Search results for "synaptic vesicle"
showing 10 items of 52 documents
Zinc-positive presynaptic boutons of the rabbit hippocampus during early postnatal development
1998
Abstract The evolution of vesicular zinc-containing boutons in the developing rabbit hippocampus has been studied during early postnatal life using the selenite–Danscher histochemical method. By P3, large immature mossy fiber boutons with labeled synaptic vesicles were seen in the hilus of the dentate gyrus and in the stratum lucidum of the CA3–CA4 hippocampal areas. After P5, smaller boutons with labeled vesicles were identified in the stratum oriens and stratum radiatum of all hippocampal areas, and even transiently in the stratum lacunosum of P6 animals. Vesicular zinc-containing boutons increased in number and underwent ultrastructural maturation; light microscope densitometric–volumetr…
Mouse photoreceptor synaptic ribbons lose and regain material in response to illumination changes
2004
Abstract Chemical synapses equipped with ribbons are tonically active, high-output synapses. The ribbons may play a role in the trafficking of synaptic vesicles. Recent findings in retinal rod cells of BALB/c mice indicate that ribbons are large and smooth in the dark phase, and, due to the formation and release of protrusions, small during the light phase. As a consequence of these changes, ribbons may traffick fewer vesicles in the light than in the dark phases. The aim of the present study was to find out whether the above ribbon changes in this mouse strain are strictly illumination-dependent and which signalling processes may be involved. Here, we show that ribbons form protrusions and…
Axonal pathology of the skin in infantile neuroaxonal dystrophy.
1987
Ultrastructural studies on the skin of two patients affected by infantile neuroaxonal dystrophy (INAD) were performed to evaluate its diagnostic value and to discuss the etiology of INAD. While the majority of terminal axons around intradermal glands were dystophic consisting of tubulomembranous and tubulovesicular profiles sometimes accompanied by synaptic vesicles, there were only few dystophic axons inside intradermal nerve bundles. These observations suggest that the primary lesion of INAD is located in terminal and presynaptic axons. Therefore, terminal axons have to be investigated when a diagnostic skin biopsy is performed in INAD.
Daidzein has neuroprotective effects through ligand-binding-independent PPARγ activation.
2011
Phytoestrogens are a group of plant-derived compounds that include mainly isoflavones like daidzein. Phytoestrogens prevent neuronal damage and improve outcome in experimental stroke; however, the mechanisms of this neuroprotective action have not been fully elucidated. In this context, it has been postulated that phytoestrogens might activate the peroxisome proliferator-activated receptor-γ (PPARγ), which exerts neuroprotective effects in several settings. The aim of this study was to determine whether the phytoestrogen daidzein elicits beneficial actions in neuronal cells by mechanisms involving activation of PPARγ. Our results show that daidzein (0.05-5 μM) decreases cell death induced b…
Circadian variations of ?synaptic? bodies in the pineal glands of Brattleboro rats
1990
The function of the mammalian pineal gland is regulated primarily by the sympathetic system. Arginine-vasopressin (AVP) may also be involved in the regulation of pineal melatonin synthesis under experimental conditions. The present study was conducted in the AVP-deficient rat strain, the Brattleboro rat, to investigate whether the numbers and rhythms of pineal "synaptic" bodies in this strain are different from those found in intact rats. AVP or its non-vasoconstrictive analog, deamino-D-AVP, was also injected intra-arterially in Brattleboro or Sprague-Dawley rats to test whether this procedure influences "synaptic" body numbers. Brattleboro rats were killed at different time-points through…
Differential vesicular targeting and time course of synaptic secretion of the mammalian neurotrophins.
2005
Neurotrophins are a family of secreted neuronal survival and plasticity factors comprising NGF, BDNF, neurotrophin-3 (NT-3), and NT-4. Whereas synaptic secretion of BDNF has been described, the routes of intracellular targeting and secretion of NGF, NT-3, and NT-4 in neurons are poorly understood.To allow for a direct comparison of intracellular targeting and release properties, all four mammalian neurotrophins were expressed as green fluorescent protein fusion proteins in cultured rat hippocampal neurons. We show that BDNF and NT-3 are targeted more efficiently to dendritic secretory granules of the regulated pathway of secretion (BDNF, in 98% of cells; NT-3, 85%) than NGF (46%) and NT-4 (…
Thirty years of synaptosome research.
1993
Detached synapses (synaptosomes), first isolated by the author in 1958 and identified as such in 1960, are sealed presynaptic nerve terminals often with a portion of the target cell--sometimes amounting to a complete dendritic spine--adhering to their external surface. They can be prepared in high yield from brain tissue and also in decreasing yield from spinal cord, retina, sympathetic ganglia, myenteric plexus and electric organs. They are sealed structures which, under metabolizing conditions, respire, take up oxygen and glucose, extrude Na+, accumulate K+, maintain a normal membrane potential and, on depolarization, release transmitter in a Ca(2+)-dependent manner. They thus provide an …
Investigations on day-night differences of vesicle densities in synapses of the rat suprachiasmatic nucleus
1990
The present study was conducted to test whether the well-known circadian alterations in physiological and metabolical parameters of the hypothalamic suprachiasmatic nucleus (SCN) are accompanied by day-night differences in the number of vesicles in intrinsic synapses of the nucleus. Two groups of 5 adult male rats each were killed at mid-light or mid-dark, respectively, by perfusion with Karnovsky's fluid. The SCN were removed and processed for routine electron microscopy. In medial parts of the nucleus, synapses were characterized as being of Gray type I (asymmetrical), Gray type II (symmetrical) or of intermediate form, and the vesicles per synaptic profile (VPSP) were counted over a defi…
Determination of the Subcellular Origin of [14C] Acetylcholine (ACh) and [3H] Acetylpyrrolidinecholine (Apych) Released from Guinea-Pig Cerebral Cort…
1978
After in vivo application of radiolabelled choline, radioactive ACh is formed and can be released from the brain by electrical stimulation. However, its origin is still obscure because, due to the metabolical heterogeneity of synaptic vesicles, no subcellular compartment has been found with a specific activity (SA) corresponding to that of released transmitter. To bypass this heterogeneity problem, two different labelled precursors can be used.
Recent progress in understanding cholinergic function at the cellular and molecular levels
1992
Cholinergic transmission can claim to be the first form of chemical neurotransmission to be investigated by pharmacological and electrophysiological methods and the first in which both the transmitter and its receptor have been isolated and characterized. One reason for this is that neuromuscular transmission is cholinergic and the neuromuscular junction (especially that of frogs) is a readily investigated synapse in which responses are recorded by a muscular twitch — something which can be appreciated by direct observation and which does not require sophisticated equipment. Another is that in the form of the electric organs of strongly electric fish Nature has provided a tissue embryologic…