Immunocytochemistry of neurotransmitter receptors

Wenthold, Robert J.; Altschuler, Richard A.; Hampson, David R.

doi:10.1002/jemt.1060150108

Cited by 24 publications

(14 citation statements)

References 100 publications

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“…The cytoplasmic localization of kainate receptors in enteric neurons agrees with previous studies that have visualized these receptors in fixed and permeabilized central neurons, using C-terminal antibodies (Huntley et al, 1993). At least part of the internal labeling may represent receptor subunits in synthesis or in transport to and from the cell membrane, similar to the proposals for AMPA-selective glutamate receptor subunits (Wenthold et al, 1990). GluR5/6/7-immunoreactive neurons were only found in submucosal ganglia (Fig.…”

Section: Kainate Receptor Subunit Immunoreactivity Is Found In Enterisupporting

confidence: 87%

Excitotoxicity in the Enteric Nervous System

1997

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Glutamate, the major excitatory neurotransmitter in the CNS, is also an excitatory neurotransmitter in the enteric nervous system (ENS). We tested the hypothesis that excessive exposure to glutamate, or related agonists, produces neurotoxicity in enteric neurons. Prolonged stimulation of enteric ganglia by glutamate caused necrosis and apoptosis in enteric neurons. Acute and delayed cell deaths were observed. Glutamate neurotoxicity was mimicked by NMDA and blocked by the NMDA antagonist D-2-amino-5-phosphonopentanoate. Excitotoxicity was more pronounced in cultured enteric ganglia than in intact preparations of bowel, presumably because of a reduction in glutamate uptake. Glutamate-immunoreactive neurons were found in cultured myenteric ganglia, and a subset of enteric neurons expressed NMDA (NR1, NR2A/B), AMPA (GluR1, GluR2/3), and kainate (GluR5/6/7) receptor subunits. Glutamate receptors were clustered on enteric neurites. Stimulation of cultured enteric neurons by kainic acid led to the swelling of somas and the growth of varicosities ("blebs") on neurites. Blebs formed close to neurite intersections and were enriched in mitochondria, as revealed by rhodamine 123 staining. Kainic acid also produced a loss of mitochondrial membrane potential in cultured enteric neurons at sites where blebs tended to form. These observations demonstrate, for the first time, excitotoxicity in the ENS and suggest that overactivation of enteric glutamate receptors may contribute to the intestinal damage produced by anoxia, ischemia, and excitotoxins present in food. Key words: necrosis; apoptosis; NMDA; kainic acid; glutamate transporters; bleb formation; rhodamine 123Excessive exposure to glutamate causes cell death ("excitotoxicity") in C NS neurons (Choi, 1988(Choi, , 1995. E xcitotoxicity consists of necrosis and apoptosis and is thought to occur via a breakdown in ionic homeostasis mediated by NMDA and non-NMDA glutamate receptor subtypes. Neurons can be protected from excitotoxicity by C a 2ϩ buffers (T ymianski et al., 1993); therefore, increases in [C a 2ϩ ] i are involved in causing excitotoxic cell death (Choi, 1988(Choi, , 1992. Consistent with this idea, both NMDA and kainic acid increase [C a 2ϩ ] i in central neurons (MacDermott et al., 1986;Brorson et al., 1994). Moreover, excessive exposure to either glutamate receptor agonist produces neuronal cell loss . Increases in [C a 2ϩ ] i produced by these excitotoxins occur at sites that are rich in mitochondria and produce a loss of mitochondrial membrane potential (Ankarcrona et al., 1995;Bindokas and Miller, 1995). Mitochondrial f unction seems to determine the mode of neuronal death in excitotoxicity. Early necrosis develops in neurons that lose mitochondrial membrane potential. Delayed apoptosis develops in neurons that recover mitochondrial potential and energy levels.Substantial evidence suggests that glutamate is an excitatory neurotransmitter in the enteric nervous system (ENS). The bowel contains glutamate-immunoreactive neurons, enteric neurons express ...

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Section: Kainate Receptor Subunit Immunoreactivity Is Found In Enterisupporting

confidence: 87%

Excitotoxicity in the Enteric Nervous System

1997

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“…Within the cytoplasm of principal cells of the MNTB, there are small inclusions (Fig. lOA), which were reported previously by Wenthold et al (1990). One or two of these inclusions are usually present in principal cells following any sensitive technique that demonstrates the presence of biotin.…”

Section: Cnmentioning

confidence: 72%

Sound stimulation induces Fos‐related antigens in cells with common morphological properties throughout the auditory brainstem

Adams

1995

J of Comparative Neurology

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Cells within the auditory brainstem of cat that respond to sound by producing the transcription factor Fos or related proteins were identified by immunostaining with antisera against Fos and Zif/268. Within the cochlear nucleus, all antisera showed similar staining patterns, however, in the superior olive and inferior colliculus, staining patterns differed between antisera. Immunostained cells were characterized by their size, location, by the presence of perisomatic terminals that immunostained for glutamate decarboxylase or synaptophysin, or by electron microscopy. Most cell classes were not immunopositive. In the ventral cochlear nucleus, roughly 99% of Fos-positive cells had few perisomatic terminals. Within the superior olivary complex (SOC), the majority of immunopositive cells had few perisomatic terminals. Lateral olivocochlear cells were identified as Fos positive by their size, location, lack of perisomatic terminals, and positive costaining for acetylcholinesterase as evidenced by a novel reaction product. This report appears to be the first demonstration of these cells responding to sound stimulation. Within the inferior colliculus, bands of positive cells produced by tonal stimulation extended from the central nucleus throughout the dorsal cortex and the posterior pericentral region, a finding unexpected on the basis of previous electrophysiological recordings and anatomical studies of ascending inputs to the colliculus. Approximately 35% of Fos-positive cells in the inferior colliculus had plentiful perisomatic terminals. Results demonstrate a high degree of specificity of auditory cell types that respond to sound by producing Fos-like proteins and show that previously intractable physiological questions can be addressed by assaying for sound-induced production of these antigens.

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“…The cytoplasmic localization of the glutamate receptors in enteric neurons agrees with previous studies, which have visualized these receptors in fixed and permeabilized central neurons, using C-terminal antibodies (Petralia and Wenthold, 1992;Petralia et al, 1994a,b). At least part of the internal labeling may represent receptors in transport to and from the cell membrane (Wenthold et al, 1990).…”

Section: Enteric Neurons Express Ampa and Nmda Receptorsmentioning

confidence: 99%

Glutamatergic Enteric Neurons

et al. 1997

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We tested the hypothesis that glutamate, the major excitatory neurotransmitter of the CNS, is also an excitatory neurotransmitter in the enteric nervous system (ENS). Glutamate immunoreactivity was found in cholinergic enteric neurons, many of which were identified as sensory by their co-storage of substance P and/or calbindin. Glutamate immunoreactivity was concentrated in terminal varicosities with a majority of small clear synaptic vesicles. The immunoreactivities of both AMPA and NMDA receptor subunits were also detected on neurons in both submucosal and myenteric plexuses. The immunoreactivity of the EAAC1 neuronal glutamate transporter was widespread in both plexuses. Glutamate evoked depolarizing responses in myenteric neurons that had fast and slow components. The fast component was mimicked by AMPA, and the slow component was mimicked by NMDA. The fast component and the response to AMPA mimicked fast EPSPs evoked in 2/AH neurons; moreover, fast EPSPs as well as fast glutamate and AMPA responses were blocked by selective AMPA antagonists and potentiated by the glutamate uptake inhibitor L-(Ϫ)-threo-3-hydroxyaspartic acid. These observations demonstrate, for the first time, the presence of glutamatergic neurons and glutamate-mediated neurotransmission in the ENS.

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Immunocytochemistry of neurotransmitter receptors

Cited by 24 publications

References 100 publications

Excitotoxicity in the Enteric Nervous System

Excitotoxicity in the Enteric Nervous System

Sound stimulation induces Fos‐related antigens in cells with common morphological properties throughout the auditory brainstem

Glutamatergic Enteric Neurons

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