Corticotropin-releasing Factor mRNA Levels Research Articles

Chronic Nicotine Consumption and Withdrawal Regulate Melanocortin Receptor, CRF, and CRF Receptor mRNA Levels in the Rat Brain.

Alterations in the various neuropeptide systems in the mesocorticolimbic circuitry have been implicated in negative effects associated with drug withdrawal. The corticotropin-releasing factor (CRF) and α-melanocyte-stimulating hormone are two peptides that may be involved. This study investigated the regulatory effects of chronic nicotine exposure and withdrawal on the mRNA levels of melanocortin receptors (MC3R, MC4R), CRF, and CRF receptors (CRFR1 and CRFR2) expressed in the mesocorticolimbic system. Rats were given drinking water with nicotine or without nicotine (control group) for 12 weeks, after which they continued receiving nicotine (chronic exposure) or were withdrawn from nicotine for 24 or 48 h. The animals were decapitated following behavioral testing for withdrawal signs. Quantitative real-time PCR analysis demonstrated that nicotine exposure (with or without withdrawal) increased levels of CRF and CRFR1 mRNA in the amygdala, CRF mRNA in the medial prefrontal cortex, and CRFR1 mRNA in the septum. Nicotine withdrawal also enhanced MC3R and MC4R mRNA levels in different brain regions, while chronic nicotine exposure was associated with increased MC4R mRNA levels in the nucleus accumbens. These results suggest that chronic nicotine exposure and withdrawal regulate CRF and melanocortin signaling in the mesocorticolimbic system, possibly contributing to negative affective state and nicotine addiction.

Repeated toluene and cyclohexane inhalation produces differential effects on HPA and HPT axes in adolescent male rats

Misused volatile solvents typically contain toluene (TOL) as the main psychoactive ingredient. Cyclohexane (CHX) can also be present and is considered a safer alternative. Solvent misuse often occurs at early stages of life, leading to permanent neurobehavioral impairment and growth retardation. However, a comprehensive examination of the effects of TOL and CHX on stress regulation and energy balance is lacking. Here, we compared the effect of a binge-pattern exposure to TOL or CHX (4,000 or 8,000 ppm) on body weight, food intake, the hypothalamus-pituitary-adrenal (HPA) and hypothalamus-pituitary-thyroid (HPT) axes in male adolescent Wistar rats. At 8,000 ppm, TOL decreased body weight gain without affecting food intake. In addition, TOL and CHX altered the HPA and HPT axes’ function in a solvent- and concentration-dependent manner. The highest TOL concentration produced HPA axis hyperactivation in animals not subjected to stress, which was evidenced by increased corticotropin-releasing-factor (CRF) release from the median eminence (ME), elevated adrenocorticotropin hormone (ACTH) and corticosterone serum levels, and decreased CRF mRNA levels in the hypothalamic paraventricular nucleus (PVN). TOL (8,000 ppm) also increased triiodothyronine (T3) serum levels, decreased pro-thyrotropin-releasing-hormone (pro-TRH) mRNA transcription in the PVN, pro-TRH content in the ME, and serum thyroid stimulating hormone (TSH) levels. CHX did not affect the HPA axis. We propose that the increased HPT axis activity induced by TOL can be related to the impaired body weight gain associated with inhalant misuse. These findings may contribute to a better understanding of the effects of the misused solvents TOL and CHX.

Sex Differences in Addictive Behavior of Adult Rats: Effects of Prenatal Alcohol Exposure

Alcohol experienced during gestation is associated with the development of neurodevelopmental and neuropsychiatric dysfunctions, as well as addictive behavior in the offspring. However, the biological basis of these effects remains poorly understood. Taking into account that the extrahypothalamic corticotropin-releasing factor (CRF) system plays an important role in regulation of the negative emotional state produced by alcohol abuse and withdrawal, the present study was aimed at investigating: 1) the effect of prenatal alcohol exposure (PA) on voluntary alcohol drinking (free choice 24 hours/day) or intermittent (“drinking in the dark”) regimen in adult Wistar rats; 2) differences in the basal gene expression levels of CRF and CRF-R1 in amygdala of adult PA and control rats; and 3) the effect of voluntary alcohol drinking on the above mRNA levels. PA males displayed a significantly greater voluntary alcohol intake than control males as observed by both drinking paradigms. 24 hours after the first withdrawal episode, PA males demonstrated a higher level of anxiety in the light-dark box test. No differences were found between PA and control females. Basal amygdalar CRF and CRFR1 mRNA levels did not differ between PA and control rats of both sexes. No difference was observed in the amygdalar CRF and CRFR1 mRNA levels after alcohol drinking in PA and control males. Conversely, the CRF mRNA levels in amygdala of PA female rats decreased under the action of alcohol consumption, compared to control female rats. The results show that the PA effect on future alcohol-related behavior is sex-specific, but do not support the hypothesis that changes in CRF and CRFR1 mRNA levels in amygdala may be responsible for high alcohol intake in males.

Social effects on AVT and CRF systems

Stress and aggression have negative effects on fish welfare and productivity in aquaculture. Thus, research to understand aggression and stress in farmed fish is required. The neuropeptides arginine-vasotocin (AVT) and corticotropin-releasing factor (CRF) are involved in the control of stress and aggression. Therefore, we investigated the effect of agonistic interactions on the gene expression of AVT, CRF and their receptors in juvenile rainbow trout (Oncorhynchus mykiss). The social interactions lead to a clear dominant-subordinate relationship with dominant fish feeding more and being more aggressive. Subordinate fish had an upregulation of the AVT receptor (AVT-R), an upregulation of CRF mRNA levels, and higher plasma cortisol levels. The attenuating effect of AVT on aggression in rainbow trout is proposed to be mediated by AVT-R, and the attenuating effect of the CRF system is proposed to be mediated by CRF.

Long-term exposure to ephedrine leads to neurotoxicity and neurobehavioral disorders accompanied by up-regulation of CRF in prefrontal cortex and hippocampus in rhesus macaques

Drug addiction continues to threaten the health and welfare of people worldwide, and ephedrine abuse is a serious drug problem in many areas of the world. Ephedrine toxicity is thought to induce behavioral effects primarily through actions on the central nervous system. The corticotropin-releasing factor (CRF) system plays an important role in regulating behavioral effects induced by addictive drugs, but whether CRF is related to ephedrine toxicity remains unclear. This study seeks to examine whether there is a correlation between the CRF and chronic ephedrine neurotoxicity. To this end, we established a chronic ephedrine (0.4–1.6 mg/kg/d) exposure model in rhesus macaques, assessed its effects on body weight and behavior, examined neuronal changes in the prefrontal cortex and hippocampus, and measured the CRF expression in the prefrontal cortex and hippocampus. After 8-weeks of exposure to ephedrine, the toxic effects of ephedrine included significant weight loss and induction of behavioral changes in rhesus macaques. In particular, in the modeling group, the abnormal behavioral changes mainly manifested as irritability and behavioral sensitization. Meanwhile, the histological abnormalities included neuronal morphological changes, pyknosis and irregular shapes of neurons in the prefrontal cortex and hippocampus. In addition, the expression levels of CRF mRNA and protein were increased in the prefrontal cortex and hippocampus of ephedrine-treated animals. In summary, the finding of this study indicated that ephedrine neurotoxicity can cause neuronal damage in cerebral cortex, which in turn can result in certain neurobehavioral abnormalities, and that CRF expression in prefrontal cortex and hippocampus is elevated in response to ephedrine exposure. These observations suggested that long-term exposure to ephedrine might be causing neurotoxicity and leading to neurobehavioral disorders accompanied by up-regulation of CRF in prefrontal cortex and hippocampus.

Maternal high fat diet programs hypothalamic-pituitary-adrenal function in adult rat offspring

Abstract Maternal environmental factors such as diet have profound effects on offspring development and later health. The hypothalamic-pituitary-adrenal (HPA) axis is an important stress neuroendocrine system that is subject to programming by early life challenges. The present study was further to investigate whether maternal high fat diet (HFD) exposure during rat pregnancy and lactation can alter the HPA axis activity in adult male offspring. We observed that maternal HFD consumption exerted long-term effects on the basal activity of the HPA axis in adult offspring, with increased mean plasma corticosterone levels that result from elevated steroid pulse frequence and pulse amplitude. More importantly, maternal HFD offspring displayed enhanced corticosterone responses to restraint (1 h) and lipopolysaccharide (25 μg/kg, iv) but not insulin-induced hypoglycemia (0.3U/kg, iv) stress, suggesting a stressor-specific effect of maternal diet on the hyperresponsiveness of the HPA axis to stress. Additionally, maternal HFD exposure markedly attenuated the habituation of HPA responses to repeated restraint stress. These findings demonstrate that perinatal HFD exposure has a potent and long-lasting influence on development of neuroendocrine regulatory mechanisms. Maternal HFD consumption significantly increased basal corticotropin-releasing factor (CRF) mRNA expression in the paraventricular nucleus; nevertheless, similar increments in CRF mRNA levels following restraint were observed between maternal HFD offspring and control rats. Furthermore, the medial and central nuclei of amygdala played a pivotal role in maternal HFD-induced sensitization of the HPA response to psychological and systemic stress, respectively, suggesting that different neural pathways may mediate maternal HFD-induced HPA hyperresponsivity to different types of stressors. Take together, the long-term effects of maternal HFD challenge on the central regulation of the HPA axis, therefore, expose the adult offspring to greater HPA function throughout lifespan, in stressor-specific and region-specific manner.

Increased protein and mRNA expression of corticotropin-releasing factor (CRF), decreased CRF receptors and CRF binding protein in specific postmortem brain areas of teenage suicide subjects

Overactivity of hypothalamic-pituitary-adrenal (HPA) axis function has been implicated in depression and suicidal behavior. This is based on the observation of an abnormal dexamethasone (DEX) and DEX-adrenocorticotropic hormone (ACTH) test in patients with depression and suicidal behavior. Recently, some studies have also found abnormalities of glucocorticoid receptors (GR), mineralocorticoid receptors (MR), corticotropin releasing factor (CRF), CRF receptors (CRF-R) and CRF binding protein (CRF-BP) in depressed and suicidal patients. Some investigators have also observed increased levels of CRF in the cerebrospinal fluid (CSF) and altered levels of MR, GR and CRF in the postmortem brain of depressed and suicidal subjects. We have earlier reported decreased protein and mRNA expression of GR and GILZ, a chaperone protein, in the postmortem brain of teenage suicide subjects. We have further studied CRF and its receptors in different areas of the postmortem brain of suicide subjects, i.e., the prefrontal cortex (PFC), hippocampus (HIPPO), subiculum and amygdala (AMY) from teenage suicide subjects. The CRF and its receptors were determined in the PFC (Brodmann area 9), HIPPO, subiculum and different amygdaloid nuclei from 24 normal control subjects and 24 teenage suicide subjects. Protein expression of CRF, its receptors and CRF-BP was determined by immunolabeling using the Western blot technique and mRNA expression was determined by real-time PCR (qPCR) technique. We found that the mRNA levels of CRF were significantly increased in the PFC, in the central amygdaloid nucleus (CeAMY) and in the subiculum. mRNA levels of CRF-R1 and CRF-BP were significantly decreased in the PFC. We did not find any changes in the HIPPO of any of the CRF components we studied. When we compared the protein expression of CRF components we found that CRF was significantly increased and CRF-R1, CRF-R2 and CRF-BP significantly decreased in the PFC. On the other hand, there were no changes in the protein expression of CRF components in the HIPPO. Our results in the postmortem brain suggest that, as found by clinical studies in the CSF, there are significant alterations of CRF and its receptors in the postmortem brain of teenage suicide subjects. These alterations of CRF and its components were region-specific, as changes were not generally observed in the HIPPO.

Case-control study of cognitive and communicative development in premature infants

Maternal environmental factors such as diet have profound effects on offspring development and later health. The hypothalamic-pituitary-adrenal (HPA) axis is an important stress neuroendocrine system that is subject to programming by early life challenges. The present study was further to investigate whether maternal high fat diet (HFD) exposure during rat pregnancy and lactation can alter the HPA axis activity in adult male offspring. We observed that maternal HFD consumption exerted long-term effects on the basal activity of the HPA axis in adult offspring, with increased mean plasma corticosterone levels that result from elevated steroid pulse frequence and pulse amplitude. More importantly, maternal HFD offspring displayed enhanced corticosterone responses to restraint (1 h) and lipopolysaccharide (25 μg/kg, iv) but not insulin-induced hypoglycemia (0.3U/kg, iv) stress, suggesting a stressor-specific effect of maternal diet on the hyperresponsiveness of the HPA axis to stress. Additionally, maternal HFD exposure markedly attenuated the habituation of HPA responses to repeated restraint stress. These findings demonstrate that perinatal HFD exposure has a potent and long-lasting influence on development of neuroendocrine regulatory mechanisms. Maternal HFD consumption significantly increased basal corticotropin-releasing factor (CRF) mRNA expression in the paraventricular nucleus; nevertheless, similar increments in CRF mRNA levels following restraint were observed between maternal HFD offspring and control rats. Furthermore, the medial and central nuclei of amygdala played a pivotal role in maternal HFD-induced sensitization of the HPA response to psychological and systemic stress, respectively, suggesting that different neural pathways may mediate maternal HFD-induced HPA hyperresponsivity to different types of stressors. Take together, the long-term effects of maternal HFD challenge on the central regulation of the HPA axis, therefore, expose the adult offspring to greater HPA function throughout lifespan, in stressor-specific and region-specific manner.

Maternal high fat diet programs hypothalamic-pituitary-adrenal function in adult rat offspring

Maternal environmental factors such as diet have profound effects on offspring development and later health. The hypothalamic-pituitary-adrenal (HPA) axis is an important stress neuroendocrine system that is subject to programming by early life challenges. The present study was further to investigate whether maternal high fat diet (HFD) exposure during rat pregnancy and lactation can alter the HPA axis activity in adult male offspring. We observed that maternal HFD consumption exerted long-term effects on the basal activity of the HPA axis in adult offspring, with increased mean plasma corticosterone levels that result from elevated steroid pulse frequence and pulse amplitude. More importantly, maternal HFD offspring displayed enhanced corticosterone responses to restraint (1 h) and lipopolysaccharide (25 μg/kg, iv) but not insulin-induced hypoglycemia (0.3U/kg, iv) stress, suggesting a stressor-specific effect of maternal diet on the hyperresponsiveness of the HPA axis to stress. Additionally, maternal HFD exposure markedly attenuated the habituation of HPA responses to repeated restraint stress. These findings demonstrate that perinatal HFD exposure has a potent and long-lasting influence on development of neuroendocrine regulatory mechanisms. Maternal HFD consumption significantly increased basal corticotropin-releasing factor (CRF) mRNA expression in the paraventricular nucleus; nevertheless, similar increments in CRF mRNA levels following restraint were observed between maternal HFD offspring and control rats. Furthermore, the medial and central nuclei of amygdala played a pivotal role in maternal HFD-induced sensitization of the HPA response to psychological and systemic stress, respectively, suggesting that different neural pathways may mediate maternal HFD-induced HPA hyperresponsivity to different types of stressors. Take together, the long-term effects of maternal HFD challenge on the central regulation of the HPA axis, therefore, expose the adult offspring to greater HPA function throughout lifespan, in stressor-specific and region-specific manner.

Corticotrophin-releasing factor mediates vasoactive intestinal peptide-induced hypophagia and changes in plasma parameters

Vasoactive intestinal peptide (VIP) and corticotrophin-releasing factor (CRF) are anorexigenic neuropeptides that act in the hypothalamus to regulate food intake. Intracerebroventricular (ICV) microinjection of VIP promotes increased plasma adrenocorticotrophic hormone (ACTH) and corticosterone, indicating that VIP activates hypothalamic-pituitary-adrenal axis. The aim of this study was to evaluate the interaction between VIP and CRF, by verifying the effects of ICV administration of VIP on the activity of neurons and CRF mRNA expression in paraventricular nucleus of hypothalamus (PVN). In addition, it was evaluated the effects of pretreatment with CRF type 1 receptor (CRFR1) antagonist (Antalarmin, ANT) or CRF type 2 receptor (CRFR2) antagonist (Antisauvagine-30, AS30) on VIP-induced changes on food intake and plasma parameters of male rats. Compared to Saline group, VIP increased not only the number of Fos-related antigens (FRA)-immunoreactive neurons in the PVN but also CRF mRNA levels in this nucleus. Both ANT and AS30 treatment attenuated the inhibition of food intake promoted by VIP, ANT showing a more pronounced effect. Both antagonists also attenuated VIP-induced reduction and enhancement of free fatty acids and corticosterone plasma levels, respectively, and only AS30 was able to attenuate the hyperglycemia. These results suggest that CRF is an important mediador of VIP effects on energy balance, and CRFR1 and CRFR2 are involved in these responses.

Effects of adolescent alcohol exposure on stress-induced reward deficits, brain CRF, monoamines and glutamate in adult rats.

Adolescent alcohol exposure may increase depression vulnerability in adulthood by increasing the anhedonic response to stress. Male Wistar rats (postnatal days 28-53) were exposed to binge-like adolescent intermittent ethanol (AIE) or water. In adulthood, rats were exposed to social defeat, consisting of daily confrontations with an aggressive conspecific, followed by testing of brain reward function in a discrete-trial current-intensity intracranial self-stimulation procedure for 10 consecutive days. Neurochemistry and corticotropin-releasing factor (CRF) and CRF receptor 1 (CRFR1) mRNA levels were assessed in corticolimbic brain areas on day 11 of social defeat stress. Social defeat elevated reward thresholds in both AIE- and water-exposed rats indicating stress-induced anhedonia. However, AIE-exposed rats were more likely to show threshold elevations after repeated stress compared to water-exposed rats. AIE exposure decreased CRF mRNA levels in the nucleus accumbens and increased CRFR1 mRNA levels in the prefrontal cortex, while stress increased CRF mRNA levels in the central amygdala. In the caudate putamen, AIE exposure decreased dopamine turnover, while stress increased glutamate and serotonin metabolism and turnover. These results demonstrate increased risk of repeated stress-induced anhedonia after AIE exposure, an effect that may be due to alterations in brain CRF and dopamine systems. These results suggest that the increased rates of depression reported in people with a history of adolescent alcohol exposure may be related to alterations in brain reward and stress systems that may contribute to increased stress-induced anhedonia.

Corticotropin Releasing Factor in the Bed Nucleus of the Stria Terminalis in Socially Defeated and Non-stressed Mice with a History of Chronic Alcohol Intake.

Stress exposure has been identified as one risk factor for alcohol abuse that may facilitate the transition from social or regulated use to the development of alcohol dependence. Preclinical studies have shown that dysregulation of the corticotropin releasing factor (CRF) neurotransmission has been implicated in stress-related psychopathologies such as depression and anxiety, and may affect alcohol consumption. The bed nucleus of the stria terminalis (BNST) contains CRF-producing neurons which seem to be sensitive to stress. In this study, adult male C57BL/6 mice previously defeated in resident-intruder confrontations were evaluated in the elevated plus-maze and tail suspension test. Mice were also tested for sweet solution intake before and after social stress. After having had continuous access to ethanol (20% weight/volume) for 4 weeks, control and stressed mice had CRF type 1 (CRFR1) or type 2 (CRFR2) receptor antagonists infused into the BNST and then had access to ethanol for 24 h. In separate cohorts of control and stressed mice, we assessed mRNA levels of BNST CRF, CRFR1 and CRFR2. Stressed mice increased their intake of sweet solution after ten sessions of social defeat and showed reduced activity in the open arms of the elevated plus-maze. When tested for ethanol consumption, stressed mice persistently drank significantly more than controls during the 4 weeks of access. Also, social stress induced higher BNST CRF mRNA levels. The selective blockade of BNST CRFR1 with CP376,395 effectively reduced alcohol drinking in non-stressed mice, whereas the selective CRFR2 antagonist astressin2B produced a dose-dependent increase in ethanol consumption in both non-stressed controls and stressed mice. The 10-day episodic defeat stress used here elicited anxiety- but not depressive-like behaviors, and promoted an increase in ethanol drinking. CRF-CRFR1 signaling in the BNST seems to underlie ethanol intake in non-stressed mice, whereas CRFR2 modulates alcohol consumption in both socially defeated and non-stressed mice with a history of chronic intake.

Effects of Intermittent Alcohol Exposure on Emotion and Cognition: A Potential Role for the Endogenous Cannabinoid System and Neuroinflammation.

Intermittent alcohol exposure is a common pattern of adolescent alcohol use that can lead to binge drinking episodes. Alcohol use is known to modulate the endocannabinoid system (ECS), which is involved in neuronal communication, neuroplasticity, neuroinflammation and behavior. Adolescent male Wistar rats were exposed to 4-week intermittent alcohol intoxication (3 g/kg injections for 4 days/week) or saline (N = 12 per group). After alcohol deprivation, adult rats were assessed for emotionality and cognition and the gene expression of the ECS and other factors related to behavior and neuroinflammation was examined in the brain. Alcohol-exposed rats exhibited anxiogenic-like responses and impaired recognition memory but no motor alterations. There were brain region-dependent changes in the mRNA levels of the ECS and molecular signals compared with control rats. Thus, overall, alcohol-exposed rats expressed higher mRNA levels of endocannabinoid synthetic enzymes (N-acyl-phosphatidylethanolamine phospholipase D and diacylglycerol lipases) in the medial-prefrontal cortex (mPFC) but lower mRNA levels in the amygdala. Furthermore, we observed lower mRNA levels of receptors CB1 CB2 and peroxisome proliferator-activated receptor-α in the striatum. Regarding neuropeptide signaling, alcohol-exposed rats displayed lower mRNA levels of the neuropeptide Y signaling, particularly NPY receptor-2, in the amygdala and hippocampus and higher mRNA levels of corticotropin-releasing factor in the hippocampus. Additionally, we observed changes of several neuroinflammation-related factors. Whereas, the mRNA levels of toll-like receptor-4, tumor necrosis factor-α, cyclooxygenase-2 and glial fibrillary acidic protein were significantly increased in the mPFC, the mRNA levels of cyclooxygenase-2 and glial fibrillary acidic protein were decreased in the striatum and hippocampus. However, nuclear factor-κβ mRNA levels were lower in the mPFC and striatum and allograft inflammatory factor-1 levels were differentially expressed in the amygdala and hippocampus. In conclusion, rats exposed to adolescent intermittent alcohol displayed anxiety-like behavior and cognitive deficits in adulthood and these alterations were accompanied by brain region-dependent changes in the gene expression of the ECS and other signals associated with neuroinflammation and behavior. An intermittent adolescent alcohol exposure has behavioral and molecular consequences in the adult brain, which might be linked to higher vulnerability to addictive behaviors and psychopathologies.

Stress differentially regulates brain expression of corticotropin-releasing factor in binge-like eating prone and resistant female rats

The expression of corticotropin-releasing factor (CRF), a neuropeptide that regulates endocrine and behavioral responses to stress, was assessed in the brain in rats prone or resistant to stress-induced binge-like eating of sucrose. Female Sprague-Dawley rats were subjected to unpredictable intermittent 1-h access to sucrose in non-stressful conditions or after exposure to three foot shock stress sessions. Experimental sessions were performed at metestrus, diestrus, and proestrus. The rats were assigned to the binge-like eating prone (BEP) or the binge-like eating resistant (BER) phenotypes according to the rats' persistently high or low sucrose intake following three stress sessions. The BEP rats displayed elevated consumption of sucrose in non-stressful conditions and an additional significant increase in sucrose intake in response to stress. Conversely, the BER rats showed lower sucrose intake in non-stressful conditions, and stress did not increase sucrose intake in this phenotype. The brain expression of CRF mRNA and plasma corticosterone levels were assessed 30 min after the last stress session at the diestrous phase of the estrous cycle. Stress triggered a significant increase in plasma corticosterone levels and strongly increased CRF mRNA expression in the paraventricular hypothalamic nucleus in the BER but not in the BEP rats. However, the BEP but not the BER rats demonstrated a significant increase in CRF mRNA expression in the bed nucleus of the stria terminalis (BNST) after stress. Hyporeactivity of the hypothalamic-pituitary-adrenal axis and the higher CRF expression in the BNST in BEP rats may contribute to stress-induced binge-like sucrose eating in the BEP phenotype.

Binge Drinking Decreases Corticotropin‐Releasing Factor‐Binding Protein Expression in the Medial Prefrontal Cortex of Mice

Dysregulation of the corticotropin-releasing factor (CRF) system has been observed in rodent models of binge drinking, with a large focus on CRF receptor 1 (CRF-R1). The role of CRF-binding protein (CRF-BP), a key regulator of CRF activity, in binge drinking is less well understood. In humans, single-nucleotide polymorphisms in CRHBP are associated with alcohol use disorder and stress-induced alcohol craving, suggesting a role for CRF-BP in vulnerability to alcohol addiction. The role and regulation of CRF-BP in binge drinking were examined in mice exposed to the drinking in the dark (DID) paradigm. Using insitu hybridization, the regulation of CRF-BP, CRF-R1, and CRF mRNA expression was determined in the stress and reward systems of C57BL/6J mice after repeated cycles of DID. To determine the functional role of CRF-BP in binge drinking, CRF-BP knockout (CRF-BP KO) mice were exposed to 6 cycles of DID, during which alcohol consumption was measured and compared to wild-type mice. CRF-BP mRNA expression was significantly decreased in the prelimbic (PL) and infralimbic medial prefrontal cortex (mPFC) of C57BL/6J mice after 3 cycles and in the PL mPFC after 6 cycles of DID. No significant changes in CRF or CRF-R1 mRNA levels were observed in mPFC, ventral tegmental area, bed nucleus of the stria terminalis, or amygdala after 3 cycles of DID. CRF-BP KO mice do not show significant alterations in drinking compared to wild-type mice across 6 cycles of DID. These results reveal that repeated cycles of binge drinking alter CRF-BP mRNA expression in the mPFC, a region responsible for executive function and regulation of emotion and behavior, including responses to stress. We observed a persistent decrease in CRF-BP mRNA expression in the mPFC after 3 and 6 DID cycles, which may allow for increased CRF signaling at CRF-R1 and contribute to excessive binge-like ethanol consumption.

Risky choice and brain CRF after adolescent ethanol vapor exposure and social stress in adulthood

Adolescent ethanol exposure increases risky choice and alters corticotropin releasing factor (CRF) systems in adulthood. The impact of stress on risky choice after adolescent intermittent ethanol (AIE) exposure is not known. We investigated time-specific effects of AIE vapor exposure during early adolescence on risky choice after stress or no stress in adulthood. Male Wistar rats were exposed to air or AIE vapor on postnatal days 28–42 (adolescence) and were exposed to 10days of social defeat or no stress on postnatal days 172–181 (adulthood). Risky choice was assessed in the probability discounting task under baseline conditions and after days 1 and 10 of social defeat. CRF and CRF receptor 1 (CRFR1) mRNA levels were assessed in the prefrontal cortex (PFC) and the central nucleus of the amygdala (CeA) 24h post-stress to evaluate persistent effects of stress on the brain. AIE exposure had no effect on risky choice either at baseline or after social defeat. Additionally, neither acute nor chronic social defeat affected risky choice in air-exposed rats. In the PFC, chronic social defeat selectively decreased CRF mRNA levels in air-exposed rats and increased CRFR1 mRNA levels in all rats. AIE exposure increased CRF mRNA levels in the CeA with no effect of social stress. Our results indicate no effect of ethanol exposure via vapor during early adolescence on risky choice, while our previous findings indicated that AIE exposure via gavage affected risky choice. Both AIE exposure and social defeat altered CRF and CRFR1 mRNA levels in the brain.

Regulation of the expression of corticotropin-releasing factor gene by pyroglutamylated RFamide peptide in rat hypothalamic 4B cells

Pyroglutamylated RFamide peptide (QRFP), an important regulator of metabolism and energy homeostasis, has orexigenic effects. QRFP acts via a specific receptor, Gpr103. Gpr103 mRNA is expressed in the rat hypothalamic paraventricular nucleus (PVN). In the PVN, corticotropin-releasing factor (CRF), which plays a central role in regulating the stress response and is produced in response to stress, stimulates the release of adrenocorticotropic hormone from the anterior pituitary. We hypothesized that QRFP regulates CRF gene expression directly in the hypothalamus, and thus examined the direct effect of QRFP on the promoter activity and mRNA levels of CRF in hypothalamic cells. To examine these pathways, we used hypothalamic 4B cells, a homologous PVN neuronal cell line. Gpr103a and Gpr103b mRNA, and Gpr103 (a and b) proteins were expressed in the hypothalamic cells. The Gpr103 mRNA and protein levels were increased by QRFP. QRFP also stimulated CRF mRNA levels and CRF promoter activity directly in 4B cells following their transfection with the CRF promoter. The protein kinase A (PKA) and protein kinase C (PKC) pathways were involved in the QRFP-induced increases in CRF promoter activity. QRFP stimulated cAMP response element-binding protein (CREB) phosphorylation. CREB phosphorylation was inhibited by a PKC inhibitor. PKC-dependent signaling would be upstream of the CREB phosphorylation. Thus, QRFP-dependent pathways are involved in the regulation of CRF gene expression in the hypothalamus.

Effects of acute and chronic stress on telencephalic neurochemistry and gene expression in rainbow trout (Oncorhynchus mykiss).

By filtering relevant sensory inputs and initiating stress responses, the brain is an essential organ in stress coping and adaptation. However, exposure to chronic or repeated stress can lead to allostatic overload, where neuroendocrinal and behavioral reactions to stress become maladaptive. This work examines forebrain mechanisms involved in allostatic processes in teleost fishes. Plasma cortisol, forebrain serotonergic (5-HTergic) neurochemistry, and mRNA levels of corticotropin-releasing factor (CRF), CRF-binding protein (CRF-BP), CRF receptors (CRFR1 and CRFR2), mineralocorticoid receptor (MR), glucocorticoid receptors (GR1 and GR2) and serotonin type 1A (5-HT1A) receptors (5-HT1Aα and 5-HT1Aβ) were investigated at 1 h before and 0, 1 and 4 h after acute stress, in two groups of rainbow trout held in densities of 25 and 140 kg m-3 for 28 days. Generally, being held at 140 kg m-3 resulted in a less pronounced cortisol response. This effect was also reflected in lower forebrain 5-HTergic turnover, but not in mRNA levels in any of the investigated genes. This lends further support to reports that allostatic load causes fish to be incapable of mounting a proper cortisol response to an acute stressor, and suggests that changes in forebrain 5-HT metabolism are involved in allostatic processes in fish. Independent of rearing densities, mRNA levels of 5-HT1Aα and MR were downregulated 4 h post-stress compared with values 1 h post-stress, suggesting that these receptors are under feedback control and take part in the downregulation of the hypothalamic-pituitary-interrenal (HPI) axis after exposure to an acute stressor.

Endogenous CRF in rat large intestine mediates motor and secretory responses to stress.

Corticotropin-releasing factor (CRF) mediates our body's overall responses to stress. The role of central CRF in stress-stimulated colonic motility is well characterized. We hypothesized that transient perturbation in expression of enteric CRF is sufficient to change stress-induced colonic motor and secretory responses. Sprague-Dawley rats (adult, male) were subjected to 1-h partial restraint stress (PRS) and euthanized at 0, 4, 8, and 24h. CRF mRNA and peptide levels in the colon were quantified by real-time RT-PCR, enzyme immuno-assay and immunohistochemistry. Double-stranded RNA (dsRNA) designed to target CRF (dsCRF) was injected into the colonic wall to attain RNA interference-mediated inhibition of CRF mRNA expression. DsRNA for β-globin was used as a control (dsControl). Four days after dsRNA injection, rats were subjected to 1-h PRS. Fecal output was measured. Ussing chamber techniques were used to assess colonic mucosal ion secretion and transepithelial tissue conductance. Exposure to PRS elevated CRF expression and increased CRF release in the rat colon. Injection of dsCRF inhibited basal CRF expression and prevented the PRS-induced increase in CRF expression, whereas CRF expression in dsControl-injected colons remained high after PRS. In rats treated with dsControl, PRS caused a significant increase in fecal pellet output, colonic baseline ion secretion, and transepithelial tissue conductance. Inhibition of CRF expression in the colon prevented PRS-induced increase in fecal output, baseline ion secretion, and transepithelial tissue conductance. These results provide direct evidence that transient perturbation in peripherally expressed CRF prevents colonic responses to stress.

A simple melatonin treatment protocol attenuates the response to acute stress in the sole Solea senegalensis

Several compounds have been tested in fish in order to attenuate the effects of different stressors, most often following previous observations in mammals. The hormone melatonin (MEL) and the amino acid L-tryptophan have been tested for this purpose with different degree of success. In Senegalese sole (Solea senegalensis) we have previously observed that during prolonged exposure to relatively mild stressors, the presence of MEL in the water helped to reduce the stress response. Here, we aimed to investigate the potential anti-stress effects of a short melatonin exposure that could be easily performed in fish farms before an intended manipulative event with the animals. Our results demonstrate that adding MEL to the tanks 30min before an acute chasing stress is effective in reducing the intensity of the stress response in fish from its beginning, as evidenced by the attenuated and delayed cortisol response in MEL-exposed animals. The hypothalamic levels of serotonergic activity and the mRNA levels of corticotropin-releasing factor were also attenuated in MEL-treated fish, suggesting that MEL effects occur through its inhibitory actions on the CNS pathways controlling the stress response in Senegalese sole. In view of the observed anti-stress effects of MEL, further research is warranted in order to optimize doses and timing of application to improve the effectiveness of the MEL treatment for aquaculture purposes.