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Effects of early postnatal environment on hypothalamic gene expression in OLETF rats
Abstracts / Appetite 57S (2011) S1–S49
Effects of early postnatal environment on hypothalamic gene expression in OLETF rats Y.J. KIM 1 , M. SCHROEDER 2 , N.C. LIANG 1 , P.T. CHAO 1 , T.H. MORAN 1 , A. WELLER 2 , S. BI 1 1 Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, USA 2 Psychology Department and Gonda Brain Research Center, Bar Ilan University, Ramat Gan, Israel Previous reports have shown that the early postnatal environment altered the obesity phenotype of Otsuka Long-Evans Tokushima Fatty (OLETF) rats. To determine whether this early postnatal environment affects hypothalamic signaling systems involved in energy balance, OLETF pups and lean control LETO pups were cross-fostered to same or opposite strain Dams (designated as LdLp: LETO pups with LETO dams; LdOp: OLETF pups with LETO dams; OdLp: LETO pups with OLETF dams; and OdOp: OLETF pups with OLETF dams) on postnatal day 1 (PND 1) and sacrificed at PND 23 or PND 90 for examination of hypothalamic gene expression. Rats had access to regular chow throughout the study. On PND 23, NPY gene expression was significantly increased in the DMH in both LdOp and OdOp pups compared to LdLp pups. DMH NPY expression did not differ between OdLp and LdLp pups. On PND 90, DMH NPY expression was significantly increased in both OdOp and OdLp rats, but was unchanged in LdOp rats compared to LdLp controls. In contrast to DMH NPY, gene expression for NPY and proopiomelanocortin (POMC) in the arcuate nucleus appeared to appropriately respond to alterations in body weight and plasma leptin levels. Together, our results demonstrate the effects of both genotype and early postnatal environment on obesity of OLETF rats and further suggest an important role of DMH NPY in the development of obesity of OLETF rats. Supported by: DK57609. doi:10.1016/j.appet.2011.05.198 Lithium chloride induces nuclear activation of transducer of regulated CREB (TORC) in the rat hindbrain A. KIMBROUGH, T.A. HOUPT Florida State University, Biological Science, Neuroscience, Tallahassee, USA Visceral or toxic stimuli such as lithium chloride induce c-Fos in the nucleus of the solitary tract (NTS) and parabrachial nucleus (PBN; e.g. Houpt et al., 1994). Induction of c-Fos can occur when the phosphorylated transcription factor cAMP response elementbinding (pCREB) binds to the CRE in the c-Fos promoter. However, basal levels of pCREB are very high in the NTS and PBN even in the absence of stimulation(e.g. Houpt, 1997). Therefore, the presence of pCREB is not sufficient for c-Fos induction. There are several additional factors that together with pCREB might lead to c-Fos induction after stimulation: activation of other transcription factors such as serum response factor (SRF); modification of histones by acetyl transferases such as CREB-binding protein (CBP); or recruitment of obligatory cofactors such as transducers of regulated CREB (TORCs). To test if an obligatory cofactor is recruited to the nucleus after LiCl stimulation, we examined TORC1 staining in the NTS and PBN of rats. Adult male Sprague-Dawley rats were injected with 12 ml/kg 0.15 M LiCl (n = 4) or NaCl (n = 3). One hour following injection the rats were perfused and hindbrain sections processed for TORC1 immunohistochemistry (Cell Signaling). There was a significant elevation of nuclear TORC1 staining in the NTS 1 h after LiCl (159 ± 8.5) compared to NaCl (93.4 ± 15.2; p < 0.05). No difference was found in nuclear TORC1 staining in the PBN. Thus, increases in nuclear TORC1 levels may act with pCREB to induce c-Fos in the NTS. We hypothesize that TORC1 is not synthesized upon neuronal activation, but instead is sequestered in the cytoplasm and translocates to the nucleus after stimulation. The high levels of TORC1 after NaCl injection and the failure of LiCl to increase nuclear TORC1 in
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the PBN suggests that additional factors may also regulate c-Fos expression. Supported by: NIDCD T32-00044. doi:10.1016/j.appet.2011.05.199 Leptin in Anorexia Nervosa. Relationship to physical activity and weight suppression D.A. KLEIN 1,2 , M. SIEGEL 1,2 , Z.O.E. GRUNEBAUM 1,2 , Y. WANG 1,2 , H. CHEN 1,2 , B.T. WALSH 1,2 1 Columbia University College of Physicians and Surgeons, New York, USA 2 The New York State Psychiatric Institute, New York, USA Anorexia Nervosa (AN) is a life-threatening disorder of selfstarvation. Multiple neuroendocrine abnormalities are known but the extent to which they are an effect and/or cause of starvation remains unclear. We investigated clinical correlates of leptin levels in patients with AN. Methods: Forty-four women with AN had fasting serum leptin levels measured both before and after beginning inpatient weight restoration therapy. Physical activity was monitored twice using an accelerometer, and Weight Suppression was calculated as the difference between lifetime highest weight and current weight. Results: Leptin levels at weight restoration ranged from 0.2 to 33.5 ng/ml, despite similar BMI across patients. Leptin measured at weight restoration was inversely associated with both physical activity measures and weight suppression. Leptin level at weight restoration itself significantly predicted resumption of menses. Conclusions: Data are preliminary, but suggest that patients with AN may have different physiological “set-points,” as reflected by menstrual status, depending on lifetime highest weight. Hypoleptinemia appears to be a marker of, and may also serve to perpetuate, behavioral and physiological dysregulation in AN. Implications for further research and treatment are discussed. Supported by: NARSAD, NIMH. doi:10.1016/j.appet.2011.05.200 Energy deficits dissociate motivation from performance and reward C.M. KLINGERMAN 1 , A. PATEL 1 , V.L. HEDGES 2 , R.L. MEISEL 2 , J.E. SCHNEIDER 1 1 Lehigh University, Bethelehm, USA 2 U. Minn., Minneapolis, USA Animals switch their behavioral priorities from ingestive to sex behavior to optimize reproductive success in environments where energy availability fluctuates. We hypothesized that energy availability differentially affects each of the components of behavior: motivation, performance, and reward. In Syrian hamsters (n = 16), 7–11 days of 25% food restriction significantly affected the motivation for food and sex by increasing food hoarding and decreasing vaginal scent marking and the preference for spending time with male hamsters, but had no significant effect on performance (food intake and lordosis). A similar level of food restriction failed to dissociate sexual motivation from sexual reward (as measured by the formation of a conditioned place preference (CPP)). The formation of a CPP to mating is reflected in the nucleus accumbens (NAc) as increased neural activation of the immediate early gene, c-fos. Mating-induced neural activation in the NAc did not differ between food-restricted and fed hamsters (n = 24). Both foodrestricted and ad libitum-fed females formed a CPP in response to 4 copulatory experiences despite the fact that food restriction significantly inhibited sexual motivation (n = 24). Together these data are consistent with the idea that mild food restriction inhibits sexual motivation while it fails to attenuate sexual performance and the rewarding consequences of mating. This likely ensures vigilant food hoarding in preparation for possible reproductive opportunities during the more fertile periods of the females’ estrous cycle. doi:10.1016/j.appet.2011.05.201
Effects of early postnatal environment on hypothalamic gene expression in OLETF rats Y.J. KIM 1 , M. SCHROEDER 2 , N.C. LIANG 1 , P.T. CHAO 1 , T.H. MORAN 1 , A. WELLER 2 , S. BI 1 1 Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, USA 2 Psychology Department and Gonda Brain Research Center, Bar Ilan University, Ramat Gan, Israel Previous reports have shown that the early postnatal environment altered the obesity phenotype of Otsuka Long-Evans Tokushima Fatty (OLETF) rats. To determine whether this early postnatal environment affects hypothalamic signaling systems involved in energy balance, OLETF pups and lean control LETO pups were cross-fostered to same or opposite strain Dams (designated as LdLp: LETO pups with LETO dams; LdOp: OLETF pups with LETO dams; OdLp: LETO pups with OLETF dams; and OdOp: OLETF pups with OLETF dams) on postnatal day 1 (PND 1) and sacrificed at PND 23 or PND 90 for examination of hypothalamic gene expression. Rats had access to regular chow throughout the study. On PND 23, NPY gene expression was significantly increased in the DMH in both LdOp and OdOp pups compared to LdLp pups. DMH NPY expression did not differ between OdLp and LdLp pups. On PND 90, DMH NPY expression was significantly increased in both OdOp and OdLp rats, but was unchanged in LdOp rats compared to LdLp controls. In contrast to DMH NPY, gene expression for NPY and proopiomelanocortin (POMC) in the arcuate nucleus appeared to appropriately respond to alterations in body weight and plasma leptin levels. Together, our results demonstrate the effects of both genotype and early postnatal environment on obesity of OLETF rats and further suggest an important role of DMH NPY in the development of obesity of OLETF rats. Supported by: DK57609. doi:10.1016/j.appet.2011.05.198 Lithium chloride induces nuclear activation of transducer of regulated CREB (TORC) in the rat hindbrain A. KIMBROUGH, T.A. HOUPT Florida State University, Biological Science, Neuroscience, Tallahassee, USA Visceral or toxic stimuli such as lithium chloride induce c-Fos in the nucleus of the solitary tract (NTS) and parabrachial nucleus (PBN; e.g. Houpt et al., 1994). Induction of c-Fos can occur when the phosphorylated transcription factor cAMP response elementbinding (pCREB) binds to the CRE in the c-Fos promoter. However, basal levels of pCREB are very high in the NTS and PBN even in the absence of stimulation(e.g. Houpt, 1997). Therefore, the presence of pCREB is not sufficient for c-Fos induction. There are several additional factors that together with pCREB might lead to c-Fos induction after stimulation: activation of other transcription factors such as serum response factor (SRF); modification of histones by acetyl transferases such as CREB-binding protein (CBP); or recruitment of obligatory cofactors such as transducers of regulated CREB (TORCs). To test if an obligatory cofactor is recruited to the nucleus after LiCl stimulation, we examined TORC1 staining in the NTS and PBN of rats. Adult male Sprague-Dawley rats were injected with 12 ml/kg 0.15 M LiCl (n = 4) or NaCl (n = 3). One hour following injection the rats were perfused and hindbrain sections processed for TORC1 immunohistochemistry (Cell Signaling). There was a significant elevation of nuclear TORC1 staining in the NTS 1 h after LiCl (159 ± 8.5) compared to NaCl (93.4 ± 15.2; p < 0.05). No difference was found in nuclear TORC1 staining in the PBN. Thus, increases in nuclear TORC1 levels may act with pCREB to induce c-Fos in the NTS. We hypothesize that TORC1 is not synthesized upon neuronal activation, but instead is sequestered in the cytoplasm and translocates to the nucleus after stimulation. The high levels of TORC1 after NaCl injection and the failure of LiCl to increase nuclear TORC1 in
S23
the PBN suggests that additional factors may also regulate c-Fos expression. Supported by: NIDCD T32-00044. doi:10.1016/j.appet.2011.05.199 Leptin in Anorexia Nervosa. Relationship to physical activity and weight suppression D.A. KLEIN 1,2 , M. SIEGEL 1,2 , Z.O.E. GRUNEBAUM 1,2 , Y. WANG 1,2 , H. CHEN 1,2 , B.T. WALSH 1,2 1 Columbia University College of Physicians and Surgeons, New York, USA 2 The New York State Psychiatric Institute, New York, USA Anorexia Nervosa (AN) is a life-threatening disorder of selfstarvation. Multiple neuroendocrine abnormalities are known but the extent to which they are an effect and/or cause of starvation remains unclear. We investigated clinical correlates of leptin levels in patients with AN. Methods: Forty-four women with AN had fasting serum leptin levels measured both before and after beginning inpatient weight restoration therapy. Physical activity was monitored twice using an accelerometer, and Weight Suppression was calculated as the difference between lifetime highest weight and current weight. Results: Leptin levels at weight restoration ranged from 0.2 to 33.5 ng/ml, despite similar BMI across patients. Leptin measured at weight restoration was inversely associated with both physical activity measures and weight suppression. Leptin level at weight restoration itself significantly predicted resumption of menses. Conclusions: Data are preliminary, but suggest that patients with AN may have different physiological “set-points,” as reflected by menstrual status, depending on lifetime highest weight. Hypoleptinemia appears to be a marker of, and may also serve to perpetuate, behavioral and physiological dysregulation in AN. Implications for further research and treatment are discussed. Supported by: NARSAD, NIMH. doi:10.1016/j.appet.2011.05.200 Energy deficits dissociate motivation from performance and reward C.M. KLINGERMAN 1 , A. PATEL 1 , V.L. HEDGES 2 , R.L. MEISEL 2 , J.E. SCHNEIDER 1 1 Lehigh University, Bethelehm, USA 2 U. Minn., Minneapolis, USA Animals switch their behavioral priorities from ingestive to sex behavior to optimize reproductive success in environments where energy availability fluctuates. We hypothesized that energy availability differentially affects each of the components of behavior: motivation, performance, and reward. In Syrian hamsters (n = 16), 7–11 days of 25% food restriction significantly affected the motivation for food and sex by increasing food hoarding and decreasing vaginal scent marking and the preference for spending time with male hamsters, but had no significant effect on performance (food intake and lordosis). A similar level of food restriction failed to dissociate sexual motivation from sexual reward (as measured by the formation of a conditioned place preference (CPP)). The formation of a CPP to mating is reflected in the nucleus accumbens (NAc) as increased neural activation of the immediate early gene, c-fos. Mating-induced neural activation in the NAc did not differ between food-restricted and fed hamsters (n = 24). Both foodrestricted and ad libitum-fed females formed a CPP in response to 4 copulatory experiences despite the fact that food restriction significantly inhibited sexual motivation (n = 24). Together these data are consistent with the idea that mild food restriction inhibits sexual motivation while it fails to attenuate sexual performance and the rewarding consequences of mating. This likely ensures vigilant food hoarding in preparation for possible reproductive opportunities during the more fertile periods of the females’ estrous cycle. doi:10.1016/j.appet.2011.05.201