Excitatory and inhibitory amino acid neurotransmitter binding sites in the cerebellar cortex of the pigeon (Columba livia)

We used receptor autoradiography to determine the distribution of excitatory and inhibitory amino acid neurotransmitter binding sites in the cerebellar cortex of the pigeon (Columba livia). [alpha]-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid, kainate and metabotropic binding sites had highest levels in the molecular layer. N-methyl--aspartate binding sites, assayed with both [3H]glutamate under selective conditions and with [3H]glycine binding to the associated strychnine-insensitive glycine site, had highest levels in the granule cell layer. There was little specific binding of the non-competitive N-methyl--aspartate antagonist, [3H]MK-801. The level of gamma-aminobutyric acid (GABA)-A binding sites was higher than GABA-B binding sites in both molecular and granule cell layers with the highest level of GABA-A sites in the granule cell layer. The highest level of GABA-B binding sites was in the molecular layer. [3H]Flunitrazepam binding levels were approximately the same in both molecular and granule cell layers. With the exception of kainate binding sites, the distribution of binding sites was identical to that seen in the cerebellar cortex of mammals. Our results support the concept that the chemoarchitecture of the cerebellar cortex has been conserved in the course of vertebrate evolution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29063/1/0000096.pd

-[3H]Glutamate labels the metabotropic excitatory amino acid receptor in rodent brain

A quantitative autoradiographic assay for a novel -[3H]glutamate binding site in rodent brain has been developed. Binding to this site was distinguished by its high affinity for quisqualate (QA), ibotenate, glutamate and trans-1-amino-cyclopentyl-1,3-dicarboxylic acid (trans-ACPD), but low affinity for [RS]-[alpha]-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and (NMDA). `AMPA-insensitive, QA-sensitive [3H]glutamate binding' (AiQsGB) had a heterogeneous distribution in rat brain with high levels observed in molecular layer of cerebellum, striatum, and lateral septum. AiQsGB was reduced in molecular layer of cerebellum in mice lacking Purkinje cells. AiQsGB appears to represent binding to the `metabotropic' neuronal excitatory amino acid receptor linked to phosphoinositide metabolism.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28567/1/0000369.pd

Excitatory amino acid binding sites in the basal ganglia of the rat: A quantitative autoradiographic study

Quantitative receptor autoradiography was used to determine the distribution of excitatory amino acid binding sites in the basal ganglia of rat brain. [alpha]-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid, , kainate, quisqualate-sensitive metabotropic and , non-kainate, non-quisqualate glutamate binding sites had their highest density in striatum, nucleus accumbens, and olfactory tubercle. Kainate binding was higher in the lateral striatum but there was no medial-lateral striatal gradient for other binding sites. and [alpha]-amino-3-hydroxy-5-methylisoxazole-4-propionic acid binding sites were most dense in the nucleus accumbens and olfactory tubercle. There was no dorsal-ventral gradient within the striatal complex for the other binding sites. Other regions of the basal ganglia had lower densities of ligand binding. To compare binding site density within non-striatal regions, binding for each ligand was normalized to the striatal binding density. When compared to the striatal complex, [alpha]-amino-3-hydroxy-5-methylisoxazole-4-propionic acid and metabotropic binding sites had higher relative density in the globus pallidus, ventral pallidum, and subthalamic nucleus than other binding sites. Metabotropic binding also had a high relative density in the substantia nigra. , non-kainate, non-quisqualate glutamate binding sites had a high relative density in globus pallidus, ventral pallidum, and substantia nigra. binding sites had a low relative density in pallidum, subthalamic nucleus, substantia nigra and ventral tegmental area.Our data indicate heterogeneous distribution of excitatory amino acid binding sites within rat basal ganglia and suggest that the character of excitatory amino acid-mediated neurotransmission within the basal ganglia is also heterogeneous.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30265/1/0000666.pd

Two types of quisqualate receptors are decreased in human olivopontocerebellar atrophy cerebellar cortex

We used receptor autoradiography to study the distribution of ionotropic and metabotropic quisqualate (QA) receptors in normal human cerebellar cortex and cerebellar cortex from 7 cases of olivopontocerebellar atrophy (OPCA). In normal human cerebellar cortex, both types of QA receptors were densest in the molecular layer. Both ionotropic and metabotropic QA receptors were significantly diminished in the molecular layer of OPCA specimens. These results suggest that both ionotropic and metabotropic QA receptors are localized on Purkinje cell dendrites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28456/1/0000246.pd

Excitatory amino acid binding sites in the periaqueductal gray of the rat

We used receptor autoradiography to determine the distribution of excitatory amino acid (EAA) binding site subtypes in the periaqueductal gray (PAG) of the rat. (NMDA), kainate, quisqualate-ionotropic, and quisqualate-metabotropic binding sites were all present in the PAG. Distribution was inhomogeneous with greatest density of all binding site subtypes in the dorsolateral subdivision and lowest density in the ventrolateral subdivision. Relative to regions of brain with high densities of EAA binding site subtypes, quisqualate-metabotropic binding sites had the highest relative density and NMDA binding sites the least. The presence of all subtypes of EAA binding sites in the PAG suggests that EAA action within the PAG is likely to be complex.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28357/1/0000120.pd