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Simultaneous Demonstration of Serotonin‐immunoreactive Terminals and GABAergic Neurons in the VPL Nucleus of the Cat Thalamus
Author(s) -
Liu X.B.,
Jones E. G.
Publication year - 1992
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1992.tb00133.x
Subject(s) - gabaergic , neuroscience , axon , thalamus , nucleus , biology , serotonergic , synapse , soma , serotonin , parvalbumin , chemistry , inhibitory postsynaptic potential , biochemistry , receptor
Pre‐embedding immunoperoxidase (for serotonin) and postembedding immunogold (for γ‐aminobutyric acid; GABA) labelling were combined at light and electron microscopic levels to demonstrate the neuronal targets of serotonin (5‐HT) afferents in the ventral posterior lateral nucleus (VPL) of the cat thalamus. 5‐HT‐immunoreactive fibres and terminal varicosities were found in close proximity to GABA‐immunoreactive interneurons and non‐GABAergic relay neurons. Ultrastructurally, the vast majority of 5‐HT terminals made close membrane contacts without overt membrane specializations with GABAergic axon terminals, GABAergic presynaptic dendrites and GABAergic somata. A very small number of 5‐HT terminals formed typical asymmetrical synapses with GABAergic presynaptic dendrites and with dendritic shafts of relay cells. Some 5‐HT terminals participated with the presynaptic dendrites in triadic synaptic arrangements. These findings suggest a dual innervation pattern by 5‐HT afferents in VPL and the release of 5‐HT in large part at sites not associated with morphologically detectable synapses.