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Light‐ and electron‐microscopic analysis of vasoactive intestinal polypeptide‐immunoreactive amacrine cells in the guinea pig retina
Author(s) -
Lee EunJin,
Park SungHee,
Kim InBeom,
Kang WhaSun,
Oh SuJa,
Chun MyungHoon
Publication year - 2002
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.10181
Subject(s) - amacrine cell , inner plexiform layer , vasoactive intestinal peptide , retina , biology , neuroscience , postsynaptic potential , immunocytochemistry , axon , outer plexiform layer , microbiology and biotechnology , neuropeptide , endocrinology , biochemistry , receptor
Vasoactive intestinal polypeptide (VIP) is a neuroactive substance that is expressed in both nonmammalian and mammalian retinas. This study investigated the morphology and synaptic connections of VIP‐containing neurons in the guinea pig retina by immunocytochemistry, by using antisera against VIP. Specific VIP immunoreactivity was localized to a population of wide‐field and regularly spaced amacrine cells with processes ramifying mainly in strata 1 and 2 of the inner plexiform layer (IPL). Double‐label immunohistochemistry demonstrated that all VIP‐immunoreactive cells possessed γ‐aminobutyric acid immunoreactivity. The synaptic connectivity of VIP‐immunoreactive amacrine cells was identified in the IPL by electron microscopy. The VIP‐labeled amacrine cell processes received synaptic input from other amacrine cell processes and bipolar cell axon terminals in strata 1 to 3 of the IPL. The most frequent postsynaptic targets of VIP‐immunoreactive amacrine cells were other amacrine cell processes in strata 1 to 3 of the IPL. Synaptic outputs to bipolar cells were also observed in strata 1 to 3 of the IPL. In addition, ganglion cell dendrites were also postsynaptic to VIP‐immunoreactive neurons in the sublamina a of the IPL. These studies show that one type of VIP‐immunoreactive amacrine cells make contact predominantly with other amacrine cell processes. This finding suggests that VIP‐containing amacrine cells may influence inner retinal circuitry, thus mediating visual processing. J. Comp. Neurol. 445: 325–335, 2002. © 2002 Wiley‐Liss, Inc.