RESUMEN
Previous studies in rodents have repeatedly demonstrated that the centrally-projecting Edinger-Westphal nucleus (EWcp) is highly sensitive to alcohol and is also involved in regulating alcohol intake and body temperature. Historically, the EWcp has been known as the main site of Urocortin 1 (Ucn1) expression, a corticotropin-releasing factor-related peptide, in the brain. However, the EWcp also contains other populations of neurons, including neurons that express the vesicular glutamate transporter 2 (Vglut2). Here we transduced the EWcp with adeno-associated viruses (AAVs) encoding Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) to test the role of the EWcp in alcohol drinking and in the regulation of body temperature. Activation of the EWcp with excitatory DREADDs inhibited alcohol intake in a 2-bottle choice procedure in male C57BL/6J mice, whereas inhibition of the EWcp with DREADDs had no effect. Surprisingly, analysis of DREADD expression indicated Ucn1-containing neurons of the EWcp did not express DREADDs. In contrast, AAVs transduced non-Ucn1-containing EWcp neurons. Subsequent experiments showed that the inhibitory effect of EWcp activation on alcohol intake was also present in male Ucn1 KO mice, suggesting that a Ucn1-devoid population of EWcp regulates alcohol intake. A final set of chemogenetic experiments showed that activation of Vglut2-expressing EWcp neurons inhibited alcohol intake and induced hypothermia in male and female mice. These studies expand on previous literature by indicating that a glutamatergic, Ucn1-devoid subpopulation of the EWcp regulates alcohol consumption and body temperature.
Asunto(s)
Temperatura Corporal/efectos de los fármacos , Drogas de Diseño/farmacología , Núcleo de Edinger-Westphal/efectos de los fármacos , Etanol/farmacología , Proteína 2 de Transporte Vesicular de Glutamato/efectos de los fármacos , Consumo de Bebidas Alcohólicas/patología , Animales , Regulación de la Temperatura Corporal/efectos de los fármacos , Dependovirus , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Urocortinas/efectos de los fármacosRESUMEN
Urocortin 3 (Ucn 3) was tested for anxiolytic action in mice an elevated plus maze. For detection of the possible involvement of neurotransmitters, the mice were pretreated with receptor blockers: haloperidol, phenoxybenzamine, propranolol, atropine, methysergide, bicuculline or naloxone. The peptide was administered into the lateral brain ventricle; the receptor blockers were applied intra- peritoneally. Ucn 3 alone elicited dose-dependent bell-shaped anxiolytic action. The most effective dose was 0.5 µg. In the combined testing a 0.5 µg dose was used. Haloperidol, propranolol, atropine, methysergide, and naloxone, blocked the Ucn 3-induced anxiolytic action, while phenoxybenzamine and bicuculline were ineffective. The results suggest that dopaminergic, beta-adrenergic, cholinergic, serotonergic and opiate transmissions are involved in the anxiolytic action of Ucn 3.
Asunto(s)
Ansiedad/inducido químicamente , Neurotransmisores/metabolismo , Urocortinas/toxicidad , Análisis de Varianza , Animales , Atropina/uso terapéutico , Bicuculina/uso terapéutico , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Haloperidol/uso terapéutico , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Metisergida/uso terapéutico , Ratones , Naloxona/uso terapéutico , Neurotransmisores/uso terapéutico , Propranolol/uso terapéutico , Factores de Tiempo , Urocortinas/efectos de los fármacosRESUMEN
BACKGROUND: Obesity now constitutes a leading global public health problem. Studies have shown that insulin resistance affiliated with obesity is associated with intramyocellular lipid (IMCL) accumulation. Therefore, identification of genes associated with the phenotype would provide a clear target for pharmaceutical intervention and care for the condition. We hypothesized that urocortin 3 (UCN3) and corticotropin-releasing hormone receptor 2 (CRHR2) are associated with IMCL and subcutaneous fat depth (SFD), because the corticotropin-releasing hormone family of peptides are capable of strong anorectic and thermogenic effects. METHODOLOGY/PRINCIPAL FINDINGS: We annotated both bovine UCN3 and CRHR2 genes and identified 12 genetic mutations in the former gene and 5 genetic markers in the promoter region of the latter gene. Genotyping of these 17 markers on Wagyu times Limousin F(2) progeny revealed significant associations between promoter polymorphisms and SFD (P = 0.0203-0.0685) and between missense mutations of exon 2 and IMCL (P = 0.0055-0.0369) in the bovine UCN3 gene. The SFD associated promoter SNPs caused a gain/loss of 12 potential transcription regulatory binding sites, while the IMCL associated coding SNPs affected the secondary structure of UCN3 mRNA. However, none of five polymorphisms in CRHR2 gene clearly co-segregated with either trait in the population (P>0.6000). CONCLUSIONS/SIGNIFICANCE: Because UCN3 is located on human chromosome 10p15.1 where quantitative trait loci for obesity have been reported, our cross species study provides further evidence that it could be proposed as a potential target for developing antiobesity drugs. None of the markers in CRHR2 was associated with obesity-type traits in cattle, which is consistent with findings in human. Therefore, CRHR2 does not lend itself to the development of antiobesity drugs.