RESUMEN
Adenylyl cyclases (ACs) synthesize the second messenger cyclic AMP (cAMP) which influences the function of multiple ion channels. Former studies point to a malfunction of cAMP-dependent ion channel regulation in thalamocortical relay neurons that contribute to the development of the absence epileptic phenotype of a rat genetic model (WAG/Rij). Here, we provide detailed information about the thalamic gene and protein expression of Ca(2+)/calmodulin-activated AC isoforms in rat thalamus. Data from WAG/Rij were compared to those from non-epileptic controls (August-Copenhagen Irish rats) to elucidate whether differential expression of ACs contributes to the dysregulation of thalamocortical activity. At one postnatal stage (P21), we found the gene expression of two specific Ca(2+)-activated AC isoforms (AC-1 and AC-3) to be significantly down-regulated in epileptic tissue, and we identified the isoform AC-1 to be the most prominent one in both strains. However, Western blot data and analysis of enzymatic AC activity revealed no differences between the two strains. While basal AC activity was low, cAMP production was boosted by application of a forskolin derivative up to sevenfold. Despite previous hints pointing to a major contribution of ACs, the presented data show that there is no apparent causality between AC activity and the occurrence of the epileptic phenotype.
Asunto(s)
Adenilil Ciclasas/genética , Epilepsia Tipo Ausencia/enzimología , Epilepsia Tipo Ausencia/genética , Tálamo/enzimología , Tálamo/fisiología , Adenilil Ciclasas/metabolismo , Animales , Corteza Cerebral/citología , Corteza Cerebral/enzimología , AMP Cíclico/metabolismo , Modelos Animales de Enfermedad , Epilepsia Tipo Ausencia/fisiopatología , Regulación Enzimológica de la Expresión Génica/fisiología , Vías Nerviosas/citología , Vías Nerviosas/enzimología , Fenotipo , Ratas , Ratas Endogámicas , Ratas Mutantes , Tálamo/citologíaRESUMEN
Hyperthyroidism is characterized in rats by increased energy expenditure and marked hyperphagia. Alterations of thermogenesis linked to hyperthyroidism are associated with dysregulation of hypothalamic AMPK and fatty acid metabolism; however, the central mechanisms mediating hyperthyroidism-induced hyperphagia remain largely unclear. Here, we demonstrate that hyperthyroid rats exhibit marked up-regulation of the hypothalamic mammalian target of rapamycin (mTOR) signalling pathway associated with increased mRNA levels of agouti-related protein (AgRP) and neuropeptide Y (NPY), and decreased mRNA levels of pro-opiomelanocortin (POMC) in the arcuate nucleus of the hypothalamus (ARC), an area where mTOR co-localizes with thyroid hormone receptor-α (TRα). Central administration of thyroid hormone (T3) or genetic activation of thyroid hormone signalling in the ARC recapitulated hyperthyroidism effects on feeding and the mTOR pathway. In turn, central inhibition of mTOR signalling with rapamycin in hyperthyroid rats reversed hyperphagia and normalized the expression of ARC-derived neuropeptides, resulting in substantial body weight loss. The data indicate that in the hyperthyroid state, increased feeding is associated with thyroid hormone-induced up-regulation of mTOR signalling. Furthermore, our findings that different neuronal modulations influence food intake and energy expenditure in hyperthyroidism pave the way for a more rational design of specific and selective therapeutic compounds aimed at reversing the metabolic consequences of this disease.
Asunto(s)
Ingestión de Alimentos , Conducta Alimentaria , Hiperfagia/etiología , Hipertiroidismo/complicaciones , Hipotálamo/enzimología , Transducción de Señal , Serina-Treonina Quinasas TOR/metabolismo , Proteínas Quinasas Activadas por AMP/metabolismo , Proteína Relacionada con Agouti/genética , Animales , Modelos Animales de Enfermedad , Ingestión de Alimentos/efectos de los fármacos , Conducta Alimentaria/efectos de los fármacos , Hiperfagia/enzimología , Hiperfagia/genética , Hiperfagia/fisiopatología , Hiperfagia/prevención & control , Hipertiroidismo/inducido químicamente , Hipertiroidismo/enzimología , Hipertiroidismo/genética , Hipertiroidismo/fisiopatología , Hipotálamo/efectos de los fármacos , Hipotálamo/fisiopatología , Masculino , Vías Nerviosas/efectos de los fármacos , Vías Nerviosas/enzimología , Neuropéptido Y/genética , Fosforilación , Proopiomelanocortina/genética , Inhibidores de Proteínas Quinasas/farmacología , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacos , Sirolimus/farmacología , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Receptores alfa de Hormona Tiroidea/metabolismo , Factores de Tiempo , Triyodotironina , Pérdida de PesoRESUMEN
It is considered that hypothalamus is important in the regulation of the blood glucose, but how chronic stress leads to hyperglycemia is not known. In this experiment, we used chronic immobilization stress rat as a model, and observed that only rats with increased expression of GAD65 in the amygdala had an elevated level of blood glucose. Considering there are fiber tracks between the amygdala and hypothalamus, some of which are GABAergic, this result may indicate that the change of GAD65 expression in the amygdala may be related to changes in blood glucose levels. Therefore, the amygdala may be involved in the hyperglycemic response to stress.
Asunto(s)
Amígdala del Cerebelo/enzimología , Glucemia/fisiología , Diabetes Mellitus Tipo 2/fisiopatología , Glutamato Descarboxilasa/biosíntesis , Hiperglucemia/fisiopatología , Hipotálamo/metabolismo , Estrés Psicológico/fisiopatología , Regulación hacia Arriba/fisiología , Amígdala del Cerebelo/fisiopatología , Animales , Enfermedad Crónica , Diabetes Mellitus Tipo 2/enzimología , Diabetes Mellitus Tipo 2/etiología , Modelos Animales de Enfermedad , Glutamato Descarboxilasa/fisiología , Hiperglucemia/enzimología , Hiperglucemia/etiología , Hipotálamo/enzimología , Hipotálamo/fisiopatología , Inmovilización/efectos adversos , Masculino , Vías Nerviosas/enzimología , Vías Nerviosas/fisiopatología , Ratas , Ratas Sprague-Dawley , Estrés Psicológico/enzimología , Estrés Psicológico/metabolismoRESUMEN
Leptin signaling in the hypothalamus is obligatory for normal food intake and body weight homeostasis. It is now well established that besides the signal transducer and activator of transcription-3 (STAT3) pathway, several non-STAT3 pathways mediate leptin signaling in the hypothalamus. We have previously demonstrated that leptin stimulates phosphodiesterase-3B (PDE3B) activity in the hypothalamus, and PDE3 inhibitor cilostamide reverses anorectic and bodyweight reducing effects of leptin. Recently, we have demonstrated that cilostamide reversed the leptin-induced increase in proopiomelanocortin (POMC) gene expression in the hypothalamus. Because POMC and neuropeptide Y (NPY) neurons are thought to be the major targets of leptin signaling in the hypothalamus, to establish the physiological role of the PDE3B pathway it is important to demonstrate if PDE3B is expressed in these neurons. To this end we examined co-localization of PDE3B with POMC and NPY neurons using immunocytochemistry in POMC-GFP and NPY-GFP mice, respectively. Results showed that PDE3B was highly localized throughout the various hypothalamic sites including the arcuate nucleus (ARC), ventromedial nucleus, dorsomedial nucleus, ventral premammillary nucleus, paraventricular nucleus, and lateral hypothalamus. Importantly, almost all NPY (91.7%) and POMC (97.7%) neurons co-expressed PDE3B. These results suggest a direct role of the PDE3B pathway in mediating leptin signaling in the POMC and NPY neurons-a potential mechanism of leptin signaling in the hypothalamus.
Asunto(s)
Fosfodiesterasas de Nucleótidos Cíclicos Tipo 3/biosíntesis , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 3/genética , Hipotálamo/enzimología , Neuronas/enzimología , Neuropéptido Y/biosíntesis , Proopiomelanocortina/biosíntesis , Animales , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 3/fisiología , Regulación de la Expresión Génica/genética , Hipotálamo/metabolismo , Leptina/genética , Leptina/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Vías Nerviosas/enzimología , Neuronas/metabolismo , Neuropéptido Y/genética , Proopiomelanocortina/genética , Transducción de Señal/genéticaRESUMEN
Long-term potentiation (LTP) at thalamic input synapses to the lateral nucleus of the amygdala (LA) has been proposed as a cellular mechanism of the formation of auditory fear memories. We have previously shown that signaling via ERK/MAPK in both the LA and the medial division of the medial geniculate nucleus/posterior intralaminar nucleus (MGm/PIN) is critical for LTP at thalamo-LA synapses. Here, we show that LTP-inducing stimulation of thalamo-LA inputs regulates the activation of ERK and the expression of ERK-driven immediate early genes (IEGs) in both the LA and MGm/PIN. Further, we show that pharmacological blockade of NMDAR-driven synaptic plasticity, NOS activation, or PKG signaling in the LA significantly impairs high-frequency stimulation-(HFS-) induced ERK activation and IEG expression in both regions, while blockade of extracellular NO signaling in the LA impairs HFS-induced ERK activation and IEG expression exclusively in the MGm/PIN. These findings suggest that NMDAR-driven synaptic plasticity and NO-cGMP-PKG signaling within the LA coordinately regulate ERK-driven gene expression in both the LA and the MGm/PIN following LTP induction at thalamo-LA synapses, and that synaptic plasticity in the LA promotes ERK-driven transcription in MGm/PIN neurons via NO-driven "retrograde signaling".
Asunto(s)
Amígdala del Cerebelo/enzimología , Proteínas Quinasas Dependientes de GMP Cíclico/fisiología , Quinasas MAP Reguladas por Señal Extracelular/genética , Potenciación a Largo Plazo/fisiología , Óxido Nítrico/fisiología , Transducción de Señal/fisiología , Tálamo/enzimología , Amígdala del Cerebelo/fisiología , Animales , GMP Cíclico/fisiología , Estimulación Eléctrica/métodos , Regulación Enzimológica de la Expresión Génica/fisiología , Potenciación a Largo Plazo/genética , Masculino , Vías Nerviosas/enzimología , Vías Nerviosas/fisiología , Ratas , Ratas Sprague-Dawley , Transducción de Señal/genética , Transmisión Sináptica/genética , Tálamo/fisiologíaRESUMEN
Ascending sensory information flowing through the visual thalamus is dynamically regulated by a number of modulatory influences. An important part of this ascending modulation is a cholinergic projection from the parabrachial region of the brainstem (PBR). In addition to containing cholinergic fibers, this projection has been identified in some species as the exclusive extrinsic source of fibers containing the neuronal form of nitric oxide synthase (nNOS). In this study, we examined the nitrergic innervation to the adult mouse visual thalamus. Retrograde tract-tracing with fluorescent microspheres was combined with nNOS and choline acetyltransferase (ChAT) immunocytochemistry, and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry to identify the source of nitrergic innervation. Double-labeling revealed that only two regions of the mouse brain contained nitrergic neurons that projected to the visual thalamus: the pedunculopontine tegmentum and, to a lesser extent, the lateral dorsal tegmentum (LDT). Though the LDT projected heavily to the mouse visual thalamus, very few of the retrogradely labeled neurons in that region colocalized NADPH-d. These observations suggest that the parabrachial brainstem region is the primary source of nitrergic fibers in the mouse visual thalamus, similar to that found in cat and monkey. Such similarity suggests that the presence of nNOS in presynaptic terminal fields of the visual thalamus is an important conserved property of thalamic physiology and that the mouse is a valid model for studies of nNOS functions in the brain.
Asunto(s)
Tronco Encefálico/citología , Vías Nerviosas/citología , Óxido Nítrico Sintasa/metabolismo , Tálamo/citología , Animales , Tronco Encefálico/enzimología , Colina O-Acetiltransferasa/metabolismo , Técnica del Anticuerpo Fluorescente , Inmunohistoquímica , Ratones , NADPH Deshidrogenasa/metabolismo , Vías Nerviosas/enzimología , Tálamo/enzimologíaRESUMEN
Experimental evidence from mutant or genetically altered mice indicates that the formation of barrels and the proper maturation of thalamocortical (TC) synapses in the primary somatosensory (barrel) cortex depend on mechanisms mediated by neural activity. Type 1 adenylyl cyclase (AC1), which catalyzes the formation of cAMP, is stimulated by increases in intracellular Ca(2+) levels in an activity-dependent manner. The AC1 mutant mouse, barrelless (brl), lacks typical barrel cytoarchitecture, and displays presynaptic and postsynaptic functional defects at TC synapses. However, because AC1 is expressed throughout the trigeminal pathway, the barrel cortex phenotype of brl mice may be a consequence of AC1 disruption in cortical or subcortical regions. To examine the role of cortical AC1 in the development of morphological barrels and TC synapses, we generated cortex-specific AC1 knock-out (CxAC1KO) mice. We found that neurons in layer IV form grossly normal barrels and TC axons fill barrel hollows in CxAC1KO mice. In addition, whisker lesion-induced critical period plasticity was not impaired in these mice. However, we found quantitative reductions in the quality of cortical barrel cytoarchitecture and dendritic asymmetry of layer IV barrel neurons in CxAC1KO mice. Electrophysiologically, CxAC1KO mice have deficits in the postsynaptic but not in the presynaptic maturation of TC synapses. These results suggest that activity-dependent postsynaptic AC1-cAMP signaling is required for functional maturation of TC synapses and the development of normal barrel cortex cytoarchitecture. They also suggest that the formation of the gross morphological features of barrels is independent of postsynaptic AC1 in the barrel cortex.
Asunto(s)
Adenilil Ciclasas/biosíntesis , Corteza Cerebral/enzimología , Corteza Cerebral/crecimiento & desarrollo , Sinapsis/fisiología , Tálamo/enzimología , Tálamo/crecimiento & desarrollo , Adenilil Ciclasas/genética , Animales , Corteza Cerebral/ultraestructura , Potenciales Postsinápticos Excitadores/genética , Potenciales Postsinápticos Excitadores/fisiología , Femenino , Masculino , Ratones , Ratones Noqueados , Ratones Mutantes , Vías Nerviosas/enzimología , Vías Nerviosas/ultraestructura , Plasticidad Neuronal/genética , Plasticidad Neuronal/fisiología , Sinapsis/genética , Sinapsis/ultraestructura , Tálamo/ultraestructuraRESUMEN
Subthalamic stimulation enhances striatal tyrosine hydroxylase activity, which is regulated by phosphorylation at different serine residues. Western blotting was performed to investigate phosphorylation at the serine residues 19, 31 and 40 in striatal tissue of rats that had received subthalamic stimulation or sham stimulation for 2 h. In animals that were killed directly after stimulation, the tyrosine hydroxylase protein content was unchanged, whereas phosphorylation at the serine residue 19 was increased and phosphorylation at the serine residues 31 and 40 tended to be higher compared with controls. By contrast, tyrosine hydroxylase protein content and phosphorylation were similar in rats that were killed 24 h after stimulation. Our results suggest that subthalamic stimulation may increase tyrosine hydroxylase activity via increased phosphorylation.
Asunto(s)
Cuerpo Estriado/enzimología , Dopamina/biosíntesis , Núcleo Subtalámico/enzimología , Tirosina 3-Monooxigenasa/metabolismo , Secuencia de Aminoácidos/fisiología , Animales , Sitios de Unión , Cuerpo Estriado/anatomía & histología , Estimulación Eléctrica , Terapia por Estimulación Eléctrica , Masculino , Vías Nerviosas/anatomía & histología , Vías Nerviosas/enzimología , Enfermedad de Parkinson/enzimología , Enfermedad de Parkinson/fisiopatología , Enfermedad de Parkinson/terapia , Fosforilación , Ratas , Ratas Wistar , Serina/metabolismo , Núcleo Subtalámico/anatomía & histología , Tirosina 3-Monooxigenasa/química , Regulación hacia Arriba/fisiologíaRESUMEN
Our recent data, obtained using a zymosan-induced inflammatory air pouch model in mice, have demonstrated that subcutaneous bee venom (BV) injection into the hind limb selectively activates the contralateral brain stem locus coeruleus (LC) and then via a descending noradrenergic pathway and subsequent adrenal medullary catecholamine release induces a potent anti-inflammatory effect. While the efferent limb of this BV-induced neuroimmune anti-inflammatory pathway is well documented, the afferent limb of this pathway is poorly understood. In particular the spinal mechanisms involved with BV activation of the LC are currently unknown. Spinal nitric oxide (NO) and its synthase (NOS) have been shown to play an important role in the transmission and amplification of neuronal information from the spinal cord to the brain stem. In the present study we evaluated whether spinal NO plays a role in BV-induced LC activation, since we have previously shown that LC activation underlies this 'BV-induced anti-inflammatory effect' (BVAI) using the mouse air pouch model. Intrathecal (i.t.) pretreatment with l-nitro arginine methyl ester (l-NAME, non-selective NOS inhibitor), hemoglobin (NO scavenger) or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, soluble guanylate cyclase inhibitor) abolished BVAI on zymosan-induced leukocyte migration into the air pouch. Moreover, i.t. injection of l-N-iminoethyl-lysine (l-NIL, inducible NOS inhibitor), but not 7-nitroindazole (7-NI, neuronal NOS inhibitor), also inhibited BVAI. BV injection significantly increased both the number of Fos immunoreactive neurons and tyrosine hydroxylase-Fos double labeling neurons in the contralateral LC in zymosan-induced inflamed mice. Importantly this increase in Fos expression in the LC was also completely inhibited by i.t. injection of l-NIL, but not by i.t. injection of 7-NI. Collectively these results indicate that spinal NO generated from inducible NOS is involved in the BV-induced LC activation that underlies BVAI.
Asunto(s)
Antiinflamatorios/uso terapéutico , Venenos de Abeja/uso terapéutico , Locus Coeruleus/enzimología , Óxido Nítrico/metabolismo , Enfermedades del Sistema Nervioso Periférico/tratamiento farmacológico , Médula Espinal/enzimología , Animales , Modelos Animales de Enfermedad , Interacciones Farmacológicas , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Indazoles/farmacología , Leucocitos/efectos de los fármacos , Locus Coeruleus/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos ICR , NG-Nitroarginina Metil Éster/farmacología , Vías Nerviosas/efectos de los fármacos , Vías Nerviosas/enzimología , Proteínas Oncogénicas v-fos/metabolismo , Médula Espinal/efectos de los fármacos , Tirosina 3-Monooxigenasa/metabolismoRESUMEN
Nitric oxide (NO) within the brain is known to have an important influence on sympathetic nerve activity (SNA). NO is found in the paraventricular nucleus (PVN), caudal ventrolateral medulla (CVLM) and the nucleus tractus solitarius (NTS), regions that project to the rostral ventrolateral medulla (RVLM), an area that is critical in the regulation of SNA. The aim of the present study was to determine whether neurons in the PVN, NTS and CVLM that project to the RVLM contain the neuronal isoform of nitric oxide synthase (nNOS) and are, therefore, capable of producing NO. Under pentobarbitone general anaesthesia, the retrogradely-transported tracer, rhodamine-tagged microspheres, were microinjected into the RVLM of rats (n = 6). Two weeks later, the animals were re-anaesthetised, perfused with para-formaldehyde and the brains were removed. Hypothalamic and medullary sections were processed for nNOS immunohistochemistry and the RVLM-projecting neurons were identified using fluorescence microscopy. We found nNOS-containing neurons were present throughout the PVN, CVLM and NTS and that these were intermingled with neurons that projected to the RVLM. Of the neurons in the PVN and CVLM that projected to the RVLM, approximately 12 +/- 1% and 8 +/- 3%, respectively, contained nNOS. In the NTS only 1 +/- 1% of the neurons were double-labeled. This study highlights anatomical pathways emanating from the PVN and CVLM, in particular, which may contribute to the effects on SNA elicited by NO within the brain.
Asunto(s)
Hipotálamo/citología , Bulbo Raquídeo/citología , Proteínas del Tejido Nervioso/metabolismo , Neuronas/enzimología , Óxido Nítrico Sintasa/metabolismo , Animales , Hipotálamo/enzimología , Procesamiento de Imagen Asistido por Computador , Inmunohistoquímica , Masculino , Bulbo Raquídeo/enzimología , Vías Nerviosas/citología , Vías Nerviosas/enzimología , Óxido Nítrico Sintasa de Tipo I , Núcleo Hipotalámico Paraventricular/citología , Núcleo Hipotalámico Paraventricular/enzimología , Ratas , Ratas Sprague-Dawley , Núcleo Solitario/citología , Núcleo Solitario/enzimología , Fijación del TejidoRESUMEN
Neurosteroids are steroids produced within the nervous system. Based on behavioural responses evoked in animals by synthetic steroid injections, several studies suggested neurosteroid involvement in important neurophysiological processes. These observations should be correlated only to neuroactive effects of the injected steroids. Neurosteroids mostly control the CNS activity through allosteric modulation of neurotransmitter receptors within concentration ranges used by neurotransmitters themselves. Therefore, neurosteroid production within pathways controlling a neurophysiological process is necessary to consider neurosteroid involvement in that process. Because of the increasing speculation about pain modulation by neurosteroids based on pharmacological observations, we decided to clarify the situation by investigating neurosteroidogenesis occurrence in sensory pathways, particularly in nociceptive structures. We studied the presence and activity of cytochrome P450side chain cleavage (P450scc) in rat pain pathways. P450scc-immunoreactive cells were localized in dorsal root ganglia (DRG), spinal cord (SC) dorsal horn, nociceptive supraspinal nuclei (SSN) and somatosensory cortex. Incubation of DRG, SSN or SC tissue homogenates with [3H]cholesterol yielded the formation of radioactive metabolites including [3H]pregnenolone of which the synthesis was reduced in presence of aminogluthetimide, a P450scc inhibitor. These first neuroanatomical and neurochemical results demonstrate the occurrence of neurosteroidogenesis in nociceptive pathways and strongly suggest that neurosteroids may control pain mechanisms.
Asunto(s)
Enzima de Desdoblamiento de la Cadena Lateral del Colesterol/metabolismo , Vías Nerviosas/enzimología , Neuronas Aferentes/enzimología , Animales , Tronco Encefálico/citología , Tronco Encefálico/enzimología , Colesterol/metabolismo , Enzima de Desdoblamiento de la Cadena Lateral del Colesterol/análisis , Enzima de Desdoblamiento de la Cadena Lateral del Colesterol/antagonistas & inhibidores , Inhibidores Enzimáticos/farmacología , Femenino , Ganglios Espinales/citología , Ganglios Espinales/enzimología , Inmunohistoquímica , Masculino , Vías Nerviosas/citología , Neuronas Aferentes/citología , Especificidad de Órganos , Pregnenolona/análisis , Pregnenolona/biosíntesis , Ratas , Ratas Sprague-Dawley , Corteza Somatosensorial/citología , Corteza Somatosensorial/enzimología , Médula Espinal/citología , Médula Espinal/enzimología , Tálamo/citología , Tálamo/enzimología , TritioRESUMEN
The mechanisms generating precise connections between specific thalamic nuclei and cortical areas remain poorly understood. Using axon tracing analysis of ephrin/Eph mutant mice, we provide in vivo evidence that Eph receptors in the thalamus and ephrins in the cortex control intra-areal topographic mapping of thalamocortical (TC) axons. In addition, we show that the same ephrin/Eph genes unexpectedly control the inter-areal specificity of TC projections through the early topographic sorting of TC axons in an intermediate target, the ventral telencephalon. Our results constitute the first identification of guidance cues involved in inter-areal specificity of TC projections and demonstrate that the same set of mapping labels is used differentially for the generation of topographic specificity of TC projections between and within individual cortical areas.
Asunto(s)
Corteza Cerebral/metabolismo , Efrina-A4/genética , Efrina-A5/genética , Receptor EphA4/genética , Receptor EphA5/genética , Tálamo/metabolismo , Animales , Mapeo Encefálico/métodos , Corteza Cerebral/embriología , Corteza Cerebral/enzimología , Efrina-A4/biosíntesis , Efrina-A4/fisiología , Efrina-A5/biosíntesis , Efrina-A5/fisiología , Femenino , Ligandos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Vías Nerviosas/embriología , Vías Nerviosas/enzimología , Vías Nerviosas/metabolismo , Vías Nerviosas/fisiología , Receptor EphA4/biosíntesis , Receptor EphA4/fisiología , Receptor EphA5/biosíntesis , Receptor EphA5/fisiología , Tálamo/embriología , Tálamo/enzimologíaRESUMEN
Adenylyl cyclase types 1 (AC1) and 8 (AC8), the two major calmodulin-stimulated adenylyl cyclases in the brain, couple NMDA receptor activation to cAMP signaling pathways. Cyclic AMP signaling pathways are important for many brain functions, such as learning and memory, drug addiction, and development. Here we show that wild-type, AC1, AC8, or AC1&8 double knockout (DKO) mice were indistinguishable in tests of acute pain, whereas behavioral responses to peripheral injection of two inflammatory stimuli, formalin and complete Freund's adjuvant, were reduced or abolished in AC1&8 DKO mice. AC1 and AC8 are highly expressed in the anterior cingulate cortex (ACC), and contribute to inflammation-induced activation of CREB. Intra-ACC administration of forskolin rescued behavioral allodynia defective in the AC1&8 DKO mice. Our studies suggest that AC1 and AC8 in the ACC selectively contribute to behavioral allodynia.
Asunto(s)
Adenilil Ciclasas/deficiencia , Encéfalo/enzimología , Calmodulina/metabolismo , AMP Cíclico/metabolismo , Hiperalgesia/genética , Vías Nerviosas/enzimología , Dolor/genética , Adenilil Ciclasas/genética , Animales , Conducta Animal/fisiología , Encéfalo/fisiopatología , AMP Cíclico/análogos & derivados , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Inhibidores Enzimáticos/farmacología , Antagonistas de Aminoácidos Excitadores/farmacología , Adyuvante de Freund , Hiperalgesia/enzimología , Hiperalgesia/fisiopatología , Masculino , Ratones , Ratones Noqueados , Vías Nerviosas/fisiopatología , Dolor/enzimología , Dolor/fisiopatología , Dimensión del Dolor , ARN Mensajero/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismoRESUMEN
The nigro-collicular pathway that links the basal ganglia to the sensorimotor layers of superior colliculus plays a crucial role in promoting orienting behaviors. This connection originating in the pars reticulata and lateralis of the substantia nigra has been shown in rat and cat to be topographically organized. In rat, a functional compartmentalization of the substantia nigra has also been shown reflecting that of the striatum. In light of this, we reinvestigated the topographical arrangement of the nigro-collicular pathway by examining the innervation of each nigral functional zone. We performed small injections of either biocytin or wheatgerm agglutinin conjugated with horseradish peroxidase restricted to identified somatic, visual and auditory nigral zones. Frontally cut sections showed that innervations provided by the three main nigral zones form a mosaic of complementary domains stratified from the stratum opticum to the ventral part of the intermediate collicular layers, with the somatic afferents sandwiched between the visual and the auditory ones. When reconstructed from semi-horizontal sections, nigral innervations organized in the form of a honeycomb-like array composed of 100 cylindrical modules covering three-quarters of the collicular surface. Such a modular architecture is reminiscent of the acetylcholinesterase lattice we previously described in rat intermediate collicular layers. In the enzyme lattice, the surroundings of the cylindrical modules are composed of a mosaic of dense and diffuse enzyme subdomains. Thus, we compared the distribution of the overall nigral projection and of its constituent channels with the acetylcholinesterase lattice. The procedure combined axonal labelling with histochemistry on single sections for acetylcholinesterase activity. The results demonstrate that the overall nigral projection overlaps the acetylcholinesterase lattice and its constituent channels converge with either the dense or the diffuse enzyme subdomains. The stereometric arrangement of the nigro-collicular pathway is suggestive of an architecture promoting the selection of collicular motor programs for different classes of orienting behavior.
Asunto(s)
Acetilcolinesterasa/metabolismo , Tipificación del Cuerpo/fisiología , Lisina/análogos & derivados , Vías Nerviosas/citología , Orientación/fisiología , Terminales Presinápticos/ultraestructura , Sustancia Negra/citología , Colículos Superiores/citología , Acetilcolina/metabolismo , Animales , Vías Auditivas/citología , Vías Auditivas/enzimología , Percepción Auditiva/fisiología , Histocitoquímica , Lisina/farmacocinética , Masculino , Sondas Moleculares/farmacocinética , Vías Nerviosas/enzimología , Terminales Presinápticos/enzimología , Desempeño Psicomotor/fisiología , Ratas , Ratas Sprague-Dawley , Sustancia Negra/enzimología , Colículos Superiores/enzimología , Vías Visuales/citología , Vías Visuales/enzimología , Aglutinina del Germen de Trigo-Peroxidasa de Rábano Silvestre Conjugada/farmacocinéticaRESUMEN
We examined protein kinase C gamma-like immunoreactivity (PKCgamma-LI) of trigeminothalamic neurons in the rat medullary dorsal horn (MDH) after injecting a retrograde tracer, Fluoro-Gold (FG), into the thalamus. Over 90% of FG-labeled neurons in the marginal layer (lamina I) and a few FG-labeled neurons in the superficial part of the magnocellular layer (lamina III) showed PKCgamma-LI. No PKCgamma-neurons in the substantia gelatinosa (lamina II) were labeled with FG. PKCgamma-mediated regulation of trigeminothalamic neurons may contribute to the changes in MDH activity during persistent pain.
Asunto(s)
Isoenzimas/metabolismo , Vías Nerviosas/enzimología , Neuronas/enzimología , Dolor/enzimología , Proteína Quinasa C/metabolismo , Transducción de Señal/fisiología , Tálamo/enzimología , Núcleo Caudal del Trigémino/enzimología , Animales , Recuento de Células , Inmunohistoquímica , Núcleos Talámicos Intralaminares/citología , Núcleos Talámicos Intralaminares/enzimología , Masculino , Núcleos Talámicos de la Línea Media/citología , Núcleos Talámicos de la Línea Media/enzimología , Vías Nerviosas/citología , Neuronas/citología , Dolor/fisiopatología , Núcleos Talámicos Posteriores/citología , Núcleos Talámicos Posteriores/enzimología , Ratas , Ratas Sprague-Dawley , Receptores de Neuroquinina-1/metabolismo , Sustancia P/metabolismo , Sustancia Gelatinosa/citología , Sustancia Gelatinosa/enzimología , Transmisión Sináptica/fisiología , Tálamo/citología , Núcleo Caudal del Trigémino/citología , Núcleos Talámicos Ventrales/citología , Núcleos Talámicos Ventrales/enzimologíaRESUMEN
Previously, we demonstrated that exposure to morphine during gestation increases hypothalamic norepinephrine (NE) content and turnover rate in adult male rats and decreases these measures in adult females. To investigate the basis of these alterations, the present study examined the effects of prenatal exposure to morphine on tyrosine hydroxylase immunoreactivity (TH-IR) in the brains of adult male and female progeny. In male rats, prenatal morphine exposure significantly increased the density of TH-IR in cells and fibers in the caudal paraventricular nucleus of the hypothalamus (PVN) and locus coeruleus (LC), but had no effects in the lateral hypothalamus (LH). In female rats that were ovariectomized (OVX), prenatal morphine exposure significantly decreased the density of TH-IR in cells and fibers in the LC. Interestingly, an injection of estrogen in OVX control females reduced the mean optical density of TH-IR in the LC, but it was ineffective in drug-exposed females in the same brain region. Estrogen injections also reduced the mean optical density of TH-IR in the LH but not in the PVN of females, regardless of prenatal drug exposure. Thus, the present study suggests that prenatal morphine exposure induces long-term, sex-specific alterations in TH-IR in the PVN and LC of adult progeny.
Asunto(s)
Encéfalo/enzimología , Morfina/farmacología , Narcóticos/farmacología , Efectos Tardíos de la Exposición Prenatal , Estrés Fisiológico/enzimología , Tirosina 3-Monooxigenasa/metabolismo , Animales , Estradiol/farmacología , Femenino , Hipotálamo/enzimología , Locus Coeruleus/enzimología , Masculino , Vías Nerviosas/enzimología , Ovariectomía , Embarazo , Ratas , Ratas Sprague-Dawley , Distribución TisularRESUMEN
The thalamic connectivity and basal forebrain cholinergic input to the posterior parietal cortex (PPC) of Long-Evans rats was examined using combined retrograde tracing and immunocytochemical methods. As in previous studies, the PPC could be distinguished by its input from the lateral posterior, lateral dorsal, and posterior nuclei of the thalamus, but not the lateral geniculate nucleus or ventrobasal complex. These nuclei were also observed to receive reciprocal projections from the ipsilateral PPC. Cholinergic neurons innervating the PPC were primarily localized to the substantia innominata/nucleus basalis region. The implications of these data for possible functions of the cholinergic input to PPC are discussed.
Asunto(s)
Colina O-Acetiltransferasa/metabolismo , Lóbulo Parietal/fisiología , Prosencéfalo/fisiología , Núcleos Talámicos/fisiología , Animales , Lóbulo Frontal/citología , Lóbulo Frontal/fisiología , Masculino , Sondas Moleculares , Vías Nerviosas/enzimología , Vías Nerviosas/fisiología , Neuronas/enzimología , Neuronas/fisiología , Lóbulo Parietal/citología , Prosencéfalo/citología , Prosencéfalo/enzimología , Ratas , Ratas Long-Evans , Núcleos Talámicos/citología , Núcleos Talámicos/enzimología , Aglutinina del Germen de Trigo-Peroxidasa de Rábano Silvestre ConjugadaRESUMEN
The retrograde tracer fluoro-gold was injected into the periaqueductal grey, thalamus or hypothalamus, and spinal cord sections were processed for neuronal nitric oxide synthase (nNOS) immunohistochemistry to investigate the relationships of nNOS immunoreactive, and spinomesencephalic, spinothalamic and spinohypothalamic projection neurones. In addition, in the lateral spinal nucleus the relationship between spinomesencephalic, -thalamic and -hypothalamic projection neurones, and nNOS and interferon-gamma receptor immunoreactive structures was investigated at the lumbar level. No single retrogradely labelled spinomesencephalic, -thalamic or -hypothalamic neurone showed nNOS immunoreactivity. In the lateral spinal nucleus, however, many fluoro-gold-labelled neurones were closely apposed by both nNOS and interferon-gamma receptor immunoreactive structures, especially prominent in the hypothalamic injection cases. This study gave no evidence for nNOS immunoreactivity in spinal neurones projecting to the periaqueductal grey, thalamus or hypothalamus, but suggests that in the lateral spinal nucleus such neurones are contacted by both nNOS- and interferon-gamma receptor-containing axon terminals.
Asunto(s)
Hipotálamo/metabolismo , Óxido Nítrico Sintasa/metabolismo , Sustancia Gris Periacueductal/metabolismo , Receptores de Interferón/metabolismo , Médula Espinal/metabolismo , Estilbamidinas , Tálamo/metabolismo , Animales , Transporte Axonal/fisiología , Colorantes Fluorescentes/farmacocinética , Hipotálamo/citología , Inmunohistoquímica , Masculino , Vías Nerviosas/enzimología , Vías Nerviosas/fisiología , Neuronas/citología , Neuronas/enzimología , Óxido Nítrico Sintasa de Tipo I , Sustancia Gris Periacueductal/citología , Ratas , Ratas Sprague-Dawley , Médula Espinal/citología , Tálamo/citología , Distribución Tisular , Receptor de Interferón gammaRESUMEN
Acetylcholinesterase (AChE) is transiently expressed in several immature axon systems. Its presence in developing thalamocortical afferents has led to the use of enzyme histochemistry to visualize this axon system in rats. Because of the spatiotemporal distribution of the enzyme in the rat neocortex, it has been suggested that AChE plays a role in the establishment of thalamocortical connectivity. We show here that AChE is distributed in a pattern that is markedly different in SI cortex of rats as compared to that of mice and hamsters. In rat pups, AChE-rich patches are distributed in a vibrissa-related array in the SI cortex soon after birth, whereas regions of cortex that lie between individual patches, and between rows of patches, are impoverished in the enzyme. In contrast, sections through flattened cortices from PND3 and older mice and hamsters reveal lightly stained AChE-positive spots in the center of barrel cores, while barrel walls remain devoid of AChE; septae that divide individual barrels are densely enzyme positive. Differences in laminar localization of the enzyme for all three species are also visible. In the thalamus of postnatal rats, both the ventral posterior medial (VPM) and ventral posterior lateral (VPL) nuclei express AChE, correlating with the presence of enzyme-containing patches throughout the barrelfield cortex. In the other two rodents, however, the enzyme is present in VPL but not in VPM, despite the fact that in these species the cortical barrels associated with both thalamic nuclei have very little of the enzyme. Thus, the relationship between the distribution of AChE in nuclei of the thalamic ventrobasal complex and the presence of AChE in the terminals of their cortical axons in the barrelfield is not consistent across different rodent species. Our results call for caution in the use of AChE histochemistry as a universal marker for immature thalamocortical axons, and challenge the generality of currently hypothesized roles for this transiently expressed enzyme during the development of the rodent thalamocortical projection.
Asunto(s)
Acetilcolinesterasa/biosíntesis , Corteza Somatosensorial/enzimología , Vibrisas/fisiología , Animales , Axones/enzimología , Carbocianinas , Cricetinae , Colorantes Fluorescentes , Histocitoquímica , Mesocricetus , Ratones , Vías Nerviosas/enzimología , Vías Nerviosas/crecimiento & desarrollo , Piamadre/enzimología , Ratas , Ratas Sprague-Dawley , Corteza Somatosensorial/crecimiento & desarrollo , Especificidad de la Especie , Tálamo/enzimología , Tálamo/crecimiento & desarrolloRESUMEN
The patterns of histochemical staining for acetylcholinesterase (AChE) activity in the macaque thalamus were analyzed and compared with the distribution of cells and terminals labeled from injections of axonal tracers in the dorsolateral and orbital prefrontal cortex, in area 7a of the posterior parietal cortex and in the polysensory cortex of the superior temporal sulcus. AChE histochemistry is very useful in delineating the thalamic nuclei connected with the association cortex and in uncovering thalamic subdivisions that are barely evident on cytoarchitectonic grounds. Moreover, AChE activity reveals previously unrecognized heterogeneities within several thalamic nuclei, like the ventral anterior (VA), where a new ventromedial subdivision (VAvm) is described, the medial pulvinar (PulM) or the mediodorsal nucleus (MD). In this nucleus three distinct chemical domains are present: the medial, ventral and lateral sectors characterized by low, moderate and high AChE activities, respectively. The staining pattern of the lateral sector is markedly heterogeneous with patches of intense AChE activity surrounded by a moderately stained matrix. The MD medial sector is connected with the orbitofrontal cortex, whereas the AChE-rich patches in the lateral sector are selectively connected with the dorsolateral prefrontal, parietal and temporal association cortices. In the PulM, a dorsomedial AChE-rich patch is selectively connected with the orbitofrontal cortex, whereas the surrounding territory, which shows moderate AChE activity, is preferentially connected with the parietal and temporal cortices. Chemically specific domains in the anterior, ventral anterior, midline, and intralaminar thalamic nuclei are also connected with the examined association cortices. These findings indicate that the topographic patterns of the thalamo-cortical connections of primate association areas conform to the chemical architecture of the thalamus. This implies that because each cortical area is connected to a particular set of thalamic regions, the influence of the thalamus on cortical function is exclusive for each area, highly diverse among the various association areas, and subject to a wide range of modulation at the thalamic level.