vasoactive-intestinal-peptide and lucifer-yellow

Recent work has shown that behaviorally meaningful sensory information processing is accompanied by the induction of several transcription factors in the barrel cortex of rodents. It is now generally accepted that stimulus-transcription coupling is an important step in the sequence of events leading to long-term plastic changes in neuronal structure and function. Nevertheless, so far few data are available as to what types of neurons are involved in such a genomic response. Here, we determined the morphological and neurochemical identity of neurons in rat barrel cortex showing a c-Fos-immunoreactive nucleus after exploration of an enriched environment. Double stainings of c-Fos and glial fibrillary acidic protein excluded astrocytes as a possible cell type expressing this transcription factor. By morphological phenotyping with intracellular Lucifer Yellow injections, it was found that a large majority were probably excitatory pyramidal cells, but inhibitory interneurons were also found to contain c-Fos-immunoreactive nuclei. By neurochemical phenotyping of GABAergic interneurons with specific antibodies, a significant induction was found, in a layer-dependent manner, for the populations of glutamic acid decarboxylase-, parvalbumin-, calbindin- and vasoactive intestinal polypeptide-immunoreactive neurons but not for calretinin-immunoreactive cells in experimental compared to control columns. From these data we conclude that thalamic afferents effectively drive cortical excitatory as well as inhibitory intracortical circuits. Thus, the adaptations of receptive field properties of cortical neurons after different manipulations of the sensory periphery are likely to be caused by plastic changes in excitatory and inhibitory networks.

Topics: Afferent Pathways; Animals; Calcium-Binding Proteins; Excitatory Postsynaptic Potentials; Exploratory Behavior; gamma-Aminobutyric Acid; Glial Fibrillary Acidic Protein; Glutamate Decarboxylase; Interneurons; Isoenzymes; Isoquinolines; Male; Neural Inhibition; Neuronal Plasticity; Phenotype; Proto-Oncogene Proteins c-fos; Pyramidal Cells; Rats; Rats, Wistar; Somatosensory Cortex; Touch; Transcription, Genetic; Vasoactive Intestinal Peptide; Vibrissae

This study shows that foetal neurons from the suprachiasmatic area, after dissociation and culture, contain in vitro the same characteristics as are found in the in vivo situation. The main peptidergic neurotransmitters present in the suprachiasmatic nucleus in vivo, vasoactive intestinal polypeptide (VIP) and vasopressin, are expressed in vitro while the cytoskeleton of these cells possesses phosphorylated neurofilaments. The exclusive uptake of Lucifer Yellow liposomes by neurons is also refound in suprachiasmatic cultures. The electrophysiological results are in agreement with those characteristics found in vitro and in vivo.

Topics: Action Potentials; Animals; Culture Techniques; Drug Carriers; Fluorescent Dyes; Immunohistochemistry; Intermediate Filaments; Isoquinolines; Liposomes; Rats; Suprachiasmatic Nucleus; Vasoactive Intestinal Peptide; Vasopressins

1. Electrophysiological recordings were made from neurones in the submucous plexus of the guinea-pig small intestine, and these neurones were classified according to their synaptic inputs. 2. The neurones from which recording were made were filled during the recording period with the fluorescent dye, Lucifer Yellow, so they could be re-identified after processing for immunohistochemical localization of vasoactive intestinal peptide (VIP). 3. The presence or absence of VIP-like immunoreactivity was determined for a total of 130 neurones whose synaptic inputs had been fully characterized and eighty-two were found to be VIP reactive. After the VIP reactivity had been assessed, the preparations were reprocessed to reveal immunoreactivity for neuropeptide Y (NPY) and a further twenty-three neurones (none of which were reactive for VIP) were found to be reactive for this peptide. Of the remaining twenty-five neurones, nineteen were not reactive for either VIP or NPY and six could not be re-identified after reprocessing. 4. Electrical stimulation of internodal strands evoked excitatory synaptic potentials lasting 20-30 ms (fast responses) in all but one of the 130 neurones studied. 5. Almost all the VIP-reactive neurones (seventy-eight of eighty-two cells) exhibited inhibitory synaptic potentials, ranging in amplitude from 2 to 30 mV and lasting 150-1500 ms, but few of the VIP-negative neurones had such responses (six of forty-eight cells). No inhibitory synaptic potentials could be evoked in any of the NPY-reactive neurones. 6. Most VIP-reactive neurones (sixty-nine) had a slow excitatory synaptic potential which could be evoked by a single stimulus, lasted 5-20 s and was associated with an increase in input resistance. Only one NPY-reactive neurone had a slow excitatory potential, but such potentials were seen in nine of the nineteen VIP-negative, NPY-negative neurones. 7. In nine of the twenty-three NPY-reactive neurones a single stimulus evoked an excitatory synaptic potential (intermediate excitatory synaptic potential) lasting 500-1500 ms and associated with a fall in the input resistance. None of the VIP-negative, NPY-negative neurones exhibited the intermediate excitatory potentials but it was not possible to determine whether such potentials could be evoked in VIP-reactive neurones because the inhibitory synaptic potentials would obscure such events. 8. It is concluded that neurochemically distinct populations of submucous neurones can be distinguished

Topics: Action Potentials; Animals; Fluorescent Antibody Technique; Guinea Pigs; In Vitro Techniques; Isoquinolines; Neural Inhibition; Neurons; Neuropeptide Y; Submucous Plexus; Synapses; Time Factors; Vasoactive Intestinal Peptide

In cats, intracellular dye injection of single sensory neurones of known fibre type and sensory modality has been combined with peptide immunohistochemistry. There was no clear relationship between the sensory function of a neurone and the presence of the neuropeptides substance P, somatostatin, cholecystokinin and vasoactive intestinal polypeptide, in its cytoplasm. In particular, substance P was not detected in many nociceptive sensory neurons even though it could be demonstrated with the same technique in many sensory neurones which did not have cutaneous receptive fields. These results mean that the role, if any, of these neuropeptides in the transmission of pain, must be regarded as complex.

Topics: Animals; Cats; Cholecystokinin; Electrophysiology; Ganglia, Spinal; Isoquinolines; Nerve Tissue Proteins; Neurons, Afferent; Somatostatin; Substance P; Vasoactive Intestinal Peptide