons send projections to somatomotor and sympathetic targets and likely participate in sympatho-somatomotor integration. A significant portion of these neurons is found within brainstem areas known to contain serotonergic neurons. Thus, we hypothesized that some of the PSPMNs utilize serotonin as their neurotransmitter. To test this hypothesis we first produced an antibody against TPH2, a brain-specific isoform of tryptophan hydroxylase (serotonin synthetic enzyme). We identified PSPMNs by using recombinant strains of the pseudorabies virus (PRV) for transsynaptic tract-tracing. PRV-152, a strain that expresses enhanced green fluorescent protein, was injected into sympathectomized gastrocnemius muscle, while PRV-BaBlu, which expresses beta-galactosidase, was injected into the adrenal gland in the same animals. Using immunofluorescent methods we determined whether coinfected neurons expressed TPH2. Our findings demonstrate that TPH2-positive PSPMNs are present at different rostrocaudal levels of the brainstem. Just over half of them are found at the pontomedullary junction within raphe obscurus, raphe magnus, and gigantocellular nucleus pars alpha. These cells may play a role in mediating responses to acute pain stimuli and/or participate in the central control of exercise. Overactivity of these serotonergic sympatho-somatomotor circuits may also play a role in the pathophysiology of serotonin syndrome.

Animals↗
PubMed1993

Localization of cholinergic neurons in the forebrain and brainstem that project to the suprachiasmatic nucleus of the hypothalamus in rat.

In mammals, the suprachiasmatic nucleus is responsible for the generation of most circadian rhythms and their entrainment to environmental cues. Cholinergic agents can alter circadian rhythm phase, and fibres immunoreactive for choline acetyltransferase, the biosynthetic enzyme for acetylcholine, are present in the suprachiasmatic nucleus. Since there are no cholinergic somata in the suprachiasmatic nucleus, these fibres must represent the terminals of cholinergic neurons whose cell bodies are located elsewhere in the brain. This study was aimed at locating the cholinergic neurons that project to the suprachiasmatic nucleus by retrograde and anterograde tract-tracing and immunohistochemistry for choline acetyltransferase in the rat. After injection of fluorogold, a retrograde tracer, into the suprachiasmatic nucleus, retrogradely labelled neurons that were immunopositive for choline acetyltransferase were located throughout the rostrocaudal extent of the cholinergic basal nuclear complex, with highest densities in the substantia innominata and the nucleus basalis magnocellularis. A few cells were also located in the medial septum and in the vertical and horizontal limbs of the diagonal band of Broca. In the brainstem, double-labelled neurons were located in the laterodorsal tegmental nucleus, pedunculopontine tegmental nucleus and the parabigeminal nucleus. Injections of the anterograde tracer biocytin in these three brainstem nuclei resulted in fibre labelling in the suprachiasmatic nucleus, consistent with the retrograde findings. No clearly double-labelled cells were located in the retina. These results suggest that the suprachiasmatic nucleus receives cholinergic afferents from both the basal forebrain and mesopontine tegmentum which may mediate cholinergic effects on circadian rhythms.

Animals↗
PubMed1994

Projections of GABAergic and cholinergic basal forebrain and GABAergic preoptic-anterior hypothalamic neurons to the posterior lateral hypothalamus of the rat.

Within the basal forebrain, gamma-aminobutyric acid (GABA)-synthesizing neurons are codistributed with acetylcholine-synthesizing neurons (Gritti et al. [1993] J. Comp. Neurol. 329:438-457), which constitute one of the major forebrain sources of subcortical afferents to the cerebral cortex. In the present study, descending projections of the GABAergic and cholinergic neurons were investigated to the lateral posterior hypothalamus (LHp) through which the medial forebrain bundle passes and where another major forebrain source of subcortical afferents is situated. Retrograde transport of cholera toxin b subunit (CT) from the LHp was combined with immunohistochemical staining for glutamic acid decarboxylase (GAD) and choline acetyl transferase (ChAT) using a sequential peroxidase-antiperoxidase (PAP) technique. A relatively large number of GAD+ neurons (estimated at approximately 6,200), which represented > 15% of the total population of GAD+ cells in the basal forebrain (estimated at approximately 39,000), were retrogradely labeled from the LHp. These cells were distributed through the basal forebrain cell groups, where ChAT+ cells are also located, including the medial septum and diagonal band nuclei, the magnocellular preoptic nucleus, and the substantia innominata, with few cells in the globus pallidus. In these same nuclei, a small number of ChAT+ cells were retrogradely labeled (estimated at approximately 800), which represented only a small percentage (< 5%) of the ChAT+ cell population in the basal forebrain (estimated at approximately 18,000). Both the GAD+ and ChAT+ LHp-projecting neurons represented a small subset of their respective populations in the basal forebrain, distinct from the magnocellular, presumed cortically projecting, basal neurons. In addition to the GAD+ cells in the basal forebrain, GAD+ cells in the adjacent preoptic and anterior hypothalamic regions were also retrogradely labeled in significant numbers (estimated at approximately 5,500) and proportion (> 20%) of the total population (estimated at approximately 30,000) from the LHp. The retrogradely labeled GAD+ neurons were distributed in continuity with those in the basal forebrain through the lateral preoptic area, medial preoptic area, bed nucleus of the stria terminals, and anterior and dorsal hypothalamic areas. Of the large number of cells that project to the LHp in the basal forebrain and preoptic-anterior hypothalamic regions (estimated at approximately 66,000), the GAD+ neurons represented a significant proportion (> 15%) and the ChAT+ neurons a very small proportion (approximately 2%). The relative magnitude of the GABAergic projection suggests that it may represent an important inhibitory influence of the descending efferent output from the basal forebrain and preoptic-anterior hypothalamic regions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Monosynaptic projections from the medullary gigantocellular reticular formation to sympathetic preganglionic neurons in the thoracic spinal cord.

Microinjection of L-glutamate into a restricted area of the medullary gigantocellular reticular formation, the gigantocellular depressor area (GiDA), lowers arterial pressure. Unlike the nuclei tractus solitarii and the caudal ventrolateral medulla, the two principle medullary vasodepressor areas, the GiDA projects directly to the spinal cord and not to the rostral ventrolateral medulla (Aicher et al. [1994] Neuroscience 60:761-779). We investigated whether neurons within GiDA directly innervate autonomic areas of the thoracic spinal cord. Fluoro-Gold injected into the thoracic spinal cord labeled neurons within functionally defined vasodepressor sites in the GiDA in the same animal. To examine the morphology of GiDA efferents to the spinal cord, the anterograde tracer Phaseolus vulgaris-leucoagglutinin was iontophoresed into the GiDA, and efferent processes in the intermediolateral cell column and nucleus intercalatus spinalis were examined by electron microscopy. Labeling was confined to axons and axon terminals (n = 144) that usually contained primarily small clear vesicles, contacted large and small dendrites, and formed symmetric (inhibitory) synapses. To determine whether some of the postsynaptic targets of GiDA efferent terminals in the thoracic spinal cord were sympathoadrenal preganglionic neurons, these neurons were retrogradely labeled from the adrenal gland with Fluoro-Gold in rats that had deposits of the anterograde tracer, biotinylated dextran amine (BDA), in the GiDA. Some BDA-containing terminals formed symmetric synapses with dendrites containing Fluoro-Gold. We conclude that a population of neurons in the GiDA monosynaptically innervates some sympathetic preganglionic neurons. The findings suggest the presence of a novel reticulospinal sympathoinhibitory projection originating in the GiDA.

Adrenergic Fibers↗
PubMed2006

The ontogeny of autonomic measures in 6- and 12-month-old infants.

The purpose of this study was to develop a standardized protocol to measure preejection period (PEP), a measure of sympathetic nervous system, and respiratory sinus arrhythmia (RSA), a measure of parasympathetic nervous system, during resting and challenging states for 6- and 12-month-old infants and to determine developmental changes and individual stability of these measures. A 7-min reactivity protocol was administered to Latino infants at 6 months (n=194) and 12 months (n=181). Results showed: (1) it is feasible to measure PEP and RSA in infants, (2) the protocol elicited significant autonomic changes, (3) individual resting autonomic measures were moderately stable from 6 to 12 months, but reactivity measures were not stable, and (4) heart rate and RSA resting and challenge group means changed significantly from 6 to 12 months. Findings suggest that although infants' autonomic responses show developmental changes, individuals' rank order is stable from 6 to 12 months of age.

Age Factors↗
PubMed2004

Pressor effects of electrical stimulation of medial prefrontal cortex in unanesthetized rats.

The medial prefrontal cortex (MPFC) is involved in central nervous system (CNS)-mediated cardiovascular modulation. We compared the cardiovascular effects of electrical stimulation (EE) of the MPFC in unanesthetized rats to those observed after stimulation of the same area in urethane-anesthetized rats. Electrical stimulation (35, 106, 177, 247, 318, and 389 microA rms/10 sec, 60-Hz sine wave) of the MPFC of urethane-anesthetized rats caused depressor responses of stimulus-related intensity. The cardiovascular response to electrical stimulation of the MPFC in unanesthetized rats was characterized by stimulus-related pressor responses. No significant heart rate changes were observed during the EE period in any case. The pressor response to electrical stimulation (106 microA rms/10 sec, 60-Hz sine wave) of the MPFC was not affected by intravenous pretreatment with the vasopressin antagonist dTyr(CH(2))(5)(Me)AVP (50 microg/kg, intravenously), by hypophysectomy, or by intravenous pretreatment with the angiotensin II antagonist losartan (1 mg/kg, intravenously). The pressor response was blocked by intravenous pretreatment with the ganglionic blocker mecamylamine (2 mg/kg, intravenously) but was not affected by adrenal demedullation, thus suggesting involvement of the neural component of the sympathetic nervous system without a major involvement of its hormonal component. Our results confirmed the occurrence of depressor responses after electrical stimulation of the MPFC in urethane-anesthetized rats and evidenced that only pressor responses are observed after its stimulation in unanesthetized rats. The fact that the pressor response to the stimulation of the MPFC was blocked by a ganglioplegic suggests that the MPFC has functional excitatory actions over the sympathetic nervous system.

Adrenal Medulla↗
PubMed2006

17beta-estradiol attenuates excitatory neurotransmission and enhances the excitability of rat parabrachial neurons in vitro.

The steroid hormone 17beta-estradiol and its respective receptors have been found in several cardiovascular nuclei in the central nervous system including the parabrachial nucleus. In a previous study, we provided evidence that 17beta-estradiol attenuated an outward potassium conductance in parabrachial neurons of male rats, using an in vitro slice preparation. In this study we sought to enhance the comprehensive information provided previously on estradiol's postsynaptic effects in the parabrachial nucleus by directly examining whether 17beta-estradiol application will modulate excitatory synaptic neurotransmission. Using a pontine slice preparation and whole-cell patch-clamp recording, bath application of either 17beta-estradiol (20-100 muM) or BSA-17beta-estradiol (50 muM) decreased the amplitude of evoked excitatory postsynaptic currents (from 30-60% of control) recorded from neurons in the parabrachial nucleus. The paired pulse ratio was not significantly affected and suggests a post-synaptic site of action. The inhibitory effect on the synaptic current was relatively long-lasting (non-reversible) and was blocked by the selective estrogen receptor antagonist, ICI 182,780. Furthermore, 17beta-estradiol reduced the maximum current elicited by a ramp protocol, increased the input resistance measured between resting membrane potential and action potential threshold and caused an increase in the firing frequency of the cells under current-clamp. In summary, 17beta-estradiol caused 3 effects: first, a depolarization; second, a reduction in evoked excitatory postsynaptic potentials; and third, an enhancement of action potential firing frequency in neurons of the parabrachial nucleus. These observations are consistent with our previous findings and support a role for estrogen in modulating neurotransmission in this nucleus.

Action Potentials↗
PubMed2000

Laparoscopic total mesorectal excision with autonomic nerve preservation.

Laparoscopy has greatly influenced abdominal surgery. We hypothesize that the benefits of minimally invasive surgery are applicable to rectal cancer. A cadaver model of laparoscopic rectal resection with total mesorectal excision (TME) and autonomic nerve preservation was utilized to explore this hypothesis. The principles of TME were followed, including high vascular ligation, sharp mesorectal dissection, and identification and preservation of the autonomic pelvic nerves. After proving feasibility in the cadaver model, a clinical study was performed on patients with mid to low rectal cancers. We observed acceptable morbidity with this minimally invasive technique of rectal resection and TME. We conclude that there is growing evidence that laparoscopic methods can be applied to patients with rectal cancer.

Adenocarcinoma↗