Development of substance P-immunoreactive neurons in cranial sensory ganglia of the rat

Substance P-like immunoreactivity has been observed in fetal and adult cranial sensory ganglia. It first appears at day 16 of gestation in sensory neurons of trigeminal, superior-jugular, petrous and nodose ganglia, as well as in the autonomic myenteric plexus, and at day 17 in cervical dorsal root ganglion cells. Substance P immunoreactivity can be visualized much earlier (day 12) in the central nervous system. The ganglionic immunoreactivity subsequently increases during fetal life but drops at birth. The reactive material is first diffuse, then slowly becomes granular, and is mostly concentrated in coarse perinuclear inclusions in adult sensory neurons. Most substance P-positive neurons in trigeminal and superior-jugular ganglia are small, but medium-sized and large positive neurons are also observed in the trigeminal, petrous and nodose ganglia.Our observations give a precise picture of the development of substance P immunoreactivity in sensory neurons and are in general agreement with previous reports on some fetal and adult rat sensory ganglia. They indicate that in the rat, maturation of peripheral substance P-containing sensory neurons is slower than that of central substance P neurons or equivalent sensory neurons in other species. The examination of fetal material allows the observation of numerous immunoreactive sensory neurons which cannot be visualized after birth. We hypothesize a possible different embryonic origin (neural crest or placodal) for small nociceptive and larger substance P-containing neurons in rat cranial sensory ganglia.     

Galanin-like immunoreactivity in capsaicin sensitive sensory neurons and ganglia

In rats treated with capsaicin (CAP) as neonates, galanin-like (GA) immunoreactivity is markedly decreased in the trigeminal ganglion and the dorsal root ganglia as well as in the superficial layers of the dorsal spinal cord (laminae I and II), the substantia gelatinosa, the nucleus and tractus of the spinal trigeminal nerve and the nucleus commissuralis. Since CAP causes selective degeneration of primary sensory neurons of the C-fiber type and type B-cells of sensory ganglia, it is concluded that GA in CAP-sensitive primary sensory neurons represents a novel peptidergic system possibly involved in the transformation or modulation of peripheral nociceptive impulses. This system differs from the CAP-resistant GA-like neurons in other brain areas.     

Axonal cytoskeletal pathology in aged and diabetic human sympathetic autonomic ganglia

Prevertebral sympathetic ganglia develop markedly enlarged argyrophilic neurites as a function of age, gender and diabetes. Immunolocalization studies demonstrate their preferential labeling with antisera to highly phosphorylated 200 kDa neurofilament (NF-H) epitopes, NPY, peripherin and synapsin I, but not to hypophosphorylated NF-M and NF-H or MAP-2. The immunophenotype of dystrophic neurites in conjunction with the results of histochemical and ultrastructural studies are consistent with the terminal axonal and/or synaptic origin of neuritic dystrophy in the sympathetic ganglia of aged and diabetic human subjects.     

The life span of ganglionic glia in murine sensory ganglia estimated by uptake of bromodeoxyuridine

Studies of ganglionic glia turnover in the sensory nervous system have implications for understanding nervous system maintenance and repair. These glial cells of the sensory ganglia in the peripheral nervous system (PNS) comprise satellite cells (SCs) and, to a lesser extent, Schwann cells. SCs proliferate in response to trauma such as axotomy; however, the half-life of these glial cells under normal circumstances has not been estimated. To estimate the half-life of sensory ganglionic glial cells, we employed the DNA precursor analog 5-bromo-2'-deoxyuridine (BrdU) to measure the rate of turnover of these cells. BrdU was administered to inbred C57BL6 and outbred Swiss white mice via their drinking water. BrdU incorporation into ganglionic glia in the PNS was estimated by immunofluorescent staining of nervous tissue sections, and the fraction of ganglionic glial cells that acquired BrdU label was measured as a function of time. Mathematical modeling of the rate of uptake of BrdU into murine ganglionic glia enables calculation of the half-life of these cells. The kinetics of BrdU uptake is linear, consistent with ganglionic glia being a homogenous population. The value of the proliferation rate (p) plus death rate (d) derived from the slope of BrdU uptake as a function of time is approximately 2.4 x 10(-3) cells per day. Assuming that p = d (because ganglionic glial numbers are in equilibrium and they are assumed to neither emigrate from, or immigrate into, sensory ganglia), then the daily death rate is d = 1.2 x 10(-3) cells/day, which implies a half-life for ganglionic glia of about 600 days. Thus murine ganglionic glia in the untraumatized state appear to behave as a homogenous, slowly replicating population.     

Selective distribution of the 66-kDa neuronal intermediate filament protein in the sensory and autonomic nervous system of the guinea-pig

The immunohistochemical distribution of a recently identified 66-kDa neurofilament protein (NF-66) was investigated in peripheral and autonomic ganglia of the guinea-pig where it has been previously established that other neuronal intermediate filament proteins have a selective distribution. NF-66 immunoreactivity was observed in distinct subpopulations of neurons and did not coexist completely with either the neurofilament triplet or a 57-kDa intermediate filament protein (peripherin). NF-66 labelling was identical to that observed with an antibody to a 150-kDa intermediate filament or associated protein (CH1). These results further demonstrate that different neuronal intermediate filament proteins are present in selective subpopulations of neurons and that these proteins are, therefore, likely to have cell type-specific roles.     

A subpopulation of chicken primary sensory neurons defined by complete co-localization of Peripherin- and ovalbumin-immunoreactivities

In a previous study, we have demonstrated that an ovalbumin-like antigen is present within approximately one-half of all neurons of chicken spinal ganglia. The current study demonstrates this antigen co-localizes absolutely with neural intermediate filament protein (Peripherin) in small to medium-sized neurons of spinal ganglia. While the function of ovalbumin in neurons is unknown, its precise co-localization with Peripherin suggests a functional role restricted to neurons of a defined phenotype.     

Localization of neurotrophin-3-like immunoreactivity in peripheral tissues of the rat

Neurotrophin-3 (NT-3) mRNA is widely distributed in both the peripheral and central nervous systems but neither the distribution of the native factor nor its physiological function is known. In the present study we produced and characterized an antibody to a synthetic peptide and showed that it specifically recognised endogenous rat and recombinant human NT-3 (rNT-3), but not mouse nerve growth factor and recombinant brain derived-neurotrophic factor. NT-3-like immunoreactivity (NT-3-ir) was detected within the distal tubular cells of the kidney, the zona glomerulosa and reticularis of the adrenal cortex, ganglion cells of the adrenal medulla, red pulp of the spleen, epithelial cells of the intestinal villi and parenchymal cells of the liver. Within peripheral ganglia, NT-3-ir was observed in a subpopulation of large sensory neurons of dorsal root, trigeminal and cochleovestibular ganglia but not in principle neurons of the sympathetic ganglia. These results provide the first evidence for the localization of NT-3-ir and indicate its presence in various peripheral organs and large sensory neurons. We conclude that NT-3 may function outside the nervous system in addition to a neurotrophic role within large sensory neurons.     

Fine structure of presynaptic axonal terminals in sympathetic autonomic ganglia of aging and diabetic human subjects.

The neuropathologic changes that may underlie autonomic nervous system dysfunction in nondiabetic elderly human subjects or as a complication of diabetes have been systematically examined in sympathetic ganglia of a series of autopsied human subjects. As in animal models of aging and diabetes, enormously swollen terminal axons were found closely apposed to the perikarya of principal sympathetic neurons in prevertebral superior mesenteric sympathetic ganglia of aged and diabetic human subjects. Dystrophic axons consisted of two stereotyped forms: the first was composed of large numbers of misaligned aggregates of neurofilaments surrounded by variable numbers of small dense core vesicles; the second was characterized by large numbers of mitochondria, vacuoles, and dense and multivesicular bodies. The fine structural characteristics of neuroaxonal dystrophy, its predilection for prevertebral rather than paravertebral sympathetic ganglia, and the tendency for multiple dystrophic axons to cluster preferentially around selected neurons were identical in aged and diabetic human ganglia and were similar to changes seen in animal models of aging and diabetes. Neither diabetic nor aging ganglia demonstrated evidence of neuronal degeneration. Such structural changes may represent a degenerative influence of diabetes and aging on the normal remodeling of nerve terminals in autonomic ganglia, i.e., the continually ongoing process of turnover and replacement of axonal terminals. Similarity of lesions in human diabetes and aging suggests the possibility of pathogenetic mechanisms that are common to diabetes and the aging process. The substantial parallels between humans and animal models provide support for the validity of testing some proposed pathogenetic mechanisms directly in animal models.     

Substance P-like immunoreactivity in developing cranial parasympathetic neurons of the rat

Substance P-like immunoreactivity (SPLI) has been observed in cell bodies of fetal cranial parasympathetic ganglia of rat. It first appears at day 16 of gestation at the same time as in cranial sensory ganglia. From day 17 to 21, SPLI neurons constitute most, if not all, submandibular-sublingual and intralingual ganglia, they form 30–40% of otic and pterygopalatine ganglia and numerous such neurons are found in the myenteric plexus of the esophagus as well as in pharyngeal and buccal walls. The immunoreactive material is thinly granular, and its appearance does not change with prenatal development. The immunoreactivity in cell bodies of parasympathetic ganglia decreases at the end of the gestational period, and cannot be evidenced any more in most cells of normal adult ganglia. However, the corresponding SPLI fibers remain intensely immunoreactive. When grafted to rat irides, which have been chemically depleted of intrinsic SPLI fibers, submandibular, otic and pterygopalatine ganglia from pre- or postnatal rats rapidly produce a large amount of SPLI fibers on the iris mimicking the pattern of sensory innervation. This proves the presence of SPLI neurons in adult parasympathetic ganglia, at least in experimental conditions.This study of fetuses and grafts demonstrates the existence of neurons in SPLI parasympathetic cranial ganglia which has been underestimated or ignored previously as a result of observations on adult ganglia. The very large proportion of SPLI neurons in the ganglia of the salivary gland might be of importance for the interpretation of experimental studies on the control of salivation. The presence of SPLI in all three types of peripheral ganglia, sensory, sympathetic and parasympathetic, raises the question of its functional significance in the different compartments of the peripheral nervous system.     

Secretoneurin-like immunoreactivity in rat sympathetic, enteric and sensory ganglia

Distribution of secretoneurin-like immunoreactivity (SN-LI) was studied in the rat sympathetic ganglia/adrenal gland, enteric and sensory ganglia by immunohistochemical methods. SN-LI nerve fibers formed basket-like terminals surrounding many of the postganglionic neurons of the superior cervical, stellate, paravertebral chain ganglia, coeliac/superior mesenteric and inferior mesenteric ganglia. Postganglionic neurons of the superior cervical and other sympathetic ganglia exhibited low-to-moderate levels of SN-LI. In all these sympathetic ganglia, clusters of small diameter (<10 μm) cells, which may correspond to the small intensely fluorescent (SIF) cells, were found to be intensely labeled. Surgical sectioning or ligation of the cervical sympathetic trunk for 7–10 days resulted in a nearly total loss of SN-LI fibers in the superior cervical ganglia, whereas immunoreactivity in the postganglionic neurons and small diameter cells remained essentially unchanged. In the thoracolumbar and sacral segments of the spinal cord, SN-LI nerve fibers were detected in the superficial layers of the dorsal horn as well as in the intermediolateral cell column (IL_p). Occasionally, SN-LI somata were noted in the IL_p. SN-LI nerve fibers formed a delicate plexus underneath the capsule of the adrenal gland, some of which traversed the adrenal cortex and reached the adrenal medulla. While heavily invested with SN-LI nerve terminals, chromaffin cells seemed to express a low level of SN-LI. In the enteric plexus, varicose SN-LI nerve fibers and terminals formed a pericellular network around many myenteric and submucous ganglion cells; the ganglionic neurons were lightly to moderately labeled. A population of ganglion cells in the dorsal root, nodose and trigeminal ganglia exhibited moderate-to-strong SN-LI. The detection of SN-LI in nerve fibers and somata of various sympathetic ganglia, enteric plexus and adrenal medulla and in somata of the sensory ganglia implies an extensive involvement of this peptide in sympathetic, enteric and sensory signal processing.     

VRL-1 immunoreactivity in the rat cranial autonomic ganglia.

Immunohistochemistry for VRL-1, a newly cloned capsaicin-receptor homologue, was performed on the rat cranial autonomic ganglia. The immunoreactivity (ir) was detected in the majority of neurones in the pterygopalatine (66%) and submandibular ganglia (68%). In the tongue and carotid body, parasympathetic neurones contained VRL-I ir. In the superior cervical ganglion, only 2% of postganglionic sympathetic neurones showed the immunoreactivity. VRL-1-ir nerve endings could not be detected in their peripheral tissues. These findings may suggest that VRL-1 has functions within neuronal cell bodies of the cranial autonomic ganglia.     

Peptide 19 in the rat vagal and glossopharyngeal sensory ganglia

Peptide 19 (PEP 19) is a 7.6-kDa polypeptide which binds to calmodulin and inhibits calcium-calmodulin signaling. In this study, PEP 19-immunoreactivity (PEP 19-IR) was examined in the rat vagal and glossopharyngeal sensory ganglia. Twenty-nine percent, 59%, and 41% of sensory neurons contained PEP 19-IR in the jugular, petrosal, and nodose ganglia, respectively. These neurons were of various sizes (jugular, mean +/- SD = 635.8 +/- 392.6 microm2, range = 105.9-1695.9 microm2; petrosal, mean +/- SD = 370.9 +/- 228.5 microm2, range = 57.7-1662.7 microm2; nodose, mean +/- SD = 380.5 +/- 157 microm2, range = 87.5-950.4 microm2) and scattered throughout these ganglia. Double immunofluorescence method revealed that PEP 19-IR neurons which had parvalbumin-IR were rare in the ganglia (jugular, 4%; petrosal, 10%; nodose, 8%). PEP 19-IR neurons which contained calbindin D-28k were abundant in the petrosal (20%) and nodose (22%) ganglia but not in the jugular ganglion (8%). Retrograde tracing method indicated that many PEP 19-IR neurons projected to the circumvallate papilla and soft palate. In the soft palate, taste buds were innervated by PEP 19-IR nerve fibers. The present study suggests that PEP 19-IR neurons include chemoreceptors in the vagal and glossopharyngeal sensory ganglia.     

Embryonic expression of pituitary adenylate cyclase-activating polypeptide in sensory and autonomic ganglia and in spinal cord of the rat

Pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide that is related structurally to vasoactive intestinal polypeptide (VIP), has been shown to stimulate neuronal growth and differentiation, indicating a possible function in the development of the nervous system. Studies have indicated that the PACAP receptor is expressed during development, but data on PACAP expression are limited mainly to postnatal development. In the present study, we used immunohistochemistry and in situ hybridization histochemistry to examine the expression of PACAP in autonomic and sensory ganglia and spinal cord of rat fetuses at embryonic days 12–21 (E12–E21). PACAP immunoreactivity was visualized by using a specific monoclonal anti-PACAP antibody to detect both PACAP-38 and PACAP-27, and PACAP mRNA was visualized by using a [³³P]-labeled cRNA-probe. PACAP⁺ nerve fibers were observed in the spinal cord as early as E13. At E14, PACAP-immunoreactive nerve fibers projected to the sympathetic trunk, where few PACAP⁺ nerve cell bodies were seen from E15. On the same embryonic day, PACAP-immunoreactive nerve cell bodies appeared in the intermediolateral column of the spinal cord. From E15 to E16, PACAP-immunoreactive nerve cell bodies were visible within sensory and autonomic ganglia, such as the dorsal root, the trigeminal, the sphenopalatine, the otic, the submandibular, and the nodose ganglia. At E16, PACAP⁺ nerve fibers were innervating the adrenal medulla, and immunoreactive fibers could also be observed in the superior cervical ganglion, in which PACAP-immunoreactive cell bodies were detected occasionally from E18. The synthesis of PACAP in neuronal cell bodies was confirmed by the demonstration of PACAP mRNA with in situ hybridization histochemistry. Thus, in all of the structures examined, PACAP appeared at roughly the same embryonic stage and, thereafter, increased to the adult level before birth. Because PACAP occurred with the same distribution pattern as that described in the adult rat, there is no evidence for transient expression. The early expression of PACAP suggests a possible role for the peptide in the developing nervous system. J. Comp. Neurol. 394:403–415, 1998. © 1998 Wiley-Liss, Inc.     

Osteocalcin-immunoreactive neurons in the vagal and glossopharyngeal sensory ganglia of the rat

Immunohistochemistry for osteocalcin (OC) was performed on the rat vagal and glossopharyngeal sensory ganglia. OC-immunoreactive (IR) neurons were detected in the jugular (10%), petrosal (11%) and nodose ganglia (6%). The cell size analysis demonstrated that OC-IR neurons were predominantly small to medium-sized in the jugular ganglion (mean+/-S.D.=356.3+/-192.2 microm(2), range=86.5-831.5 microm(2)). On the other hand, such neurons were medium-sized to large in the petrosal (mean+/-S.D.=725.6+/-280.7 microm(2), range=124.7-1540.4 microm(2)) and nodose ganglia (mean+/-S.D.=857.5+/-330.2 microm(2), range=367.1-1608.0 microm(2)). In the circumvallate papilla, OC-IR nerve fibers were located in the vicinity of taste buds. Some taste bud cells were also immunoreactive for the calcium-binding protein (CaBP). In the carotid body, however, OC-IR nerve fibers could not be detected. Retrograde tracing with fluorogold revealed that OC-IR nerve fibers in the circumvallate papilla mainly originated from the petrosal ganglion. These findings may suggest that OC-IR petrosal neurons have chemoreceptive function in the tongue.     

犬脑积水后轴索损伤的神经微丝免疫组化研究

目的探讨脑积水后大脑半球白质内轴索损伤的特点及意义.方法20只成年雄性犬通过枕大池穿刺注射白陶土的方法建立脑积水模型,按处死时间分为3 d组、2周组、8周组及对照组,每组5只.观察实验犬的行为及神经功能,并通过神经微丝免疫组化染色研究大脑半球白质内轴索的变化,同时观察轴索骨架系统超微结构改变.结果各实验组实验犬均有不同程度的行为学改变,但明显的神经功能障碍仅出现于脑积水诱导8周后;白质内轴索在3 d组即有损害发生,并随病程进展而进行性加重,在3 d组和2周组限于脑室周围,8周组则范围扩大,累及皮层下区域.结论轴索损伤贯穿于脑积水的早中晚期,其损害程度和范围与神经功能障碍密切相关.     

Interleukin-1 induces c-Fos immunoreactivity in primary afferent neurons of the vagus nerve

Peripheral administration of bacterial endotoxin, an immune stimulant, induces evidence of activation in vagal primary afferent neurons. To determine whether interleukin-1β (IL-1β) is part of the molecular pathway leading to this activation, we assessed the expression of the neuronal activation marker c-Fos in vagal primary afferent neurons after intraperitoneal injections of IL-1β (2 μg/kg). IL-1β, but not vehicle, induced c-Fos expression, demonstrating that IL-1β is likely an important signal from the immune system to the vagus nerve, and thus the brain.