Mouse α1B‐adrenergic receptor is expressed in neurons and NG2 oligodendrocytesPapay, Robert; Gaivin, Robert; McCune, Dan F.; Rorabaugh, Boyd R.; Macklin, Wendy B.; McGrath, John C.; Perez, Dianne M.
doi: 10.1002/cne.20215pmid: 15334645
α1‐Adrenergic receptors (ARs) are well‐known mediators of the sympathetic nervous system, are highly abundant in the brain, but are the least understood in the central nervous system. The particular cell types in the brain that contain these receptors or their functions are not known because of the lack of high avidity antibodies and selective ligands. We developed transgenic mice that endogenously overexpress the α1B‐AR subtype fused with the enhanced green fluorescent protein (EGFP). Endogenous expression was obtained by using a 3.4 kb fragment of the mouse α1B‐AR promoter. Using this model, we determined cellular localization of the α1B‐AR throughout the brain. The α1B‐AR‐EGFP fusion protein is expressed in neurons throughout the brain and in the Purkinje cells of the cerebellum. The α1B‐AR is also expressed in NG2 oligodendrocyte precursor cells in both neonatal cell cultures and in the adult cerebral cortex, but is weakly expressed in mature oligodendrocytes. The α1B‐AR was not observed in astrocytes or in cerebral vascular smooth muscle, cell types previously suggested to contain α1‐ARs. We conclude that the α1B‐AR is highly abundant throughout the brain, predominately in neurons, and may be involved in the development of the oligodendrocyte. In adult NG2 cells, implicated in stem cell‐like functions, the α1B‐AR may also play a role. This is the first report of a transgenic tagged‐GPCR approach to determine in vivo localization of a receptor. J. Comp. Neurol. 478:1–10, 2004. © 2004 Wiley‐Liss, Inc.
Localization of neurokinin 1 receptor (NK1R) immunoreactivity in rat esophagusKuramoto, Hirofumi; Oomori, Yukio; Murabayashi, Hiroshi; Kadowaki, Makoto; Karaki, Shin‐Ichiro; Kuwahara, Atsukazu
doi: 10.1002/cne.20169pmid: 15334646
The aim of the present immunohistochemical study was to investigate the localization of neurokinin 1 receptor (NK1R) in rat esophagus and examine the relationship between NK1Rs and intrinsic cholinergic, nitrergic, or substance P (SP) neurons. NK1R immunoreactivity (IR) was observed on the nerve cell bodies in the myenteric ganglia throughout the esophagus, but not on striated muscles and smooth muscle cells of the muscularis mucosae. The frequency of occurrence of NK1R neurons was highest in the cervical esophagus and lowest in the lower thoracic esophagus. Considerable immunoreactivity was seen on the nerve cell surfaces and was also present in the cytoplasm of cell somas and in the initial part of the axons, but not in any other nerve fibers or terminals. Dogiel type I‐like morphology was observed in some of the NK1R neurons; however, the majority exhibited polymorphic morphology. Double immunolabeling indicated that a majority (77%) of the NK1R neurons were immunoreactive for choline acetyltransferase (ChAT), while a minority (23%) were immunoreactive for nitric oxide synthase (NOS)‐IR. Most of the NK1R neurons (92%) were innervated by the SP nerve fibers. Triple immunolabeling indicated that 70% of the NK1R neurons were associated with intrinsic SP nerve fibers (without CGRP‐IR), 59% were associated with extrinsic SP nerve fibers (with CGRP‐IR), and 35% were associated with both intrinsic and extrinsic SP nerve fibers. These results suggest that SP/tachykinin released from the SP nerve fibers of intrinsic and/or extrinsic origin activates the predominantly intrinsic cholinergic neurons via NK1Rs to influence neuronal transmission or motility in rat esophagus. J. Comp. Neurol. 478:11–21, 2004. © 2004 Wiley‐Liss, Inc.
Hypothalamic paraventricular nucleus neurons regulate medullary catecholamine cell responses to restraint stressDayas, Christopher V.; Buller, Kathryn M.; Day, Trevor A.
doi: 10.1002/cne.20259pmid: 15334647
Both physical and psychological stressors recruit catecholamine cells (CA) located in the ventrolateral medulla (VLM) and the nucleus of the solitary tract (NTS). In the case of physical stressors, this effect is initiated by signals that first access the central nervous system at or below the level of the medulla. For psychological stressors, however, CA cell recruitment depends on higher structures within the neuraxis. Indeed, we have recently provided evidence of a pivotal role for the medial amygdala (MeA) in this regard, although such a role must involve a relay, as MeA neurons do not project directly to the medulla. However, some of the MeA neurons that respond to psychological stress have been found to project to the hypothalamic paraventricular nucleus (PVN), a structure that provides significant input to the medulla. To determine whether the PVN might regulate medullary CA cell responses to psychological stress, animals were prepared with unilateral injections of the neurotoxin ibotenic acid into the PVN (Experiment 1), or with unilateral injections of the retrograde tracer wheat germ agglutinin‐gold (WGA‐Au) into the CA cell columns of the VLM or NTS (Experiment 2). Seven days later, animals were subjected to a psychological stressor (restraint; 15 minutes), and their brains were subsequently processed for Fos plus appropriate cytoplasmic markers (Experiment 1), or Fos plus WGA‐Au (Experiment 2). PVN lesions significantly suppressed the stress‐related induction of Fos in both VLM and NTS CA cells, whereas tracer deposits in the VLM or NTS retrogradely labeled substantial numbers of PVN cells that were also Fos‐positive after stress. Considered in concert with previous results, these data suggest that the activation of medullary CA cells in response to psychological stress may involve a critical input from the PVN. J. Comp. Neurol. 478:22–34, 2004. © 2004 Wiley‐Liss, Inc.
Morphology and axonal projection pattern of neurons in the telencephalon of the fire‐bellied toad Bombina orientalis: An anterograde, retrograde, and intracellular biocytin labeling studyRoth, Gerhard; Mühlenbrock‐Lenter, Sabine; Grunwald, Wolfgang; Laberge, Frédéric
doi: 10.1002/cne.20265pmid: 15334648
The connectivity and cytoarchitecture of telencephalic centers except dorsal and medial pallium were studied in the fire‐bellied toad Bombina orientalis by anterograde and retrograde biocytin labeling and intracellular biocytin injection (total of 148 intracellularly labeled neurons or neuron clusters). Our findings suggest the following telencephalic divisions: (1) a central amygdala–bed nucleus of the stria terminalis in the caudal midventral telencephalon, connected to visceral–autonomic centers; (2) a vomeronasal amygdala in the caudolateral ventral telencephalon receiving input from the accessory olfactory bulb and projecting mainly to the preoptic region/hypothalamus; (3) an olfactory amygdala in the caudal pole of the telencephalon lateral to the vomeronasal amygdala receiving input from the main olfactory bulb and projecting to the hypothalamus; (4) a medial amygdala receiving input from the anterior dorsal thalamus and projecting to the medial pallium, septum, and hypothalamus; (5) a ventromedial column formed by a nucleus accumbens and a ventral pallidum projecting to the central amygdala, hypothalamus, and posterior tubercle; (6) a lateral column constituting the dorsal striatum proper rostrally and the dorsal pallidum caudally, and a ventrolateral column constituting the ventral striatum. We conclude that the caudal mediolateral complex consisting of the extended central, vomeronasal, and olfactory amygdala of anurans represents the ancestral condition of the amygdaloid complex. During the evolution of the mammalian telencephalon this complex was shifted medially and involuted. The mammalian basolateral amygdala apparently is an evolutionary new structure, but the medial portion of the amygdalar complex of anurans reveals similarities in input and output with this structure and may serve similar functions. J. Comp. Neurol. 478:35–61, 2004. © 2004 Wiley‐Liss, Inc.
Expression of vanilloid receptor TRPV1 in the rat trigeminal sensory nucleiBae, Yong Chul; Oh, Jung Min; Hwang, Se Jin; Shigenaga, Yoshio; Valtschanoff, Juli G.
doi: 10.1002/cne.20272pmid: 15334649
Little is known about the central projection patterns of trigeminal afferent neurons expressing the vanilloid receptor TRPV1 and their coexpression of neuromodulatory peptides. To address these issues, we examined the distribution of TRPV1‐positive neurons in the trigeminal ganglion (TG) and trigeminal sensory nuclei principalis (Vp), oralis (Vo), interpolaris (Vi), and caudalis (Vc) in the rat via light and electron microscopy. In addition, we studied the colocalization of TRPV1‐positive neurons with substance P (SP) and calcitonin gene‐related peptide (CGRP) via confocal microscopy. In TG, only small and medium‐sized neurons were immunopositive for TRPV1. The staining for TRPV1 was found in axon collaterals in the dorsal parts of Vp, Vo, and Vi and in terminals and fibers throughout lamina I and the outer zone of lamina II (IIo) of Vc. With electron microscopy, TRPV1‐positive fibers in the ascending and descending trigeminal tracts were found to be unmyelinated. Almost all TRPV1‐positive terminals in Vc contained numerous large dense‐core vesicles and formed synaptic contacts with single small dendrites. Multiple immunofluorescence revealed a high degree of colocalization of TRPV1 with SP and CGRP in TG neurons as well as in fibers and terminals confined to laminae I and IIo of Vc. These results suggest that the central projections of unmyelinated (C) afferents sensitive to noxious heat and capsaicin are organized differently between Vc and the rostral trigeminal nuclei and that Vc may play a role in the development of hyperalgesia. J. Comp. Neurol. 478:62–71, 2004. © 2004 Wiley‐Liss, Inc.
Localization of myosin phosphatase target subunit 1 in rat brain and in primary cultures of neuronal cellsLontay, Beáta; Serfőző, Zoltán; Gergely, Pál; Ito, Masaaki; Hartshorne, David J.; Erdődi, Ferenc
doi: 10.1002/cne.20273pmid: 15334650
Myosin phosphatase (PP1M) is composed of the δ isoform of the PP1 catalytic subunit (PP1cδ), the myosin phosphatase target subunit (MYPT), and a 20 kDa subunit. Western blots detected higher amounts of the MYPT1 isoform compared to MYPT2 in whole brain extracts. The localization of MYPT1 was studied in rat brain and in primary cell cultures of neurons using specific antibodies. Analysis of lysates of brain regions for MYPT1 and PP1M by Western blots using anti‐MYPT1 antibodies and by phosphatase assays with myosin as substrate suggested a ubiquitous distribution. Immunohistochemistry of tissue sections revealed that MYPT1 was distributed in all areas of the brain, with staining observed in many different cell types. Depending on the method used for fixation, the MYPT1 appeared with varying intensity in nuclei, in nucleoli, and in the cytoplasm. In primary hippocampal cultures, MYPT1 was identified by confocal microscopy in the cytoplasm and in the nucleus, whereas a predominantly cytoplasmic localization was found in cochlear nucleus cells. In cultured cells, MYPT1 and PP1cδ colocalized with synaptophysin. PP1M activity was high in synaptosomes isolated from the cerebral cortex, but was relatively low in the postsynaptic densities. The interaction of MYPT1 with synaptophysin and with known partners (Rho‐kinase, PP1cδ) in brain extracts was shown by immunoprecipitation with anti‐MYPT1. Pull‐down assays from synaptosomes, using GST‐MYPT1, also confirmed these interactions. In conclusion, the widespread cellular and subcellular localization of MYPT1 implies that PP1M may play an important role in the dephosphorylation of key regulatory proteins in neuronal cells. J. Comp. Neurol. 478:72–87, 2004. © 2004 Wiley‐Liss, Inc.