Human pancreatic afferent and efferent nerves: mapping and 3-D illustration of exocrine, endocrine, and adipose innervation.

The pancreas consists of both the exocrine (acini and ducts) and endocrine (islets) compartments to participate in and regulate the body's digestive and metabolic activities. These activities are subjected to neural modulation, but characterization of the human pancreatic afferent and efferent nerves remains difficult because of the lack of three-dimensional (3-D) image data. Here we prepare transparent human donor pancreases for 3-D histology to reveal the pancreatic microstructure, vasculature, and innervation in a global and integrated fashion. The pancreatic neural network consists of the substance P (SP)-positive sensory (afferent) nerves, the vesicular acetylcholine transporter (VAChT)-positive parasympathetic (efferent) nerves, and the tyrosine hydroxylase (TH)-positive sympathetic (efferent) nerves. The SP+ afferent nerves were found residing along the basal domain of the interlobular ducts. The VAChT+ and TH+ efferent nerves were identified at the peri-acinar and perivascular spaces, which follow the blood vessels to the islets. In the intrapancreatic ganglia, the SP+ (scattered minority, ~7%) and VAChT+ neurons co-localize, suggesting a local afferent-efferent interaction. Compared with the mouse pancreas, the human pancreas differs in 1) the lack of SP+ afferent nerves in the islet, 2) the lower ganglionic density, and 3) the obvious presence of VAChT+ and TH+ nerves around the intralobular adipocytes. The latter implicates the neural influence on the pancreatic steatosis. Overall, our 3-D image data reveal the human pancreatic afferent and efferent innervation patterns and provide the anatomical foundation for future high-definition analyses of neural remodeling in human pancreatic diseases.NEW & NOTEWORTHY Modern three-dimensional (3-D) histology with multiplex optical signals identifies the afferent and efferent innervation patterns of human pancreas, which otherwise cannot be defined with standard histology. Our 3-D image data reveal the unexpected association of sensory and parasympathetic nerves/neurons in the intrapancreatic ganglia and identify the sympathetic and parasympathetic nerve contacts with the infiltrated adipocytes. The multiplex approach offers a new way to characterize the human pancreas in remodeling (e.g., fatty infiltration and duct lesion progression).

Posterior ventral tegmental area-nucleus accumbens shell circuitry modulates response to novelty.

Dopamine release in the nucleus accumbens from ventral tegmental area (VTA) efferent neurons is critical for orientation and response to novel stimuli in the environment. However, there are considerable differences between neuronal populations of the VTA and it is unclear which specific cell populations modulate behavioral responses to environmental novelty. A retroDREADDs (designer drugs exclusively activated by designer receptors) technique, comprising designer G protein-coupled receptors exclusively activated by designer drugs and modulated by retrograde transported Cre, was used to selectively stimulate neurons of the VTA which project to the nucleus accumbens shell (AcbSh). First, the selectivity and expression of the human M3 muscarinic receptor-based adeno-associated virus (AAV-hM3D) was confirmed in primary neuronal cell cultures. Second, AAV-CMV-GFP/Cre was infused into the AcbSh and AAV-hSyn-DIO-hM3D(Gq)-mCherry (a presynaptic enhancer in the presence of its cognate ligand clozapine-N-oxide) was infused into the VTA of ovariectomized female Fisher 344 rats to elicit hM3D(Gq)-mCherry production specifically in neurons of the VTA which synapse in the AcbSh. Finally, administration of clozapine-N-oxide significantly altered rodents' response to novelty (e.g. absence of white background noise) by activation of hM3D(Gq) receptors, without altering gross locomotor activity or auditory processing per se. Confocal imaging confirmed production of mCherry in neurons of the posterior aspect of the VTA (pVTA) suggesting these neurons contribute to novelty responses. These results suggest the pVTA-AcbSh circuit is potentially altered in motivational disorders such as apathy, depression, and drug addiction. Targeting the pVTA-AcbSh circuit, therefore, may be an effective target for pharmacological management of such psychopathologies.

A population of descending tyraminergic/octopaminergic projection neurons of the insect deutocerebrum.

In this study, we describe a cluster of tyraminergic/octopaminergic neurons in the lateral dorsal deutocerebrum of desert locusts (Schistocerca gregaria) with descending axons to the abdominal ganglia. In the locust, these neurons synthesize octopamine from tyramine stress-dependently. Electrophysiological recordings in locusts reveal that they respond to mechanosensory touch stimuli delivered to various parts of the body including the antennae. A similar cluster of tyraminergic/octopaminergic neurons was also identified in the American cockroach (Periplaneta americana) and the pink winged stick insect (Sipyloidea sipylus). It is suggested that these neurons release octopamine in the ventral nerve cord ganglia and, most likely, convey information on arousal and/or stressful stimuli to neuronal circuits thus contributing to the many actions of octopamine in the central nervous system.

Cell-Type-Specific D1 Dopamine Receptor Modulation of Projection Neurons and Interneurons in the Prefrontal Cortex.

Dopamine modulation in the prefrontal cortex (PFC) mediates diverse effects on neuronal physiology and function, but the expression of dopamine receptors at subpopulations of projection neurons and interneurons remains unresolved. Here, we examine D1 receptor expression and modulation at specific cell types and layers in the mouse prelimbic PFC. We first show that D1 receptors are enriched in pyramidal cells in both layers 5 and 6, and that these cells project to intratelencephalic targets including contralateral cortex, striatum, and claustrum rather than to extratelencephalic structures. We then find that D1 receptors are also present in interneurons and enriched in superficial layer VIP-positive (VIP+) interneurons that coexpresses calretinin but absent from parvalbumin-positive (PV+) and somatostatin-positive (SOM+) interneurons. Finally, we determine that D1 receptors strongly and selectively enhance action potential firing in only a subset of these corticocortical neurons and VIP+ interneurons. Our findings define several novel subpopulations of D1+ neurons, highlighting how modulation via D1 receptors can influence both excitatory and disinhibitory microcircuits in the PFC.

Stimulation or lesion of the medial vestibular nucleus increases the number of choline acetyltransferase-positive efferent vestibular neurons in the brainstem.

The vestibular center of the brainstem contains afferent and efferent vestibular neurons, which play an important role in information perception, processing, and sensory integration. Vestibular efferent neurons (VENs) can receive changes in vestibular afferent information and regulate peripheral vestibular function; however, it remains unclear how VENs change after vestibular afferent information increases or weakens. In this study, we used animal models with altered vestibular afferent information by electrically stimulating or destroying the vestibular medial nucleus (MVe). We confirmed the location of VENs in the brainstem by injecting five adult male Wistar rats in the vestibular region with a retrograde tracer. Following this, the MVe was stimulated electrically for 30 min in 20 naive rats. Rats were anesthetized and euthanized 1, 3, 6, and 12 h after stimulation. The MVe was electrolytically lesioned in another group (n=20); then, the rats were anesthetized and euthanized 1, 3, 5, and 7 days after lesioning. VENs were clearly identified dorsolateral to the genu of the facial nerve (g7) in coronal brainstem sections using choline acetyltransferase (ChAT) staining. The number of ChAT-positive VENs dorsolateral to g7 increased significantly on both sides compared with the control group 3 and 6 h after electrical stimulation. The number of ChAT-positive VENs dorsolateral to g7 was significantly greater on both sides compared with controls 3 and 5 days after electrolytic lesion. In summary, we found that the number of ChAT-positive VENs was significantly increased following a change in the excitability of MVe neurons. This suggests that VENs can respond to changes in afferent vestibular information and feedback, and regulate the peripheral vestibule. In addition, this shows that acetylcholine is an important neurotransmitter that plays an important role in the perception and fine regulation of the vestibular system.

Talking back: Development of the olivocochlear efferent system.

Developing sensory systems must coordinate the growth of neural circuitry spanning from receptors in the peripheral nervous system (PNS) to multilayered networks within the central nervous system (CNS). This breadth presents particular challenges, as nascent processes must navigate across the CNS-PNS boundary and coalesce into a tightly intermingled wiring pattern, thereby enabling reliable integration from the PNS to the CNS and back. In the auditory system, feedforward spiral ganglion neurons (SGNs) from the periphery collect sound information via tonotopically organized connections in the cochlea and transmit this information to the brainstem for processing via the VIII cranial nerve. In turn, feedback olivocochlear neurons (OCNs) housed in the auditory brainstem send projections into the periphery, also through the VIII nerve. OCNs are motor neuron-like efferent cells that influence auditory processing within the cochlea and protect against noise damage in adult animals. These aligned feedforward and feedback systems develop in parallel, with SGN central axons reaching the developing auditory brainstem around the same time that the OCN axons extend out toward the developing inner ear. Recent findings have begun to unravel the genetic and molecular mechanisms that guide OCN development, from their origins in a generic pool of motor neuron precursors to their specialized roles as modulators of cochlear activity. One recurrent theme is the importance of efferent-afferent interactions, as afferent SGNs guide OCNs to their final locations within the sensory epithelium, and efferent OCNs shape the activity of the developing auditory system. This article is categorized under: Nervous System Development > Vertebrates: Regional Development.

The transgenic mouse line Igsf9-eGFP allows targeted stimulation of inferior olive efferents.

BACKGROUND: The inferior olive (IO) innervates the cerebellum forming synapses in the deep cerebellar nuclei (DCN) and the cerebellar cortex. Beside the well-known exception of synapses on Purkinje neurons, synapses between IO efferents and other neuronal targets have not been studied intensively, mostly due to the technical challenge of unequivocally identifying IO efferents in electrophysiological experiments. NEW METHOD: We describe the transgenic mouse line Igsf9-eGFP, which expresses GFP in IO neurons, as a suitable tool for studying IO efferents using live imaging, immunohistochemistry and electrophysiology. RESULTS: In the Igsf9-eGFP line, GFP-positive neurons are found in all IO subnuclei. Their efferents show the expected trajectories innervating the DCN and, as climbing fibers (CFs), the cerebellar cortex. In the DCN the dentate nucleus shows the strongest innervation, and, within the cerebellar cortex, CFs show a rostral-to-caudal gradient. GFP-positive CFs undergo a normal postnatal maturation, and evoke normal synaptic responses in Purkinje neurons and DCN neurons. COMPARISON WITH EXISTING METHODS: IO efferents have been labelled via anterograde labelling, viral transfection and in transgenic mouse lines. The latter approach does not require stereotactic injections. However, available mouse lines show only a sparse GFP expression, harbor GFP-positive axons of other cerebellar fibers, or have not been characterized in detail. CONCLUSIONS: The Igsf9-eGFP line is characterized by a moderate density of GFP-positive IO efferents, which can be visually targeted for extracellular stimulation with micrometer precision. The mouse line will allow studying fiber-specific responses in all neurons targeted by the IO.

Renal Nerves and Long-Term Control of Arterial Pressure.

The objective of this review is to provide an in-depth evaluation of how renal nerves regulate renal and cardiovascular function with a focus on long-term control of arterial pressure. We begin by reviewing the anatomy of renal nerves and then briefly discuss how the activity of renal nerves affects renal function. Current methods for measurement and quantification of efferent renal-nerve activity (ERNA) in animals and humans are discussed. Acute regulation of ERNA by classical neural reflexes as well and hormonal inputs to the brain is reviewed. The role of renal nerves in long-term control of arterial pressure in normotensive and hypertensive animals (and humans) is then reviewed with a focus on studies utilizing continuous long-term monitoring of arterial pressure. This includes a review of the effect of renal-nerve ablation on long-term control of arterial pressure in experimental animals as well as humans with drug-resistant hypertension. The extent to which changes in arterial pressure are due to ablation of renal afferent or efferent nerves are reviewed. We conclude by discussing the importance of renal nerves, relative to sympathetic activity to other vascular beds, in long-term control of arterial pressure and hypertension and propose directions for future research in this field. © 2017 American Physiological Society. Compr Physiol 7:263-320, 2017.

The pan-Kv7 (KCNQ) Channel Opener Retigabine Inhibits Striatal Excitability by Direct Action on Striatal Neurons In Vivo.

Central Kv7 (KCNQ) channels are voltage-dependent potassium channels composed of different combinations of four Kv7 subunits, being differently expressed in the brain. Notably, striatal dopaminergic neurotransmission is strongly suppressed by systemic administration of the pan-Kv7 channel opener retigabine. The effect of retigabine likely involves the inhibition of the activity in mesencephalic dopaminergic neurons projecting to the striatum, but whether Kv7 channels expressed in the striatum may also play a role is not resolved. We therefore assessed the effect of intrastriatal retigabine administration on striatal neuronal excitability in the rat determined by c-Fos immunoreactivity, a marker of neuronal activation. When retigabine was applied locally in the striatum, this resulted in a marked reduction in the number of c-Fos-positive neurons after a strong excitatory striatal stimulus induced by acute systemic haloperidol administration in the rat. The relative mRNA levels of Kv7 subunits in the rat striatum were found to be Kv7.2 = Kv7.3 = Kv7.5 > >Kv7.4. These data suggest that intrastriatal Kv7 channels play a direct role in regulating striatal excitability in vivo.

Development of the intrinsic and extrinsic innervation of the gut.

The gastrointestinal (GI) tract is innervated by intrinsic enteric neurons and by extrinsic efferent and afferent nerves. The enteric (intrinsic) nervous system (ENS) in most regions of the gut consists of two main ganglionated layers; myenteric and submucosal ganglia, containing numerous types of enteric neurons and glial cells. Axons arising from the ENS and from extrinsic neurons innervate most layers of the gut wall and regulate many gut functions. The majority of ENS cells are derived from vagal neural crest cells (NCCs), which proliferate, colonize the entire gut, and first populate the myenteric region. After gut colonization by vagal NCCs, the extrinsic nerve fibers reach the GI tract, and Schwann cell precursors (SCPs) enter the gut along the extrinsic nerves. Furthermore, a subpopulation of cells in myenteric ganglia undergoes a radial (inward) migration to form the submucosal plexus, and the intrinsic and extrinsic innervation to the mucosal region develops. Here, we focus on recent progress in understanding the developmental processes that occur after the gut is colonized by vagal ENS precursors, and provide an up-to-date overview of molecular mechanisms regulating the development of the intrinsic and extrinsic innervation of the GI tract.

Subcortical connections of the perirhinal, postrhinal, and entorhinal cortices of the rat. II. efferents.

This is the second of two studies detailing the subcortical connections of the perirhinal (PER), the postrhinal (POR) and entorhinal (EC) cortices of the rat. In the present study, we analyzed the subcortical efferents of the rat PER areas 35 and 36, POR, and the lateral and medial entorhinal areas (LEA and MEA). Anterograde tracers were injected into these five regions, and the resulting density of fiber labeling was quantified in an extensive set of subcortical structures. Density and topography of fiber labeling were quantitatively assessed in 36 subcortical areas, including olfactory structures, claustrum, amygdala nuclei, septal nuclei, basal ganglia, thalamic nuclei, and hypothalamic structures. In addition to reporting the density of labeled fibers, we incorporated a new method for quantifying the size of anterograde projections that takes into account the volume of the target subcortical structure as well as the density of fiber labeling. The PER, POR, and EC displayed unique patterns of projections to subcortical areas. Interestingly, all regions examined provided strong input to the basal ganglia, although the projections arising in the PER and LEA were stronger and more widespread. PER areas 35 and 36 exhibited similar pattern of projections with some differences. PER area 36 projects more heavily to the lateral amygdala and much more heavily to thalamic nuclei including the lateral posterior nucleus, the posterior complex, and the nucleus reuniens. Area 35 projects more heavily to olfactory structures. The LEA provides the strongest and most widespread projections to subcortical structures including all those targeted by the PER as well as the medial and posterior septal nuclei. POR shows fewer subcortical projections overall, but contributes substantial input to the lateral posterior nucleus of the thalamus. The MEA projections are even weaker. Our results suggest that the PER and LEA have greater influence over olfactory, amygdala, and septal nuclei, whereas PER area 36 and the POR have greater influence over thalamic nuclei. © 2016 Wiley Periodicals, Inc.

Efferent innervation of turtle semicircular canal cristae: comparisons with bird and mouse.

In the vestibular periphery of nearly every vertebrate, cholinergic vestibular efferent neurons give rise to numerous presynaptic varicosities that target hair cells and afferent processes in the sensory neuroepithelium. Although pharmacological studies have described the postsynaptic actions of vestibular efferent stimulation in several species, characterization of efferent innervation patterns and the relative distribution of efferent varicosities among hair cells and afferents are also integral to understanding how efferent synapses operate. Vestibular efferent markers, however, have not been well characterized in the turtle, one of the animal models used by our laboratory. Here we sought to identify reliable efferent neuronal markers in the vestibular periphery of turtle, to use these markers to understand how efferent synapses are organized, and to compare efferent neuronal labeling patterns in turtle with two other amniotes using some of the same markers. Efferent fibers and varicosities were visualized in the semicircular canal of red-eared turtles (Trachemys scripta elegans), zebra finches (Taeniopygia guttata), and mice (Mus musculus) utilizing fluorescent immunohistochemistry with antibodies against choline acetyltransferase (ChAT). Vestibular hair cells and afferents were counterstained using antibodies to myosin VIIa and calretinin. In all species, ChAT labeled a population of small diameter fibers giving rise to numerous spherical varicosities abutting type II hair cells and afferent processes. That these ChAT-positive varicosities represent presynaptic release sites were demonstrated by colabeling with antibodies against the synaptic vesicle proteins synapsin I, SV2, or syntaxin and the neuropeptide calcitonin gene-related peptide. Comparisons of efferent innervation patterns among the three species are discussed.

Efferent pathways of the mouse lateral habenula.

The lateral habenula (LHb) is part of the habenula complex of the dorsal thalamus. Recent studies of the LHb have focused on its projections to the ventral tegmental area (VTA) and rostromedial tegmental nucleus (RMTg), which contain γ-aminobutyric acid (GABA)ergic neurons that mediate reward prediction error via inhibition of dopaminergic activity. However, older studies in the rat have also identified LHb outputs to the lateral and posterior hypothalamus, median raphe, dorsal raphe, and dorsal tegmentum. Although these studies have shown that the medial and lateral divisions of the LHb have somewhat distinct projections, the topographic specificity of LHb efferents is not completely understood, and the relative extent of these projections to brainstem targets is unknown. Here we have used anterograde tracing with adeno-associated virus-mediated expression of green fluorescent protein, combined with serial two-photon tomography, to map the efferents of the LHb on a standard coordinate system for the entire mouse brain, and reconstruct the efferent pathways of the LHb in three dimensions. Using automated quantitation of fiber density, we show that in addition to the RMTg, the median raphe, caudal dorsal raphe, and pontine central gray are major recipients of LHb efferents. By using retrograde tract tracing with cholera toxin subunit B, we show that LHb neurons projecting to the hypothalamus, VTA, median raphe, caudal dorsal raphe, and pontine central gray reside in characteristic, but sometimes overlapping regions of the LHb. Together these results provide the anatomical basis for systematic studies of LHb function in neural circuits and behavior in mice. J. Comp. Neurol. 523:32-60, 2015. © 2014 Wiley Periodicals, Inc.

Prickle1 is necessary for the caudal migration of murine facial branchiomotor neurons.

Facial branchiomotor neurons (FBMs) of vertebrates typically develop in rhombomere 4 (r4), and in mammals and several other vertebrate taxa, migrate caudally into r6 and subsequently laterally and ventrally to the pial surface. How similar or dissimilar these migratory processes between species are at a molecular level remains unclear. In zebrafish and mouse, mutations in certain PCP genes disrupt normal caudal migration of FBMs. Zebrafish prickle1a (prickle-like 1a) and prickle1b, two orthologs of Prickle1, act non-cell-autonomously and cell-autonomously, respectively, to regulate FBM migration. Here, we show that, in Prickle1 (C251X/C251X) mice which have reduced Prickle1 expression, the caudal migration of FBMs is affected. Most FBM neurons do not migrate caudally along the floor plate. However, some neurons perform limited caudal migration such that the neurons eventually lie near the pial surface from r4 to anterior r6. FBMs in Prickle1 (C251X/C251X) mice survive until P0 and form an ectopic nucleus dorsal to the olivo-cochlear efferents of r4. Ror2, which modifies the PCP pathway in other systems, is expressed by the migrating mouse FBMs, but is not required for FBM caudal migration. Our results suggest that, in mice, Prickle1 is part of a molecular mechanism that regulates FBM caudal migration and separates the FBM and the olivo-cochlear efferents. This defective caudal migration of FBMs in Prickle1C251X mutants resembles Vangl2 mutant defects. In contrast to other developing systems that show similar defects in Prickle1, Wnt5a and Ror2, the latter two only have limited or no effect on FBM caudal migration.

Connections of the magnocellular medial preoptic nucleus (MPN mag) in male Syrian hamsters. II. The efferents.

The magnocellular medial preoptic nucleus (MPN mag) plays a critical role in the regulation of male copulatory behavior in the Syrian hamster. Our study of the afferents are consistent with the hypothesis that the MPN mag receives input from areas in the chemosensory pathway and nuclear groups that contain receptors for gonadal steroids (Wang and Swann, 2006). The goal of the present study is to identify targets of the MPN mag by describing the location of labeled fibers following an injection of biotinylated dextran amine (BDA) into the MPN mag. Our results indicate that targets of the MPN mag include: (1) brainstem nuclei implicated in regulating male mating behavior in other species, such as the periaqueductal gray, deep mesencephalic nucleus, retrorubral field, ventral tegmental area and lateral paragigantocellular nucleus and (2) steroid-concentrating nuclei in the septum, preoptic area and hypothalamus. The lack of projections from the MPN mag to its chemosensory afferents indicate that the connections of the MPN mag with the posterior medial bed nucleus of the stria terminalis, medial and anterior cortical nuclei of the amygdala are unidirectional, and that chemosensory information flows from the medial amygdala and bed nucleus of the stria terminalis (BST) to the MPN mag. The bidirectional nature of the connections between the MPN mag and steroid-concentrating nuclei suggest that the MPN mag may influence the function of a steroid-concentrating network that regulates behaviors. Together these results support the hypothesis that the MPN mag regulates male mating behavior by integrating chemosensory and hormonal signals and relaying this information to brainstem areas that control motor output.

Olivocochlear innervation maintains the normal modiolar-pillar and habenular-cuticular gradients in cochlear synaptic morphology.

Morphological studies of inner hair cell (IHC) synapses with cochlear nerve terminals have suggested that high- and low-threshold fibers differ in the sizes of their pre- and postsynaptic elements as well as the position of their synapses around the hair cell circumference. Here, using high-power confocal microscopy, we measured sizes and spatial positions of presynaptic ribbons, postsynaptic glutamate receptor (GluR) patches, and olivocochlear efferent terminals at eight locations along the cochlear spiral in normal and surgically de-efferented mice. Results confirm a prior report suggesting a modiolar > pillar gradient in ribbon size and a complementary pillar > modiolar gradient in GluR-patch size. We document a novel habenular < cuticular gradient in GluR patch size and a complementary cuticular < habenular gradient in olivocochlear innervation density. All spatial gradients in synaptic elements collapse after cochlear de-efferentation, suggesting a major role of olivocochlear efferents in maintaining functional heterogeneity among cochlear nerve fibers. Our spatial analysis also suggests that adjacent IHCs may contain a different synaptic mix, depending on whether their tilt in the radial plane places their synaptic pole closer to the pillar cells or to the modiolus.

Single-unit labeling of medial olivocochlear neurons: the cochlear frequency map for efferent axons.

Medial olivocochlear (MOC) neurons are efferent neurons that project axons from the brain to the cochlea. Their action on outer hair cells reduces the gain of the "cochlear amplifier," which shifts the dynamic range of hearing and reduces the effects of noise masking. The MOC effects in one ear can be elicited by sound in that ipsilateral ear or by sound in the contralateral ear. To study how MOC neurons project onto the cochlea to mediate these effects, single-unit labeling in guinea pigs was used to study the mapping of MOC neurons for neurons responsive to ipsilateral sound vs. those responsive to contralateral sound. MOC neurons were sharply tuned to sound frequency with a well-defined characteristic frequency (CF). However, their labeled termination spans in the organ of Corti ranged from narrow to broad, innervating between 14 and 69 outer hair cells per axon in a "patchy" pattern. For units responsive to ipsilateral sound, the midpoint of innervation was mapped according to CF in a relationship generally similar to, but with more variability than, that of auditory-nerve fibers. Thus, based on CF mappings, most of the MOC terminations miss outer hair cells involved in the cochlear amplifier for their CF, which are located more basally. Compared with ipsilaterally responsive neurons, contralaterally responsive neurons had an apical offset in termination and a larger span of innervation (an average of 10.41% cochlear distance), suggesting that when contralateral sound activates the MOC reflex, the actions are different than those for ipsilateral sound.

Origin of efferent fibers of the renal plexus in the rat autonomic nervous system.

To clarify the origin of efferent nerves containing renal plexus, the retrograde neuronal tracing was utilized with a new exact closed injection system with microcapsules. The microcapsule was positioned in the rat left renal plexus, and the capsule was filled with fluoro-gold. Retrograde labeled cells were observed in the ipsilateral sympathetic trunk, especially T12 and T13, and the ipsilateral suprarenal ganglia (SrG). There were no labeled cells in the parasympathetic nuclei in medulla oblongata and sacral cords. These results indicated that the origins of efferent nerves in the rat renal plexus are almost all sympathetic ganglia, such as sympathetic trunk and SrG, and cells in other ganglia may be secondary or accessory innervations.

A hindbrain segmental scaffold specifying neuronal location in the adult goldfish, Carassius auratus.

The vertebrate hindbrain develops as a series of well-defined neuroepithelial segments or rhombomeres. While rhombomeres are visible in all vertebrate embryos, generally there is not any visible segmental anatomy in the brains of adults. Teleost fish are exceptional in retaining a rhombomeric pattern of reticulospinal neurons through embryonic, larval, and adult periods. We use this feature to map more precisely the segmental imprint in the reticular and motor basal hindbrain of adult goldfish. Analysis of serial sections cut in three planes and computer reconstructions of retrogradely labeled reticulospinal neurons yielded a segmental framework compatible with previous reports and more amenable to correlation with surrounding neuronal features. Cranial nerve motoneurons and octavolateral efferent neurons were aligned to the reticulospinal scaffold by mapping neurons immunopositive for choline acetyltransferase or retrogradely labeled from cranial nerve roots. The mapping corresponded well with the known ontogeny of these neurons and helps confirm the segmental territories defined by reticulospinal anatomy. Because both the reticulospinal and the motoneuronal segmental patterns persist in the hindbrain of adult goldfish, we hypothesize that a permanent "hindbrain framework" may be a general property that is retained in adult vertebrates. The establishment of a relationship between individual segments and neuronal phenotypes provides a convenient method for future studies that combine form, physiology, and function in adult vertebrates.

The brainstem localization of gastric preganglionic parasympathetic neurons in the Agouti (Dasyprocta leporina) / Localización del tronco encefálico de las neuronas parasimpáticas preganglionares gástricas en el agutí (Dasyprocta leporina)

This study was designed to determine qualitatively, the source of gastric vagal nerve fibres in the Agouti. A total of 18 male and female adult agoutis were used for the present investigation. Following anaesthesia, laparotomy was performed and the stomach exteriorized. Multiple intramuscular injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) were then made into different areas of the stomach in the experimental animals. The control animals were divided into four groups of two animals each. The first group had intraperitoneal injection of the tracer, the second had intramuscular injection of normal saline, the third group had injection of tracer into the hepatic portal vein and the last group had injection of the tracer into the gastric walls followed immediately by bilateral vagotomy. Following a survival period offive to seven days, the animals were sacrificed by transcardial perfusion, first with normal saline followed by fixative and finally with 20% buffered sucrose. Following perfusion, the brainstem was extracted from the brain, immersed in 20% buffered sucrose and kept refrigerated overnight for cryoprotection. The brainstems were subsequently sectioned serially, processed for WGA-HRP neurohistochemistry and then analysed under light and dark-field illuminations. The analysis of the sections taken from the experimental animals revealed bilateral presence of WGA-HRP labelled neurons in the dorsal motor nucleus of the vagus nerve (DMNV) and the nucleus ambiguus (nA) of the medulla oblongata. No labelled neurons were seen in any of the sections taken from the control animals. The implications of the findings are discussed.

Este estudio fue diseñado para determinar cualitativamente el origen de las fibras gástricas del nervio vago en el agutí. Un total de 18 agutíes adultos masculinos y femeninos fueron utilizados para la presente investigación. Después de la anestesia, se realizó una laparotomía y se sacó el estómago al exterior. Luego se hicieron múltiples inyecciones intramusculares de aglutinina de germen de trigo con peroxidasa de rábano (WGA-HRP) en diferentes áreas del estómago de los animales experimentales. Los animales del control fueron divididos en cuatro grupos de dos animales cada uno. Al primer grupo se le puso una inyección intraperitoneal del marcador; al segundo se le administró una inyección intramuscular de solución salina normal; al tercer grupo se le inyectó el marcador en la vena porta hepática; y al último grupo se le puso la inyección del marcador en las paredes gástricas, seguida inmediatamente por una vagotomía bilateral. Tras un periodo de supervivencia de cinco a siete días, los animales fueron sacrificados por perfusión transcardíaca, primero con solución salina normal, seguida de fijador, y finalmente con sacarosa tamponada al 20%. Después de la perfusión, el tronco encefálico fue extraído del cerebro, inmerso en sacarosa tamponada al 20%, y mantenido en refrigeración durante la noche para su crioprotección. Los tronos encefálicos fueron luego seccionados en serie, procesados para para el análisis neuro-histoquímico mediante aglutinina de germen de trigo con peroxidasa de rábano, y analizados entonces bajo iluminaciones de campo de luz y campo oscuro. El análisis de las secciones tomadas de animales experimentales reveló la presencia bilateral de neuronas etiquetadas WGA-HRP en el núcleo motor dorsal del nervio vago (DMNV) y en el núcleo ambiguo (nA) de la médula oblonga. No se observaron neuronas etiquetadas en ninguna de las secciones tomadas de los animales de control. Se discuten las implicaciones de los hallazgos.