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L de Lecea

Publications and source records attributed to L de Lecea.

At least 19 recordsLinked to original sources
PubMed2005

The corticotropin-releasing factor-hypocretin connection: implications in stress response and addiction.

The hypothalamic neuropeptides hypocretins (orexins) play a crucial role in the stability of arousal and alertness. Recent data have raised the hypothesis that hypocretin neurons are also part of the circuitries that mediate the hypothalamic stress response. In particular, we have recently demonstrated that corticotrophin-releasing factor (CRF)-immunoreactive terminals make direct synaptic contacts with hypocretin-expressing neurons and that numerous hypocretinergic neurons express the CRF-R1/2 receptors. Furthermore, CRF excites hypocretinergic cells ex vivo through CRF-R1 receptors. Activation of hypocretinergic neurons in response to acute stress is severely impaired in CRF-R1 knockout mice. Moreover, the stress response is impaired in hypocretin-deficient mice. We propose that upon stressor stimuli, CRF stimulates the release of hypocretins, and this circuit contributes to activation and maintenance of arousal associated with the stress response and addiction.

Amygdala↗
PubMed2005

Cortistatin: a natural somatostatin analog.

Cortistatin (CST) is a recently discovered neuropeptide from the somatostatin gene family named after its predominantly cortical expression and ability to depress cortical activity. CST shows many remarkable structural and functional similarities to its related neuropeptide somatostatin. However, the many physiological differences between CST and somatostatin are just as remarkable as the similarities. CST-14 shares 11 of its 14 amino acids with somatostatin-14, including the FWKT tetramer thought to be responsible for somatostatin's receptor interactions and the pair of cysteine residues that likely render the peptides cyclic. Yet the nucleotide sequences and chromosomal localizations of these genes clearly indicate they are products of separate genes and CST's activity in the brain is widely distinct from that of somatostatin. Now cloned from human, mouse and rat sources, in vitro assays show that CST is able to bind all five cloned somatostatin receptors and shares many pharmacological and functional properties with somatostatin, including the depression of neuronal activity and inhibition of GH release. However, distinct from somatostatin, CST has been shown to induce slow-wave sleep, reduce locomotor activity, and activate cation selective currents not responsive to, or antagonized by, somatostatin. Here we address the discovery and characterization of this novel somatostatin-like neuropeptide, including its cloning, expression and pharmacology. We also examine the evidence pointing towards a specific receptor for this novel neuropeptide member of the somatostatin gene family.

Amino Acid Sequence↗
PubMed2001

Pattern of expression of the tetraspanin Tspan-5 during brain development in the mouse.

Here, we report the pattern of expression of the tetraspanin mTspan-5 at various developmental stages. Expression was first seen at E10 and remained until adulthood, with increased levels between P0 and P5. mTspan-5 showed high expression in the cortical areas and Purkinje cells throughout development. Moreover, transcripts were also detected in the developing heart, forelimbs, and hindlimbs.

Animals↗
PubMed2000

The hypocretins: excitatory neuromodulatory peptides for multiple homeostatic systems, including sleep and feeding.

The hypocretins are two neuropeptides of related sequence that are produced from a common precursor whose expression is restricted to 1, 100 large neurons of the rat dorsal-lateral hypothalamus. The hypocretins have been detected immunohistochemically in secretory vesicles at synapses of fibers that project to areas within the posterior hypothalamus that are implicated in feeding behaviors and hormone secretion and diverse targets in other brain regions and in the spinal cord, including several areas implicated in cardiovascular function and sleep-wake regulation. The hypocretin-producing cells have receptors for leptin and receive input from arcuate neuropeptide Y neurons. The peptides are excitatory when applied to cultured hypothalamic, cortical, or spinal cord neurons. Two G protein-coupled receptors for the hypocretins have been identified, and these have different distributions within the CNS and differential affinities for the two hypocretins. Administration of the hypocretins stimulates food intake; affects blood pressure, hormone secretion, and locomotor activity; and increases wakefulness while suppressing REM sleep. The hypocretin mRNA accumulates during food deprivation. An inactivating insertion into the hypocretin receptor 2 gene in dogs results in narcolepsy. Mice whose hypocretin gene has been inactivated exhibit a narcolepsy-like phenotype. Human patients with narcolepsy have greatly reduced levels of hypocretin peptides in their cerebral spinal fluid. One aspect of hypocretin activity is the direct excitation of noradrenergic neurons in the locus coeruleus to prevent entry into REM sleep. These peptides appear to be part of a complex circuit that integrates aspects of energy metabolism, cardiovascular function, hormone homeostasis, and sleep-wake behaviors.

Animals↗
PubMed2000

Hypocretin-1 modulates rapid eye movement sleep through activation of locus coeruleus neurons.

The hypocretins (hcrts), also known as orexins, are two recently identified excitatory neuropeptides that in rat are produced by approximately 1200 neurons whose cell bodies are located in the lateral hypothalamus. The hypocretins/orexins have been implicated in the regulation of rapid eye movement (REM) sleep and the pathophysiology of narcolepsy. In the present study, we investigated whether the locus coeruleus (LC), a structure receiving dense hcrtergic innervation, which is quiescent during REM sleep, might be a target for hcrt to regulate REM sleep. Local administration of hcrt1 but not hcrt2 in the LC suppressed REM sleep in a dose-dependent manner and increased wakefulness at the expense of deep, slow-wave sleep. These effects were blocked with an antibody that neutralizes hcrt binding to hcrt receptor 1. In situ hybridization and immunocytochemistry showed the presence of hcrt receptor 1 but not the presence of hcrt receptor 2 in the LC. Iontophoretic application of hcrt1 enhanced the firing rate of LC neurons in vivo, and local injection of hcrt1 into the LC induced the expression of c-fos in the LC area. We propose that hcrt receptor 1 in the LC is a key target for REM sleep regulation and might be involved in the pathophysiological mechanisms of narcolepsy.

Animals↗
PubMed2000

Mouse Tspan-5, a member of the tetraspanin superfamily, is highly expressed in brain cortical structures.

Using a subtractive hybridization method for the identification of genes related to the development of the murine cerebral cortex, we cloned a mouse homologue of a human tetraspanin family member, Tspan-5. We have isolated a 3.1 Kb cDNA fragment containing the entire coding region. Analysis of the cDNA nucleotide sequence revealed that mouse Tspan-5 shares 98% amino acid sequence identity with its human homologue. The predicted length of the mouse protein is 268 amino acids, with four putative hydrophobic domains with N- and C-intracellular tails, and two extracellular domains. Northern blot analysis of adult mouse tissues showed a single transcript, which is preferentially expressed in the brain. In situ hybridization showed prominent expression of Tspan-5 in the neocortex, the hippocampus, amygdala and in Purkinje cells in the cerebellum. The pattern of expression of Tspan-5 in the mouse brain suggests a role for the tetraspanins in the maintenance of adult brain function.

Animals↗
PubMed2000

Developmental regulation of two isoforms of Ca(2+)/calmodulin-dependent protein kinase I beta in rat brain.

Subtractive hybridization analysis of region-specific gene expression in brain has demonstrated a mRNA species enriched in rat hypothalamus [K.M. Gautvik, L. de Lecea, V.T. Gautvik, P.E. Danielson, P. Tranque, A. Dopazo, F.E. Bloom, J.G. Sutcliffe, Proc. Natl. Acad. Sci. USA 93 (1996) 8733-8738.]. We here show that this mRNA encodes a Ca(2+)/calmodulin-dependent (CaM) kinase belonging in the CaM kinase I beta subgroup. cDNA analysis showed that this enzyme was differentially spliced into two isoforms (designated beta1 and beta2) with distinct C-termini. The C-terminal of the translated CaM kinase I beta2 protein (38.5 kDa molecular size), contained 25 amino acid residues not present in the beta1 isoform. The two isoforms were differentially developmentally regulated, with the beta1 isoform being present in rat embryos from day 18 and the beta2 isoform being present from day 5 postnatally. In situ hybridization analysis of adult rat CNS showed CaM kinase I beta2 mRNA being enriched in the hypothalamus and the hippocampal formation. Expression was also observed in a number of ventral limbic structures and in the thalamus. Northern blot analysis showed additional expression of multiple beta2 isoforms in heart and skeletal muscle. The human mRNA showed a similar distribution. Our data suggest that the two isoforms of CaM kinase I beta, created by a splicing process occurring within a week around birth, may have distinct pre- and postnatal functions in a distinct set of CNS neurons and excitable tissues.

Animals↗
PubMed2000

Cortistatin: a member of the somatostatin neuropeptide family with distinct physiological functions.

Cortistatin is a recently discovered neuropeptide relative of somatostatin named after its predominantly cortical expression and ability to depress cortical activity. Cortistatin-14 shares 11 of the 14 amino acids of somatostatin-14 yet their nucleotide sequences and chromosomal localization clearly indicate they are products of separate genes. Now cloned from human, mouse and rat sources, cortistatin is known to bind all five cloned somatostatin receptors and share many pharmacological and functional properties with somatostatin including the depression of neuronal activity. However, cortistatin also has many properties distinct from somatostatin including induction of slow-wave sleep, apparently by antagonism of the excitatory effects of acetylcholine on the cortex, reduction of locomotor activity, and activation of cation selective currents not responsive to somatostatin. Expression of mRNA encoding cortistatin follows a circadian rhythm and is upregulated on deprivation of sleep, suggesting cortistatin is a sleep modulatory factor. This review summarizes recent advances in our understanding of the neurobiology of cortistatin, examines the similarities and differences between cortistatin and somatostatin, and asks the question: does cortistatin bind to a cortistatin-specific receptor?

Amino Acid Sequence↗
PubMed1999

The hypocretins/orexins: novel hypothalamic neuropeptides involved in different physiological systems.

The hypothalamus regulates diverse physiological functions, including the control of energy metabolism, circadian rhythms, stress and anxiety, sexual and reproductive behaviors. An overview of the most prevalent hypothalamus-enriched mRNAs revealed that this area of the brain specializes in producing intercellular signaling molecules. Two new secreted peptides derived from a single neuropeptide precursor, named hypocretins and orexins by two different groups, are synthesized in a small set of neurons in the perifornical area of the hypothalamus. Intracerebroventricular injection of the hypocretins/orexins increases food consumption in rats. Here we review recent progress in identifying the role of the hypocretins/orexins in the control of energy balance and in other physiological systems.

Amino Acid Sequence↗
PubMed1999

Cortistatin and somatostatin mRNAs are differentially regulated in response to kainate.

Cortistatin (CST) is a presumptive neuropeptide that shares 11 of its 14 amino acids with somatostatin (SST). CST and SST are expressed in partially overlapping but distinct populations of cortical interneurons. In the hippocampal formation, most CST-positive cells are also positive for SST. In contrast to SST, administration of CST into the rat brain ventricles reduces locomotor activity and specifically enhances slow wave sleep. Intracerebroventricular injection of CST or SST has been shown to protect against the neurotoxic effects of kainic acid. Here, we show that CST and SST mRNAs respond differently to kainate-induced seizures. Furthermore, comparison of the upstream sequences from the CST and SST precursor genes reveal that they contain binding motifs for different transcriptional regulatory factors. Our data demonstrate that CST and SST, which are often co-expressed in the same neurons, are regulated by different stimuli.

Amino Acid Sequence↗
PubMed1999

Structural and compositional determinants of cortistatin activity.

Cortistatin-14 (CST-14) is a putative novel neuropeptide that shares 11 of its 14 residues with somatostatin-14 (SRIF-14), yet its effects on sleep physiology, locomotor behavior and hippocampal function are different from those of somatostatin. We studied the structural basis for cortistatin's distinct biological activities. As with SRIF-14, CST-14 does not show any preferred conformation in solution, as determined by circular dichroism and nuclear magnetic resonance. Synthetic cortistatin analogs were designed and synthesized based on the cyclic structure of octreotide. Biological assays were carried out to determine their binding affinities to five somatostatin receptors (sstl-5) and their ability to produce changes in locomotor activity and to modulate hippocampal physiology and sleep. The results show that the compound with N-terminal proline and C-terminal lysine amide exhibits cortistatin-like biological activities, including reduction of population spike amplitudes in the hippocampal CA1 region, decrease in locomotor activity and enhancement of slow-wave sleep 2. These findings suggest that both proline and lysine are necessary for cortistatin binding to its specific receptor.

Amino Acid Sequence↗
PubMed1999

OCD-Like behaviors caused by a neuropotentiating transgene targeted to cortical and limbic D1+ neurons.

To study the behavioral role of neurons containing the D1 dopamine receptor (D1+), we have used a genetic neurostimulatory approach. We generated transgenic mice that express an intracellular form of cholera toxin (CT), a neuropotentiating enzyme that chronically activates stimulatory G-protein (Gs) signal transduction and cAMP synthesis, under the control of the D1 promoter. Because the D1 promoter, like other CNS-expressed promoters, confers transgene expression that is regionally restricted to different D1+ CNS subsets in different transgenic lines, we observed distinct but related psychomotor disorders in different D1CT-expressing founders. In a D1CT line in which transgene expression was restricted to the following D1+ CNS regions-the piriform cortex layer II, layers II-III of somatosensory cortical areas, and the intercalated nucleus of the amygdala-D1CT mice showed normal CNS and D1+ neural architecture but increased cAMP content in whole extracts of the piriform and somatosensory cortex. These mice also exhibited a constellation of compulsive behavioral abnormalities that strongly resembled human cortical-limbic-induced compulsive disorders such as obsessive-compulsive disorder (OCD). These compulsive behaviors included episodes of perseverance or repetition of any and all normal behaviors, repetitive nonaggressive biting of siblings during grooming, and repetitive leaping. These results suggest that chronic potentiation of cortical and limbic D1+ neurons thought to induce glutamatergic output to the striatum causes behaviors reminiscent of those in human cortical-limbic-induced compulsive disorders.

Aggression↗
PubMed1999

Novel neurotransmitters for sleep and energy homeostasis.

We have developed methodologies for identifying mRNAs with highly restricted expression within the brain. One postnatal-onset mRNA, restricted to sparse GABAergic interneurons of the cerebral cortex and hippocampus, encodes preprocortistatin, the precursor of a 14-residue peptide that shares 11 amino acids with somatostatin. Cortistatin binds to all five cloned somatostatin receptors when they are expressed in transfected cells and depresses neuronal activity, but, unlike somatostatin, it reduces locomotor activity and induces slow-wave sleep. Cortistatin, whose mRNA accumulates during sleep deprivation, apparently acts by antagonizing the effects of acetylcholine on cortical excitability, thereby causing synchronization brain slow waves. A single amino acid difference with somatostatin accounts for the dramatic differences in the effects of the two peptides on physiology and behavior. A second postnatal-onset mRNA, restricted to 1100 large neuronal cell bodies of the dorsal-lateral hypothalamus, encodes preprohypocretin, the precursor of two peptides that share homology with each other and with members of the secretin peptide family. The peptides are detected immunohistochemically in secretory vesicles at synapses of fibers that project to posterior hypothalamus and diverse targets in other brain regions. The peptides are excitatory when applied to cultured hypothalamic neurons. Recent studies by Sakurai and colleagues (1998) have identified the hypocretin peptides (called the orexins by those workers) as ligands for two orphan receptors at which they stimulate food-intake behavior. Sakurai and collaborators showed that the mRNA for these peptides accumulates during food deprivation. The hypocretin projections suggest additional homeostatic roles for the peptides. These studies suggest the common mechanism of regulation for necessary, but voluntary, behaviors (sleep and feeding) by transcription-based accumulation of peptide transmitters that create a pressure for the voluntary activities.

Amino Acid Sequence↗
PubMed1999

Leptin receptor- and STAT3-immunoreactivities in hypocretin/orexin neurones of the lateral hypothalamus.

Hypocretins/orexins are recently characterized peptides that are synthesized in neurones of the lateral hypohalamus and stimulate food intake in rats. To clarify whether leptin may interact with hypocretin/orexin to reduce ingestive behaviour, the presence of leptin receptor-immunoreactivity in hypocretin/orexin-containing neurones was examined. Many leptin receptor-and hypocretin/orexin-immunoreactive neurones were demonstrated in the lateral hypothalamic area and perifornical region. Both direct double-labelling and elution-restaining methods showed that leptin receptor-immunoreactivity was present in the vast majority of hypocretin/orexin-containing neurones. Immunoreactivity for STAT3, a transcription factor activated by leptin, was also demonstrated in hypocretin/orexin-containing neurones. Isolated hypocretin/orexin cell bodies in the dorsal part of the lateral hypothalamic area and the ventral perifornical region were shown to contain immunoreactivity for galanin, another peptide known to affect feeding. Galanin neurones were also seen to contain leptin receptor-and STAT3-immunoreactivity. Melanin-concentrating hormone (MCH)-containing neurones constituted a cell population within the lateral hypothalamus distinct from the one containing hypocretin/orexin-immunoreactivity, as shown by elution-restaining methodology. The presence of leptin receptor-and STAT3-immunoreactivities in hypocretin/orexin-containing neurones of the lateral hypothalamus suggests that leptin may directly regulate these hypothalamic neurones, most likely via an inhibitory action on hypocretin/orexin expression and/or secretion resulting in reduced food intake.

Animals↗
PubMed1998

Neurons containing hypocretin (orexin) project to multiple neuronal systems.

The novel neuropeptides called hypocretins (orexins) have recently been identified as being localized exclusively in cell bodies in a subregion of the tuberal part of the hypothalamus. The structure of the hypocretins, their accumulation in vesicles of axon terminals, and their excitatory effect on cultured hypothalamic neurons suggest that the hypocretins function in intercellular communication. To characterize these peptides further and to help understand what physiological functions they may serve, we undertook an immunohistochemical study to examine the distribution of preprohypocretin-immunoreactive neurons and fibers in the rat brain. Preprohypocretin-positive neurons were found in the perifornical nucleus and in the dorsal and lateral hypothalamic areas. These cells were distinct from those that express melanin-concentrating hormone. Although they represent a restricted group of cells, their projections were widely distributed in the brain. We observed labeled fibers throughout the hypothalamus. The densest extrahypothalamic projection was found in the locus coeruleus. Fibers were also seen in the septal nuclei, the bed nucleus of the stria terminalis, the paraventricular and reuniens nuclei of the thalamus, the zona incerta, the subthalamic nucleus, the central gray, the substantia nigra, the raphe nuclei, the parabrachial area, the medullary reticular formation, and the nucleus of the solitary tract. Less prominent projections were found in cortical regions, central and anterior amygdaloid nuclei, and the olfactory bulb. These results suggest that hypocretins are likely to have a role in physiological functions in addition to food intake such as regulation of blood pressure, the neuroendocrine system, body temperature, and the sleep-waking cycle.

Animals↗
PubMed1998

Regional and cellular patterns of reelin mRNA expression in the forebrain of the developing and adult mouse.

The reelin gene encodes an extracellular protein that is crucial for neuronal migration in laminated brain regions. To gain insights into the functions of Reelin, we performed high-resolution in situ hybridization analyses to determine the pattern of reelin expression in the developing forebrain of the mouse. We also performed double-labeling studies with several markers, including calcium-binding proteins, GAD65/67, and neuropeptides, to characterize the neuronal subsets that express reelin transcripts. reelin expression was detected at embryonic day 10 and later in the forebrain, with a distribution that is consistent with the prosomeric model of forebrain regionalization. In the diencephalon, expression was restricted to transverse and longitudinal domains that delineated boundaries between neuromeres. During embryogenesis, reelin was detected in the cerebral cortex in Cajal-Retzius cells but not in the GABAergic neurons of layer I. At prenatal stages, reelin was also expressed in the olfactory bulb, and striatum and in restricted nuclei in the ventral telencephalon, hypothalamus, thalamus, and pretectum. At postnatal stages, reelin transcripts gradually disappeared from Cajal-Retzius cells, at the same time as they appeared in subsets of GABAergic neurons distributed throughout neocortical and hippocampal layers. In other telencephalic and diencephalic regions, reelin expression decreased steadily during the postnatal period. In the adult, there was prominent expression in the olfactory bulb and cerebral cortex, where it was restricted to subsets of GABAergic interneurons that co-expressed calbindin, calretinin, neuropeptide Y, and somatostatin. This complex pattern of cellular and regional expression is consistent with Reelin having multiple roles in brain development and adult brain function.

Age Factors↗
PubMed1998

Endogenous protein kinase A inhibitor (PKIalpha) modulates synaptic activity.

Protein kinase A (PKA) has long been known to be involved in major regulatory mechanisms underlying synaptic plasticity and complex behaviors such as learning and memory. The endogenous PKA inhibitor, PKIalpha, has been extensively studied for its effects on PKA and PKA-mediated signal transduction. Clear functions for PKIalpha in vivo, however, remain to be established. Here we describe that several forms of synaptic stimulation in the rat hippocampus cause a dramatic decrease in the concentration of PKIalpha in dentate granule cells. Furthermore, chronic infusion of antisense oligonucleotides against PKIalpha into the rat brain results in a dramatic reduction of the excitability of these neurons and elimination of their ability to exhibit long-term potentiation (LTP) and long-term depression (LTD), suggesting a stimulus-dependent regulatory role for PKIalpha in PKA signal transduction.

Adaptor Proteins, Signal Transducing↗