RESUMEN
BACKGROUND: Chronic alcohol intake produces multiple neuroadaptive changes, including up- and down-regulation of neuropeptides and receptors. There are widespread projections of relaxin-3 containing neurons to, and abundant relaxin family peptide 3 receptor (RXFP3) expression within, brain regions involved in modulating alcohol intake. Recently we demonstrated the involvement of relaxin-3/RXFP3 signalling in alcohol-seeking in rats; therefore in this study we examined whether relaxin-3 and/or RXFP3 expression were altered by chronic alcohol intake in alcohol-preferring iP rats. METHODS: Expression of relaxin-3 mRNA in the hindbrain nucleus incertus and RXFP3 radioligand binding levels in discrete forebrain regions were investigated following voluntary intake of alcohol or sucrose for 12 weeks, with a 2 day washout, using quantitative in situ hybridisation histochemistry and in vitro receptor autoradiography, respectively, in cohorts of adult, male iP rats. RESULTS: Levels of relaxin-3 mRNA in the hindbrain nucleus incertus were positively correlated with the level of intake of both alcohol (r(12)=0.59, p=0.03) and sucrose (r(7)=0.70, p=0.04) in iP rats. Dense binding of the RXFP3-selective radioligand, [(125)]-R3/I5, was detected in hypothalamic and extrahypothalamic sites, but no significant changes in the density of RXFP3 were observed in the brain regions quantified following chronic sucrose or ethanol intake. CONCLUSIONS: Our findings suggest high endogenous relaxin-3 expression may be associated with higher intake of rewarding substances, rather than its expression being regulated in response to their intake, consistent with an active role for the relaxin-3/RXFP3 system in modulating ingestive and alcohol-related behaviours.
Asunto(s)
Consumo de Bebidas Alcohólicas/genética , Ingestión de Alimentos/genética , ARN Mensajero/biosíntesis , Núcleos del Rafe/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores de Péptidos/genética , Consumo de Bebidas Alcohólicas/psicología , Animales , Ingestión de Líquidos/fisiología , Masculino , Ratas , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Péptidos/metabolismo , Rombencéfalo/efectos de los fármacos , Rombencéfalo/metabolismo , Sacarosa/farmacologíaRESUMEN
Corticotropin-releasing factor is a neuropeptide associated with the integration of physiological and behavioural responses to stress and also in the modulation of affective state and drug reward. The selective, centrally acting corticotropin-releasing factor type 1 receptor antagonist, antalarmin, is a potent anxiolytic and reduces volitional ethanol consumption in Fawn-Hooded rats. The efficacy of antalarmin to reduce ethanol consumption increased with time, suggestive of adaptation to reinforcement processes and goal-directed behaviour. The aim of the present study was to examine the effects of chronic antalarmin treatment on reward-related regions of Fawn-Hooded rat brain. Bi-daily antalarmin treatment (20 mg/kg, i.p.) for 10 days increased tyrosine hydroxylase messenger RNA expression throughout the ventral mesencephalon. Following chronic antalarmin the density of dopaminergic terminals within the basal ganglia and amygdaloid complex were reduced, as was dopamine transporter binding within the striatum. Receptor autoradiography indicated an up-regulation of dopamine D2, but no change in D1, binding in striatum, and Golgi-Cox analysis of striatal medium spiny neurones indicated that chronic antalarmin treatment increased spine density. Thus, chronic antalarmin treatment modulates dopaminergic pathways and implies that chronic treatment with drugs of this class may ultimately alter postsynaptic signaling mechanisms within the basal ganglia.
Asunto(s)
Encéfalo/efectos de los fármacos , Hormona Liberadora de Corticotropina/metabolismo , Dopamina/metabolismo , Pirimidinas/farmacología , Pirroles/farmacología , Receptores de Hormona Liberadora de Corticotropina/antagonistas & inhibidores , Recompensa , Amígdala del Cerebelo/efectos de los fármacos , Amígdala del Cerebelo/metabolismo , Animales , Ganglios Basales/efectos de los fármacos , Ganglios Basales/metabolismo , Encéfalo/metabolismo , Encéfalo/fisiopatología , Espinas Dendríticas/efectos de los fármacos , Espinas Dendríticas/metabolismo , Esquema de Medicación , Masculino , Mesencéfalo/efectos de los fármacos , Mesencéfalo/metabolismo , Vías Nerviosas/efectos de los fármacos , Vías Nerviosas/metabolismo , Terminales Presinápticos/efectos de los fármacos , Terminales Presinápticos/metabolismo , ARN Mensajero/efectos de los fármacos , ARN Mensajero/metabolismo , Ratas , Receptores de Hormona Liberadora de Corticotropina/metabolismo , Receptores de Dopamina D1/efectos de los fármacos , Receptores de Dopamina D1/metabolismo , Refuerzo en Psicología , Transmisión Sináptica/efectos de los fármacos , Transmisión Sináptica/fisiología , Tirosina 3-Monooxigenasa/genética , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/fisiologíaRESUMEN
Following partial substantia nigra lesions, remaining dopaminergic neurones sprout, returning terminal density in the dorsal striatum to normal by 16 weeks. This suggests regeneration and maintenance of terminal density is regulated to release appropriate levels of dopamine. This study examined the structure and function of these reinnervated terminals, defining characteristics of dopamine uptake and release, density and affinity of the dopamine transporter (DAT) and ultrastructural morphology of dopamine terminals in the reinnervated dorsal striatum. Finally, rotational behaviour of animals in response to amphetamine was examined 4 and 16 weeks after substantia nigra pars compacta (SNpc) lesions. Dopamine transport was markedly reduced 16 weeks after lesioning along with reduced density and affinity of DAT. Rate of dopamine release and peak concentration, measured electrochemically, was similar in lesioned and control animals, while clearance was prolonged after lesioning. Ultrastructurally, terminals after lesioning were morphologically distinct, having increased bouton size, vesicle number and mitochondria, and more proximal contacts on post-synaptic cells. After 4 weeks, tendency to rotate in response to amphetamine was proportional to lesion size. By 16 weeks, rotational behaviour returned to near normal in animals where lesions were less than 70%, although some animals demonstrated unusual rotational patterns at the beginning and end of the amphetamine effect. Together, these changes indicate that sprouted terminals are well compensated for dopamine release but that transport mechanisms are functionally impaired. We discuss these results in terms of implications for dyskinesia and other behavioural states.
Asunto(s)
Cuerpo Estriado/fisiología , Dopamina/metabolismo , Glicoproteínas de Membrana , Regeneración Nerviosa/fisiología , Proteínas del Tejido Nervioso , Terminales Presinápticos/fisiología , Terminales Presinápticos/ultraestructura , Sustancia Negra/fisiología , Anfetamina/farmacología , Animales , Conducta Animal/efectos de los fármacos , Unión Competitiva/efectos de los fármacos , Transporte Biológico/efectos de los fármacos , Recuento de Células , Cuerpo Estriado/ultraestructura , Agonistas de Dopamina/farmacología , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática , Inhibidores de Captación de Dopamina/farmacocinética , Inhibidores de Captación de Dopamina/farmacología , Electroquímica , Masculino , Mazindol/farmacocinética , Proteínas de Transporte de Membrana/metabolismo , Regeneración Nerviosa/efectos de los fármacos , Oxidopamina/farmacología , Quinpirol/farmacología , Ratas , Ratas Wistar , Sustancia Negra/efectos de los fármacos , Sinaptosomas/química , Sinaptosomas/efectos de los fármacos , Sinaptosomas/metabolismoRESUMEN
The present study employed standard peroxidase immunohistochemistry to map the distribution of P2Y(1) receptors in the rat brainstem and nodose ganglia and characterised the binding profile of [alpha(33)P]dATP. Binding of [alpha(33)P]dATP was fully displaceable by adenosine 5'-triphosphate (ATP), and was found on both human and rat nodose ganglia, and throughout the rat brainstem, including the nucleus tractus solitarius and ventrolateral medulla. [Alpha(33)P]dATP binding in the human nodose ganglia was significantly displaced by both 2-methylthio ATP and alpha,beta-methylene ATP, but not by uridine 5'-triphosphate, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid, 8,8'-(carbonylbis(imino-4,1-phenylenecarbonylimino-4,1-phenylenecarbonylimino))bis(1,3,5-naphtalenetrisulfonic) acid (NF279) or N-ethylcarboxamidoadenosine. [Alpha(33)P]dATP binding in the rat nodose ganglia and brainstem was significantly displaced by only 2-methylthio ATP, suggesting that [alpha(33)P]dATP is binding to P2Y receptors in the rat. Binding of [alpha(33)P]dATP was also significantly displaced by alpha,beta-methylene adenosine 5'-diphosphate, suggesting a component of the binding is to endogenous ecto-5'-nucleotidase, however, almost all binding could be displaced by a combination of receptor agonists (2-methylthio ATP, uridine 5'-triphosphate and alpha,beta-methylene ATP), suggesting preferential binding to receptors. Immunoreactivity to P2Y(1) receptor (P2Y(1)-IR) exhibited similar distribution patterns to [alpha(33)P]dATP binding, with a clear topographic profile. Particularly dense P2Y(1)-IR labeling was evident in cells and fibres of the dorsal vagal complex. Immunolabeling was also present in the dorsal motor nucleus of the vagus and nucleus ambiguus, indicating the possibility of P2Y(1) receptors on vagal efferents. Unilateral vagal ligation was also performed to examine the transport of P2Y(1) receptor, using both immunohistochemistry and [alpha(33)P]dATP autoradiography. Accumulations of both P2Y(1)-IR and [alpha(33)P]dATP binding were apparent adjacent to both ligatures, suggesting bi-directional transport of P2Y(1) receptors along the rat vagus nerve. This current study represents the first description of P2Y(1) receptor distribution within the rodent brainstem and nodose ganglion and also characterises [alpha(33)P]dATP binding to P2Y receptors.
Asunto(s)
Tronco Encefálico/metabolismo , Nucleótidos de Desoxiadenina/metabolismo , Ganglio Nudoso/metabolismo , Receptores Purinérgicos P2/metabolismo , Adolescente , Adulto , Anciano , Animales , Autorradiografía/métodos , Autorradiografía/estadística & datos numéricos , Tronco Encefálico/química , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Ganglio Nudoso/química , Radioisótopos de Fósforo/metabolismo , Ratas , Ratas Endogámicas WKY , Receptores Purinérgicos P2/análisis , Receptores Purinérgicos P2Y1RESUMEN
1. Novel analogues of antisauvagine-30 (aSvg-30), a selective antagonist for CRF(2) receptors, have been synthesized and characterized in vitro and in vivo. 2. The analogues were tested for their ability to compete for [(125)I-Tyr(0)]Svg binding and to inhibit Svg-stimulated adenylate cyclase activity in human embryonic kidney (HEK) 293 cells, permanently transfected with cDNA coding for the human CRF(1) (hCRF(1)), hCRF(2alpha) and hCRF(2beta) receptor. One analogue [D-Phe(11), His(12), Nle(17)]Svg(11-40), named K41498, showed high affinity binding to hCRF(2alpha) (K(i)=0.66+/-0.03 nM) and hCRF(2beta) (K(i)=0.62+/-0.01 nM) but not the hCRF(1) receptor (k(i)=425+50 nM) and decreased Svg-stimulated cAMP accumulation in hCRF(2) expressing cells. In conscious Wistar-Kyoto rats, K41498 (1.84 microg, i.v.) antagonized the hypotensive response to systemic urocortin (1.4 microg, i.v.), but did not block the pressor response to centrally administered urocortin (2.35 microg, i.c.v.). 3. K41498 was subsequently radio-iodinated, and in autoradiographic studies, specific (sensitive to rat urocortin, astressin and aSvg30, but insensitive to antalarmin) binding of (125)I-K41498 (100 pM) was detected in the heart and in selected brain regions including the nucleus tractus solitarius (NTS), spinal trigeminal nucleus, lateral septum and around the anterior and middle cerebral arteries. 4. Following unilateral nodose ganglionectomy, binding of (125)I-K41498 was reduced by 65% in the ipsilateral NTS, indicative of presynaptic CRF(2) receptors on vagal afferent terminals. 5. These data demonstrate that K41498 is a useful tool to study native CRF(2) receptors in the brain and periphery.
Asunto(s)
Fármacos Cardiovasculares/farmacología , Fármacos Cardiovasculares/farmacocinética , Fragmentos de Péptidos/metabolismo , Receptores de Hormona Liberadora de Corticotropina/metabolismo , Receptores Presinapticos/metabolismo , Secuencia de Aminoácidos , Proteínas Anfibias , Análisis de Varianza , Animales , Autorradiografía , Sitios de Unión , Unión Competitiva , Presión Sanguínea/efectos de los fármacos , Encéfalo/metabolismo , Línea Celular , AMP Cíclico/biosíntesis , Humanos , Técnicas In Vitro , Inyecciones Intravenosas , Masculino , Datos de Secuencia Molecular , Miocardio/metabolismo , Ganglio Nudoso/metabolismo , Fragmentos de Péptidos/farmacología , Hormonas Peptídicas , Ensayo de Unión Radioligante , Ratas , Ratas Endogámicas WKY , Receptores de Hormona Liberadora de Corticotropina/antagonistas & inhibidores , Receptores Presinapticos/antagonistas & inhibidoresRESUMEN
Hyperthermia during or after stroke is known to worsen neuronal damage. Paradoxically, when hyperthermia precedes stroke, it can protect against a subsequent ischemic insult. Other stressors including restraint also have a similar pre-conditioning effect. In the present study, we report the unanticipated finding that conscious rats, restrained for the purpose of intravenous infusion, had markedly reduced neuronal and functional deficits after middle cerebral artery occlusion compared with unrestrained rats. Restrained rats had significantly higher body temperature prior to stroke than unrestrained rats. The findings suggest restraint leading to mild hyperthermia may be sufficient to induce adaptive processes which protect against subsequent ischemia.
Asunto(s)
Isquemia Encefálica/fisiopatología , Hipertermia Inducida , Adaptación Fisiológica , Animales , Temperatura Corporal , Isquemia Encefálica/patología , Corteza Cerebral/patología , Infarto Cerebral/inducido químicamente , Infarto Cerebral/patología , Infarto Cerebral/fisiopatología , Cuerpo Estriado/patología , Endotelina-1 , Masculino , Actividad Motora , Ratas , Ratas Wistar , Restricción Física , Accidente Cerebrovascular/inducido químicamente , Accidente Cerebrovascular/patologíaRESUMEN
Indomethacin (2.8 mumol/l) did not consistently affect basal tone of sheep coronary artery strips, while a ten-fold higher concentration increased tension in 50% of the preparations tested. When acetylcholine was used as a spasmogen, oscillations in induced tone and relaxations produced by arachidonic acid (6.6 mumol/l) were abolished by indomethacin, 2.8 mumol/l and 7 mumol/l, respectively. Prostacyclin (PGI2) and prostaglandin E1 decreased and PGE2 increased arterial tension while PGF2 alpha was inactive. Responses to PGI2 were reduced by indomethacin (28 mumol/l) but not by indomethacin (2.8 mumol/l). It is suggested that sheep isolated coronary arteries synthesize and release prostacyclin in the presence of acetylcholine and arachidonic acid and that such synthesis can be inhibited by indomethacin.