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I Gozes

Publications and source records attributed to I Gozes.

At least 109 records · Page 6Linked to original sources
PubMed1991

A VIP antagonist distinguishes VIP receptors on spinal cord cells and lymphocytes.

Vasoactive intestinal peptide (VIP) is a neuropeptide which also interacts with cells of the immune system. The paucity of specific VIP receptor antagonists has hampered studies of possible receptor heterogeneity and of VIP function. To aid in achieving these goals, a new VIP antagonist, a hybrid between neurotensin and VIP, has been synthesized. This peptide interacted with VIP receptors on spinal cord cells with an affinity 10-fold greater than VIP itself. In contrast, 1000-fold higher concentrations of the antagonist were required to displace labeled VIP from its receptor on lymphoid cells as compared to VIP itself, suggesting VIP receptor heterogeneity between immune and spinal cord cells.

Amino Acid Sequence↗
PubMed1991

Spontaneous electrical activity regulates vasoactive intestinal peptide expression in dissociated spinal cord cell cultures.

Activity-dependent expression of vasoactive intestinal peptide (VIP) was investigated in spinal cord/dorsal root ganglia cultures derived from embryonic mice. Since all spinal cord neurons appear to exhibit spontaneous action potentials after one week in vitro, activity-dependent regulation of VIP-transcripts (mRNAVIP) could be studied with or without electrical blockade induced by tetrodotoxin (TTX). In 10-day-old cultures, a 50% decrease in mRNAVIP was observed after 3 days of treatment with TTX. The decrease in mRNAVIP was reversed upon removal of the TTX and was dependent on the age of the cultures: no decreases from control were observed in 5-day-old cultures and much smaller decrements were produced in one month old cultures treated with TTX. A variety of neuroactive substances were tested for effects on mRNAVIP in electrically active and electrically blocked cultures. Application of 8-bromo-cAMP (cAMP), N-methyl-D-aspartate (NMDA), substance P, muscimol, A23187 and VIP to electrically active cultures resulted in a 2- to 3-fold increase in mRNAVIP, while phorbol myristate 13-acetate (PMA) and 8-bromo-cGMP (cGMP) had no effect. In contrast, electrically inactive cultures exhibited a 3 to 4-fold increase in mRNAVIP after treatment with PMA, cAMP and VIP, while NMDA, substance P, muscimol, A23187 and cGMP produced no increases. In summary, the regulation of VIP gene expression in embryonic spinal cord neurons shows a temporal sensitivity to TTX-induced electrical blockade and may be mediated by multiple neurotransmitter inputs which converge on cAMP- and calcium-related processes in an activity-dependent manner.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

An antagonist to vasoactive intestinal peptide affects cellular functions in the central nervous system.

A vasoactive intestinal peptide (VIP) antagonist was synthesized and used to investigate the interactions of VIP with its receptors present in the central nervous system (CNS). The VIP antagonist is a hybrid peptide consisting of a portion of VIP and a portion of neurotensin, designed to change the membrane permeability of the VIP portion. The hybrid antagonist displaced 80 to 90% of [125I]VIP binding to cell cultures from cerebral cortex, hippocampus or spinal cord. The displacement curve was biphasic, suggesting two binding sites. In the case of cortical astrocytes, the antagonist had a Ki of 45 pM at one site and a Ki of 74 nM at the other. At the lower affinity binding site, the antagonist was about 10-fold more potent than VIP in displacing radiolabeled VIP. The accumulation of cyclic AMP (cAMP) in VIP-stimulated cortical glia cultures was decreased by the new antagonist (EC50, 59 nM). This decrease in cAMP was greater than that achieved in the presence of other putative VIP antagonists. Finally, the addition of 1 nM hybrid antagonist to dissociated spinal cord cultures resulted in a 42% reduction in neuronal cell counts as compared with controls, and the EC50 of this effect was about 30 pM, which corresponded closely to the Ki of antagonist displacement of [125I]VIP binding at the high-affinity site. The antagonist appears to be a competitive blocker for both VIP-mediated increases in cAMP formation or VIP-associated maintenance of neuronal survival in spinal cord cultures. Thus, we describe a potent VIP antagonist which interacts with two functionally distinct VIP receptors in the CNS.

Amino Acid Sequence↗
PubMed1990

The complete structure of the rat VIP gene.

Vasoactive intestinal polypeptide (VIP) is a regulatory neuropeptide/neurotransmitter of 28 amino acids involved in a wide variety of physiological functions. Using synthetic oligodeoxynucleotide probes related to the rat VIP-cDNA, we have isolated and characterized the gene encoding the rat pre-pro VIP/PHI-27 and compared it to the human VIP gene. The rat VIP gene spanned 7400 base pairs, and contained 7 exons interrupted by 6 introns. 100% identity was found between the gene exons and the cDNA sequence. Differences in sizes of introns 2, 4 and 5 (shorter in the rat gene) are the reason for the shorter rat gene compared with the human gene of 8837 base pairs. Comparison of the genes in the two species showed a high homology in the exon sequences, 80-90% in exons 2, 4, 5, 6 and 30-50% in exons 1 and 7. In addition, the exon-intron junctions shared high identity between the genes. The rat untranslated exon 1 had little homology (30%) with human exon 1 and was 13 base pairs shorter. Interestingly, the 160 base pairs at the 5'-flanking region upstream of the cap-site share more than 75% identity between the two genes, including the exact position of TATA-boxes in positions -28, -145, -155, a cAMP-responsive element in position -80 and a CAAT sequence in position -127. The conservation of the 5'-flanking region of the VIP gene in parallel with the conservation of its coding exons emphasize the importance of these sequences during evolution.

Amino Acid Sequence↗
PubMed1989

VIP-mRNA is increased in hypertensive rats.

Vasoactive intestinal peptide (VIP) is a potent vasodilator. We therefore set out to investigate VIP-gene expression in spontaneous hypertensive rats. By quantitative in situ hybridization histochemistry as well as by RNA blot hybridization experiments we discovered a significant increase in VIP transcripts in the brains of those hypertensive rats. We suggest that the increase in VIP-gene expression may play a compensatory role in these rats where otherwise the rise in blood pressure may have had a much more adverse effect.

Animals↗
PubMed1989

VIP: molecular biology and neurobiological function.

In the mammalian brain, a major regulatory peptide is vasoactive intestinal peptide (VIP). This 28 amino acid peptide, originally isolated from the porcine duodenum, was later found in the central and peripheral nervous systems and in endocrine cells, where it exhibits neurotransmitter and hormonal roles. Increasing evidence points to VIP's importance as a mediator or a modulator of several basic functions. Thus, VIP is a major factor in brain activity, neuroendocrine functions, cardiac activity, respiration, digestion, and sexual potency. In view of this peptide's importance, the mechanisms controlling its production and the pathways regulating its functions have been reviewed. VIP is a member of a peptide family, including peptides such as glucagon, secretin, and growth hormone releasing hormone. These peptides may have evolved by exon duplication coupled with gene duplication. The human VIP gene contains seven exons, each encoding a distinct functional domain on the protein precursor or the mRNA. VIP gene transcripts are mainly found in neurons or neuron-related cells. VIP gene expression is regulated by neuronal and endocrine signals that contribute to its developmental control. VIP exerts its function via receptor-mediated systems, activating signal transduction pathways, including cAMP. It can act as a neurotransmitter, neuromodulator, and a secretagog. As a growth and developmental regulator, VIP may have a crucial effect as a neuronal survival factor. We shall proceed from the gene to its multiple functions.

Amino Acid Sequence↗
PubMed1989

Estrogen regulation of vasoactive intestinal peptide mRNA in rat hypothalamus.

The participation of gonadal steroid hormones in regulation of the vasoactive intestinal peptide (VIP) gene expression in the hypothalamus was studied using a quantitative densitometric hybridization assay. In the female rat the levels of VIP mRNA were found to be significantly decreased following ovariectomy (4.41 +/- 0.7 arbitrary units of absorbance vs. 8.52 +/- 0.18). This decrease was largely reversed after three days of treatment with estradiol dibenzoate. In contrast to the female rats, no significant change in VIP mRNA levels was observed in the male rats, following orchidectomy. These results suggest a sexual dimorphism with regard to the steroid regulation of hypothalamic VIP gene expression in the rat.

Animals↗
PubMed1989

Lactation elevates vasoactive intestinal peptide messenger ribonucleic acid in rat suprachiasmatic nucleus.

Vasoactive intestinal peptide (VIP) has been suggested to play a role in lactation; indeed several studies implied that VIP induces the release of PRL in the pituitary. Quantitative RNA studies from our laboratory show an increase in the VIP messenger RNA (mRNA) content in the hypothalamus of lactating rats. The purpose of this investigation is to determine which hypothalamic neurons are increasing the expression of VIP. A sensitive in situ hybridization assay employing synthetic oligodeoxynucleotide probes corresponding to specific exons of the VIP gene was used to study VIP gene expression at the neuronal level. We were able to detect VIP-encoding transcripts in various brain regions including the ventrolateral thalamus, neocortex, pyriform cortex, and hypothalamus with a particularly high concentration in the suprachiasmatic nucleus. When lactating animals were compared to non-lactating animals, a 2-fold increase was observed in VIP transcripts in the suprachiasmatic nucleus. Since the suprachiasmatic nucleus is not directly associated with the physiology of lactation, the response of the VIP gene to lactation may be, in part, indirect. Taken together, our results suggest that lactation and the expression of the VIP gene are interrelated.

Animals↗
PubMed1989

Vasoactive intestinal peptide potentiates sexual behavior: inhibition by novel antagonist.

Vasoactive intestinal peptide (VIP) has been suggested as a neurotransmitter mediating penile erection. We now show that VIP can stimulate sexual behavior in rats with reduced masculine potential due to pituitary grafting or castration. This effect was attenuated in the presence of a novel VIP antagonist, devised by a hybrid peptide strategy. Thus, we have synthesized a molecule combining a portion of VIP with a portion of neurotensin, peptides of opposite pharmacological action on cAMP formation and smooth muscle relaxation. The hybrid peptide markedly inhibited VIP's effect on sexual behavior. This inhibition was manifested by a significant increase in the mean interval between copulatory events (greater than 3-fold change) coupled with a blockade of VIP-stimulated ejaculation. Other putative VIP antagonists were not as effective in blocking these activities. Thus, our results imply that VIP is not only associated with penile erection, but is involved in sexual behavior as well. Furthermore, the hybrid antagonist was shown to inhibit VIP binding in glial cell cultures. The availability of highly potent VIP antagonists may offer a route to study the possible multiple VIP receptors as well as help delineate other biological activities attributable to VIP.

Amino Acid Sequence↗
PubMed1989

Disruption of the optic pathway during development affects vasoactive intestinal peptide mRNA expression.

Vasoactive intestinal polypeptide (VIP) is a regulatory peptide widely distributed in the central and peripheral nervous systems. To understand the activities of VIP it is necessary to study the mechanisms governing its production. The highest concentration of VIP-producing cells occurs in the suprachiasmatic nucleus (SCN) of the hypothalamus. Because the SCN is directly innervated by the optic nerve, we decided to investigate the effect of visual input on VIP gene expression. By means of Northern blot hybridization, we measured VIP mRNA levels in the hypothalami of 36-day-old normal rats and rats that had been enucleated at birth. The concentration of VIP mRNA in the hypothalami of enucleated rats was approximately double that in the hypothalami of normal rats. In contrast, the concentration of VIP mRNA in the cerebral cortex significantly decreased after enucleation. The concentrations of VIP mRNA were also measured by in situ hybridization to brain sections. The hypothalamic VIP mRNA was located mainly in the SCN. Enucleation resulted in an increase of VIP transcripts in the SCN. These results indicate that visual input may participate in the regulation of VIP production.

Animals↗
PubMed1989

Localization of VIP and PHI-27 messenger RNA in rat thalamic and cortical neurons.

Messenger RNA (mRNA) coding for vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI-27) were localized in cortical and thalamic neurons with synthetic DNA probes complementary to the PHI-27 and VIP exon coding sequence of the rat VIP precursor gene. Hybridization signal with these probes was found widely distributed in the thalamus, neocortex, and pyriform cortex, and the distribution of hybridization signal for each probe was identical. Furthermore, the distribution of each message was correlated closely with peptide distribution demonstrated immunohistochemically. Labeling of individual neurons with in situ hybridization histochemistry was characterized by a dense accumulation of silver grains in the cytoplasm of these cells with little or no label in the nucleus. Labeled neurons in the thalamus were observed in the ventrolateral, ventromedial, ventrobasal, and lateral reticular nuclei. In the neocortex, the distribution of labeled neurons was concentrated in layers II and III with scattered cells also apparent in deeper cortical layers. Hybridization signal was limited to nonpyramidal neurons in both the neo- and pyriform cortex. The coextensive distribution of immunoreactivity and mRNA coding regions for VIP and PHI-27 establishes that these peptides are synthesized from the same precursor mRNA in the same thalamic and cortical cell groups. Although the physiological role of these peptides in thalamocortical function remains unknown, these data provide an anatomical substrate which suggests that VIP and PHI-27 may be cotransmitters in thalamic and cortical neurons.

Animals↗
PubMed1988

Steroid regulation of somatostatin mRNA in the rat hypothalamus.

The participation of gonadal steroid hormones in the regulation of the expression of the somatostatin gene in the hypothalamus and cerebral cortex was studied by using a quantitative densitometric hybridization assay which allows the direct measurement of specific somatostatin mRNA levels. The levels of somatostatin mRNA in hypothalamus were found to be significantly decreased following gonadectomy in both male and female rats (67% in males and 75% in females). Moreover, with in situ hybridization histochemistry somatostatin mRNA was similarly reduced following gonadectomy in the dorsal portion of the periventricular region and in the ventromedial nucleus. Estradiol dibenzoate treatment reversed the decrease in somatostatin mRNA in females within 24 h and testosterone treatment reversed the decrease in castrated males. In contrast, there was no significant change in cerebral cortex somatostatin mRNA levels after gonadectomy. These results suggest that sex steroids are involved in the regulation of the somatostatin gene in the hypothalamus, possibly at the transcriptional level.

Animals↗
PubMed1988

Hormonal regulation of somatostatin messenger RNA.

The ability of gonadal steroids to regulate the expression of the somatostatin gene in several regions of the CNS was investigated with in situ hybridization histochemistry. The amount of somatostatin mRNA was found to be significantly decreased 2-3 weeks after ovariectomy or orchidectomy in the periventricular hypothalamus, the ventromedial nucleus of the hypothalamus, and the medial and central nuclei of the amygdala. Treatment of gonadectomized rats with estradiol benzoate or testosterone enanthate reversed this decrease in somatostatin mRNA. No significant effect was noted in the cerebral cortex or bed nucleus of the stria terminalis. In some regions, there was a high degree of convergence between the distribution of neurons containing estrogen/androgen receptors and somatostatin neurons that were responsive to gonadectomy. These results suggest that sex steroids regulate the expression of somatostatin through an action at the level of transcription.

Amygdala↗
PubMed1988

Localization of vasopressin-, vasoactive intestinal polypeptide-, peptide histidine isoleucine- and somatostatin-mRNA in rat suprachiasmatic nucleus.

Messenger RNAs (mRNA) coding for vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), somatostatin and vasopressin were localized in the suprachiasmatic nucleus (SCN) of the rat hypothalamus using in situ hybridization histochemistry. Specific mRNA coding for each of these peptides was distributed in areas coextensive with the immunohistochemical localization of the appropriate peptide. The autoradiographic signal produced with probes to VIP and PHI created dense concentrations of silver grains over neuronal perikarya in the ventrolateral SCN, and the coextensive distribution of both VIP- and PHI-mRNAs suggests that both peptides are synthesized within the same neurons. The distribution of somatostatin-mRNA was distinct from the of VIP and PHI. Labeled neurons are observed at the interface of the two SCN subdivisions and the distribution of these neurons is identical to those shown to contain somatostatin immunoreactivity. Vasopressin-mRNA is also differentially concentrated within neurons in the dorsomedial subdivision of the SCN in an area that is coextensive with vasopressin-immunoreactive perikarya. The discrete pattern of hybridization for each of these mRNAs indicates that each of these peptides are synthesized in SCN neurons and reaffirms the differential distribution of each of these chemically defined cell populations within cytoarchitecturally distinct subdivisions of the nucleus.

Animals↗
PubMed1988

Vasoactive intestinal peptide gene expression from embryos to aging rats.

Vasoactive intestinal peptide (VIP) gene transcripts were demonstrated by RNA blot hybridization using VIP-specific RNA hybridization probes. High levels of expression were observed as early as in 16-day-old embryos. In aging rats, the VIP-mRNA levels were reduced significantly (in the cerebral cortex) as compared to 21-day-old rats. Our results suggest a role for the VIP gene protein products during embryonal development. During aging processes the decrease in VIP gene transcripts may be a consequence of either a reduction in the transcriptional activity of VIP neurons or death of VIP-producing cells.

Aging↗
PubMed1987

The survival of dentate gyrus neurons in dissociated culture.

Using a technique for dissociating cells from the area dentata of postnatal rats, we have been able to routinely establish low density cultures of dentate granule neurons that can be grown in the presence or absence of serum. Non-granule neurons from the hilar region and glial cells (both astrocytes and oligodendrocytes) are also present, but can be readily distinguished from the granule cells in these cultures. Unlike dissociated hippocampal pyramidal cells, which frequently resemble their in vivo morphology, dissociated dentate granule cells bear little resemblance to their normal in vivo counterparts, but are very similar in appearance to the ectopic granule cells seen in the reeler mouse. This suggests that extrinsic factors are the principal determinants of the mature form which granule neurons assume in vivo. On the other hand, the dissociated granule cells are able to express certain other aspects of their in vivo phenotype including the synthesis and transport of an antigen which is characteristically found in mossy fibers. Certain neuropeptide-containing non-granule neurons found in these cultures are also capable of maintaining aspects of their in vivo phenotype.

Animals↗