大鼠Barrington核内脊髓投射神经元直接接受腰骶髓传入的电镜研究

将结合生物素的葡聚糖胺 (BDA)注射到大鼠腰骶髓后 ,在电镜下观察脑桥Barrington核内腰骶髓投射神经元与来自腰骶髓传入投射纤维间的突触联系。与先前的研究相一致 ,注射BDA到腰 6和骶 1节段后 ,光镜下可见Barrington核内出现大量顺行标记的神经末梢和一定数量的逆行标记细胞。电镜下发现标记的轴突末梢和标记的树突之间存在直接的突触连接。结果表明 ,Barrington核直接接受腰骶髓的传入投射 ,提示大鼠脑桥排尿反射的脊髓内上行投射通路中可能存在一条直接通路。     

Anatomical and physiological observations on supraspinal control of bladder and urethral sphincter muscles in the cat

In 15 cats injections of 3H-leucine were made in the pontine tegmentum. Injections in the medial part of the dorsolateral pontine tegmentum (M-region) resulted in specific projections to the sacral intermediomedial and intermediolateral cell groups. The intermediolateral cell group contains preganglionic parasympathetic neurons that form the motor supply of the detrusor muscle of the bladder. Injections in the lateral part of the pontine tegmental field (L-region) produced labeled fibers in the nucleus of Onuf, which contains motoneurons innervating the pelvic floor including the anal and urethral sphincters. L-region projections to the sacral preganglionic parasympathetic neurons and M-region projections to the nucleus of Onuf were very limited or absent. In 12 cats physiological experiments were performed. Electrical stimulation in the L-region elicited a prompt increase in the pelvic floor EMG and urethral pressure but had little influence on the intravesical pressure. Stimulation in the M-region elicited a prompt decrease in the pelvic floor EMG and urethral pressure followed, after a delay of 2 seconds, by an increase in the intravesical pressure, so simulating normal micturition.     

Distinct cell groups in the lumbosacral cord of the cat project to different areas in the periaqueductal gray

The periaqueductal gray (PAG) is involved in aggressive and defensive behavior, micturition, and lordosis. Especially for the latter two functions, PAG afferents from the lumbosacral cord are of vital importance because, in addition to information regarding homeostasis and thermoregulation, they convey information from the pelvic viscera and sex organs. In the present retro- and antero-grade tracing study, the projection patterns of different lumbosacral cell groups in the PAG were determined. In the retrograde study, wheatgerm agglutinin-horseradish peroxidase (WGA-HRP) injections were made in the PAG and/or adjacent tegmentum, and in the anterograde study, WGA-HRP was injected in different lumbosacral segments. The results revealed that lumbosacral-PAG neurons could be divided into three groups. The first and largest group was present in lumbar 7-sacral 3 segments (L7-S3) and consisted of small, oval, and fusiform neurons. It extended from the dorsolateral part of lamina I in L7, along the lateral part of the dorsal horn in S1, and into lamina V of S2. In the lateral part of S2, some of its neurons formed clusters with intervals of ± 230 μm. The location of the first group overlapped extensively with the termination area of pelvic and pudendal afferents. The main midbrain target of the first group was the medial part of the lateral PAG. The second group consisted of small to large multipolar neurons in laminae VIII and medial VII of caudal L6, L7, and rostral S1. This group projected strongly to a distinct region in the lateral part of the lateral PAG and the laterally adjacent tegmentum. About 10% of the labeled neurons did not fit in the two groups. They were evenly distributed throughout lumbar 4-coccygeal 3 segments (L4-Co3) and consisted of large multipolar lamina V neurons and small lamina I neurons that projected diffusely to the lateral and dorsal PAG. The large lamina V neurons also targeted the laterally adjacent tegmentum. The possible involvement of the lumbosacral-PAG projections in micturition, lordosis, and defensive and aggressive behavior is discussed. © 1996 Wiley-Liss, Inc.     

Collateral branching in axonal projections to spinal cord from paramedian reticular nucleus neurons

Experiments were done in cats to identify neurons in the paramedian reticular nucleus (PRN) sending collateral axons to the region of the intermediolateral nucleus (IML) at different levels of the thoracic cord by using lectin-conjugated horseradish peroxidase (HRP) and double-labeling fluorochrome histochemistry to retrogradely label PRN neurons. Injections of Fast blue (FB) into the spinal cord at the T2 level centered in the region of the IML were coupled with injections of Nuclear yellow (NY) into the ipsilateral cord at either the T4 or T7 levels centered in the region of the IML. Neurons in the PRN retrogradely labeled after diffusion of HRP into the region of the IML at the T2 level were observed throughout the rostrocaudal extent of the ventral PRN. In addition, a few labeled neurons were noted in the ventral portion of the dorsal PRN. About 40% of the neurons in the PRN which were labeled with FB after an injection at the T2 level were also labeled with NY injected into the cord in further caudal segments. These data suggest that the PRN may exert its influence on the cardiovascular system partly through collateral axonal branches to widely separated populations of sympathetic preganglionic neurons in different spinal segmental levels.     

Primary afferent projections from dorsal and ventral roots to autonomic preganglionic neurons in the cat sacral spinal cord: light and electron microscopic observations

HRP applied to cut dorsal and ventral roots of the cat sacral spinal cord labeled afferent axons with swellings in close apposition to labeled preganglionic neurons (PGNs) in the sacral parasympathetic nucleus. Electron microscopy allowed characterization of synaptic contacts between afferents and PGNs. The results suggest that both the dorsal and ventral root afferents can directly activate autonomic preganglionic neurons.     

Evidence for corticotropin-releasing hormone projections from Barrington's nucleus to the periaqueductal gray and dorsal motor nucleus of the vagus in the rat

The present study used anterograde and retrograde tract tracing and immunohistochemistry to determine the efferent projections of corticotropin-releasing hormone (CRH) neurons of Barrington's nucleus in the rat. Injections of Phaseolus vulgaris-leucoagglutinin into Barrington's nucleus resulted in anterograde labeling in the dorsal motor nucleus of the vagus, periaqueductal gray, medial thalamic nuclei, lateral hypothalamus, paraventricular nucleus of the hypothalamus, lateral preoptic area, and lateral septum. The retrograde tract tracer, fluorogold, injected into the lumbosacral spinal cord labeled many, but not all, CRH-immunoreactive neurons in Barrington's nucleus. Moreover, some Barrington's neurons that were retrogradely labeled from the spinal cord were not CRH-immunoreactive. Several CRH-immunoreactive Barrington's neurons were retrogradely labeled by fluorogold injections into the periaqueductal gray, and these were located predominantly in the dorsal part of the nucleus. Additionally, some CRH-immunoreactive Barrington's neurons were retrogradely labeled from fluorogold injections into the dorsal motor nucleus of the vagus. In contrast, fluorogold injections into the lateral hypothalamus, lateral preoptic area, or lateral septum did not result in double labeling of CRH-immunoreactive neurons in Barrington's nucleus. These results suggest that many, but not all, CRH-containing neurons of Barrington's nucleus project to the lumbosacral spinal cord. In addition to their previously documented projections to the spinal cord, these neurons may be a source of CRH in the periaqueductal gray and dorsal motor nucleus of the vagus. CRH projections of Barrington's nucleus may play a role in behavioral or autonomic aspects of stress responses, in addition to their proposed role in micturition. © 1995 Wiley-Liss, Inc.     

Edinger-Westphal nucleus: cholecystokinin immunocytochemistry and projections to spinal cord and trigeminal nucleus in the cat

Immunocytochemical methods were used to determine the distribution of cells with cholecystokinin-like immunoreactivity (CCK-LI) in the cat Edinger-Westphal complex (EW). Numerous cells with CCK-LI are found throughout the length of EW. The distribution and frequency of such cells are similar to the pattern of EW neurons that show substance P-like immunoreactivity (SP-LI). Companion retrograde transport experiments reveal that EW neurons which project to spinal cord or the region of the caudal trigeminal nucleus are found throughout the length of EW, and that some EW neurons which project to spinal cord also show CCK-LI.     

The subdivisions of the intermediolateral nucleus in the sacral spinal cord of the cat

The subdivisions of the sacral intermediolateral nucleus (IML) of the cat have been studied by using a double-labeling technique of retrograde Fluoro-gold (FG) and wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) tracing. The parasympathetic preganglionic neurons (PGNs) that were labeled by the FG injected into the pelvic nerve formed a ‘V’-shaped column known as the sacral parasympathetic nucleus (SPN) in the sacral IML. The neurons that were labeled by the WGA-HRP applied to the lateral parabrachial nucleus (PBL) formed an elongated spindle-shaped column extending throughout the IML of the sacral segments. We designated it by the name of sacral visceral sensory nucleus (SVSN). These findings indicate that the sacral IML of the cat contain two distinct subdivisions, SPN and SVSN.     

Estrogen receptor-immunoreactive neurons are present in the female rat lumbosacral spinal cord

Presence of an estrogen receptor is crucial for cells to respond to estrogen; thus, estrogen-responsive neurons should be identifiable by immunohistochemically staining for the estrogen receptor (ER). Even though spinal neurons are involved in sexual behaviors and innervation of genital organs, little information is available about ER-containing neurons in the spinal cord. Consequently, we have undertaken a study of ER-containing neurons in the female rat lumbosacral cord, an area involved in reproductive functions and predicted to contain estrogen-responsive neurons. In addition, since parasympathetic preganglionic neurons in the lumbosacral cord produce nitric oxide (NO), we also sought to determine if ER-immunoreactive (-IR) neurons contain the enzymes for NO production. Finally, we compared the distribution of ER-IR neurons to the presence of uterine cervix-related neurons. Uterine cervix-related neurons were identified by expression of FOS-immunoreactivity after vaginocervical mechanostimulation (VCS). The lumbosacral spinal cords were removed from intact, ovariectomized, and VCS-treated rats and sections stained by immunohistochemistry. ER-IR was present in the nuclei of neurons located predominately in the dorsal one-half of the spinal cord. Specific sites include the dorsal horn, lamina V, the sacral parasympathetic nucleus (SPN) (which contains preganglionic parasympathetic neurons) and extending into the lateral funiculus, and lamina X. Some ER-IR neurons were NADPH-d-positive and were localized in laminae V and VII. FOS-IR neurons had a distribution pattern similar to the distribution of neurons containing ER. The presence of ER neurons in these regions suggest that they are responsive to circulating estrogen. © 1996 Wiley-Liss, Inc.     

Barrington's nucleus in the guinea pig (Cavia porcellus): location in relation to noradrenergic cell groups and connections to the lumbosacral spinal cord

Micturition is largely controlled by Barrington's nucleus in the dorsolateral tegmentum of the pons. This nucleus coordinates simultaneous bladder contraction and external urethral sphincter relaxation, by means of a specific pattern of projections to the lumbosacral spinal cord. The most widely used small animal model in neurourological research is the rat. However, urodynamic studies suggest that, in sharp comparison to rat, guinea pig micturition is very similar to human micturition. Therefore, the present study, using retrograde and anterograde tracing and double immunofluorescence, was designed to investigate the location of Barrington's nucleus in the guinea pig, to identify Barrington's nucleus projections to the spinal cord and to clarify the relationship of Barrington's nucleus to pontine noradrenergic cell groups. Results show that Barrington's nucleus is located in the dorsolateral pons, projects to the intermediolateral and intermediomedial cell groups of the lumbosacral spinal cord and is clearly distinct from the pontine noradrenergic cell groups. These results show that the neuroanatomical circuitry in the spinal cord and brainstem that controls micturition in the guinea pig is similar to that in rat. This means that the differences between rat and guinea pig micturition on a behavioral level are not the result of different neuroanatomical connections in these parts of the central nervous system. These results provide a neuroanatomical basis for further neurourological studies in guinea pig.     

Morphological and physiological identification of excitatory pontine reticular neurons projecting to the cat abducens nucleus and spinal cord

The current study provides strong morphological and physiological evidence for identifying reticular neurons which project to the ipsilateral abducens nucleus. In conjunction with recent work in the alert cat, these neurons are believed to be excitatory and are implicated to play a role in the generation of saccadic and/or vestibular fast phase eye movements.     

Direct projections from the cardiovascular nucleus tractus solitarii to pontine preganglionic parasympathetic neurons: a link to cerebrovascular regulation

Peripheral or central interruption of the baroreflex or the parasympathetic innervation of cerebral vessels leads to similar changes in regulation of cerebral blood flow. Therefore, we sought to test the hypothesis that the cardiovascular nucleus tractus solitarii, the site of termination of arterial baroreceptor nerves, projects to pontine preganglionic neurons whose stimulation elicits cerebral vasodilatation. The current study utilized both light and electron microscopic techniques to analyze anterograde tracing from the cardiovascular nucleus tractus solitarii to preganglionic parasympathetic neurons in the pons. We further used retrograde tracing from that same pontine region to the cardiovascular nucleus tractus solitarii and evaluated the confluence of tracing from the cardiovascular nucleus tractus solitarii to pontine preganglionic neurons labeled retrogradely from the pterygopalatine ganglia. The cardiovascular nucleus tractus solitarii projected to pontine preganglionic parasympathetic neurons, but more rostral and caudal regions of nucleus tractus solitarii did not. In contrast, all three regions of nucleus tractus solitarii projected to the nucleus ambiguus and dorsal motor nucleus of the vagus. Although not projecting to pontine preganglionic parasympathetic neurons, regions lateral, rostral, and caudal to cardiovascular nucleus tractus solitarii sent projections through the pons medial to the preganglionics. The study establishes the presence of a direct monosynaptic pathway from neurons in the cardiovascular nucleus tractus solitarii to pontine preganglionic parasympathetic neurons that project to the pterygopalatine ganglia, the source of nitroxidergic vasodilatory innervation of cerebral blood vessels. It provides evidence that activation of those preganglionic neurons can cause cerebral vasodilatation and increased cerebral blood flow. Finally, it demonstrates differential innervation of medullary and pontine preganglionic parasympathetic neurons by different regions of the nucleus tractus solitarii.     

Barrington's nucleus: Neuroanatomic landscape of the mouse “pontine micturition center”

Barrington's nucleus (Bar) is thought to contain neurons that trigger voiding and thereby function as the “pontine micturition center.” Lacking detailed information on this region in mice, we examined gene and protein markers to characterize Bar and the neurons surrounding it. Like rats and cats, mice have an ovoid core of medium‐sized Bar neurons located medial to the locus coeruleus (LC). Bar neurons express a GFP reporter for Vglut2, develop from a Math1/Atoh1 lineage, and exhibit immunoreactivity for NeuN. Many neurons in and around this core cluster express a reporter for corticotrophin‐releasing hormone (Bar^CRH). Axons from Bar^CRH neurons project to the lumbosacral spinal cord and ramify extensively in two regions: the dorsal gray commissural and intermediolateral nuclei. Bar^CRH neurons have unexpectedly long dendrites, which may receive synaptic input from the cerebral cortex and other brain regions beyond the core afferents identified previously. Finally, at least five populations of neurons surround Bar: rostral‐dorsomedial cholinergic neurons in the laterodorsal tegmental nucleus; lateral noradrenergic neurons in the LC; medial GABAergic neurons in the pontine central gray; ventromedial, small GABAergic neurons that express FoxP2; and dorsolateral glutamatergic neurons that express FoxP2 in the pLC and form a wedge dividing Bar from the dorsal LC. We discuss the implications of this new information for interpreting existing data and future experiments targeting Bar^CRH neurons and their synaptic afferents to study micturition and other pelvic functions.     

Localization of enkephalinergic neurons in the dorsolateral pontine tegmentum projecting to the spinal cord of the cat

The dorsolateral pontine tegmentum of the cat is known to contain enkephalinergic neurons, with most of the enkephalin co-contained in the catecholaminergic neurons; however, enkephalinergic cells projecting to the spinal cord have not been identified. This study employs retrograde transport of horseradish peroxidase in combination with methionine-enkephalin or tyrosine hydroxylase immunocytochemistry to 1) determine the locations of pontospinal enkephalinergic neurons and 2) compare these with the locations of pontospinal catecholaminergic neurons. Pontospinal enkephalinergic neurons were observed in the nuclei locus coeruleus and subcoeruleus and the K?lliker-Fuse nucleus. A high concentration of these neurons was evident in the K?lliker-Fuse nucleus when compared to the nuclei locus coeruleus and subcoeruleus (P less than .01). Both the enkephalinergic and catecholaminergic neurons projecting to the spinal cord were located in the same general areas of the dorsolateral pontine tegmentum and there was no significant difference in the mean diameters of these two neuronal types (P greater than .05). Quantitative data concerning the pontospinal enkephalinergic neurons correlated well with previous data on pontospinal catecholaminergic neurons (Reddy et al., Brain Res. 491:144-149, '89). A majority of the descending neurons from the dorsolateral pontine tegmentum contain enkephalin (72-80%) and catecholamine (80-87%). The observations suggest that enkephalin is contained in many of the pontospinal catecholaminergic neurons.     

Proximal colon distention increases Fos expression in the lumbosacral spinal cord and activates sacral parasympathetic NADPHd-positive neurons in rats

Fos expression induced by nociceptive mechanical distention of the proximal colon was examined in the lumbosacral spinal cord in freely moving rats equipped with a chronic balloon in the proximal colon. Fos protein in lumbosacral neurons was detected immunocytochemically, and colocalization with nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) activity was determined histochemically at 1 hour after distention. Distention of the proximal colon (10 ml, 30 seconds on/off for 10 minutes, about 90 mm Hg) increased the number of Fos-positive cells in the lumbar 6 (L6) and sacral 1 and 2 (S1, S2) segments, whereas no change was observed in the L1–L5 and S3 segments compared with the sham distended group or with animals that received no treatment. In L6–S2 segments, Fos-positive neurons were increased by two-fold in laminae I-VII (mainly in laminae I and outer II) and area X (surrounding the central canal) and by nine-fold in the sacral parasympathetic nucleus. Results of time course studies indicate that the maximal increase in Fos expression observed at 1 hour after distention returns to basal levels within 4 hours. In the S1 segment, distention of the proximal colon increased the percentage of NADPHd/Fos-positive neurons selectively in the parasympathetic nucleus by 40% compared with less than 4% in the sham distention group; the number and pattern of NADPHd-stained cells were not modified. These results indicate that noxious distention of the proximal colon for a short duration in awake rats selectively activates neurons in the L6-S2 segments of the dorsal horn mainly in laminae involved in nociceptive and autonomic processing. The marked activation of NADPHd-positive neurons in the sacral parasympathetic nucleus suggests a possible role of nitric oxide in the visceroautonomic reflexes induced by distention of the proximal colon. J. Comp. Neurol. 390:311–321, 1998. © 1998 Wiley-Liss, Inc.     

Projections from the periaqueductal gray to the rostromedial pericoerulear region and nucleus locus coeruleus: anatomic and physiologic studies.

Previous studies showed that the nucleus locus coeruleus (LC) receives two major afferent inputs from 1) nucleus paragigantocellularis and 2) nucleus prepositus hypoglossi, both in the rostral medulla. Recent reports suggested that the midbrain periaqueductal gray (PAG) projects to the rostromedial pericoerulear area and LC. Since the PAG is a major site for control of central antinociception, and since descending noradrenergic fibers have been implicated in pain modulation, we have investigated in detail the functional anatomy of projections from PAG to the dorsolateral pontine tegmentum. A combined anatomical and electrophysiological approach was used to assess the organization and synaptic influence of PAG on neurons in the rostromedial pericoerulear region and in LC proper. Injections of the tracer wheatgerm agglutinin conjugated to horseradish peroxidase encompassing LC proper and the rostromedial pericoerulear area retrogradely labeled neurons in PAG located lateral and ventrolateral to the cerebral aqueduct; injections restricted to LC proper did not consistently label PAG neurons. Deposits of the anterograde axonal tracer Phaseolus vulgaris leucoagglutinin into this same region of PAG labeled axons that robustly innervated the zone rostral and medial to LC. Only sparse fibers were observed in LC proper. Consistent with these results, focal electrical stimulation of LC antidromically activated only a few PAG neurons (6 of 100); all of these driven cells were located lateral and ventrolateral to the cerebral aqueduct. The majority of neurons in the rostromedial pericoerulear area were robustly activated by single pulse stimulation of PAG. In contrast, single pulse electrical stimulation of lateral PAG produced weak to moderate synaptic activation of some LC neurons; stimulation of ventrolateral PAG produced predominant inhibition of LC discharge, perhaps through recurrent collaterals subsequent to antidromic activation of neighboring LC cells. Taken together, these results indicate that PAG strongly innervates the region rostral and medial to LC, including Barrington's nucleus, but only weakly innervates LC proper. Although recent studies indicate that the dendrites of LC neurons ramify heavily and selectively in the rostromedial pericoerulear region, the results of the present physiological studies suggest that PAG preferentially targets rostromedial pericoerulear neurons rather than LC dendrites.     

Transneuronal labeling of neurons in the adult rat brainstem and spinal cord after injection of pseudorabies virus into the urethra

Transneuronal tracing techniques were used to identify sites in the central nervous system involved in the neural control of urethral function. The distribution of virus-infected neurons was examined in the spinal cord and brainstem at various intervals (56-96 hours) following pseudorabies virus (PRV) injection into the urethra. In the lumbosacral (L6-Sl) spinal cord at 56 hours, neurons containing PRV immunoreactivity (PRV-IR) were located in the region of the sacral parasympathetic nucleus (SPN), around the central canal, and in the dorsal commissure. Some animals also exhibited PRV-IR in cells in the L6 dorsolateral motor nucleus. At longer survival times (72-96 hours), PRV-IR cells were observed in the superficial and deeper laminae of the dorsal horn, and increased numbers of PRV-IR cells were consistently detected in the region of the SPN, around the central canal, and in the dorsal commissure. PRV-IR fiber-like staining also occurred along the lateral edge of the dorsal horn extending from Lissauer's tract to the region of the SPN. In rostral lumbar segments (Ll-L2), PRV-IR cells were located in the region of the dorsal commissure and the intermediolateral cell nucleus (IML), around the central canal, and in the dorsal horn. After 72-84 hours, PRV-IR cells were also noted at more rostral levels of the neuraxis including the medulla, pons, midbrain, and diencephalon. At 72 hours, PRV-IR cells were consistently observed in Barrington's nucleus (pontine micturition center), nucleus raphe magnus (RMg), parapyramidal reticular formation, and the A5 and A7 regions. At 78–84 hours, additional regions exhibited PRV-IR cells, including the periaqueductal gray, locus coeruleus, the dorsal and ventral subcoeruleus alpha, and the red nucleus. A few cells were also located in the lateral hypothalamic area. This distribution of PRV-labeled cells in the spinal cord and brainstem is similar in many respects to the distribution of cells labeled in previous studies by PRV injection into the urinary bladder. This overlap of urethra and bladder neurons is consistent with the results of physiological experiments indicating a close coordination between the central nervous control of bladder and urethral activity.     

Serotonergic collateralized projections from Barrington's nucleus to the medial preoptic area and lumbo-sacral spinal cord

In this study, we employed triple fluorescent labelling to reveal the distribution of the direct serotonergic neurons within Barrington's nucleus (BN) that supply branching collateral input to the medial preoptic area (MPA) and to the lumbo-sacral spinal cord (LSC). Immunocytochemical detection of the monoclonal antibody raised against serotonin was used for identification of the neurons. The projections were defined by injections of two retrograde tracers: fluoro gold and rhodamine in the MPA and LSC, respectively. The aim of this study is to identify the direct projections to BN and MPA and/or LSC. The present study confirms findings of others describing BN-LSC projections and extends previous findings by demonstrating an single or collateralized fibers with MPA, and serotonergic immunoreactive fibers.     

Hypothalamic paraventricular axons projecting to the female rat lumbosacral spinal cord contain oxytocin immunoreactivity

Oxytocin-containing axons project from the hypothalamic paraventricular nucleus to the neurohypophysis and thoracic spinal cord to ultimately influence uterine contractions and autonomic activity, respectively. Whether or not oxytocin-immunoreactive axons project to the female rat lumbosacral spinal cord to influence autonomic outflow to pelvic organs has not been investigated. Thus, the present study was designed to investigate the presence, distribution, and origin of oxytocin-immunoreactive axons in the female rat lumbosacral spinal cord. Immunohistochemistry, spinal cord transections, and axonal tracing with Fluorogold, True Blue, and pseudorabies virus were used. Oxytocin-immunoreactive nerve fibers were present in the L6/S1 segments of the spinal cord. Prominent varicose axons were evident throughout the dorsal horn, along the lateral and medial collateral pathways, in the dorsal intermediate gray area, around the central canal in lamina X, and throughout the sacral parasympathetic nucleus. Injection of retrograde tracer into the L6/S1 spinal cord labeled neurons in the hypothalamic paraventricular nucleus. Transection of the thoracic spinal cord eliminated oxytocin-immunoreactive nerve axons in the L6/S1 spinal cord. In addition, transection of the thoracic spinal cord eliminated transport of retrograde axonal tracer from the L6/S1 spinal cord to the paraventricular nucleus. Pseudorabies virus, a transneuronal retrograde tracer, injected into the uterus and cervix marked uterine-related preganglionic neuronal cell bodies in the sacral parasympathetic nucleus and uterine-related neurons in the hypothalamic paraventricular nucleus. Double immuno-labeling of viral-infected spinal cord sections showed oxytocin-immunoreactive axons closely associated with viral labeled uterine-related preganglionic cell bodies of the sacral parasympathetic nucleus. The results of this study revealed that oxytocin-immunoreactive neurons of the hypothalamic paraventricular nucleus project axons to the lumbosacral spinal cord to areas involved in sensory processing and parasympathetic outflow to the uterus.     

Differential mossy fiber projections to the dorsal and ventral uvula in the cat

The brainstem afferents to the uvula were studied by using retrograde axonal transport of horseradish peroxidase in the cat. Findings indicate differential afferent projections to the ventral and dorsal uvula. Major sources projecting to the ventral uvula include the caudal parts of the medial and inferior vestibular nuclei, the x- and f-groups of the vestibular nuclei, the dorsal and central parts of the superior vestibular nucleus, the rostral dorsomedial part of the paramedian nucleus of the pontine nuclei, the caudal part of the prepositus hypoglossal nucleus, and the infratrigeminal nucleus. Labeled cells in the vestibular nuclei were 74.7% of the total number of labeled cells in cat 40. On the other hand, the major sources projecting to the dorsal uvula are the peduncular, paramedian, and lateral nuclei of the pontine nuclei at the rostral and intermediate levels. Labeled cells in the pontine nuclei comprised 82.1% of the total number of labeled cells in cat 1. Findings also indicate that the lateral part of the ventral uvula receives input mainly from the pontine nuclei, whereas the medial part of the ventral uvula receives input mainly from the vestibular nuclei. Mediolateral differences were not found for the dorsal uvula. These mossy fiber zones are mediolaterally wide, with a dorsoventral partition in the uvula, in contrast to the climbing fiber zones, which are narrow (about 0.4 mm) and extend longitudinally throughout the uvula. There are quantitative differences in afferent sources to the ventral uvula and flocculus, both of which belong to the vestibulocerebellum. The largest afferent sources for the ventral uvula are the vestibular nerve and nuclei, whereas the largest sources for the flocculus are the reticular formation and raphe nuclei. These quantitative differences may have an important role for differential functions between the ventral uvula and flocculus. It has been suggested that the ventral uvula controls the velocity storage integrator of the vestibuloocular and optokinetic reflexes, whereas the flocculus is responsible for rapid changes of eye velocity in these reflexes.