Mechanism of hippocampal CRHR1 regulating chronic stress-induced learning and memory impairment in early aged mice / 安徽医科大学学报

Objective @# To explore the mechanism of hippocampal corticotropin-releasing hormone ( CRH) receptor type 1 ( CRHR1 ) in chronic stress-induced learning and memory impairment in early aged mice．@*Methods@#C57BL /6J mice aged 12 －14 months were divided into two groups according to gender，and then divided into wild type (WT) group and hippocampal CRHR1 conditional gene knockout (KN) group according to genotype．Mice in each group were randomly divided into control group and stress group，and the stress group was subjected to chronic unpredictable stress ( CUS ) for 30 days． Genotyping of mice was performed using polymerase chain reaction ( PCR) ，agarose gel electrophoresis and real-time fluorescence quantitative PCR (RT-qPCR) ．The new object rec- ognition experiment and Morris Water maze measured learning and memory ability．Golgi-Cox staining was used to observe damage to hippocampal neuronal dendrites． The protein expressions of target protein of rapamycin (mTOR) ，p-mTOR (Ser2448) ，ribosomal protein S6 kinase ( p70S6K) and p-p70S6K ( Thr389 / Thr412 ) were detected by Western blot．Serum levels of corticotropin releasing hormone ( CRH) were measured by ELISA. @*Results @# Compared to mice without chronic stress，the cognitive coefficient of WT stress groups decreased after chron- ic stress，and the difference was statistically significant (P ＜0. 05) ，while there was no significant difference in cognitive coefficient of KN stress groups before and after chronic stress．Compared with the WT stress group，the escape latency of the WT control group was shortened (P＜0. 05) ，and the number of crossing the platform and tar- get quadrant increased (P ＜0. 01) ，and there was no significant difference in the KN groups above． Compared with the WT control group，the WT stress group had a significant reduction in the neuronal complexity in the hipp- ocampal CA1，CA3 and DG regions (P ＜0. 05) and significant reductions in the expression of p-mTOR and p- p70S6K in the hippocampus (P＜0. 05) ．There was no significant difference in the expression of p-mTOR between the KN stress group and the KN control group (P＞0. 05) ，except that the expression of p-mTOR in the hippocam- pus of the female group decreased (P＜0. 05) ．In addition，the serum level of CRH in the stress group was higher than that in the control group (P＜0. 01) ．@*Conclusion @#Hippocampal CRHR1 regulates learning and memory im- pairment and neuronal dendrite damage in early aged mice induced by chronic stress．The mechanism may be that high levels of CRH induced by chronic stress cannot bind to CRHR1 receptor，thereby enhancing the expression of down-regulated mTOR / p70S6K signaling pathway.

The Nucleus Accumbens CRH-CRHR1 System Mediates Early-Life Stress-Induced Sleep Disturbance and Dendritic Atrophy in the Adult Mouse / 神经科学通报·英文版

Adverse experiences in early life have long-lasting negative impacts on behavior and the brain in adulthood, one of which is sleep disturbance. As the corticotropin-releasing hormone (CRH)-corticotropin-releasing hormone receptor 1 (CRHR1) system and nucleus accumbens (NAc) play important roles in both stress responses and sleep-wake regulation, in this study we investigated whether the NAc CRH-CRHR1 system mediates early-life stress-induced abnormalities in sleep-wake behavior in adult mice. Using the limited nesting and bedding material paradigm from postnatal days 2 to 9, we found that early-life stress disrupted sleep-wake behaviors during adulthood, including increased wakefulness and decreased non-rapid eye movement (NREM) sleep time during the dark period and increased rapid eye movement (REM) sleep time during the light period. The stress-induced sleep disturbances were accompanied by dendritic atrophy in the NAc and both were largely reversed by daily systemic administration of the CRHR1 antagonist antalarmin during stress exposure. Importantly, Crh overexpression in the NAc reproduced the effects of early-life stress on sleep-wake behavior and NAc morphology, whereas NAc Crhr1 knockdown reversed these effects (including increased wakefulness and reduced NREM sleep in the dark period and NAc dendritic atrophy). Together, our findings demonstrate the negative influence of early-life stress on sleep architecture and the structural plasticity of the NAc, and highlight the critical role of the NAc CRH-CRHR1 system in modulating these negative outcomes evoked by early-life stress.

An activating mutation in the CRHR1 gene is rarely associated with pituitary-dependent hyperadrenocorticism in poodles

OBJECTIVES: Pituitary-dependent hyperadrenocorticism is the most common cause of naturally occurring hypercortisolism in dogs. CRHR1 expression in human and dog corticotrophinomas suggested that this gene affects pituitary tumorigenesis. The present study aimed to investigate mutations in the CRHR1 coding region in poodles with pituitary-dependent hyperadrenocorticism. METHODS: Fifty poodles with pituitary-dependent hyperadrenocorticism and 50 healthy poodles were studied. Genomic DNA was amplified by PCR and analyzed by Sanger sequencing. RESULTS: The novel CRHR1 p.V97M mutation was identified in one dog. This valine residue, located in the amino-terminal extracellular domain, exhibits high affinity for its corticotropin-releasing hormone (CRH) ligand. Bioinformatic analysis revealed structural rearrangements in the mutant protein, with a 17% increase in the surface binding affinity between CRHR1 and CRH. In vitro functional studies showed that mutant CRHR1 induced higher ACTH secretion than the wild type after stimulation with human CRH. CONCLUSION: These results suggest that germline activating mutations in CRHR1 may be a rare cause of pituitary hyperadrenocorticism in poodles.

Preeclampsia alters the expression of HPA axis related genes in the hippocampus of offspring rats / 复旦学报（医学版）

Objective To explore the effect of preeclampsia on the expression of hypothalamic-pituitary-adrenal (HPA) axis related genesin the hippocampus of adolescent offspring rats.Methods The pregnant Sprague-Dawley rats were randomly divided into two groups to be given 125 mg · kg-1 ·d-1 L-NAME or 1 mL pure saline by daily injection from day 14 to delivery.Serum corticosterone (CORT) levels in neonatal offspring rats were detected by ELISA.The mRNA and protein levels of glucocorticoid receptor (GR),corticotropin releasing hormone (CRH),CRH receptor 1 (CRHR1) and IL-6 in the hippocampus of 8-week offspring rats were determined by real-time PCR and Western blot,respectively.Results Compared with normal neonatal rats,the serum CORT concentration of neonatal rats with preeclampsia was increased (P＜0.05).Compared with normal adolescent offspring,the levels of GR,CRH and CRHR1 mRNA and protein were increased in the hippocampus of adolescent rats with preeclampsia (P＜0.05),accompanied by increased IL-6 mRNA and protein (P＜0.05),as a downstream inflammatory gene of the GR.Conclusions We found that adolescent SD rats exposed to preeclampsia showed alteration in the expression of HPA related genes in the hippocampus,which played a role in the impairment of learning and memory in children.

Genetic Polymorphism in Corticotropin-releasing Hormone Receptor Type-1 in Preeclamptic Korean Women

PURPOSE: Placental corticotropin-releasing hormone receptor type 1 (CRHR1) expression is reduced in pregnancies with abnormal placental function such as preeclampsia (PE), and the levels and/or function of CRHR1 are genetically influenced. The aim of this study was to investigate the association between the c.33+8199C>T polymorphism in the CRHR1 gene and PE in a Korean population. MATERIALS AND METHODS: Using a case-control design, the association between the CRHR1 polymorphism and the risk of PE was investigated in 203 individuals with PE and 211 normotensive controls. Genotypes were determined using a SNapShot kit and an ABI Prism 3100 Genetic analyzer. RESULTS: Genotypes and allele frequencies for the CRHR1 polymorphism did not differ between PE and normotensive pregnancies. The variant T allele was more frequent than the ancestral C allele in both of the groups and was more frequent in the controls than in the cases. In risk analysis for PE, there was not an increased risk of preeclampsia in subjects who were concomitant homozygous rare allele genotypes (CC) (OR, 0.3; P=0.15) or heterozygous rare allele genotypes (TC) (OR, 0.8; P=0.29). There were no differences in the complications of PE such as severity or preterm delivery in patients with the CRHR1 polymorphism. CONCLUSION: Our findings indicate that the CRHR1 polymorphism was not associated with PE in the present Korean study group.