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V D'Agata

Publications and source records attributed to V D'Agata.

At least 19 recordsLinked to original sources
PubMed2003

Down regulation of cerebellar memory related gene-1 following classical conditioning.

We have isolated and characterized the mRNA of a mouse gene named cerebellar memory related gene-1, previously found by microarray analysis to be differentially expressed following classical conditioning of the rabbit nictitating membrane response. Quantitative RT-PCR analysis showed a significant reduction in mRNA expression in cerebellar lobule HVI but not in the hippocampus of rabbits that received classical conditioning compared to control rabbits that received either unpaired stimulus presentations or were simply restrained. The mouse mRNA encodes a protein of 485 amino acids that includes different potential post-translational modification sites and five copies of the WD-repeat suggesting involvement in protein-protein interaction and regulatory function. In-situ hybridization experiments show highly localized expression of the transcript in mouse brain with the highest expression levels located in the cerebellum, hippocampus and cortex. Taken together, our results reveal a novel gene encoding a WD-repeat protein that is down-regulated in cerebellar lobule HVI as a result of learning and memory.

Animals↗
PubMed2001

Gene expression profiles during long-term memory consolidation.

Changes in gene expression have been postulated to occur during long-term memory (LTM). We used high-density cDNA microarrays to assess changes in gene expression 24 h after rabbit eye blink conditioning. Paired animals were presented with a 400 ms, 1000 Hz, 82 dB tone conditioned stimulus that coterminated with a 100 ms, 60 Hz, 2 mA electrical pulse unconditioned stimulus. Unpaired animals received the same conditioned and unconditioned stimuli but presented in an explicitly unpaired manner. Differences in expression levels between paired and unpaired animals in the hippocampus and cerebellar lobule HVI, two regions activated during eye blink conditioning, indicated the involvement of novel genes as well as the participation of previously implicated genes. Patterns of gene expression were validated by in situ hybridization. Surprisingly, the data suggest that an underlying mechanism of LTM involves widespread decreased, rather than increased, gene expression. These results demonstrate the feasibility and utility of a cDNA microarray system as a tool for dissecting the molecular mechanisms of associative memory.

Animals↗
PubMed2000

Cloning and distribution of the rat parkin mRNA.

We have isolated by RT-PCR and sequenced a partial cDNA coding for the rat homolog of parkin, a gene mutated in autosomal recessive juvenile parkinsonism. The 1.46 kb rat cDNA clone contains a 1376 bp coding sequence that shares strong similarity with the human parkin cDNA. RT-PCR and in situ hybridization revealed widespread expression of parkin in the rat brain and the periphery. The availability of the rat parkin cDNA and the initial elucidation of its distribution should facilitate further research on the pathophysiological role of parkin in the nervous system.

Amino Acid Sequence↗
PubMed2000

Regional and cellular expression of the parkin gene in the rat cerebral cortex.

A mutation in the parkin gene has been identified as the cause for an autosomal recessively inherited form of early onset Parkinson's disease. We have recently isolated the mRNA coding for the rat homologue of parkin and showed its widespread expression in the central nervous system (CNS) by in situ hybridization. In the present study we investigated the distribution of parkin in the rat cerebral cortex with a polyclonal antibody that reacts with a single approximately 52-kDa protein, corresponding to the predicted molecular mass of parkin. Conventional light microscopic studies revealed intense parkin immunoreactivity (IR) throughout the cortex. Examination of mixed cortical neuro-glial cultures by indirect immunofluorescence technique coupled to traditional epifluorescence and confocal microscopy analysis demonstrated the expression of parkin in the cytoplasm and neurites of neurons, and its absence in glial fibrillary acidic protein (GFAP)-positive astrocytes. The predominant neuronal parkin-IR and -mRNA expression was confirmed by Western blot analysis and reverse transcription-polymerase chain reaction (RT-PCR), respectively, performed on highly enriched neuronal and type I astrocytes cultures. The information gathered in our study about the cellular and subcellular distribution of parkin should facilitate further research on its physiological role in the nervous system.

Animals↗
PubMed1999

Molecular and functional characterization of pituitary adenylate cyclase-activating polypeptide (PACAP-38)/vasoactive intestinal polypeptide receptors in pancreatic beta-cells and effects of PACAP-38 on components of the insulin secretory system.

It has been previously demonstrated that pituitary adenylate cyclase-activating polypeptide (PACAP) regulates insulin secretion. PACAP exerts its biological action by binding to at least three different receptor subtypes coupled to different signal transduction mechanisms. The signaling pathways underlying the insulinotropic effect of PACAP involve mainly the activation of adenylate cyclase to form cAMP, which directly and indirectly, through increased intracellular Ca2+, stimulates insulin exocytosis. In the present study we have characterized the functional and molecular expression of PACAP/vasoactive intestinal polypeptide receptors isoforms and subtypes and its isoforms in a beta-cell line and in isolated rat pancreatic islets. Although insulinoma cells express the messenger RNA encoding PAC1 (-R and -hop variants), VPAC1 and VPAC2, binding experiments indicate the preponderance of PAC1 over VPAC 1-2 receptors. We have also shown that the main signaling pathway of PACAP in beta-cells is mediated by adenylate cyclase, whereas the inositol 1,4,5-trisphosphate pathway is almost inactive. Furthermore, we have demonstrated that PACAP exerts long-term effects on beta-cells, such as transcriptional regulation of the insulin gene and genes of the glucose-sensing system (GLUT1 and hexokinase 1).

Adenylyl Cyclases↗
PubMed1998

Cloning and expression of the programmed cell death regulator Bad in the rat brain.

The Bcl-2 family of proteins consists of both antagonists (e.g. Bcl-2) and agonists (e.g. Bax) that regulate apoptosis and compete through dimerization. In the present study we cloned the cDNA encoding the rat brain BAD, a distant member of the Bcl-2 family that was shown to promote cell death. The cloned cDNA encoded a protein of 205 amino acids, containing three putative Bcl-2 homology domains (BH1, BH2 and BH3) and no C-terminal signal-anchor sequence. The predicted amino acid sequence was identical to the Bad-cDNA recently cloned from the rat ovary with the exception of a stretch of six amino acids, thus indicating the existence of two Bad alternative splice variants or a sequence artifact in the rat ovary Bad-cDNA. Immunohistochemical analysis in the rat brain revealed the exclusive expression of Bad in the epithelial cells of the choroid plexus, a result which is consistent with a very specialized function of Bad in the brain.

Amino Acid Sequence↗
PubMed1998

Functional and molecular expression of PACAP/VIP receptors in the rat retina.

Receptor binding sites for pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP), positively coupled to adenylate cyclase, have been previously described in the retina of different mammalian species. In the present study, we determined the mRNA expression of PACAP/VIP receptor variants in the rat retina and investigated their coupling to phospholipase C in addition to adenylate cyclase. The two forms of PACAP, PACAP27 and PACAP38, induced a dose-dependent (1-100 nM) increase of cAMP and [3H]inositol monophosphate levels, whereas VIP stimulated, with lower potency and efficacy, cAMP formation only. Reverse transcription-PCR analysis in the rat retina detected both type-I (PACAP-R and PACAP-HOP splice variants) and type-II (VIP-I and -2) receptor-mRNAs. These data indicate that PACAP and VIP may interact with multiple receptor subtypes and activate one (VIP) or two (PACAP) signal transduction mechanisms in the rat retina.

Adenylyl Cyclases↗
PubMed1996

Tissue-specific and developmental expression of pituitary adenylate cyclase-activating polypeptide (PACAP) receptors in rat brain.

The two forms of pituitary adenylate cyclase-activating polypeptide, PACAP27,and PACAP38, are novel members of the vasoactive intestinal peptide (VIP)/secretin/glucagon family of peptides. PACAP receptors that are positively coupled to adenylate cyclase and phospholipase C have been recently identified. We examined the expression of PACAP receptors in the rat cortex, hippocampus, cerebellum and hypothalamus during postnatal development. Functional studies revealed PACAP stimulation of cAMP formation in all the brain areas examined and [3H]inositol monophosphate ([3H]InsP) accumulation only in the cerebellum and hypothalamus. Throughout development, the efficacy or PACAP in stimulating cAMP formation slightly increased in the cortex and hypothalamus and decreased in the hippocampus and cerebellum; PACAP stimulation of [3H]InsP formation decreased in the cerebellum and remained steady in the hypothalamus. The effects of PACAP27 and PACAP38 on cAMP levels and inositol phospholipid hydrolysis were dose-dependent between 1 and 100 nM. In the same brain areas, treatment with VIP increased cAMP formation at doses greater than 100nM and failed to affect [3H]InsP content, thus suggesting the existence of type-1 PACAP receptors. The reverse transcription polymerase chain reaction (RT-PCR) was used to analyse the mRNA expression of type-1 PACAP receptor splice variants. PACAP receptor gene expression in the central nervous system was regulated in a developmental- and tissue-specific manner. The PACAP-R transcript was detected in all the brain areas examined whereas PACAP-R-hop mRNA ocurred only in the cerebellum and hypothalamus. The different expression profiles and functional properties of PACAP receptors in the developing rat brain suggest an involvement of PACAP in histogenesis, maturation and neurotransmission.

Adenylyl Cyclases↗
PubMed1996

Pituitary adenylate cyclase activating polypeptide prevents apoptosis in cultured cerebellar granule neurons.

The two forms of pituitary adenylate cyclase-activating polypeptide, PACAP27 and PACAP38, are two neuropeptide hormones related to the vasoactive intestinal peptide/secretin/ glucagon family of peptides. PACAP receptors that are positively coupled to adenylyl cyclase and phospholipase C have been identified in cultured cerebellar granule cells. Using the reverse transcription-polymerase chain reaction methodology, we demonstrated the expression of the PACAP-R and PACAP-R-hop mRNAs in cultured granule cells. When grown in the absence of serum or in low K+ concentrations, these neurons underwent apoptosis, a naturally occurring process characterized by cell shrinkage and internucleosomal DNA cleavage. We used these models of programmed cell death to study the relationship between PACAP receptor activation and neuronal apoptosis. Treatment with PACAP27 and PACAP38 reduced the development of apoptosis in a dose-dependent manner. The neuroprotective activity of PACAP was mimicked by high concentrations of vasoactive intestinal peptide or forskolin but not by carbamylcholine. Thus, we suggest that the activation of type I PACAP receptors may contribute to the survival of cerebellar granule neurons.

Animals↗
PubMed1995

Biochemical changes induced by pyrphenoxone in the lens of rabbits and rats.

The xanthomatine analogue, pyrphenoxone, which is known to diminish the incidence of cataract in animals and in man, was applied in two different in vivo models of cataract induced in rabbits by tryptophan-free dietary regimen and in rats by hypergalactosemic diet. The drug was also applied at different concentrations in an in vitro model of cataract. It was found that soluble proteins and sulphurated amino acids of the lens in all in vivo and in vitro models of cataract were higher after pyrphenoxone was applied. Furthermore, the drug treatment was followed by a dose-dependent increase in reduced glutathione content in the lens of rabbits and rats. The same was found in the in vitro model of cataract. These results suggest that pyrphenoxone may act by inducing various biochemical changes that lead to a protection of lens against oxidative processes.

Animals↗
PubMed1995

Differentiation induces pituitary adenylate cyclase-activating polypeptide receptor expression in PC-12 cells.

The two forms of pituitary adenylate cyclase-activating polypeptide (PACAP), PACAP27 and PACAP38, are neuropeptide hormones related to the vasoactive intestinal peptide/secretin/glucagon family of peptides. PACAP receptors that are positively coupled to adenylyl cyclase and phospholipase C have been recently identified. We have investigated the expression of PACAP-Rs in undifferentiated and differentiated PC-12 cells. PACAP27 and PACAP38 failed to significantly increase cAMP or [3H]inositol monophosphate levels in undifferentiated PC-12 cells treated with vehicle, insulin-like growth factor I, or epidermal growth factor but greatly elevated levels after differentiation with nerve growth factor (NGF) or basic fibroblast growth factor. PACAP responsiveness increased significantly after 24 hr of NGF treatment, reaching a maximum within 4 days. At this time of differentiation, the effect of PACAP was dose dependent between 1 nM and 0.1 microM, whereas vasoactive intestinal peptide, at the maximal dose of 10 microM, slightly increased cAMP formation and failed to affect [3H]inositol monophosphate content. Radioreceptor assays, performed with 125I-PACAP27, revealed the induction of high affinity type I PACAP receptors in differentiated PC-12 cells. Using reverse transcription-polymerase chain reaction methodology, we showed the absence of type I PACAP receptor mRNAs in undifferentiated PC-12 cells and the expression of PACAP-R-hop mRNA after NGF or basic fibroblast growth factor treatment. The increased PACAP responsiveness induced by these growth factors in PC-12 cells may therefore result from the expression of the PACAP-R-hop isoform, positively coupled to both adenylyl cyclase and phospholipase C.

Animals↗
PubMed1993

Effects of cerebellectomy on motivation-related behavior: a time-course study.

The open field behavior and learning capacity of male rats of the Wistar strain was studied 1, 2, and 6 months after cerebellectomy (CBX). The results show a decrease in locomotor activity 1 month after CBX and thereafter a slow recovery. Grooming behavior was still normal after 1 month, but it decreased 2 months after CBX. Learning capacity, as assessed by the shuttle-box test, was remarkably decreased in cerebellectomized animals 1 month after operation. A significant impairment of memory capacity was also observed in rats tested for passive avoidance behavior 2 months after CBX. A partial recovery of this parameter was present 6 months after operation. These results support the hypothesis of a possible influence of cerebellum on motivation-related behaviors, independently of its modulatory role on motricity.

Animals↗
PubMed1992

[Cerebral actions of dihydroergocristine].

Dihydroergocristine (DEC, CAS 17479-19-5) is a dihydrogenated ergot alkaloid with a potent dopaminergic activity that has been proved both in vitro and in vivo. Apart from its effect on the secretion of pituitary hormones, the following actions have been evidenced. It induces stereotyped behaviour and changes in the sleep-waking cycle, and reduces hypoxia-induced cerebral metabolic changes and emesis. The effect of DHEC on behaviour patterns has been studied in aged male rats in comparison with young animals. The acquisition of the active avoidance response in the shuttle-box test and the retention of the passive avoidance response in a step-through passive avoidance task were facilitated in aged rats by an acute treatment with DHEC. The effect on the acquisition and extinction of the pole-jumping performance after a single injection of DHEC at the beginning of the acquisition session was restricted to the first acquisition trial. A more potent effect on the acquisition of the shuttle-box response and on the retention of passive avoidance reaction was found in animals treated subchronically with DHEC. The latter animals also showed a facilitation of acquisition and an inhibition of extinction of the pole-jumping performance. In other experiments, the repeated administration of DHEC was followed by a decrease in the excessive grooming in aged rats, which is considered a sign of the lack of adaptability of these animals. A facilitation of the compensatory mechanisms in experimental models of vertigo has also been found in animals treated with DHEC.

Animals↗
PubMed1991

The inhibition of oxytocin-induced grooming by a specific receptor antagonist.

The bilateral injection of the oxytocin receptor antagonist, N-acetyl-2-O-methyl-tyrosine-oxytocin (AMTO), in the nucleus accumbens of male rats prevented oxytocin-enhanced grooming without affecting locomotor activity. This effect was dose related. Oxytocin infusions did not alter open field activity. The present study investigated whether oxytocin receptors in the nucleus accumbens are essential for the expression of grooming enhanced by the neuropeptide.

Angiotensin Receptor Antagonists↗
PubMed1990

Effects of vinburnine on experimental models of learning and memory impairments.

Retrograde amnesia can be induced experimentally in mice by injecting them with scopolamine (3 mg/kg, IP) or by inducing seizures with pentylenetetrazol (50 mg/kg, IP), and in rats by subjecting them to hypobaric hypoxia (at a barometric pressure of 300 mmHg for 3 min). We have studied the effects of vinburnine (VNB) in these amnesic states compared to vincamine (VNC) and nicergoline (NCG), in order to assess its activity on drug-induced learning and memory impairments. Vinburnine reduced the disrupting effect of both scopolamine and pentylenetetrazol-induced seizures on the retention of a step-through passive avoidance behavior in mice and on the acquisition of shuttle-box active avoidance behavior in rats. This effect was dose-related up to 20 mg/kg, the peak effect dose after IP administration, and more pronounced than that of VNC and NCG in some tests. These results indicate that VNB influences learning and memory processes disrupted by a pharmacological manipulation. In particular, as scopolamine acts as anticholinergic drug, it is possible that VNB mechanism of action includes also a stimulation of acetylcholine neurotransmission.

Amnesia, Retrograde↗