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Tsuchida H, Nonogaki M, Takizawa M, Inoue N, Uenoyama Y, Tsukamura H. Enkephalin-δ Opioid Receptor Signaling Mediates Glucoprivic Suppression of LH Pulse and Gluconeogenesis in Female Rats. Endocrinology 2023; 164:6967063. [PMID: 36592113 DOI: 10.1210/endocr/bqac216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/23/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023]
Abstract
Energy availability is an important regulator of reproductive function at various reproductive phases in mammals. Glucoprivation induced by 2-deoxy-D-glucose (2DG), an inhibitor of glucose utilization, as an experimental model of malnutrition suppresses the pulsatile release of GnRH/LH and induces gluconeogenesis. The present study was performed with the aim of examining whether enkephalin-δ-opioid receptor (DOR) signaling mediates the suppression of pulsatile GnRH/LH release and gluconeogenesis during malnutrition. The administration of naltrindole hydrochloride (NTI), a selective DOR antagonist, into the third ventricle blocked the suppression of LH pulses and part of gluconeogenesis induced by IV 2DG administration in ovariectomized rats treated with a negative feedback level of estradiol-17 β (OVX + low E2). The IV 2DG administration significantly increased the number of Penk (enkephalin gene)-positive cells coexpressing fos (neuronal activation marker gene) in the paraventricular nucleus (PVN), but not in the arcuate nucleus (ARC) in OVX + low E2 rats. Furthermore, double in situ hybridization for Penk/Pdyn (dynorphin gene) in the PVN revealed that approximately 35% of the PVN Penk-expressing cells coexpressed Pdyn. Double in situ hybridization for Penk/Crh (corticotropin-releasing hormone gene) in the PVN and Penk/Kiss1 (kisspeptin gene) in the ARC revealed that few Penk-expressing cells coexpressed Crh and Kiss1. Taken together, these results suggest that central enkephalin-DOR signaling mediates the suppression of pulsatile LH release during malnutrition. Moreover, the current study suggests that central enkephalin-DOR signaling is also involved in gluconeogenesis during malnutrition in female rats.
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Affiliation(s)
- Hitomi Tsuchida
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Miku Nonogaki
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Marina Takizawa
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Ladisa C, Ma Y, Habibi HR. Metabolic Changes During Growth and Reproductive Phases in the Liver of Female Goldfish (Carassius auratus). Front Cell Dev Biol 2022; 10:834688. [PMID: 35295860 PMCID: PMC8919208 DOI: 10.3389/fcell.2022.834688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/31/2022] [Indexed: 11/23/2022] Open
Abstract
Hormones of the brain-pituitary-peripheral axis regulate metabolism, gonadal maturation, and growth in vertebrates. In fish, reproduction requires a significant energy investment to metabolically support the production of hundreds of eggs and billions of sperms in females and males, respectively. This study used an LC-MS-based metabolomics approach to investigate seasonally-related changes in metabolic profile and energy allocation patterns in female goldfish liver. We measured basal metabolic profile in female goldfish at three phases of the reproductive cycle, including 1) Maximum growth period in postovulatory regressed phase, 2) mid recrudescence in fish with developing follicles, and 3) late recrudescence when the ovary contains mature ovulatory follicles. We also investigated changes in the liver metabolism following acute treatments with GnRH and GnIH, known to be involved in controlling reproduction and growth in goldfish. Chemometrics combined with pathway-driven bioinformatics revealed significant changes in the basal and GnRH/GnIH-induced hepatic metabolic profile, indicating that metabolic energy allocation is regulated to support gonadal development and growth at different reproductive cycles. Overall, the findings support the hypothesis that hormonal control of reproduction involves accompanying metabolic changes to energetically support gonadotropic and somatotropic activities in goldfish and other oviparous vertebrates.
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Tsukamura H. Kobayashi Award 2019: The neuroendocrine regulation of the mammalian reproduction. Gen Comp Endocrinol 2022; 315:113755. [PMID: 33711315 DOI: 10.1016/j.ygcen.2021.113755] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/13/2021] [Accepted: 02/23/2021] [Indexed: 02/05/2023]
Abstract
Mammalian reproductive function is a complex system of many players orchestrated by the hypothalamus-pituitary-gonadal (HPG) axis. The hypothalamic gonadotropin-releasing hormone (GnRH) and the consequent pituitary gonadotropin release show two modes of secretory patterns, namely the surge and pulse modes. The surge mode is triggered by the positive feedback action of estrogen secreted from the mature ovarian follicle to induce ovulation in females of most mammalian species. The pulse mode of GnRH release is required for stimulating tonic gonadotropin secretion to drive folliculogenesis, spermatogenesis and steroidogenesis and is negatively fine-tuned by the sex steroids. Accumulating evidence suggests that hypothalamic kisspeptin neurons are the master regulator for animal reproduction to govern the HPG axis. Specifically, kisspeptin neurons located in the anterior hypothalamus, such as the anteroventral periventricular nucleus (AVPV) in rodents and preoptic nucleus (POA) in ruminants, primates and others, and the neurons located in the arcuate nucleus (ARC) in posterior hypothalamus in most mammals are considered to play a key role in generating the surge and pulse modes of GnRH release, respectively. The present article focuses on the role of AVPV (or POA) kisspeptin neurons as a center for GnRH surge generation and of the ARC kisspeptin neurons as a center for GnRH pulse generation to mediate estrogen positive and negative feedback mechanisms, respectively, and discusses how the estrogen epigenetically regulates kisspeptin gene expression in these two populations of neurons. This article also provides the mechanism how malnutrition and lactation suppress GnRH/gonadotropin pulses through an inhibition of the ARC kisspeptin neurons. Further, the article discusses the programming effect of estrogen on kisspeptin neurons in the developmental brain to uncover the mechanism underlying the sex difference in GnRH/gonadotropin release as well as an irreversible infertility induced by supra-physiological estrogen exposure in rodent models.
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Affiliation(s)
- Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
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Sato M, Minabe S, Sakono T, Magata F, Nakamura S, Watanabe Y, Inoue N, Uenoyama Y, Tsukamura H, Matsuda F. Morphological Analysis of the Hindbrain Glucose Sensor-Hypothalamic Neural Pathway Activated by Hindbrain Glucoprivation. Endocrinology 2021; 162:6308440. [PMID: 34161572 DOI: 10.1210/endocr/bqab125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Indexed: 01/06/2023]
Abstract
Lowered glucose availability, sensed by the hindbrain, has been suggested to enhance gluconeogenesis and food intake as well as suppress reproductive function. In fact, our previous histological and in vitro studies suggest that hindbrain ependymal cells function as a glucose sensor. The present study aimed to clarify the hindbrain glucose sensor-hypothalamic neural pathway activated in response to hindbrain glucoprivation to mediate counterregulatory physiological responses. Administration of 2-deoxy-D-glucose (2DG), an inhibitor of glucose utilization, into the fourth ventricle (4V) of male rats for 0.5 hour induced messenger RNA (mRNA) expression of c-fos, a marker for cellular activation, in ependymal cells in the 4V, but not in the lateral ventricle, the third ventricle or the central canal without a significant change in blood glucose and testosterone levels. Administration of 2DG into the 4V for 1 hour significantly increased blood glucose levels, food intake, and decreased blood testosterone levels. Simultaneously, the expression of c-Fos protein was detected in the 4V ependymal cells; dopamine β-hydroxylase-immunoreactive cells in the C1, C2, and A6 regions; neuropeptide Y (NPY) mRNA-positive cells in the C2; corticotropin-releasing hormone (CRH) mRNA-positive cells in the hypothalamic paraventricular nucleus (PVN); and NPY mRNA-positive cells in the arcuate nucleus (ARC). Taken together, these results suggest that lowered glucose availability, sensed by 4V ependymal cells, activates hindbrain catecholaminergic and/or NPY neurons followed by CRH neurons in the PVN and NPY neurons in the ARC, thereby leading to counterregulatory responses, such as an enhancement of gluconeogenesis, increased food intake, and suppression of sex steroid secretion.
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Affiliation(s)
- Marimo Sato
- Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Shiori Minabe
- Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Takahiro Sakono
- Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Fumie Magata
- Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Sho Nakamura
- Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime 794-8555, Japan
| | - Youki Watanabe
- Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Naoko Inoue
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Yoshihisa Uenoyama
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Fuko Matsuda
- Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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Tsuchida H, Mostari P, Yamada K, Miyazaki S, Enomoto Y, Inoue N, Uenoyama Y, Tsukamura H. Paraventricular Dynorphin A Neurons Mediate LH Pulse Suppression Induced by Hindbrain Glucoprivation in Female Rats. Endocrinology 2020; 161:5902463. [PMID: 32894768 DOI: 10.1210/endocr/bqaa161] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 09/03/2020] [Indexed: 12/11/2022]
Abstract
Malnutrition suppresses reproductive functions in mammals, which is considered to be mostly due to the inhibition of pulsatile gonadotropin-releasing hormone (GnRH)/gonadotropin secretion. Accumulating evidence suggests that kisspeptin neurons in the arcuate nucleus (ARC) play a critical role in the regulation of pulsatile GnRH/gonadotropin release. The present study aimed to examine if the hypothalamic dynorphin A (Dyn) neurons mediate the suppression of GnRH/luteinizing hormone (LH) pulses during malnutrition. Ovariectomized rats treated with a negative feedback level of estradiol-17β-treated (OVX+E2) were administered with intravenous (iv) or fourth cerebroventricle (4V) 2-deoxy-D-glucose (2DG), an inhibitor of glucose utilization, to serve as a malnutrition model. Central administration of a Dyn receptor antagonist blocked the iv- or 4V-2DG-induced suppression of LH pulses in OVX+E2 rats. The 4V 2DG administration significantly increased the number of Pdyn (Dyn gene)-positive cells co-expressing fos in the paraventricular nucleus (PVN), but not in the ARC and supraoptic nucleus (SON), and the iv 2DG treatment significantly increased the number of fos and Pdyn-co-expressing cells in the PVN and SON, but decreased it in the ARC. The E2 treatment significantly increased Pdyn expression in the PVN, but not in the ARC and SON. Double in situ hybridization for Kiss1 (kisspeptin gene) and Oprk1 (Dyn receptor gene) revealed that around 60% of ARC Kiss1-expressing cells co-expressed Oprk1. These results suggest that the PVN Dyn neurons, at least in part, mediate LH pulse suppression induced by the hindbrain or peripheral glucoprivation, and Dyn neurons may directly suppress the ARC kisspeptin neurons in female rats.
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Affiliation(s)
- Hitomi Tsuchida
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Parvin Mostari
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Koki Yamada
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Sae Miyazaki
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yuki Enomoto
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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Majarune S, Nima P, Sugimoto A, Nagae M, Inoue N, Tsukamura H, Uenoyama Y. Ad libitum feeding triggers puberty onset associated with increases in arcuate Kiss1 and Pdyn expression in growth-retarded rats. J Reprod Dev 2019; 65:397-406. [PMID: 31155522 PMCID: PMC6815743 DOI: 10.1262/jrd.2019-048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Increasing evidence shows that puberty onset is largely dependent on body weight rather than chronological age. To investigate the mechanism involved in the energetic control of puberty
onset, the present study examined effects of chronic food restriction during the prepubertal period and the resumption of ad libitum feeding for 24 and 48 h on estrous
cyclicity, Kiss1 (kisspeptin gene), Tac3 (neurokinin B gene) and Pdyn (dynorphin A gene) expression in the hypothalamus, luteinizing
hormone (LH) secretion and follicular development in female rats. When animals weighed 75 g, they were subjected to a restricted feeding to retard growth to 70–80 g by 49 days of age. Then,
animals were subjected to ad libitum feeding or remained food-restricted. The growth-retarded rats did not show puberty onset associated with suppression of both
Kiss1 and Pdyn expression in the arcuate nucleus (ARC). 24-h ad libitum feeding increased tonic LH secretion and the number of Graafian
and non-Graafian tertiary follicles with an increase in the numbers of ARC Kiss1- and Pdyn-expressing cells. 48-h ad libitum feeding
induced the vaginal proestrus and a surge-like LH increase with an increase in Kiss1-expressing cells in the anteroventral periventricular nucleus (AVPV). These results
suggest that the negative energy balance causes pubertal failure with suppression of ARC Kiss1 and Pdyn expression and then subsequent gonadotropin
secretion and ovarian function, while the positive energetic cues trigger puberty onset via an increase in ARC Kiss1 and Pdyn expression and thus
gonadotropin secretion and follicular development in female rats.
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Affiliation(s)
- Sutisa Majarune
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Pelden Nima
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Arisa Sugimoto
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Mayuko Nagae
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Mulliniks JT, Beard JK. BEEF SPECIES-RUMINANT NUTRITION CACTUS BEEF SYMPOSIUM: Sustainable and economically viable management options for cow/calf production through enhanced beef cow metabolic efficiency1. J Anim Sci 2019; 97:1398-1406. [PMID: 30561668 PMCID: PMC6396245 DOI: 10.1093/jas/sky476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/13/2018] [Indexed: 12/11/2022] Open
Abstract
Beef cow herds are expected to be metabolically and reproductively efficient in varied and ever changing environmental conditions. Therefore, selection and management of grazing beef cows provides unique and diverse challenges in achieving optimal production efficiency for any environment. Beef cows face dynamic and highly variable nutritional environments that periodically are inadequate in meeting nutrient and energy requirements. Nutritional management during high metabolically stressed and key physiological states can lead to increased or decreased metabolic efficiency. Conversely, cow metabolic efficiency may be reduced in many production systems due to surplus nutritional inputs and reduced exposure to environmental stressors. Alternatively, metabolically potent supplementation strategies targeting enhanced energy metabolism and endocrine mechanisms would increase beef cow metabolic and economic efficiency. Metabolic efficient beef cows adapt to environmental changes by adjusting their metabolic energy utilization in order to match current environmental conditions and remain reproductively competent. This mechanism involves adaptive processes that drive adjustments in nutrient partitioning and energy utilization efficiency. However, the variation in metabolic and reproductive efficiency among beef cows within cow/calf production systems is substantial, suggesting a lack of complete integration of nutrition, genetics, and reproduction with environmental constraints and conditions. Better integration and understanding of the interactions may lead to advancements in metabolic efficiency of the cowherd. Metabolic flexibility is recognized as an important trait in dairy production but has received little attention thus far in beef cattle. Overall, management and supplementation strategies in cow/calf systems from a mechanistic, targeted nutritional approach during key physiological periods would hasten improvements in metabolic efficiency.
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Affiliation(s)
- J Travis Mulliniks
- West Central Research and Extension Center, University of Nebraska, North Platte, NE
| | - Joslyn K Beard
- West Central Research and Extension Center, University of Nebraska, North Platte, NE
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Minabe S, Deura C, Ikegami K, Goto T, Sanbo M, Hirabayashi M, Inoue N, Uenoyama Y, Maeda KI, Tsukamura H. Pharmacological and Morphological Evidence of AMPK-Mediated Energy Sensing in the Lower Brain Stem Ependymocytes to Control Reproduction in Female Rodents. Endocrinology 2015; 156:2278-87. [PMID: 25822714 PMCID: PMC4430616 DOI: 10.1210/en.2014-2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ependymocytes are one of the energy-sensing cells that regulate animal reproduction through their responsiveness to changes in extracellular glucose levels and the expression of pancreatic-type glucokinase and glucose transporter 2, which play a critical role in sensing blood glucose levels in pancreatic β-cells. Molecular mechanisms underlying glucose sensing in the ependymocytes remain poorly understood. The AMP-activated protein kinase (AMPK), a serine/threonine kinase highly conserved in all eukaryotic cells, has been suggested to be an intracellular fuel gauge that detects cellular energy status. The present study aims to clarify the role AMPK of the lower brainstem ependymocytes has in sensing glucose levels to regulate reproductive functions. First, we will show that administration of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, an AMPK activator, into the 4th ventricle suppressed pulsatile LH release in female rats. Second, we will demonstrate the presence of AMPK catalytic subunit immunoreactivities in the rat lower brainstem ependymocytes. Third, transgenic mice were generated to visualize the ependymocytes with Venus, a green fluorescent protein, expressed under the control of the mouse vimentin promoter for further in vitro study. The Venus-labeled ependymocytes taken from the lower brainstem of transgenic mice revealed that AMPK activation by 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, an AMPK activator, increased in vitro intracellular calcium concentrations. Taken together, malnutrition-induced AMPK activation of ependymocytes of the lower brainstem might be involved in suppression of GnRH/LH release and then gonadal activities.
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Affiliation(s)
- Shiori Minabe
- Graduate School of Bioagricultural Sciences (S.M., C.D., K.I., T.G., N.I., Y.U., H.T.), Nagoya University, Nagoya, Aichi 464-8601, Japan; Center for Genetic Analysis of Behavior (M.S., M.H.), National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan; and Veterinary Medical Sciences (K.-i.M.), University of Tokyo, Tokyo 113-8657, Japan
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9
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Regulation of gonadotropin secretion by monitoring energy availability. Reprod Med Biol 2014; 14:39-47. [PMID: 29259401 DOI: 10.1007/s12522-014-0194-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/06/2014] [Indexed: 10/24/2022] Open
Abstract
Nutrition is a principal environmental factor influencing fertility in animals. Energy deficit causes amenorrhea, delayed puberty, and suppression of copulatory behaviors by inhibiting gonadal activity. When gonadal activity is impaired by malnutrition, the signals originating from an undernourished state are ultimately conveyed to the gonadotropin-releasing hormone (GnRH) pulse generator, leading to suppressed secretion of GnRH and luteinizing hormone (LH). The mechanism responsible for energetic control of gonadotropin release is believed to involve metabolic signals, sensing mechanisms, and neuroendocrine pathways. The availabilities of blood-borne energy substrates such as glucose, fatty acids, and ketone bodies, which fluctuate in parallel with changes in nutritional status, act as metabolic signals that regulate the GnRH pulse generator activity and GnRH/LH release. As components of the specific sensing system, the ependymocytes lining the cerebroventricular wall in the lower brainstem integrate the information derived from metabolic signals to control gonadotropin release. One of the pathways responsible for the energetic control of gonadal activity consists of noradrenergic neurons from the solitary tract nucleus in the lower brainstem, projecting to the paraventricular nucleus of the hypothalamus. Further studies are needed to elucidate the mechanisms underlying energetic control of reproductive function.
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Schneider JE, Wise JD, Benton NA, Brozek JM, Keen-Rhinehart E. When do we eat? Ingestive behavior, survival, and reproductive success. Horm Behav 2013; 64:702-28. [PMID: 23911282 DOI: 10.1016/j.yhbeh.2013.07.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 07/21/2013] [Accepted: 07/22/2013] [Indexed: 12/13/2022]
Abstract
The neuroendocrinology of ingestive behavior is a topic central to human health, particularly in light of the prevalence of obesity, eating disorders, and diabetes. The study of food intake in laboratory rats and mice has yielded some useful hypotheses, but there are still many gaps in our knowledge. Ingestive behavior is more complex than the consummatory act of eating, and decisions about when and how much to eat usually take place in the context of potential mating partners, competitors, predators, and environmental fluctuations that are not present in the laboratory. We emphasize appetitive behaviors, actions that bring animals in contact with a goal object, precede consummatory behaviors, and provide a window into motivation. Appetitive ingestive behaviors are under the control of neural circuits and neuropeptide systems that control appetitive sex behaviors and differ from those that control consummatory ingestive behaviors. Decreases in the availability of oxidizable metabolic fuels enhance the stimulatory effects of peripheral hormones on appetitive ingestive behavior and the inhibitory effects on appetitive sex behavior, putting a new twist on the notion of leptin, insulin, and ghrelin "resistance." The ratio of hormone concentrations to the availability of oxidizable metabolic fuels may generate a critical signal that schedules conflicting behaviors, e.g., mate searching vs. foraging, food hoarding vs. courtship, and fat accumulation vs. parental care. In species representing every vertebrate taxa and even in some invertebrates, many putative "satiety" or "hunger" hormones function to schedule ingestive behavior in order to optimize reproductive success in environments where energy availability fluctuates.
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Affiliation(s)
- Jill E Schneider
- Department of Biological Sciences, Lehigh University, 111 Research Drive, Bethlehem, PA 18015, USA
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Mulliniks JT, Kemp ME, Endecott RL, Cox SH, Roberts AJ, Waterman RC, Geary TW, Scholljegerdes EJ, Petersen MK. Does β-hydroxybutyrate concentration influence conception date in young postpartum range beef cows? J Anim Sci 2013; 91:2902-9. [PMID: 23478827 DOI: 10.2527/jas.2012-6029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cows in negative energy balance after calving often have reduced reproductive performance, which is mediated by metabolic signals. The objective of these studies was to determine the association of serum metabolites, days to first postpartum ovulation, milk production, cow BW change, BCS, and calf performance with conception date in spring-calving 2- and 3-yr-old beef cows grazing native range. In Exp. 1, cows were classified by conception date in a 60-d breeding season as early (EARLY; conceived in first 15 d of breeding) or late conception (LATE; conceived during the last 45 d of breeding). Beginning on d 35 postpartum, blood samples were collected twice per week for serum metabolite analysis and progesterone analysis to estimate days to resumption of estrous cycles. As a chute-side measure of nutrient status and glucose sufficiency, whole-blood β-hydroxybutyrate (BHB) concentrations were measured 14 ± 2 d before breeding. In Exp. 2, cows were classified by subsequent calving date resulting from a 55 ± 2 d breeding season as conceiving either early (EARLY; conceived in first 15 d of breeding) or late (LATE; conceived during the remaining breeding season). Blood samples were collected in 2 periods, 30 ± 4 d before calving and 14 ± 3 d before the initiation of breeding, to determine circulating concentrations of IGF-I and BHB. In Exp. 1, BHB and serum glucose concentrations were less (P ≤ 0.04) in EARLY cows than LATE cows. Serum insulin concentrations were greater (P = 0.03) in EARLY cows relative to LATE cows. Milk production and composition did not differ (P ≥ 0.24) by conception date groups. In Exp. 2, cow age × sample period × conception date interaction (P < 0.01) occurred for serum BHB concentrations. Serum BHB concentrations were similar (P > 0.10) for 2-yr-old cows (in greater nutritional plane compared with Exp. 1) regardless of their conception date classification and sampling period. However, precalving serum BHB concentrations were greater (P < 0.01) for LATE than EARLY in 3-yr-old cows with no difference (P = 0.86) at prebreeding. Serum IGF-1 concentrations were greater (P < 0.01) for EARLY cows relative to LATE cows at precalving and prebreeding. This study indicates that blood BHB concentrations during times of metabolic dysfunctions may provide a more sensitive indicator of energy status than body condition, predicting rebreeding competence in young beef cows as measured by interval from calving to conception.
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Affiliation(s)
- J T Mulliniks
- Department of Animal and Range Sciences, New Mexico State University, Las Cruces 88003, USA
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