Subject(s)
Disease Models, Animal , Hypoxia , Animals , Hypoxia/metabolism , Female , Mice , Male , Sex Characteristics , Sex FactorsABSTRACT
The aim of this study has been to investigate different neuroactive substances in the lamprey centrifugal visual neurons (CVN) by combining axonal tracing methods and immunocytochemistry. The CVN somata are immunonegative to antibodies recognizing FMRF-amide, LH-RH, 5 HT and TH, but immunopositive to an anti-GABA antiserum (GABA+) in a proportion of 40%. In the retina, the GABA+ axon terminals mainly synapse upon GABA+ and GABA- amacrine cell bodies and dendrites, and on dendrites of GABA- ganglion cells.
Subject(s)
Lampreys/physiology , Neurons/metabolism , Neurotransmitter Agents/metabolism , Visual Pathways/metabolism , Animals , FMRFamide , Gonadotropin-Releasing Hormone/metabolism , Immunohistochemistry , Lampreys/immunology , Neuropeptides/metabolism , Serotonin/metabolism , Tyrosine 3-Monooxygenase/metabolism , Visual Pathways/cytology , gamma-Aminobutyric Acid/metabolismABSTRACT
Light-microscopic immunocytochemistry was used to study serotonin (5HT)-containing retinal cells in the lamprey (Lampetra fluviatilis). Observations of sections and flatmounted retinas enabled us to distinguish four principal types of 5HT-immunoreactive neurons, on the basis of the localization of their somata and the arrangement of their processes in the inner plexiform layer, (IPL). Type 1 cell bodies (9 micron mean diameter) were numerous and were found in the innermost row of the inner nuclear layer (INL). They sent their processes into a dense plexus in sublamina a of the IPL. Type 2 cell bodies (12 micron mean diameter) were observed near the inner limiting membrane, their processes forming a plexus in sublamina b of the IPL. Most of the type 3 cells were bistratified, their cell bodies (similar in dimension to type 1) were located in the INL and their dendrites projected to both plexuses. Type 4 cell bodies (15 micron mean diameter) were observed in the middle of the IPL and could be compared with the interstitial described elsewhere. Their processes probably ended in the 5HT plexus of sublamina b but because of their sinuous course in the IPL, we could not affirm this fact. Most of 5HT immunoreactive cells were thought to be amacrine cells, but the presence of some thin processes emerging either from the soma or the primary dendrite, principally in type 1 and 2 cells, raises the possibility that some ganglion cells could be 5HT immunoreactive. The organization of the 5HT processes into two plexuses located in sublaminae a and b of the IPL resemble the functional ON and OFF pathway seen in the other vertebrates.
Subject(s)
Retina/metabolism , Serotonin/metabolism , Animals , Axons/metabolism , Dendrites/metabolism , Immunoenzyme Techniques , LampreysABSTRACT
Retinal ganglion cells (GC) of the Lamprey were studied after in vitro labeling of these cells by iontophoretic deposition of horseradish peroxidase into the optic nerve. The majority of GC are located at the boundary between the inner nuclear layer and the inner plexiform layer; a small proportion (20%) lies in the vitreous portion of the inner plexiform layer. Four types of GC were identified.
