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SNAP-25 is a synaptosomal associated protein localized at the plasma membrane of nerve terminals. SNAP-25 associates with syntaxin 1 and vesicle-associated membrane protein-2 (VAMP-2) and is thought to form a complex essential for neurotransmitter release. We have identified syndet, a novel protein related to the family of SNAP-25 isoforms. Like SNAP-25,(More)
In neuroendocrine cells, Ca2+ triggers fusion of granules with the plasma membrane and functions at earlier steps by increasing the size of the readily releasable pool of vesicles. The effect of Ca2+ at early steps of secretion may be due to the recruitment at the plasma membrane of granules localized in the cytoplasm. To study the mechanism of granule(More)
Immunocytochemical procedures on thick, unembedded sections were used to visualize the neurons and their processes that contain LHRH-immunoreactive material in the rat central nervous system (CNS). In animals pretreated with colchicine (75 micrograms, intraventricularly), cell bodies could be observed as far anterior as the olfactory bulb and posterior to(More)
Activation of LH-releasing hormone (LHRH) secretion, essential for the initiation of puberty, is brought about by the interaction of neurotransmitters and astroglia-derived substances. One of these substances, transforming growth factor alpha (TGFalpha), has been implicated as a facilitatory component of the glia-to-neuron signaling process controlling the(More)
Physiological and pharmacological evidence has suggested that both endogenous opiates and gonadotropin-releasing hormone (GnRH) itself can act centrally to exert a tonic inhibition on gonadotropin secretion via an inhibition of the neurosecretion of GnRH. To determine if the effects of these two peptides might be mediated via a direct synaptic input to the(More)
GnRH neurons form the final common pathway regulating the secretion of gonadotropins from the anterior pituitary. Since the patterns of gonadotropin release display profound sexual dimorphism among mammals including the rodent, we undertook an ultrastructural analysis to determine whether these neurosecretory cells were differentially innervated between the(More)
The secretion of the gonadotropins is modulated by the gonadal steroids, but the means by which these effects are mediated are not well understood. The present anatomical study was undertaken to investigate the possibility that the GnRH system responds to alterations in the gonadal steroid environment with reversible changes in synaptic input and glial(More)
Previous work in many laboratories has shown that luteinizing hormone-releasing hormone (LHRH) neurons display a range of shapes from smooth-contoured to extremely irregular or 'thorny'. To determine if these forms reflect or can be modified by the gonadal steroid milieu, the morphology of LHRH neurons was examined in male rats from each of four(More)
GnRH is secreted in bursts into the hypophyseal portal vasculature by a small dispersed population of neurons. The means by which the activity of these intrinsically pulsatile cells is coordinated are unknown. This study was initiated as a continuation of our examination of the synaptic input to these cells and their anatomical relationships. Brain tissue(More)
The ultrastructural appearance of luteinizing hormone-releasing hormone (LHRH) immunoreactive elements was studied in the medial preoptic area (MPOA) of adult male Fischer 344 rats. The purpose of the study was to determine the distribution and morphology of innervation of the LHRH neuron. Although not numerous, both axo-somatic and axo-dendritic synapses(More)