[Kinetics of accumulation of tritiated norepinephrine in the neuronic cytoplasm (non-secretory, pigmented giant neurons of Aplysia)].
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Animals↗
Biomedical subjects
L Segu
Publications and source records attributed to L Segu.
[Intraneuronal concentration of norepinephrine as a function of extracellular concentrations. (Aplysia neurons)].
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Animals↗
Up-regulation of substance P binding sites in the vagus nerve projection area of the cat brainstem after nodosectomy. A quantitative autoradiographic study.
Substance P (SP) regulates visceral functions in the nucleus of the solitary tract (NST) area. High affinity SP binding sites labelled with [3H]SP or [125I]SP show a heterogeneous distribution in the cat medulla with high densities in the rostral and dorso-caudal parts of both the median subnucleus of NST and the dorsal motor nucleus (DMN). We previously observed a significant loss of SP immunoreactivity in the vagal area of the cat after an ipsilateral nodosectomy. It was thus important to study the correlated plasticity of SP binding in the context of the regulation of receptor function. Whichever labelled ligand was used, a unilateral nodose excision was followed by an ipsilateral increase in SP binding in the NST (200%) and the DMN (300%) after 30 days of survival. This increase was region-specific and did not match exactly the decrease in SP immunoreactivity following nodosectomy. This SP receptor density up-regulation could be due to long-term deprivation of SP afferent fibres in the NST and partly in the DMN. In the latter the increase of SP receptors occurred in both the cytoplasm of large neurons and the neuropile and did not affect the glia. The up-regulation phenomenon seems to be specific for SP receptors in the cat (at least in the DMN) and may constitute a reactive mechanism against the injury of axotomy of DMN neurons.
Amino Acid Sequence↗
Effects of retinal deafferentation on serotonin receptor types in the superficial grey layer of the superior colliculus of the rat.
The effects of retinal axon terminal degeneration on the serotonin-1A, -1B, -2, nuerokinin-1 and gamma-amionobutyric acid-A high affinity binding sites in the superficial grey layer of the superior colliculus were tested with quantitative autoradiography on rat brain sections. The binding to serotonin-2, neurokinin-1 and gamma-aminobutyric acid-A high affinity receptors was not changed in the deafferented superficial grey layer of the superior colliculus after unilateral enucleation. By contrast, we demonstrate that the previously described 21% decrease in the binding of [3H]serotonin to serotonin-1 receptors observed in the deafferented superficial grey layer of the superior colliculus after enucleation, was not due to a decrease in the affinity of the serotonin-1 receptors for the radioligand, but to a decrease in the number of binding sites. Of the different serotonin-1 receptor subtypes, only the serotonin-1B was lost. This signifies that these receptors are probably located on the optic fibre terminals. Visual cortex lesion caused no apparent regulation of the serotonin-1 binding sites in the superficial grey layer of the superior colliculus. A bilateral enucleation produced a smaller decrease in serotonin-1 receptor density than that observed after unilateral enucleation, suggesting the existence of a compensatory mechanism.
8-Hydroxy-2-(di-n-propylamino)tetralin↗