Search results for "Synaptic Membranes"
showing 6 items of 6 documents
Stereospecific interaction of bicuculline with specific [3H]strychnine binding to rat spinal cord synaptosomal membranes
1980
The gamma-aminobutyric acid (GABA) antagonist (+/-)-bicuculline inhibits specific [3H]strychnine binding to postsynaptic glycine receptor sites in rat spinal cord synaptosomal membranes with an inhibition constant of about 5 microM, which is fairly similar to its inhibition constant reported for the GABA receptor. This effect is highly stereospecific, since the affinity of (-)-bicuculline for the specific [3H]strychnine binding sites is more than ten times less than that of the pharmacologically active (+)-bicuculline. Besides an unspecific effect at the glycine receptor, the results could suggest that the glycine and the GABA receptors are located close together in spinal cord membranes, s…
Inverse behaviour of "synaptic" ribbon and spherule numbers in the pineal gland of male guinea-pigs exposed to continuous illumination.
1986
There is increasing evidence that pineal “synaptic” ribbons are a heterogeneous population of organelles. In addition to “synaptic” ribbons (SR) sensu stricto, which consist of an electron-dense rod surrounded by electronlucent vesicles, “synaptic” spherules (SS) exist, the electrondense core of which is round and much wider than that of the SR. In the guinea-pig SR and SS numbers exhibit an inverse day/night rhythmicity. To gain more insight into the functional significance of SR and SS, guinea-pigs were exposed to continuous illumination for approximately 4 months (LL) and the respective structures in the pineal gland were quantitated under the electron microscope and compared with contro…
Interaction Between Uridine and GABA-Mediated Inhibitory Transmission: Studies In Vivo and In Vitro
1985
Na+-independent [3H]gamma-aminobutyric acid (GABA) binding to membrane preparations from frontal cortex, hippocampus, and thalamus is competitively inhibited by the in vitro addition of a naturally occurring pyrimidinic compound, uridine. Moreover, the intraperitoneal injection of uridine produces a dose-related decrease in the cerebellar content of cyclic GMP and antagonizes its increase elicited by bicuculline. The pyrimidinic compound also shows an antagonism toward bicuculline-induced seizures. The relationship between the anti-convulsant actions of uridine and GABA-mediated inhibitory neurotransmission is discussed in terms of an activation of GABA receptor function by the naturally oc…
"Synaptic" ribbons and spherules of the rat pineal gland: day/night changes in vitro?
1982
In the present study pineal glands of rats aged 69–71 days were studied in vivo and in vitro with respect to day/night changes of “synaptic” ribbons and spherules. It was found that ribbons outnumber spherules by a factor of 3. In vivo, both ribbons and spherules show a roughly 3-fold increase in number at 1 a.m. when compared to 1 p.m. Up to 39 h in vitro, the two structures in question did not reveal day/night differences in amount, suggesting that diurnal rhythmicity of the gland did apparently not persist in organ culture. After 3 h in organ culture, the spherules, but not the ribbons, showed a striking increase in number, showing that ribbons and spherules may be governed by different …
Characterization of somatostatin- and cholecystokinin-immunoreactive periglomerular cells in the rat olfactory bulb.
2005
Periglomerular cells (PG) are interneurons of the olfactory bulb (OB) that modulate the first synaptic relay of the olfactory information from the olfactory nerve to the dendrites of the bulbar principal cells. Previous investigations have pointed to the heterogeneity of these interneurons and have demonstrated the presence of two different types of PG. In the rat OB, type 1 PG receive synaptic contacts from the olfactory axons and are γ-aminobutyric acid (GABA)-ergic, whereas type 2 PG do not receive synaptic contacts from the olfactory axons and are GABA immunonegative. In this study, we analyze and characterize neurochemically a group of PG that has not been previously classified either …
Synaptogenesis in the mouse olfactory bulb during glomerulus development
2008
Synaptogenesis is essential for the development of neuronal networks in the brain. In the olfactory bulb (OB) glomeruli, numerous synapses must form between sensory olfactory neurons and the dendrites of mitral/tufted and periglomerular cells. Glomeruli develop from E13 to E16 in the mouse, coincident with an increment of the neuropil in the border between the external plexiform (EPL) and olfactory nerve layers (ONL), coupled to an extensive labelling of phalloidin and GAP-43 from the ONL to EPL. We have tracked synaptogenesis in the OB during this period by electron microscopy (EM) and immunolabelling of the transmembrane synaptic vesicle glycoprotein SV-2. No SV-2 labelling or synapses we…