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Sharma K, Govar AA, Ghimire B, Nishimori K, Hammock E, Teruyama R. Sexually dimorphic oxytocin receptor-expressing (OXTR) neurons in the anteroventral periventricular nucleus (AVPV) in the postpartum female mouse are involved in maternal behavior. J Neuroendocrinol 2023; 35:e13337. [PMID: 37784240 DOI: 10.1111/jne.13337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 08/03/2023] [Accepted: 08/03/2023] [Indexed: 10/04/2023]
Abstract
Maternal care is crucial for the survival and development of offspring. Oxytocin modulates maternal behavior by binding to oxytocin receptors (OXTRs) in various parts of the brain. Previously, we showed that OXTRs are expressed in the anteroventral periventricular nucleus (AVPV) of female, but not male mice. Because the AVPV is involved in the regulation of maternal behavior and oxytocin enhances its induction, this finding leads to the hypothesis that the female specific population of OXTR neurons in the AVPV regulates maternal behavior. To address this hypothesis, OXTR-Venus reporter mice were used to assess if expression levels of OXTR in the AVPV are changed during the postpartum period. The total number of OXTR-Venus neurons was significantly greater in postpartum dams compared to virgin females. To assess efferent projections of the AVPV-OXTR neurons, a Cre-dependent fluorescent protein (tdTomato) expressing a viral vector was injected into one side of the AVPV of female OXTR-Cre mice. Fibers expressing tdTomato were found in hypothalamic areas containing oxytocin neurons (the supraoptic and paraventricular nuclei) and the midbrain areas (the ventral tegmental area and periaqueductal gray) that are involved in the regulation of maternal motivation. To assess if activity of the AVPV-OXTR neurons is involved in the regulation of maternal behaviors, a chemogenetic approach was employed. Specific inhibition of activity of AVPV-OXTR neurons completely abolished pup retrieval and nest building behaviors. Collectively, these findings demonstrate that AVPV-OXTR neurons in postpartum female mice constitute an important node in the neural circuitry that regulates maternal behavior.
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Affiliation(s)
- Kaustubh Sharma
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Armita A Govar
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Bandana Ghimire
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Katsuhiko Nishimori
- Laboratory of Obesity and Internal Inflammation, Fukushima Medical University, Fukushima, Japan
| | - Elizabeth Hammock
- Department of Psychology, Florida State University, Tallahassee, Florida, USA
| | - Ryoichi Teruyama
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
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2
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Haddad-Tóvolli R, Claret M. Metabolic and feeding adjustments during pregnancy. Nat Rev Endocrinol 2023; 19:564-580. [PMID: 37525006 DOI: 10.1038/s41574-023-00871-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/29/2023] [Indexed: 08/02/2023]
Abstract
Eating behaviours are determined by the integration of interoceptive and environmental inputs. During pregnancy, numerous physiological adaptations take place in the maternal organism to provide an adequate environment for embryonic growth. Among them, whole-body physiological remodelling directly influences eating patterns, commonly causing notable taste perception alterations, food aversions and cravings. Recurrent food cravings for and compulsive eating of highly palatable food can contribute to the development and maintenance of gestational overweight and obesity with potential adverse health consequences for the offspring. Although much is known about how maternal eating habits influence offspring health, the mechanisms that underlie changes in taste perception and food preference during pregnancy (which guide and promote feeding) are only just starting to be elucidated. Given the limited and diffuse understanding of the neurobiology of gestational eating patterns, the aim of this Review is to compile, integrate and discuss the research conducted on this topic in both experimental models and humans. This article sheds light on the mechanisms that drive changes in female feeding behaviours during distinct physiological states. Understanding these processes is crucial to improve gestational parent health and decrease the burden of metabolic and food-related diseases in future generations.
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Affiliation(s)
- Roberta Haddad-Tóvolli
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
| | - Marc Claret
- Neuronal Control of Metabolism (NeuCoMe) Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain.
- School of Medicine, Universitat de Barcelona, Barcelona, Spain.
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Clarke GS, Gatford KL, Young RL, Grattan DR, Ladyman SR, Page AJ. Maternal adaptations to food intake across pregnancy: Central and peripheral mechanisms. Obesity (Silver Spring) 2021; 29:1813-1824. [PMID: 34623766 DOI: 10.1002/oby.23224] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/17/2021] [Accepted: 04/11/2021] [Indexed: 12/17/2022]
Abstract
A sufficient and balanced maternal diet is critical to meet the nutritional demands of the developing fetus and to facilitate deposition of fat reserves for lactation. Multiple adaptations occur to meet these energy requirements, including reductions in energy expenditure and increases in maternal food intake. The central nervous system plays a vital role in the regulation of food intake and energy homeostasis and responds to multiple metabolic and nutrient cues, including those arising from the gastrointestinal tract. This review describes the nutrient requirements of pregnancy and the impact of over- and undernutrition on the risk of pregnancy complications and adult disease in progeny. The central and peripheral regulation of food intake is then discussed, with particular emphasis on the adaptations that occur during pregnancy and the mechanisms that drive these changes, including the possible role of the pregnancy-associated hormones progesterone, estrogen, prolactin, and growth hormone. We identify the need for deeper mechanistic understanding of maternal adaptations, in particular, changes in gut-brain axis satiety signaling. Improved understanding of food intake regulation during pregnancy will provide a basis to inform strategies that prevent maternal under- or overnutrition, improve fetal health, and reduce the long-term health and economic burden for mothers and offspring.
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Affiliation(s)
- Georgia S Clarke
- Vagal Afferent Research Group, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
- Robinson Research Institute, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
- Nutrition, Diabetes & Gut Health, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Kathryn L Gatford
- Robinson Research Institute, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
- Nutrition, Diabetes & Gut Health, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Richard L Young
- Nutrition, Diabetes & Gut Health, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
- Intestinal Nutrient Sensing Group, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
- Centre of Research Excellence: Translating Nutritional Science to Good Health, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
| | - David R Grattan
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Sharon R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Amanda J Page
- Vagal Afferent Research Group, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
- Nutrition, Diabetes & Gut Health, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
- Centre of Research Excellence: Translating Nutritional Science to Good Health, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia
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Taschetto APD, Zimath PL, Silvério R, Dos Santos C, Boschero AC, Dos Santos GJ, Rafacho A. Reduced insulin sensitivity and increased β/α cell mass is associated with reduced hepatic insulin-degrading enzyme activity in pregnant rats. Life Sci 2021; 277:119509. [PMID: 33865877 DOI: 10.1016/j.lfs.2021.119509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/05/2021] [Accepted: 04/07/2021] [Indexed: 11/19/2022]
Abstract
AIMS Pregnancy is associated with the development of a transitory insulin resistance that parallels with the upregulation of pancreatic β-cell function and mass. These metabolic adaptations guarantee the higher insulin demand, but there is no evidence of whether insulin clearance contributes to this process. Thus, we investigated some of the hepatic parameters related to insulin clearance during rat pregnancy. We also investigated some molecular parameters in the hypothalamus. MAIN METHODS We evaluated the body mass and food intake, insulin sensitivity, β- and α-cell masses, insulin clearance based on an exogenous insulin load, hepatic insulin-degrading enzyme (IDE) activity, and hepatic and hypothalamic protein content of IDE and carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM-1) in three periods of gestation in Wistar rats. KEY FINDINGS In the first week of pregnancy, both insulin sensitivity and clearance increased, a pattern that inverted in the third week of gestation (reduced insulin sensitivity and clearance). Diminished insulin clearance was associated with lower hepatic IDE activity and higher pancreatic β- and α-cell masses. No alteration in the hepatic IDE and CEACAM protein content was observed throughout pregnancy, but hypothalamic IDE protein content was significantly reduced in the late gestation period. SIGNIFICANCE In conclusion, elevated insulin demand in the late period of gestation occurs not only as a result of increased β-cell mass and function but also by a potential reduction in hepatic insulin clearance. Knowing this physiological process may be valuable when considering gestational diabetes mellitus results from a failure in insulin supply during pregnancy.
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Affiliation(s)
- Ana P D Taschetto
- Laboratory of Investigation in Chronic Diseases - LIDoC, Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil; Multicenter Graduate Program in Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil
| | - Priscila L Zimath
- Laboratory of Investigation in Chronic Diseases - LIDoC, Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil; Graduate Program in Pharmacology, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil
| | - Renata Silvério
- Laboratory of Investigation in Chronic Diseases - LIDoC, Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil; Graduate Program in Pharmacology, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil
| | - Cristiane Dos Santos
- Laboratory of Investigation in Chronic Diseases - LIDoC, Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil; Graduate Program in Molecular and Functional Biology, Institute of Biology, Campinas State University - UNICAMP, 13083-862 Campinas, Brazil
| | - Antonio C Boschero
- Graduate Program in Molecular and Functional Biology, Institute of Biology, Campinas State University - UNICAMP, 13083-862 Campinas, Brazil
| | - Gustavo J Dos Santos
- Laboratory of Investigation in Chronic Diseases - LIDoC, Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil; Multicenter Graduate Program in Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil
| | - Alex Rafacho
- Laboratory of Investigation in Chronic Diseases - LIDoC, Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil; Multicenter Graduate Program in Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil; Graduate Program in Pharmacology, Center of Biological Sciences, Federal University of Santa Catarina - UFSC, 88040-900 Florianópolis, Brazil; Graduate Program in Molecular and Functional Biology, Institute of Biology, Campinas State University - UNICAMP, 13083-862 Campinas, Brazil.
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5
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Ladyman SR, Brooks VL. Central actions of insulin during pregnancy and lactation. J Neuroendocrinol 2021; 33:e12946. [PMID: 33710714 PMCID: PMC9198112 DOI: 10.1111/jne.12946] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/24/2021] [Accepted: 01/27/2021] [Indexed: 12/17/2022]
Abstract
Pregnancy and lactation are highly metabolically demanding states. Maternal glucose is a key fuel source for the growth and development of the fetus, as well as for the production of milk during lactation. Hence, the maternal body undergoes major adaptations in the systems regulating glucose homeostasis to cope with the increased demand for glucose. As part of these changes, insulin levels are elevated during pregnancy and lower in lactation. The increased insulin secretion during pregnancy plays a vital role in the periphery; however, the potential effects of increased insulin action in the brain have not been widely investigated. In this review, we consider the impact of pregnancy on brain access and brain levels of insulin. Moreover, we explore the hypothesis that pregnancy is associated with site-specific central insulin resistance that is adaptive, allowing for the increases in peripheral insulin secretion without the consequences of increased central and peripheral insulin functions, such as to stimulate glucose uptake into maternal tissues or to inhibit food intake. Conversely, the loss of central insulin actions may impair other functions, such as insulin control of the autonomic nervous system. The potential role of low insulin in facilitating adaptive responses to lactation, such as hyperphagia and suppression of reproductive function, are also discussed. We end the review with a list of key research questions requiring resolution.
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Affiliation(s)
- Sharon R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
| | - Virginia L Brooks
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, USA
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Khant Aung Z, Grattan DR, Ladyman SR. Pregnancy-induced adaptation of central sensitivity to leptin and insulin. Mol Cell Endocrinol 2020; 516:110933. [PMID: 32707081 DOI: 10.1016/j.mce.2020.110933] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 06/22/2020] [Accepted: 06/29/2020] [Indexed: 02/07/2023]
Abstract
Pregnancy is a time of increased food intake and fat deposition in the mother, and adaptations of glucose homeostasis to meet the energy demands of the growing fetus. As part of these adaptations, leptin and insulin concentrations increase in the maternal circulation during pregnancy. Central effects of leptin and insulin, however, are counterproductive to pregnancy, as increased action of these hormones in the brain lead to suppression of food intake. To prevent this, it is well documented that pregnancy induces a state of leptin- and insulin-insensitivity in the brain, particularly the hypothalamus, in a range of species. While the mechanisms underlying leptin- or insulin-insensitivity during pregnancy vary between species, there is evidence of reduced transport into the brain, impaired activation of intracellular signalling pathways, including reduced leptin receptor expression, and attenuated activation of downstream neuronal pathways, especially for leptin insensitivity. Pregnancy-induced changes in prolactin, growth hormone and leptin are discussed in terms of their role in mediating this reduced response to leptin and insulin.
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Affiliation(s)
- Z Khant Aung
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, 9016, New Zealand
| | - D R Grattan
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, 9016, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, 1010, New Zealand
| | - S R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, 9016, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, 1010, New Zealand.
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7
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Grattan DR, Ladyman SR. Neurophysiological and cognitive changes in pregnancy. HANDBOOK OF CLINICAL NEUROLOGY 2020; 171:25-55. [PMID: 32736755 DOI: 10.1016/b978-0-444-64239-4.00002-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The hormonal fluctuations in pregnancy drive a wide range of adaptive changes in the maternal brain. These range from specific neurophysiological changes in the patterns of activity of individual neuronal populations, through to complete modification of circuit characteristics leading to fundamental changes in behavior. From a neurologic perspective, the key hormone changes are those of the sex steroids, estradiol and progesterone, secreted first from the ovary and then from the placenta, the adrenal glucocorticoid cortisol, as well as the anterior pituitary peptide hormone prolactin and its pregnancy-specific homolog placental lactogen. All of these hormones are markedly elevated during pregnancy and cross the blood-brain barrier to exert actions on neuronal populations through receptors expressed in specific regions. Many of the hormone-induced changes are in autonomic or homeostatic systems. For example, patterns of oxytocin and prolactin secretion are dramatically altered to support novel physiological functions. Appetite is increased and feedback responses to metabolic hormones such as leptin and insulin are suppressed to promote a positive energy balance. Fundamental physiological systems such as glucose homeostasis and thermoregulation are modified to optimize conditions for fetal development. In addition to these largely autonomic changes, there are also changes in mood, behavior, and higher processes such as cognition. This chapter summarizes the hormonal changes associated with pregnancy and reviews how these changes impact on brain function, drawing on examples from animal research, as well as available information about human pregnancy.
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Affiliation(s)
- David R Grattan
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
| | - Sharon R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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Teixeira PDS, Couto GC, Furigo IC, List EO, Kopchick JJ, Donato J. Central growth hormone action regulates metabolism during pregnancy. Am J Physiol Endocrinol Metab 2019; 317:E925-E940. [PMID: 31479305 PMCID: PMC7132326 DOI: 10.1152/ajpendo.00229.2019] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The maternal organism undergoes numerous metabolic adaptations to become prepared for the demands associated with the coming offspring. These metabolic adaptations involve changes induced by several hormones that act at multiple levels, ultimately influencing energy and glucose homeostasis during pregnancy and lactation. Previous studies have shown that central growth hormone (GH) action modulates glucose and energy homeostasis. However, whether central GH action regulates metabolism during pregnancy and lactation is still unknown. In the present study, we generated mice carrying ablation of GH receptor (GHR) in agouti-related protein (AgRP)-expressing neurons, in leptin receptor (LepR)-expressing cells or in the entire brain to investigate the role played by central GH action during pregnancy and lactation. AgRP-specific GHR ablation led to minor metabolic changes during pregnancy and lactation. However, while brain-specific GHR ablation reduced food intake and body adiposity during gestation, LepR GHR knockout (KO) mice exhibited increased leptin responsiveness in the ventromedial nucleus of the hypothalamus during late pregnancy, although their offspring showed reduced growth rate. Additionally, both Brain GHR KO and LepR GHR KO mice had lower glucose tolerance and glucose-stimulated insulin secretion during pregnancy, despite presenting increased insulin sensitivity, compared with control pregnant animals. Our findings revealed that during pregnancy central GH action regulates food intake, fat retention, as well as the sensitivity to insulin and leptin in a cell-specific manner. Together, the results suggest that GH acts in concert with other "gestational hormones" to prepare the maternal organism for the metabolic demands of the offspring.
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Affiliation(s)
- Pryscila D S Teixeira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Gisele C Couto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Isadora C Furigo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Edward O List
- Edison Biotechnology Institute and Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio
| | - John J Kopchick
- Edison Biotechnology Institute and Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio
| | - Jose Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Trujillo-Güiza ML, Señarís R. Leptin resistance during pregnancy is also exerted at the periphery†. Biol Reprod 2018; 98:654-663. [DOI: 10.1093/biolre/ioy024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 01/28/2018] [Indexed: 01/08/2023] Open
Affiliation(s)
| | - Rosa Señarís
- CIMUS, Department of Physiology, University of Santiago de Compostela, Santiago de Compostela, Spain
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Ladyman SR, Augustine RA, Scherf E, Phillipps HR, Brown CH, Grattan DR. Attenuated hypothalamic responses to α-melanocyte stimulating hormone during pregnancy in the rat. J Physiol 2016; 594:1087-101. [PMID: 26613967 DOI: 10.1113/jp271605] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 11/23/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Increased appetite and weight gain occurs during pregnancy, associated with development of leptin resistance, and satiety responses to the anorectic peptide α-melanocyte stimulating hormone (α-MSH) are suppressed. This study investigated hypothalamic responses to α-MSH during pregnancy, using c-fos expression in specific hypothalamic nuclei as a marker of neuronal signalling, and in vivo electrophysiology in supraoptic nucleus (SON) oxytocin neurons, as a representative α-MSH-responsive neuronal population that shows a well-characterised α-MSH-induced inhibition of firing. While icv injection of α-MSH significantly increased the number of c-fos-positive cells in the paraventricular, supraoptic, arcuate and ventromedial hypothalamic nuclei in non-pregnant rats, this response was suppressed in pregnant rats. Similarly, SON oxytocin neurons in pregnant rats did not demonstrate characteristic α-MSH-induced inhibition of firing that was observed in non-pregnant animals. Given the known functions of α-MSH in the hypothalamus, the attenuated responses are likely to facilitate adaptive changes in appetite regulation and oxytocin secretion during pregnancy. ABSTRACT During pregnancy, a state of positive energy balance develops to support the growing fetus and to deposit fat in preparation for the subsequent metabolic demands of lactation. As part of this maternal adaptation, the satiety response to the anorectic peptide α-melanocyte stimulating hormone (α-MSH) is suppressed. To investigate whether pregnancy is associated with changes in the response of hypothalamic α-MSH target neurons, non-pregnant and pregnant rats were treated with α-MSH or vehicle and c-fos expression in hypothalamic nuclei was then examined. Furthermore, the firing rate of supraoptic nucleus (SON) oxytocin neurons, a known α-MSH responsive neuronal population, was examined in non-pregnant and pregnant rats following α-MSH treatment. Intracerebroventricular injection of α-MSH significantly increased the number of c-fos-positive cells in the paraventricular, arcuate and ventromedial hypothalamic nuclei in non-pregnant rats, but no significant increase was observed in any of these regions in pregnant rats. In the SON, α-MSH did induce expression of c-fos during pregnancy, but this was significantly reduced compared to that observed in the non-pregnant group. Furthermore, during pregnancy, SON oxytocin neurons did not demonstrate the characteristic α-MSH-induced inhibition of firing rate that was observed in non-pregnant animals. Melanocortin receptor mRNA levels during pregnancy were similar to non-pregnant animals, suggesting that receptor down-regulation is unlikely to be a mechanism underlying the attenuated responses to α-MSH during pregnancy. Given the known functions of α-MSH in the hypothalamus, the attenuated responses will facilitate adaptive changes in appetite regulation and oxytocin secretion during pregnancy.
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Affiliation(s)
- S R Ladyman
- Department of Anatomy and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - R A Augustine
- Department of Physiology and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - E Scherf
- Department of Anatomy and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - H R Phillipps
- Department of Anatomy and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - C H Brown
- Department of Physiology and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - D R Grattan
- Department of Anatomy and Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Gustavsson C, Andersson Hall U, Pelanis A, Karlsson OI, Andersson L, Svedin P, Mallard C, Myntti A, Andreasson U, Zetterberg H, Blennow K, Holmäng A. Cerebrospinal fluid levels of insulin, leptin, and agouti-related protein in relation to BMI in pregnant women. Obesity (Silver Spring) 2016; 24:1299-304. [PMID: 27130070 DOI: 10.1002/oby.21502] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 02/14/2016] [Indexed: 12/31/2022]
Abstract
OBJECTIVE During pregnancy, metabolic interactions must be adapted, though neuroendocrine mechanisms for increased food intake are poorly understood. The objective of this study was to characterize differences in insulin, leptin, and agouti-related protein (AgRP) levels in serum and cerebrospinal fluid (CSF) in pregnant women with normal weight (NW) and pregnant women with overweight (OW) or obesity (OB). Placenta as a source for increased peripheral AgRP levels during pregnancy was also investigated. METHODS Women were recruited at admission for elective cesarean section. Insulin, AgRP, and leptin were measured in serum and CSF from 30 NW, 25 OW, and 21 OB at term. Serum during pregnancy and placenta at term were collected for further AgRP analysis. RESULTS Immunohistology showed placental production of AgRP and serum AgRP levels increased throughout pregnancy. CSF AgRP, leptin, and insulin levels were higher in OW and OB than NW. Serum leptin and insulin levels were higher and AgRP lower in OB than NW. CONCLUSIONS High serum AgRP levels might protect from the suppressive effects of leptin during pregnancy. Pregnant women with OB and OW might further be protected from the suppressive effect of leptin by high CSF AgRP levels. Evidence was found, for the first time, of human placental AgRP production mirrored by levels in the circulation.
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Affiliation(s)
- Carolina Gustavsson
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Ulrika Andersson Hall
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Aurimantas Pelanis
- Department of Anesthesiology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Ove I Karlsson
- Department of Anesthesiology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Louise Andersson
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Pernilla Svedin
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Carina Mallard
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Alexandra Myntti
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Ulf Andreasson
- Clinical Neurochemistry Lab, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden
| | - Henrik Zetterberg
- Clinical Neurochemistry Lab, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden
- UCL Institute of Neurology, London, UK
| | - Kaj Blennow
- Clinical Neurochemistry Lab, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden
| | - Agneta Holmäng
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
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Wee NKY, Kulkarni RN, Horsnell H, Baldock PA. The brain in bone and fuel metabolism. Bone 2016; 82:56-63. [PMID: 26545334 DOI: 10.1016/j.bone.2015.10.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 10/01/2015] [Accepted: 10/31/2015] [Indexed: 12/24/2022]
Abstract
Obesity and osteoporosis have become major public health challenges worldwide. The brain is well established as a pivotal regulator of energy homeostasis, appetite and fuel metabolism. However, there is now clear evidence for regulation between the brain and bone. Similarly, evidence also indicates that the involvement of the brain in bone and adipose regulation is both related and interdependent. The hypothalamus, with its semi-permeable blood brain barrier, is one of the most powerful regulatory regions within the body, integrating and relaying signals not only from peripheral tissues but also from within the brain itself. Two main neuronal populations within the arcuate nucleus of the hypothalamus regulate energy homeostasis: The orexigenic, appetite-stimulating neurons that co-express neuropeptide Y and agouti-related peptide and the anorexigenic, appetite-suppressing neurons that co-express proopiomelanocortin and cocaine- and amphetamine related transcript. From within the arcuate, these four neuropeptides encompass some of the most powerful control of energy homeostasis in the entire body. Moreover, they also regulate skeletal homeostasis, identifying a co-ordination network linking the processes of bone and energy homeostasis. Excitingly, the number of central neuropeptides and neural factors known to regulate bone and energy homeostasis continues to grow, with cannabinoid receptors and semaphorins also involved in bone homeostasis. These neuronal pathways represent a growing area of research that is identifying novel regulatory axes between the brain and the bone, and links with other homeostatic networks; thereby revealing a far more complex, and interdependent bone biology than previously envisioned. This review examines the current understanding of the central regulation of bone and energy metabolism.
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Affiliation(s)
- Natalie K Y Wee
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia
| | - Rishikesh N Kulkarni
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia
| | - Harry Horsnell
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia; Department of Biology and Biochemistry, Bath University, Bath, UK
| | - Paul A Baldock
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia; Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia; School of Medicine, The University of Notre Dame Australia, Sydney, NSW, Australia.
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Page-Wilson G, Reitman-Ivashkov E, Meece K, White A, Rosenbaum M, Smiley RM, Wardlaw SL. Cerebrospinal fluid levels of leptin, proopiomelanocortin, and agouti-related protein in human pregnancy: evidence for leptin resistance. J Clin Endocrinol Metab 2013; 98:264-71. [PMID: 23118421 PMCID: PMC3537103 DOI: 10.1210/jc.2012-2309] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Leptin suppresses appetite by modulating the expression of hypothalamic neuropeptides including proopiomelanocortin (POMC) and agouti-related peptide (AgRP). Yet during pregnancy, caloric consumption increases despite elevated plasma leptin levels. DESIGN AND PARTICIPANTS To investigate this paradox, we measured leptin and soluble leptin receptor in plasma and leptin, POMC, and AgRP in cerebrospinal fluid (CSF) from 21 fasting pregnant women before delivery by cesarean section at a university hospital and from 14 fasting nonpregnant women. RESULTS Prepregnancy body mass index was 24.6 ± 1.1 (SE) vs. 31.3 ± 1.3 at term vs. 26.5 ± 1.6 kg/m(2) in controls. Plasma leptin (32.9 ± 4.6 vs. 16.7 ± 3.0 ng/ml) and soluble leptin receptor (30.9 ± 2.3 vs. 22.1 ± 1.4 ng/ml) levels were significantly higher in pregnant women. However, mean CSF leptin did not differ between the two groups (283 ± 34 vs. 311 ± 32 pg/ml), consistent with a relative decrease in leptin transport into CSF during pregnancy. Accordingly, the CSF/plasma leptin percentage was 1.0 ± 0.01% in pregnant subjects vs. 2.1 ± 0.2% in controls (P < 0.0001). Mean CSF AgRP was significantly higher in pregnant subjects (32.3 ± 2.7 vs. 23.5 ± 2.5 pg/ml; P = 0.03). Mean CSF POMC was not significantly different in pregnant subjects (200 ± 13.6 vs. 229 ± 17.3 fmol/ml; P = 0.190). However, the mean AgRP/POMC ratio was significantly higher among pregnant women (P = 0.003), consistent with an overall decrease in melanocortin tone favoring increased food intake during pregnancy. CONCLUSIONS These data demonstrate that despite peripheral hyperleptinemia, positive energy balance is achieved during pregnancy by a relative decrease in central leptin concentrations and resistance to leptin's effects on target neuropeptides that regulate energy balance.
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Hypothalamic neuropeptides and the regulation of appetite. Neuropharmacology 2012; 63:18-30. [PMID: 22369786 DOI: 10.1016/j.neuropharm.2012.02.004] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 12/23/2011] [Accepted: 02/07/2012] [Indexed: 12/24/2022]
Abstract
Neuropeptides released by hypothalamic neurons play a major role in the regulation of feeding, acting both within the hypothalamus, and at other appetite regulating centres throughout the brain. Where classical neurotransmitters signal only within synapses, neuropeptides diffuse over greater distances affecting both nearby and distant neurons expressing the relevant receptors, which are often extrasynaptic. As well as triggering a behavioural output, neuropeptides also act as neuromodulators: altering the response of neurons to both neurotransmitters and circulating signals of nutrient status. The mechanisms of action of hypothalamic neuropeptides with established roles in feeding, including melanin-concentrating hormone (MCH), the orexins, α-melanocyte stimulating hormone (α-MSH), agouti-gene related protein (AgRP), neuropeptide Y, and oxytocin, are reviewed in this article, with emphasis laid on both their effects on appetite regulating centres throughout the brain, and on examining the evidence for their physiological roles. In addition, evidence for the involvement of several putative appetite regulating hypothalamic neuropeptides is assessed including, ghrelin, cocaine and amphetamine-regulated transcript (CART), neuropeptide W and the galanin-like peptides. This article is part of a Special Issue entitled 'Central control of Food Intake'.
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15
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Wang PQ, Deng LM, Zhang BY, Chu MX, Hou JZ. Polymorphisms of the cocaine-amphetamine-regulated transcript (CART) gene and their association with reproductive traits in Chinese goats. GENETICS AND MOLECULAR RESEARCH 2011; 10:731-8. [PMID: 21523652 DOI: 10.4238/vol10-2gmr1091] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Polymorphisms of the CART gene were investigated by PCR-single-strand conformation polymorphism analysis in 540 samples from 10 goat breeds. Ten novel single-nucleotide polymorphisms as well as three microsatellites were detected; a mutation, 77T → C, led to an amino acid change (Leu → Ser). Associations between polymorphic loci and reproductive traits were analyzed in Chuandong White, Guizhou White and Gulin Ma breeds. Mutation at position 524 had no significant effect on litter size in these three goat breeds. The polymorphism 539C → A differed significantly among the three breeds (P < 0.05); C(7)T(8)/C(9)T(8) at 939 was associated with larger litter size (P < 0.05) than genotypes C(7)T(8)/C(7)T(8) and C(7)T(8)/C(8)T(8). No significant association of birth weight was found with gene variation (524C → T, 539C → A and 939 CnTn). These findings could be valuable for marker-assisted selection for goat breeding.
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Affiliation(s)
- P Q Wang
- College of Bioengineering, Chongqing University, Chongqing, PR. China.
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Trujillo ML, Spuch C, Carro E, Señarís R. Hyperphagia and central mechanisms for leptin resistance during pregnancy. Endocrinology 2011; 152:1355-65. [PMID: 21303957 DOI: 10.1210/en.2010-0975] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The purpose of this work was to study the central mechanisms involved in food intake regulation and leptin resistance during gestation in the rat. Sprague Dawley rats of 7, 13, and 18 d of pregnancy [days of gestation (G) 7, G13, and G18] were used and compared with nonpregnant animals in diestrus-1. Food intake was already increased in G7, before hyperleptinemia and central leptin resistance was established in midpregnancy. Leptin resistance was due to a reduction in leptin transport through the blood-brain barrier (BBB) and to alterations in leptin signaling within the hypothalamus based on an increase in suppressor of cytokine signaling 3 levels and a blockade of signal transducer and activator of transcription-3 phosphorylation (G13), followed by a decrease in LepRb and of Akt phosphorylation (G18). In early gestation (G7), no change in hypothalamic neuropeptide Y (NPY), agouti-related peptide (AgRP), or proopiomelanocortin (POMC) expression was shown. Nevertheless, an increase in NPY and AgRP and a decrease in POMC mRNA were observed in G13 and G18 rats, probably reflecting the leptin resistance. To investigate the effect of maternal vs. placental hormones on these mechanisms, we used a model of pseudogestation. Rats of 9 d of pseudogestation were hyperphagic, showing an increase in body and adipose tissue weight, normoleptinemia, and normal responses to iv/intracerebroventricular leptin on hypothalamic leptin signaling, food intake, and body weight. Leptin transport through the BBB, and hypothalamic NPY, AgRP and POMC expression were unchanged. Finally, the transport of leptin through the BBB was assessed using a double-chamber culture system of choroid plexus epithelial cells or brain microvascular endothelial cells. We found that sustained high levels of prolactin significantly reduced leptin translocation through the barrier, whereas progesterone and β-estradiol did not show any effect. Our data demonstrate a dual mechanism of leptin resistance during mid/late-pregnancy, which is not due to maternal hormones and which allows the maintenance of hyperphagia in the presence of hyperleptinemia driven by an increase in NPY and AgRP and a decrease in POMC mRNA. By contrast, in early pregnancy maternal hormones induce hyperphagia without the regulation of hypothalamic NPY, AgRP, or POMC and in the absence of leptin resistance.
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Affiliation(s)
- M L Trujillo
- Department of Physiology, Faculty of Medicine, University of Santiago de Compostela, c/San Francisco s/n, 15782 Santiago de Compostela, Spain
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Body weight decreases induced by estradiol in female rhesus monkeys are dependent upon social status. Physiol Behav 2010; 102:382-8. [PMID: 21130792 DOI: 10.1016/j.physbeh.2010.11.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 11/25/2010] [Accepted: 11/29/2010] [Indexed: 11/22/2022]
Abstract
Gonadal steroids regulate appetite and thus body weight. In addition, continuous exposure to stressors negatively influences appetite through circuits likely distinct from those of gonadal steroids. The occurrence of adverse metabolic consequences due to chronic exposure to psychosocial stressors is twice as frequent in women as men, implicating a role for ovarian hormones, estradiol (E2) and progesterone (P4), in modulating stress-induced changes in appetite. Using social subordination in female macaques as a model of social stress, the current study tested the hypothesis that subordinate females would lose more weight during E2 treatment and gain less weight during P4 administration than dominant females. Because polymorphisms in the gene encoding the serotonin transporter (5HTT; SCL6A4) are known to alter responsivity to stress, we hypothesized that weight loss during E2 administration would be greatest in females with the short variant (s-variant) allele of 5HTT. Dominant females were significantly heavier than subordinate animals throughout the study, a result consistent with previous accounts of food intake when animals are fed a low-fat, high-fiber diet. Females with the s-variant 5HTT genotype weighed significantly less than l/l animals. Dominant animals lost significantly more weight than subordinate animals during E2 treatment. Administration of P4 blocked the weight-reducing effects of E2 in all females, regardless of social status. These data provide evidence that social subordination modulates the influence of ovarian steroid hormones on body weight in female rhesus monkeys independent of 5HTT genotype. Given the prosocial effects of these steroids, future studies are necessary to determine whether status differences in E2-induced weight loss are due to diminished food intake and or increases in energy expenditure and how the change in energy availability during E2 treatments relates to a female's motivation to interact with conspecifics.
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Silveyra P, Cataldi NI, Lux-Lantos VA, Libertun C. Role of orexins in the hypothalamic-pituitary-ovarian relationships. Acta Physiol (Oxf) 2010; 198:355-60. [PMID: 19796256 DOI: 10.1111/j.1748-1716.2009.02049.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Appropriate nutritional and vigilance states are needed for reproduction. In previous works, we described the influence of the hormonal milieu of proestrus on the orexinergic system and we found that orexin receptor 1 expression in the hypothalamus, but not other neural areas, and the adenohypophysis was under the influence of oestradiol and the time of the day. Information from the sexual hormonal milieu of proestrous afternoon impacts on various components of the orexinergic system and alertness on this particular night of proestrus would be of importance for successful reproduction. In this review, we summarize the available experimental data supporting the participation of orexins in the hypothalamic-pituitary-ovarian relationships. All together, these results suggest a role of the orexinergic system as an integrative link among vital functions such as reproduction, food intake, alertness and the inner biological clock.
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Affiliation(s)
- P Silveyra
- Instituto de Biología y Medicina Experimental-CONICET, Buenos Aires, Argentina
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19
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Makarova EN, Kochubei ED, Bazhan NM. Regulation of Food Consumption during Pregnancy and Lactation in Mice. ACTA ACUST UNITED AC 2010; 40:263-7. [DOI: 10.1007/s11055-010-9253-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Indexed: 11/29/2022]
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20
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Faas MM, Melgert BN, de Vos P. A Brief Review on How Pregnancy and Sex Hormones Interfere with Taste and Food Intake. CHEMOSENS PERCEPT 2009; 3:51-56. [PMID: 20352054 PMCID: PMC2844535 DOI: 10.1007/s12078-009-9061-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2009] [Accepted: 10/07/2009] [Indexed: 12/01/2022]
Abstract
Many physiological and behavioral changes take place during pregnancy, including changes in taste and an increase in food intake. These changes are necessary to ensure growth and development of a healthy fetus. Both hyperphagia and taste changes during pregnancy may be induced by sex hormones estrogen and progesterone that are increased during pregnancy. Indeed, it has been shown that estrogen decreases food intake, while progesterone increases food intake. This is for instance apparent from the fact that food intake changes during the menstrual cycle with variation in sex hormones. This review will give a short overview of the effects of pregnancy and sex hormones on food intake and taste.
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Affiliation(s)
- Marijke M Faas
- Immunoendocrinology, Division of Medical Biology, Department of Pathology and Medical Biology, University Medical Centre Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
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Ladyman SR, Tups A, Augustine RA, Swahn-Azavedo A, Kokay IC, Grattan DR. Loss of hypothalamic response to leptin during pregnancy associated with development of melanocortin resistance. J Neuroendocrinol 2009; 21:449-56. [PMID: 19302191 DOI: 10.1111/j.1365-2826.2009.01862.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hypothalamic leptin resistance during pregnancy is an important adaptation that facilitates the state of positive energy balance required for fat deposition in preparation for lactation. Within the arcuate nucleus, pro-opiomelanocortin (POMC) neurones and neuropeptide Y (NPY)/agouti-related gene protein (AgRP) neurones are first-order leptin responsive neurones involved in the regulation of energy balance. The present study aimed to investigate whether the regulation of these neuropeptides is disrupted during pregnancy in association with the development of leptin resistance. As measured by quantitative in situ hybridisation, POMC and AgRP mRNA levels were not significantly different during pregnancy, whereas NPY mRNA levels increased such that, by day 21 of pregnancy, levels were significantly higher than in nonpregnant, animals. These data suggest that these neurones were not responding normally to the elevated leptin found during pregnancy. To further characterise the melanocortin system during pregnancy, double-label immunohistochemistry was used to quantify leptin-induced phosphorylation of signal transducer and activator of transcription 3 (pSTAT3) in POMC neurones, using α-melanocyte-stimulating hormone (MSH) as a marker. The percentage of α-MSH neurones containing leptin-induced pSTAT3 did not significantly differ from nonpregnant animals, indicating that there was no change in the number of POMC neurones that respond to leptin during pregnancy. Treatment with α-MSH significantly reduced food intake in nonpregnant rats, but not in pregnant rats, indicating resistance to the satiety actions of α-MSH during pregnancy. The data suggest that multiple mechanisms contribute to leptin resistance during pregnancy. As well as a loss of responses in first-order leptin-responsive neurones in the arcuate nucleus, there is also a downstream disruption in the melanocortin system.
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Affiliation(s)
- S R Ladyman
- Centre for Neuroendocrinology, Department of Anatomy and Structural Biology, University of Otago, Dunedin, New Zealand
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22
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Tang GB, Cui JG, Wang DH. Hypothalamic suppressor-of-cytokine-signalling 3 mRNA is elevated and pro-opiomelanocortin mRNA is reduced during pregnancy in Brandt's voles (Lasiopodomys brandtii ). J Neuroendocrinol 2008; 20:1038-44. [PMID: 18638026 DOI: 10.1111/j.1365-2826.2008.01764.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Leptin acts within the hypothalamus to diminish food intake. In Brandt's voles (Lasiopodomys brandtii), both circulating leptin levels and food intake are elevated during pregnancy, suggesting an ineffectiveness of leptin to reduce food intake. Diminished hypothalamic leptin receptors and impaired leptin signal transduction are characteristic of central leptin resistance. The present study aimed to determine whether these characteristic modulations of leptin sensitivity occurred in pregnant Brandt's voles. The mRNA expression of the long form of the leptin receptor (Ob-Rb), suppressor-of-cytokine-signalling 3 (SOCS3), neuropeptide Y (NPY), agouti-related protein (AgRP), pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) in the hypothalamus were examined on dioestrous, day 5, day 10 and day 18 of pregnancy. Compared to controls, there was no significant change in hypothalamic Ob-Rb mRNA during the pregnancy. SOCS3 mRNA was increased significantly by 68% on day 10% and 93% on day 18 of pregnancy compared to controls. Despite elevated leptin levels, POMC mRNA was decreased significantly by 60% on day 18 of pregnancy, whereas no differences were found in the mRNA expression of NPY, AgRP and CART in pregnant voles compared to controls. The elevation of SOCS3 mRNA together with disrupted leptin regulation of neuropeptides in the hypothalamus suggests that leptin resistance may develop in pregnant Brandt's voles.
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Affiliation(s)
- G-B Tang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Datun Lu, Chaoyang, Beijing, China
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Abstract
The Agouti-Related Protein (AgRP) is a powerful orexigenic peptide that increases food intake when ubiquitously overexpressed or when administered centrally. AgRP-deficiency, on the other hand, leads to increased metabolic rate and a longer lifespan when mice consume a high fat diet. In humans, AgRP polymorphisms have been consistently associated with resistance to fatness in Blacks and Whites and resistance to the development of type-2 diabetes in African Blacks. Systemically administered AgRP accumulates in the liver, the adrenal gland and fat tissue while recent findings suggest that AgRP may also have inverse agonist effects, both centrally and peripherally. AgRP could thus modulate energy balance via different actions. Its absence or reduced functionality may offer a benefit both in terms of bringing about negative energy balance in obesigenic environments, as well as leading to an increased lifespan.
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Affiliation(s)
- O. Ilnytska
- Pennington Biomedical Research Center, LSU System, Baton Rouge, Louisiana, 70809 USA
| | - G. Argyropoulos
- Pennington Biomedical Research Center, LSU System, Baton Rouge, Louisiana, 70809 USA
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Lee ES, Uhm KO, Lee YM, Kwon J, Park SH, Soo KH. Oxytocin stimulates glucose uptake in skeletal muscle cells through the calcium-CaMKK-AMPK pathway. ACTA ACUST UNITED AC 2008; 151:71-4. [PMID: 18555543 DOI: 10.1016/j.regpep.2008.05.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 04/02/2008] [Accepted: 05/04/2008] [Indexed: 11/18/2022]
Abstract
Oxytocin is a mammalian hormone that is released mainly after distension of the uterine cervix. In this study, we report that oxytocin stimulates intracellular release of calcium, and also activates AMPK (AMP-activated protein kinase) in C2C12 myoblast cells in a time/dose-dependent manner. Oxytocin receptor mRNA was detected in C2C12 cells. In addition, oxytocin stimulated glucose uptake and, moreover, inhibition of either CaMKK (Ca(2+)/calmodulin-dependent protein kinase kinase) or AMPK blocked oxytocin-mediated AMPK activation and glucose uptake. Taken together, our findings suggest that oxytocin may serve a peripheral metabolic function in skeletal muscle cells through the calcium-CaMKK-AMPK pathway.
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Affiliation(s)
- Eun Soo Lee
- Department of Anatomy, Korea University College of Medicine, 126-1,5 ga, Anam-dong, Seongbuk-gu, Seoul, 136-701, Republic of Korea
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Augustine RA, Grattan DR. Induction of central leptin resistance in hyperphagic pseudopregnant rats by chronic prolactin infusion. Endocrinology 2008; 149:1049-55. [PMID: 18063686 DOI: 10.1210/en.2007-1018] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pregnancy in rats is associated with hyperphagia, increased fat deposition, and elevated plasma leptin concentrations. Elevated leptin would be expected to inhibit food intake, but hypothalamic leptin resistance develops around midpregnancy, allowing hyperphagia to be maintained and excess energy to be stored as fat in preparation for future metabolic demands of lactation. To investigate the hormonal mechanisms inducing leptin resistance during pregnancy, the anorectic response to leptin was examined during pseudopregnancy. Pseudopregnant rats have identical hormonal profiles to early pregnancy, but no placenta formation, allowing differentiation of maternal and placental hormone effects on appetite. To investigate the effect of leptin on food intake, d-9 pseudopregnant rats were injected with leptin (4 microg) via an intracerebroventricular (icv) cannula, and then food intake was measured 24 h later. Pseudopregnant rats were hyperphagic but had normal anorectic responses to leptin. We therefore hypothesized that a longer exposure time to high concentrations of progesterone might be required to mimic the leptin resistance that occurs on d 14 of pregnancy. Pseudopregnant rats were given progesterone to prolong pseudopregnancy beyond the time that leptin resistance develops during pregnancy. However, rats remained responsive to icv leptin. To model the placental lactogen secretion that occurs during pregnancy, pseudopregnant rats were given progesterone and chronic icv ovine prolactin infusion. Central icv injection of leptin had no effect on food intake in pseudopregnant rats receiving chronic ovine prolactin. These results suggest that chronically high lactogen levels, secreted by the placenta during the second half of pregnancy, induce central leptin resistance.
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Affiliation(s)
- Rachael A Augustine
- Centre for Neuroendocrinology and Department of Anatomy and Structural Biology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Abstract
The adipose-derived hormone leptin primarily acts in the hypothalamus to decrease appetite and increase energy expenditure, thereby maintaining body fat levels around a set point. Pregnancy is a physiological state where this feedback mechanism is not beneficial. Successful reproductive efforts are highly demanding on the resources of the mother; thus, it is imperative that the maternal body can increase energy stores without restraint. Food intake, fat mass and serum leptin concentrations increase during pregnancy in the rat, suggesting that the feedback loop between adipose tissue and appetite is disrupted and a state of leptin resistance exists. In support of this, there is an attenuation of the satiety response to exogenous leptin administration in pregnant rats. This state of leptin resistance is associated with impaired activation of the leptin-induced Janus activating kinase (JAK)/signal transducer and activator of transcription (STAT) signalling pathway in the ventromedial nucleus of the hypothalamus (VMH) and arcuate nucleus, and reduced expression of leptin receptor mRNA in the VMH. Furthermore, pregnant rats do not show a satiety response to exogenous alpha-melanocyte stimulating hormone. This model offers the possibility of examining how hypothalamic leptin signalling can be modified in response to changes in physiological conditions.
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Affiliation(s)
- S R Ladyman
- Centre for Studies in Behavioural Neurobiology, Concordia University, Montreal, Quebec, Canada.
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Brunton PJ, Russell JA. The expectant brain: adapting for motherhood. Nat Rev Neurosci 2008; 9:11-25. [PMID: 18073776 DOI: 10.1038/nrn2280] [Citation(s) in RCA: 267] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A successful pregnancy requires multiple adaptations of the mother's physiology to optimize fetal growth and development, to protect the fetus from adverse programming, to provide impetus for timely parturition and to ensure that adequate maternal care is provided after parturition. Many of these adaptations are organized by the mother's brain, predominantly through changes in neuroendocrine systems, and these changes are primarily driven by the hormones of pregnancy. By contrast, adaptations in the mother's brain during lactation are maintained by external stimuli from the young. The changes in pregnancy are not necessarily innocuous: they may predispose the mother to post-partum mood disorders.
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Affiliation(s)
- Paula J Brunton
- Laboratory of Neuroendocrinology, Centre for Integrative Physiology, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, Scotland, UK
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Abstract
Recent evidence suggests that the peptide hormone prolactin (PRL) modulates energy balance through a number of mechanisms, including acting in the brain to increase food intake. In the current studies, we first demonstrated that chronic infusions of PRL into the lateral ventricles increased food intake in cycling rats without disrupting estrous cyclicity. In subsequent experiments the hypothesis that at least part of PRL's ability to increase food intake resulted from PRL-induced leptin resistance was tested. Female rats given chronic infusions of PRL (5 microg/h) into the cerebral ventricles for 10 d did not show a reduction in food intake or body weight after a central injection of 4 microg murine leptin, whereas the expected reduction in both of these parameters was seen in vehicle-infused rats. Leptin injections were without effect on these parameters, whether they were administered to free feeding PRL-infused rats or after 24-h food deprivation. This lack of a behavioral response to leptin was accompanied by an attenuation in Fos induction and phosphorylation of signal transducer and activator of transcription 3 after leptin administration in PRL-infused rats in both the ventromedial hypothalamus and paraventricular hypothalamic nucleus.
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Affiliation(s)
- Lindsay Naef
- Center for Studies in Behavioral Neurobiology, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, Canada
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Augustine RA, Ladyman SR, Grattan DR. From feeding one to feeding many: hormone-induced changes in bodyweight homeostasis during pregnancy. J Physiol 2007; 586:387-97. [PMID: 18033810 DOI: 10.1113/jphysiol.2007.146316] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pregnancy is associated with hyperphagia, increased fat mass, hyperleptinaemia and hyperprolactinaemia. The neuroendocrine control of bodyweight involves appetite-regulating centres in the hypothalamus, containing both orexigenic and anorexigenic neurons that express leptin receptors (LepR). In the rat, central leptin resistance develops during mid pregnancy, well after hyperphagia becomes apparent, to negate the appetite suppressing effects of leptin. We have investigated the hypothalamic response to leptin during pregnancy and examined the role of pregnancy hormones in inducing these changes. We have shown that there are multiple levels of leptin resistance during pregnancy. Despite elevated serum leptin, neuropeptide Y and agouti related peptide mRNA in the arcuate nucleus are not suppressed and may even be increased during pregnancy. LepR mRNA and leptin-induced pSTAT3 expression, however, are relatively normal in the arcuate nucleus. In contrast, both LepR and leptin-induced pSTAT3 are reduced in the ventromedial hypothalamic nucleus. Injecting alpha-melanocyte-stimulating hormone (alpha-MSH) into the brain, to bypass the first-order leptin-responsive neurons in the arcuate nucleus, also fails to suppress food intake during pregnancy, suggesting that pregnancy is also a melanocortin-resistant state. Using a pseudopregnant rat model, we have demonstrated that in addition to the changes in maternal ovarian steroid secretion, placental lactogen production is essential for the induction of leptin resistance in pregnancy. Thus, hormonal changes associated with pregnancy induce adaptive changes in the maternal hypothalamus, stimulating food intake and then allowing elevated food intake to be maintained in the face of elevated leptin levels, resulting in fat deposition to provide energy stores in preparation for the high metabolic demands of late pregnancy and lactation.
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Affiliation(s)
- Rachael A Augustine
- Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, PO Box 913, Dunedin, New Zealand
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Douglas AJ, Johnstone LE, Leng G. Neuroendocrine mechanisms of change in food intake during pregnancy: a potential role for brain oxytocin. Physiol Behav 2007; 91:352-65. [PMID: 17512024 DOI: 10.1016/j.physbeh.2007.04.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
During pregnancy body weight, and particularly adiposity, increase, due to hyperphagia rather than decreased energy metabolism. These physiological adaptations provide the growing fetus(es) with nutrition and prepare the mother for the metabolically-demanding lactation period following birth. Mechanisms underlying the hyperphagia are still poorly understood. Although the peripheral signals that drive appetite and satiety centers of the brain are increased in pregnancy, the brain may become insensitive to their effects. For example, leptin secretion increases but hypothalamic resistance to leptin actions develops. However, several adaptations in hypothalamic neuroendocrine systems may converge to increase ingestive behavior. Oxytocin is one of the anorectic hypothalamic neuropeptides. Oxytocin neurons, both centrally-projecting parvocellular oxytocin neurons and central dendritic release of oxytocin from magnocellular neurons, may play a key role in regulating energy intake. During feeding in non-pregnant rats, magnocellular oxytocin neurons, especially those in the supraoptic nucleus, become strongly activated indicating their imminent role in meal termination. However, in mid-pregnancy the excitability of these neurons is reduced, central dendritic oxytocin release is inhibited and patterns of oxytocin receptor binding in the brain alter. Our recent data suggest that lack of central oxytocin action may partly contribute to maternal hyperphagia. However, although opioid inhibition is a major factor in oxytocin neuron restraint during pregnancy and opioids enhance food intake, an increase in opioid orexigenic actions were not observed. While changes in several central input pathways to oxytocin neurons are likely to be involved, the high level of progesterone secretion during pregnancy is probably the ultimate trigger for the adaptations.
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Affiliation(s)
- Alison J Douglas
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
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Abstract
Despite elevated plasma leptin, food intake is increased during pregnancy leading to fat deposition. We have demonstrated that intracerebroventricular (icv) leptin is unable to suppress food intake in pregnant rats, as it does in non-pregnant animals. Hence, central leptin resistance develops during pregnancy. These changes are physiologically appropriate, providing increased energy reserves to help meet the high metabolic demands of fetal development and lactation. To characterise this central leptin resistance, we have measured levels of leptin receptor (Ob-Rb) mRNA in the hypothalamus, and examined leptin-induced phosphorylation of STAT3 (pSTAT3) in specific regions of the hypothalamus. In addition, to investigate the mechanism underlying pregnancy-induced leptin resistance, we have investigated effects of hormone treatments on hypothalamic responses to leptin in a pseudopregnant rat model. We observed a significant reduction of Ob-Rb mRNA levels in the ventromedial hypothalamic nucleus (VMH) during pregnancy, with no changes detected in other hypothalamic nuclei. Levels of leptin-induced pSTAT3 were specifically suppressed in the VMH and arcuate nucleus of pregnant rats compared to non-pregnant rats. Pseudopregnant rats were hyperphagic but did not become leptin resistant, suggesting that fetal or placental factors are required for the induction of leptin resistance. These data implicate the VMH as a key hypothalamic site involved in hormone-induced leptin resistance during pregnancy, and suggest that placental hormone secretion may mediate the hormone-induced loss of response to leptin.
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Affiliation(s)
- David R Grattan
- Centre for Neuroendocrinology and Department of Anatomy and Structural Biology, University of Otago, Dunedin, New Zealand.
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Fatima A, Haroon MF, Wolf G, Engelmann M, Spina MG. Reduced urocortin 1 immunoreactivity in the non-preganglionic Edinger-Westphal nucleus during late pregnancy in rats. ACTA ACUST UNITED AC 2007; 143:34-8. [PMID: 17391780 DOI: 10.1016/j.regpep.2007.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 02/02/2007] [Accepted: 02/02/2007] [Indexed: 11/16/2022]
Abstract
Pregnancy is accompanied by an array of adaptive changes that play an important role in pre- and postnatal events. In rats, urocortin 1, a corticotropin-releasing factor-like peptide, is expressed mainly in the non-preganglionic Edinger-Westphal nucleus. We investigated the number of neurons immunoreactive for urocortin 1 at three different levels of the Edinger-Westphal nucleus in female rats by immunohistochemistry. The number of urocortin 1 immunoreactive cells was found to be decreased in pregnant rats compared to virgin rats. These results indicate that the hormonal status of the female rat affects urocortin 1 immunoreactive neurons in the non-preganglionic Edinger-Westphal nucleus and its signaling to target brain areas.
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Affiliation(s)
- A Fatima
- Institute of Medical Neurobiology, Otto-von-Guericke University Magdeburg, Germany.
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Stütz AM, Morrison CD, Argyropoulos G. The agouti-related protein and its role in energy homeostasis. Peptides 2005; 26:1771-81. [PMID: 15961186 DOI: 10.1016/j.peptides.2004.12.024] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Accepted: 12/01/2004] [Indexed: 12/30/2022]
Abstract
The melanocortin system plays an important role in the regulation of energy homeostasis. The Agouti-related protein (AGRP) is a natural antagonist of the action of alpha-melanocyte stimulating hormone (alpha-MSH) at the melanocortin receptors (MCR). AGRP is upregulated by fasting while intracerebroventricular injections of synthetic AGRP lead to increased appetite and food intake. Transgenic mice overexpressing AGRP are also hyperphagic and eventually become obese. AGRP is, therefore, a significant regulator of energy balance and a candidate gene for human fatness. Indeed, humans with common single nucleotide polymorphisms (SNPs) in the promoter or the coding region are leaner and resistant to late-onset obesity than wild-type individuals. AGRP is also expressed in the periphery. Recent studies show that AGRP in the adrenal gland is upregulated by fasting as much as it is in the hypothalamus. These data open up the possibility for a wider role by AGRP not only in food intake but also in the regulation of energy balance through its actions on peripheral tissues. This review summarizes recent advances in the biochemical and physiological properties of AGRP in an effort to enhance our understanding of the role this powerful neuropeptide plays in mammalian energy homeostasis.
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Affiliation(s)
- Adrian M Stütz
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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Ladyman SR, Grattan DR. Suppression of leptin receptor messenger ribonucleic acid and leptin responsiveness in the ventromedial nucleus of the hypothalamus during pregnancy in the rat. Endocrinology 2005; 146:3868-74. [PMID: 15905318 DOI: 10.1210/en.2005-0194] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pregnancy in the rat is a state of leptin resistance associated with impaired leptin signal transduction in the hypothalamus. The aim of this study was to determine whether this leptin-resistant state is mediated by a change in the level of leptin receptors in the hypothalamus. Real-time RT-PCR was used to determine levels of mRNA for the various leptin receptor isoforms in a number of microdissected hypothalamic nuclei and the choroid plexus. To investigate the functional activation of the leptin receptor, immunohistochemistry for phosphorylated signal transducer and activator of transcription 3 (pSTAT3) was examined in the arcuate nucleus and the ventromedial nucleus of the hypothalamus (VMH) of fasted diestrous and d-14 pregnant rats after an intracerebroventricular (i.c.v.) injection of either leptin (4 mug) or vehicle. A significant reduction of Ob-Rb mRNA levels was observed in the VMH during pregnancy compared with the nonpregnant controls. Furthermore, in pregnant rats the number of cells positive for leptin-induced pSTAT3 in the VMH was greatly reduced during pregnancy compared with nonpregnant rats. There were no differences in the level of Ob-Rb mRNA or in the number of leptin-induced pSTAT3-positive cells in the arcuate nucleus of nonpregnant and pregnant rats. These data implicate the VMH as a key hypothalamic site involved in pregnancy-induced leptin resistance. There were also reduced levels of mRNA for Ob-Ra, a proposed leptin transporter molecule, in the choroid plexus on d 7 and 21 of pregnancy. Hence, diminished transport of leptin into the brain may also contribute to pregnancy-induced leptin resistance.
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Affiliation(s)
- S R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy and Structural Biology, School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Crowley WR, Ramoz G, Keefe KA, Torto R, Kalra SP, Hanson GR. Differential effects of methamphetamine on expression of neuropeptide Y mRNA in hypothalamus and on serum leptin and ghrelin concentrations in ad libitum-fed and schedule-fed rats. Neuroscience 2005; 132:167-73. [PMID: 15780475 DOI: 10.1016/j.neuroscience.2004.11.037] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2004] [Indexed: 11/16/2022]
Abstract
Relatively little is known concerning the interaction of psychostimulants with hypothalamic neuropeptide systems or metabolic hormones implicated in regulation of energy balance. The present studies tested whether methamphetamine alters the expression of neuropeptide Y (NPY) and agouti-related peptide (AgRP), two important orexigenic neuropeptides, or proopiomelanocortin (POMC), the precursor for the anorexigenic peptide alpha-melanocyte-stimulating hormone, or the secretion of leptin, insulin and ghrelin, concomitant with inhibition of food intake. Female rats were either fed ad libitum (AL) or placed on a scheduled feeding (SF) regimen, with access to food limited to 4 h/day. Administration of (+/-)-methamphetamine (7.5 mg/kg, i.p.) 2 h prior to food presentation significantly inhibited food intake in SF animals, but did not affect intake in AL animals. In a separate study, AL and SF animals were killed just prior to expected food presentation, and expression of NPY, AgRP and POMC mRNAs in hypothalamus was determined using in situ hybridisation; concentrations of leptin, insulin and ghrelin in serum were determined with radioimmunoassays. In saline-treated, SF controls, NPY and AgRP mRNA expression in arcuate nucleus and serum ghrelin were significantly elevated, and serum leptin and insulin were significantly reduced. Methamphetamine reversed the up-regulation of NPY mRNA expression observed in the SF condition, without affecting AgRP mRNA or the serum concentrations of metabolic hormones. However, in AL animals, NPY mRNA expression in arcuate and dorsomedial nuclei was significantly increased by methamphetamine, which also reduced serum leptin and insulin and increased serum ghrelin concentrations. These findings suggest that the inhibition of NPY expression in SF animals may be a mechanism underlying the anorexigenic effect of methamphetamine seen in this condition. The increase in NPY expression produced by methamphetamine in AL animals may be mediated by the ability of this drug to decrease secretion of leptin and insulin and increase secretion of ghrelin.
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Affiliation(s)
- W R Crowley
- Department of Pharmacology and Toxicology, University of Utah Health Sciences Center, College of Pharmacy, 30 South 2000 East, Room 201, Salt Lake City, UT 84112, USA.
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Rocha M, Bing C, Williams G, Puerta M. Physiologic estradiol levels enhance hypothalamic expression of the long form of the leptin receptor in intact rats. J Nutr Biochem 2004; 15:328-34. [PMID: 15157938 DOI: 10.1016/j.jnutbio.2004.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2003] [Revised: 12/12/2003] [Accepted: 01/04/2004] [Indexed: 10/26/2022]
Abstract
Estradiol is a potent hypophagic agent that reduces food intake and body weight without a concomitant fall in plasma leptin levels. We investigated whether the hypophagic effect of estradiol is mediated by stimulating POMC and/or inhibiting NPY neuronal pathways in the hypothalamus, which respectively inhibit and stimulate feeding. We examined hypothalamic gene expression of Ob-Rb, NPY, POMC, MC4-R, and AgRP in intact Wistar rats treated with estradiol for 48 hours. Food intake and body weight were reduced in estradiol-treated rats but fat mass was unchanged; plasma leptin and insulin levels were not significantly different from untreated, freely fed controls. In untreated rats that were pair-fed to match the estradiol-treated group, body weight was also reduced without changes in fat mass, although leptin and insulin levels decreased significantly. Ob-Rb expression was increased in both hypophagic groups despite serum leptin were only decreased in pair-fed animals, suggesting an estradiol-stimulating effect on Ob-Rb expression. No significant differences were found in POMC, AgRP, or MC4-R expression among any of the experimental groups. A significant but small decrease in NPY expression was also found in both hypophagic groups; this was explained by the combined effect of both surgery and reduced food intake. These results indicate that estradiol mediated hypophagia in intact rats could be brought about by an enhanced hypothalamic leptin sensitivity but is unlikely to be driven by changes in NPY or melanocortin system.
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Affiliation(s)
- Milagros Rocha
- Department of Physiology (Animal Physiology II), Faculty of Biological Sciences, Complutense University, 28040 Madrid, Spain
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Ladyman SR, Grattan DR. Region-specific reduction in leptin-induced phosphorylation of signal transducer and activator of transcription-3 (STAT3) in the rat hypothalamus is associated with leptin resistance during pregnancy. Endocrinology 2004; 145:3704-11. [PMID: 15142988 DOI: 10.1210/en.2004-0338] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Leptin concentrations increase during pregnancy, but this does not prevent the pregnancy-induced increase in food intake, suggesting a state of leptin resistance. This study investigated the response to intracerebroventricular leptin administration in pregnant rats. After fasting, nonpregnant, d-7 and d-14 pregnant rats received leptin (4 microg) or vehicle, then food intake was measured. Serial blood samples were collected in another group of rats to determine plasma leptin concentrations. Further groups of d-14 pregnant and nonpregnant rats were killed after leptin or vehicle treatment, and brains were collected. Hypothalamic nuclei were microdissected, and levels of signal transducer and activator of transcription (STAT)3 phosphorylation were measured using Western blot analysis. Fasting decreased leptin concentrations in both pregnant and nonpregnant rats. Leptin treatment significantly reduced food intake in nonpregnant and d-7 pregnant rats but not in d-14 pregnant rats. In addition, there was no postfasting hyperphagic response in the pregnant rats. In the pregnant rats, leptin-induced STAT3 phosphorylation was suppressed in the arcuate nucleus and, to a lesser extent, in the ventromedial hypothalamus (VMH), compared with nonpregnant rats. Unstimulated STAT3 levels were also decreased in the VMH during pregnancy. Leptin-induced phosphorylation of STAT3 in the dorsomedial and lateral hypothalamus was not different between pregnant and nonpregnant rats. These data indicate that pregnant rats become resistant to the satiety action of leptin. Furthermore, leptin-induced activation of the STAT3 is impaired during pregnancy, specifically in the arcuate nucleus and VMH. These data support the hypothesis that pregnancy is a state of hypothalamic leptin resistance.
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Affiliation(s)
- S R Ladyman
- Department of Anatomy and Structural Biology, University of Otago, Dunedin 9001, New Zealand
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