Neuroscience 2003 Abstract
| Presentation Number: | 44.14 |
|---|---|
| Abstract Title: | Acetylcholine, rather than histamine, is the photoreceptor neurotransmitter in shrimp and crayfish optic lobe. |
| Authors: |
Brandon, C. J.*1
1Cell. Biol. & Anat., Finch Univ. Hlth. Sci. / Chicago Med. Sch, North Chicago, IL |
| Primary Theme and Topics |
Synaptic Transmission and Excitability - Neurotransmitters -- Invertebrate neurotransmitters |
| Secondary Theme and Topics | Sensory Systems<br />- Vision<br />-- Retina and photoreceptors |
| Session: |
44. Invertebrate Neurotransmitters Poster |
| Presentation Time: | Saturday, November 8, 2003 2:00 PM-3:00 PM |
| Location: | Morial Convention Center - Hall F-I, Board # D68 |
| Keywords: | CHOLINE ACETYLTRANSFERASE, CRUSTACEA, INVERTEBRATE, VISION |
Cholinergic neurons contribute to the directionally-selective properties of the crayfish Tan-1 neuron. This work sought to identify these cholinergic neurons in the optic lobe of crayfish and shrimp, using an antiserum to lobster brain choline acetyltransferase (ChAT; Brandon & Garrett, SFN 2002). Identification of histamine (His), the photoreceptor transmitter of many arthropod eyes, also is described here for the first time in these species.
In both species, all photoreceptors (PR) were immunoreactive (IR) for ChAT. All regions of the retinular cells were ChAT-IR, with particularly strong labeling in their axon terminal regions within cartridges of the Lamina Ganglionaris (LG). In the shrimp LG, histamine-IR was observed in three tangential layers of punctate processes connected by radial fibers, forming a dense 3-dimensional network that surrounded the PR cartridges. His-IR cell bodies were present in the external chiasm. The crayfish LG contained no His-IR processes. PRs themselves were not His-IR in either species.
In the shrimp Medulla Externa (ME), two tangential bands of ChAT-IR processes were observed, at depth=22% and depth=46% (distal surface of ME=0% depth). His-IR was present as a single strong layer at 20% depth. In the crayfish ME, ChAT-IR processes were oriented radially, within medullary columns, and probably belonged to cholinergic transmedullary neurons. His-IR was present in cells that strongly resembled Type 3 Medullary Amacrines.
These results demonstrate that malacostracan photoreceptors are cholinergic and not histaminergic. In this respect, they differ from PRs of all other arthropods. In the shrimp, the pattern of His-IR suggests a histaminergic tangential cell, with dendrites in the ME and an axonal plexus in the LG. In the crayfish, the Type 3 Medullary Amacrine is histaminergic.
In both species, all photoreceptors (PR) were immunoreactive (IR) for ChAT. All regions of the retinular cells were ChAT-IR, with particularly strong labeling in their axon terminal regions within cartridges of the Lamina Ganglionaris (LG). In the shrimp LG, histamine-IR was observed in three tangential layers of punctate processes connected by radial fibers, forming a dense 3-dimensional network that surrounded the PR cartridges. His-IR cell bodies were present in the external chiasm. The crayfish LG contained no His-IR processes. PRs themselves were not His-IR in either species.
In the shrimp Medulla Externa (ME), two tangential bands of ChAT-IR processes were observed, at depth=22% and depth=46% (distal surface of ME=0% depth). His-IR was present as a single strong layer at 20% depth. In the crayfish ME, ChAT-IR processes were oriented radially, within medullary columns, and probably belonged to cholinergic transmedullary neurons. His-IR was present in cells that strongly resembled Type 3 Medullary Amacrines.
These results demonstrate that malacostracan photoreceptors are cholinergic and not histaminergic. In this respect, they differ from PRs of all other arthropods. In the shrimp, the pattern of His-IR suggests a histaminergic tangential cell, with dendrites in the ME and an axonal plexus in the LG. In the crayfish, the Type 3 Medullary Amacrine is histaminergic.
Supported by NSF 9812203
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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