Cholinergic and GABAergic neuronal elements in the pineal organ of lampreys, and tract-tracing observations of differential connections of pinealofugal neurons |
| |
Authors: | M A Pombal J Yáñez O Marín A González R Anadón |
| |
Institution: | (1) Department of Cell Biology and Ecology, Faculty of Biology, University of Santiago de Compostela, 15706 Santiago de Compostela, Spain;(2) Department of Functional Biology and Health Sciences, University of Vigo, 36200 Vigo, Spain;(3) Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA; |
| |
Abstract: | The putative cholinergic and GABAergic elements of the pineal organ of lampreys were investigated with immunocytochemistry
to choline acetyltransferase (ChAT) and γ-aminobutyric acid (GABA), and by acetylcholinesterase (AChE) histochemistry. For
comparison we also carried out immunocytochemistry to serotonin (5-HT) and a tract-tracing investigation of the two types
of projecting cells, i.e., ganglion cells and long-axon photoreceptors. Most photoreceptors were ChAT-immunoreactive (ChAT-ir)
and AChE-positive, while ganglion cells and the pineal tract were ChAT-negative and AChE-negative or only faintly positive.
These results strongly suggest the presence of a cholinergic system of photoreceptors in the lamprey pineal organ. GABA-ir
fibers that appear to originate from faintly to moderately stained ganglion cells were observed in the pineal stalk. Immunocytochemistry
to 5-HT indicated the presence of two types of 5-HT-ir cells, bipolar cells and ganglion-like cells. The connections of the
ganglion cells and long-axon photoreceptors were also studied by application of DiI to the pineal stalk in fixed brains or
of biotinylated dextran amine (BDA) to one of the main targets of pinealofugal fibers (optic tectum or mesencephalic tegmentum)
in isolated brains in vitro. Some long-axon photoreceptors and ganglion cells were labeled from the optic tectum. However,
BDA application to the tegmentum exclusively labeled ganglion cells in the pineal organ. These results indicate that the two
morphological types of afferent pineal neuron have different projections. No labeled cells were observed in the parapineal
organ in BDA experiments, indicating that this organ and the pineal organ are involved in different neural circuits. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|