1
|
Lanctôt S, Deacon AM, Thibault C, Blouin R, Lacasse P. Effect of prolactin concentration during the dry period on the subsequent milk production of dairy cows. J Dairy Sci 2024:S0022-0302(24)01158-5. [PMID: 39343215 DOI: 10.3168/jds.2024-25164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Accepted: 08/14/2024] [Indexed: 10/01/2024]
Abstract
Shortening the dry period has a negative impact on milk production of the following lactation. One possible explanation is that a period of low prolactin (PRL) concentration is necessary to restore mammary gland milk production capacity. Therefore, the objective of this study was to determine the effect of lowering blood PRL level on subsequent lactation milk production. In this experiment, quinagolide was used to inhibit PRL secretion during the dry period. Thirty Holstein cows were randomly assigned one of 3 dry period managements: a conventional (60 d) dry period (CD) and 2 short (35 d) dry period treatments (SD). Short dry period cows received either water (SDwater) or quinagolide (2 mg, SDquin) injections twice daily from dry-off until 14 d before calving. Cows were followed during the first 20 wks of the subsequent lactation. When CD cows were dry but SD cows were lactating, concentration of PRL was lower in the CD cows than in the SD cows. During the injection period, PRL of SDquin cows was lower than that of the other treatments and was greater in the blood of SDwater than in that of CD cows. After the injection period until calving, no difference in PRL concentration was observed between treatments. After calving, PRL concentration of the SDquin cows was greater than those of CD and SDwater cows. During the first 20 wks of lactation, energy corrected milk (ECM) was lower in SDwater cows than in CD and SDquin cows. The ECM of the latter groups were not different. During the same period, mammary expression of genes related to milk synthesis, pro-apoptotic genes, as well as the expression of the short and long isoforms of the PRLR genes were not affected; however, the expression of SOCS3 gene tended to be lower for the SDquin than the SDwater cows. Lowering the PRL level during short dry period restored milk production to the level normally observed after a conventional dry period, which suggests that higher PRL levels during short dry period are the cause of the lower milk production after a short dry period. Ultimately, strategies to lower blood PRL level may help the adoption of short dry period.
Collapse
Affiliation(s)
- S Lanctôt
- Department of Biology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - A-M Deacon
- Department of Biology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - C Thibault
- Sherbrooke Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada J1M 0C8
| | - R Blouin
- Department of Biology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - P Lacasse
- Department of Biology, Université de Sherbrooke, Sherbrooke, QC, Canada; Sherbrooke Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada J1M 0C8.
| |
Collapse
|
2
|
de Winne C, Pascual FL, Lopez-Vicchi F, Etcheverry-Boneo L, Mendez-Garcia LF, Ornstein AM, Lacau-Mengido IM, Sorianello E, Becu-Villalobos D. Neuroendocrine control of brown adipocyte function by prolactin and growth hormone. J Neuroendocrinol 2024; 36:e13248. [PMID: 36932836 DOI: 10.1111/jne.13248] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 02/08/2023] [Accepted: 02/11/2023] [Indexed: 03/06/2023]
Abstract
Growth hormone (GH) is fundamental for growth and glucose homeostasis, and prolactin for optimal pregnancy and lactation outcome, but additionally, both hormones have multiple functions that include a strong impact on energetic metabolism. In this respect, prolactin and GH receptors have been found in brown, and white adipocytes, as well as in hypothalamic centers regulating thermogenesis. This review describes the neuroendocrine control of the function and plasticity of brown and beige adipocytes, with a special focus on prolactin and GH actions. Most evidence points to a negative association between high prolactin levels and the thermogenic capacity of BAT, except in early development. During lactation and pregnancy, prolactin may be a contributing factor that limits unneeded thermogenesis, downregulating BAT UCP1. Furthermore, animal models of high serum prolactin have low BAT UCP1 levels and whitening of the tissue, while lack of Prlr induces beiging in WAT depots. These actions may involve hypothalamic nuclei, particularly the DMN, POA and ARN, brain centers that participate in thermogenesis. Studies on GH regulation of BAT function present some controversies. Most mouse models with GH excess or deficiency point to an inhibitory role of GH on BAT function. Even so, a stimulatory role of GH on WAT beiging has also been described, in accordance with whole-genome microarrays that demonstrate divergent response signatures of BAT and WAT genes to the loss of GH signaling. Understanding the physiology of BAT and WAT beiging may contribute to the ongoing efforts to curtail obesity.
Collapse
Affiliation(s)
- Catalina de Winne
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| | - Florencia L Pascual
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| | - Felicitas Lopez-Vicchi
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| | - Luz Etcheverry-Boneo
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| | - Luis F Mendez-Garcia
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| | - Ana Maria Ornstein
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| | - Isabel Maria Lacau-Mengido
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| | - Eleonora Sorianello
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| | - Damasia Becu-Villalobos
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad de Buenos Aires, Argentina
| |
Collapse
|
3
|
Soileau LG, Talbot NC, Storey NR, Spillers NJ, D'antoni JV, Carr PC, Galardo CM, Shilpadevi P, Ahmadzadeh S, Shekoohi S, Kaye AD. Impulse control disorders in Parkinson's disease patients treated with pramipexole and ropinirole: a systematic review and meta-analysis. Neurol Sci 2024; 45:1399-1408. [PMID: 38079019 DOI: 10.1007/s10072-023-07254-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 12/02/2023] [Indexed: 03/16/2024]
Abstract
BACKGROUND This analysis is the first systematic review and meta-analysis assessing occurrences of ICD in PD patients treated with oral DAs: ropinirole (ROP) and pramipexole (PRX). This study compares the two oral DAs to a transdermal patch, rotigotine (RTG). METHODS We performed an extensive systematic search for eligible studies from PubMed, Embase, Cochrane Library, and Google Scholar. The data was analyzed by various software, including EndNote, Rayyan, PRISM, and RevMan. Two studies incorporating 658 patients collectively were assessed. RESULTS This meta-analysis shows a significant correlation between the usage of PRX (25.3%) or ROP (21.8%) and the development of ICD in PD patients. Compared to the transdermal patch, RTG, PRX was found to have a significant relative risk (P < 0.0001) of 3.46 (95% CI 2.07-5.76), and ROP was found to have a significant relative risk (P < 0.0001) of 2.98 (95% CI 1.77-5.02). The data collected shows RTG is approximately three times less likely to cause ICDs than oral PRX and ROP. CONCLUSION The present investigation provides insight into ICD occurrences with PRX, ROP, and RTG to allow physicians to make more informed decisions on risk versus reward when deciding how to treat a PD patient with these drugs. However, related to various disclosed limitations, our conclusion cannot provide definitive practice protocols.
Collapse
Affiliation(s)
- Lenise G Soileau
- School of Medicine, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA
| | - Norris C Talbot
- School of Medicine, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA
| | - Nicholas R Storey
- School of Medicine, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA
| | - Noah J Spillers
- School of Medicine, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA
| | - James V D'antoni
- School of Medicine, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA
| | - Peter C Carr
- School of Medicine, Louisiana State University Health Science Center New Orleans, 433 Bolivar St, New Orleans, LA, 70112, USA
| | - Connor M Galardo
- University of Southern Mississippi, 118 College Drive, Hattiesburg, MS, 39406, USA
| | - Patil Shilpadevi
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA
| | - Shahab Ahmadzadeh
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA
| | - Sahar Shekoohi
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA.
| | - Alan D Kaye
- Department of Anesthesiology, Louisiana State University Health Sciences Center at Shreveport, Shreveport, LA, 71103, USA
- Department of Pharmacology, Louisiana State University Health Sciences Center at Shreveport, Toxicology, and Neurosciences, Shreveport, LA, 71103, USA
| |
Collapse
|
4
|
Rasmi Y, Shokati A, Hatamkhani S, Farnamian Y, Naderi R, Jalali L. Assessment of the relationship between the dopaminergic pathway and severe acute respiratory syndrome coronavirus 2 infection, with related neuropathological features, and potential therapeutic approaches in COVID-19 infection. Rev Med Virol 2024; 34:e2506. [PMID: 38282395 DOI: 10.1002/rmv.2506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 07/06/2023] [Accepted: 12/17/2023] [Indexed: 01/30/2024]
Abstract
Dopamine is a known catecholamine neurotransmitter involved in several physiological processes, including motor control, motivation, reward, cognition, and immune function. Dopamine receptors are widely distributed throughout the nervous system and in immune cells. Several viruses, including human immunodeficiency virus and Japanese encephalitis virus, can use dopaminergic receptors to replicate in the nervous system and are involved in viral neuropathogenesis. In addition, studies suggest that dopaminergic receptors may play a role in the progression and pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. When SARS-CoV-2 binds to angiotensin-converting enzyme 2 receptors on the surface of neuronal cells, the spike protein of the virus can bind to dopaminergic receptors on neighbouring cells to accelerate its life cycle and exacerbate neurological symptoms. In addition, recent research has shown that dopamine is an important regulator of the immune-neuroendocrine system. Most immune cells express dopamine receptors and other dopamine-related proteins, indicating the importance of dopaminergic immune regulation. The increase in dopamine concentration during SARS-CoV2 infection may reduce immunity (innate and adaptive) that promotes viral spread, which could lead to neuronal damage. In addition, dopaminergic signalling in the nervous system may be affected by SARS-CoV-2 infection. COVID -19 can cause various neurological symptoms as it interacts with the immune system. One possible treatment strategy for COVID -19 patients could be the use of dopamine antagonists. To fully understand how to protect the neurological system and immune cells from the virus, we need to study the pathophysiology of the dopamine system in SARS-CoV-2 infection.
Collapse
Affiliation(s)
- Yousef Rasmi
- Cellular and Molecular Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran
- Department of Biochemistry, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Ameneh Shokati
- Department of Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Multiple Sclerosis Research Center, Neuroscience Institute, Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Shima Hatamkhani
- Experimental and Applied Pharmaceutical Sciences Research Center, Urmia University of Medical Sciences, Urmia, Iran
- Department of Clinical Pharmacy, School of Pharmacy, Urmia University of Medical Sciences, Urmia, Iran
| | - Yeganeh Farnamian
- Student Research Committee, Urmia University of Medical Sciences, Urmia, Iran
| | - Roya Naderi
- Nephrology and Kidney Transplant Research Center, Clinical Research Institute, Urmia University of Medical Sciences, Urmia, Iran
- Department of Physiology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Ladan Jalali
- Cellular and Molecular Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran
- Department of Biochemistry, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| |
Collapse
|
5
|
Mood and behavior regulation: interaction of lithium and dopaminergic system. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2023:10.1007/s00210-023-02437-1. [PMID: 36843130 DOI: 10.1007/s00210-023-02437-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 02/20/2023] [Indexed: 02/28/2023]
Abstract
Lithium is one of the most effect mood-stabilizing drugs prescribed especially for bipolar disorder. Lithium has wide range effects on different molecular factors and neural transmission including dopaminergic signaling. On the other hand, mesolimbic and mesocortical dopaminergic signaling is significantly involved in the pathophysiology of neuropsychiatric disorders. This review article aims to study lithium therapeutic mechanisms, dopaminergic signaling, and the interaction of lithium and dopamine. We concluded that acute and chronic lithium treatments often reduce dopamine synthesis and level in the brain. However, some studies have reported conflicting results following lithium treatment, especially chronic treatment. The dosage, duration, and type of lithium administration, and the brain region selected for measuring dopamine level were not significant differences in different chronic treatments used in previous studies. It was suggested that lithium has various mechanisms affecting dopaminergic signaling and mood, and that many molecular factors can be involved, including brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein (CREB), β-catenin, protein kinase B (Akt), and glycogen synthase kinase-3 beta (GSK-3β). Thus, molecular effects of lithium can be the most important mechanisms of lithium that also alter neural transmissions including dopaminergic signaling in mesolimbic and mesocortical pathways.
Collapse
|
6
|
Anhê GF, Bordin S. The adaptation of maternal energy metabolism to lactation and its underlying mechanisms. Mol Cell Endocrinol 2022; 553:111697. [PMID: 35690287 DOI: 10.1016/j.mce.2022.111697] [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: 01/30/2022] [Revised: 04/15/2022] [Accepted: 06/01/2022] [Indexed: 11/29/2022]
Abstract
Maternal energy metabolism undergoes a singular adaptation during lactation that allows for the caloric enrichment of milk. Changes in the mammary gland, changes in the white adipose tissue, brown adipose tissue, liver, skeletal muscles and endocrine pancreas are pivotal for this adaptation. The present review details the landmark studies describing the enzymatic modulation and the endocrine signals behind these metabolic changes. We will also update this perspective with data from recent studies showing transcriptional and post-transcriptional mechanisms that mediate the adaptation of the maternal metabolism to lactation. The present text will also bring experimental and observational data that describe the long-term consequences that short periods of lactation impose to maternal metabolism.
Collapse
Affiliation(s)
- Gabriel Forato Anhê
- Department of Translational Medicine, School of Medical Sciences, State University of Campinas, Campinas, Brazil.
| | - Silvana Bordin
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| |
Collapse
|
7
|
Guler M, Kavak E, Kivrak A. Electrochemical Dopamine Sensor Based on Gold Nanoparticles Electrodeposited on a Polymer/Reduced Graphene Oxide-Modified Glassy Carbon Electrode. ANAL LETT 2021. [DOI: 10.1080/00032719.2021.1990310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Muhammet Guler
- Faculty of Science, Department of Chemistry, Van Yüzüncü Yıl University, Van, Turkey
| | - Emrah Kavak
- Faculty of Science, Department of Chemistry, Van Yüzüncü Yıl University, Van, Turkey
| | - Arif Kivrak
- Faculty of Sciences and Arts, Department of Chemistry, Eskisehir Osmangazi University, Eskisehir, Turkey
| |
Collapse
|
8
|
Pereira LCR, Elliott SA, McCargar LJ, Bell RC, Robson PJ, Prado CM. Associations of appetite sensations and metabolic characteristics with weight retention in postpartum women. Appl Physiol Nutr Metab 2020; 45:875-885. [PMID: 32073907 DOI: 10.1139/apnm-2019-0809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Postpartum weight retention (PPWR) is an important risk factor for long-term obesity. Appetite may be a key factor regulating PPWR. The objectives of this study were to determine the associations between (i) PPWR and appetite; and (ii) appetite, lactation, and metabolic characteristics. Data from 49 women at 9 months postpartum contributed to this cross-sectional analysis. Energy expenditure was assessed in a whole-body calorimetry unit for 24 h. Appetite sensations were rated using visual analogue scales. Lactation (min/day) was measured using a 3-day breastfeeding diary. PPWR was negatively associated with fullness (β ± SE; R2 = -2.97 ± 0.72; 0.661; P < 0.001), and satiety (-2.75 ± 0.81; 0.617; P = 0.002), and was positively associated with hunger (2.19 ± 1.02; 0.548; P = 0.039), prospective food consumption (PFC; 2.19 ± 0.91; 0.562; P = 0.021), and composite appetite score (CAS; 0.34 ± 0.09; 0.632; P = 0.001). Lactation was associated with higher CAS (39.68 ± 15.56; 0.365; P = 0.015), hunger (3.56 ± 1.61; 0.308; P = 0.033), and PFC (4.22 ± 1.78; 0.314; P = 0.023), and with reduced sensations of fullness (-4.18 ± 1.94; 0.358; P = 0.038) and satiety (-3.83 ± 1.87; 0.295; P = 0.048). Lactation was associated with appetite, which in turn was related to PPWR. Appetite control should be explored to support postpartum weight management strategies. Novelty Postpartum weight retention was associated with appetite sensations, which were assessed throughout the day under conditions in which energy intake and expenditure were precisely matched. Lactation and other maternal metabolic factors, including carbohydrate oxidation and physical activity level may play a role in controlling appetite during the postpartum period.
Collapse
Affiliation(s)
- Leticia C R Pereira
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, 2-004 Li Ka Shing Center for Health Research Innovation, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Sarah A Elliott
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, 2-004 Li Ka Shing Center for Health Research Innovation, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Linda J McCargar
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, 2-004 Li Ka Shing Center for Health Research Innovation, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Rhonda C Bell
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, 2-004 Li Ka Shing Center for Health Research Innovation, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Paula J Robson
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, 2-004 Li Ka Shing Center for Health Research Innovation, University of Alberta, Edmonton, AB T6G 2E1, Canada.,CancerControl Alberta, Alberta Health Services, Edmonton, AB T5J 3E4, Canada
| | - Carla M Prado
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, 2-004 Li Ka Shing Center for Health Research Innovation, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | | |
Collapse
|
9
|
Postolache TT, del Bosque-Plata L, Jabbour S, Vergare M, Wu R, Gragnoli C. Co-shared genetics and possible risk gene pathway partially explain the comorbidity of schizophrenia, major depressive disorder, type 2 diabetes, and metabolic syndrome. Am J Med Genet B Neuropsychiatr Genet 2019; 180:186-203. [PMID: 30729689 PMCID: PMC6492942 DOI: 10.1002/ajmg.b.32712] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 11/16/2018] [Accepted: 12/07/2018] [Indexed: 12/20/2022]
Abstract
Schizophrenia (SCZ) and major depressive disorder (MDD) in treatment-naive patients are associated with increased risk for type 2 diabetes (T2D) and metabolic syndrome (MetS). SCZ, MDD, T2D, and MetS are often comorbid and their comorbidity increases cardiovascular risk: Some risk genes are likely co-shared by them. For instance, transcription factor 7-like 2 (TCF7L2) and proteasome 26S subunit, non-ATPase 9 (PSMD9) are two genes independently reported as contributing to T2D and SCZ, and PSMD9 to MDD as well. However, there are scarce data on the shared genetic risk among SCZ, MDD, T2D, and/or MetS. Here, we briefly describe T2D, MetS, SCZ, and MDD and their genetic architecture. Next, we report separately about the comorbidity of SCZ and MDD with T2D and MetS, and their respective genetic overlap. We propose a novel hypothesis that genes of the prolactin (PRL)-pathway may be implicated in the comorbidity of these disorders. The inherited predisposition of patients with SCZ and MDD to psychoneuroendocrine dysfunction may confer increased risk of T2D and MetS. We illustrate a strategy to identify risk variants in each disorder and in their comorbid psychoneuroendocrine and mental-metabolic dysfunctions, advocating for studies of genetically homogeneous and phenotype-rich families. The results will guide future studies of the shared predisposition and molecular genetics of new homogeneous endophenotypes of SCZ, MDD, and metabolic impairment.
Collapse
Affiliation(s)
- Teodor T. Postolache
- Department of Psychiatry, Mood and Anxiety Program, University of Maryland School of Medicine, Baltimore, Maryland,Rocky Mountain Mental Illness Research Education and Clinical Center (MIRECC), Veterans Integrated Service Network (VISN) 19, Military and Veteran Microbiome: Consortium for Research and Education (MVM-CoRE), Denver, Colorado,Mental Illness Research Education and Clinical Center (MIRECC), Veterans Integrated Service Network (VISN) 5, VA Capitol Health Care Network, Baltimore, Maryland
| | - Laura del Bosque-Plata
- National Institute of Genomic Medicine, Nutrigenetics and Nutrigenomic Laboratory, Mexico City, Mexico
| | - Serge Jabbour
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolic Disease, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Michael Vergare
- Department of Psychiatry and Human Behavior, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Rongling Wu
- Department of Public Health Sciences, Penn State College of Medicine, Hershey, Pennsylvania,Department of Statistics, Penn State College of Medicine, Hershey, Pennsylvania
| | - Claudia Gragnoli
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolic Disease, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania,Department of Public Health Sciences, Penn State College of Medicine, Hershey, Pennsylvania,Molecular Biology Laboratory, Bios Biotech Multi-Diagnostic Health Center, Rome, Italy
| |
Collapse
|
10
|
Lacasse P, Zhao X, Ollier S. Effect of stage of lactation and gestation on milking-induced hormone release in lactating dairy cows. Domest Anim Endocrinol 2019; 66:72-85. [PMID: 30497910 DOI: 10.1016/j.domaniend.2018.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 10/25/2018] [Accepted: 10/26/2018] [Indexed: 11/25/2022]
Abstract
Three experiments were conducted to better understand why milking-induced prolactin (PRL) release decreases as lactation advances. Experiment 1 compared the effects of milking, 2-min manual stimulation of the mammary gland (without milking), or injection of 1 IU of oxytocin (without milking) on hormonal release in early lactation cows, late-lactation and nongestating cows, and late-lactation and gestating cows (n = 6 per physiological status). Blood samples were collected from 20 min before the start of the treatments to 60 min after. During milking, PRL release (area under the curve above the baseline) was greater in the early lactation cows than in the late-lactation cows but was unaffected by gestation. Lactation stage and gestation did not affect PRL release by manual stimulation. Oxytocin did not induce a significant release of PRL or cortisol. Cortisol release was unaffected by physiological status and was similar for milking and mammary stimulation. Milking-induced β-endorphin release was not affected by physiological status. Experiment 2 compared the effects of milking, 2-min manual stimulation, or 10-min manual stimulation in cows in early (n = 6) and late (n = 6) lactation. Prolactin release was greater in the early lactation cows than in the late-lactation cows for all 3 treatments. A 10-min manual stimulation induced greater PRL release than a 2-min stimulation did. Cortisol release was greater in the early lactation cows but was similar among the 3 treatments. Experiment 3 compared the effects of a 5-min manual stimulation and the injection of domperidone (a dopamine antagonist) in cows in early (n = 6) and late (n = 6) lactation. Manually induced PRL release was greater in the early lactation cows than in the late-lactation cows. Prolactin release was greater with domperidone injection than with manual stimulation and was not affected by lactation stage. Thus, the reduction of milking-induced PRL release in late lactation is not a consequence of the lower sensitivity of the mammary gland to stimulation, a shorter milking time, the gestation stage, or the reduced capacity of the pituitary gland to secrete PRL.
Collapse
Affiliation(s)
- Pierre Lacasse
- Sherbrooke Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec J1M 0C8, Canada.
| | - Xin Zhao
- Department of Animal Science, McGill University, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Séverinne Ollier
- Sherbrooke Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec J1M 0C8, Canada
| |
Collapse
|
11
|
Dopamine: Functions, Signaling, and Association with Neurological Diseases. Cell Mol Neurobiol 2018; 39:31-59. [PMID: 30446950 DOI: 10.1007/s10571-018-0632-3] [Citation(s) in RCA: 480] [Impact Index Per Article: 80.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/02/2018] [Indexed: 02/07/2023]
Abstract
The dopaminergic system plays important roles in neuromodulation, such as motor control, motivation, reward, cognitive function, maternal, and reproductive behaviors. Dopamine is a neurotransmitter, synthesized in both central nervous system and the periphery, that exerts its actions upon binding to G protein-coupled receptors. Dopamine receptors are widely expressed in the body and function in both the peripheral and the central nervous systems. Dopaminergic signaling pathways are crucial to the maintenance of physiological processes and an unbalanced activity may lead to dysfunctions that are related to neurodegenerative diseases. Unveiling the neurobiology and the molecular mechanisms that underlie these illnesses may contribute to the development of new therapies that could promote a better quality of life for patients worldwide. In this review, we summarize the aspects of dopamine as a catecholaminergic neurotransmitter and discuss dopamine signaling pathways elicited through dopamine receptor activation in normal brain function. Furthermore, we describe the potential involvement of these signaling pathways in evoking the onset and progression of some diseases in the nervous system, such as Parkinson's, Schizophrenia, Huntington's, Attention Deficit and Hyperactivity Disorder, and Addiction. A brief description of new dopaminergic drugs recently approved and under development treatments for these ailments is also provided.
Collapse
|
12
|
Tong J, Thompson I, Zhao X, Lacasse P. Effect of 17β-estradiol on milk production, hormone secretion, and mammary gland gene expression in dairy cows. J Dairy Sci 2018; 101:2588-2601. [DOI: 10.3168/jds.2017-13353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/02/2017] [Indexed: 11/19/2022]
|
13
|
Tong JJ, Thompson IM, Zhao X, Lacasse P. Effect of the concentration of circulating prolactin on dairy cows' responsiveness to domperidone injection. J Dairy Sci 2018; 101:2579-2587. [PMID: 29331457 DOI: 10.3168/jds.2017-13828] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/18/2017] [Indexed: 11/19/2022]
Abstract
The objective of this study was to determine whether the responsiveness of the mammary gland to prolactin (PRL) is affected by the concentration of the hormone. After 1 pre-experimental week (d -7 to -1), 18 Holstein cows in mid to late lactation were injected intramuscularly twice daily with either 0.5 mg of quinagolide (QN) or 2 mL of water (control) for 2 wk (d 1 to 14; treatment period). After the treatment period, all cows received daily subcutaneous injections of 300 mg of domperidone (DOMP) for 3 wk (d 15 to 35; DOMP period). The cows were monitored for an additional 2 wk as a posttreatment period (d 36 to 49). Blood and milk samples were collected 3 times per week. Additionally, blood samples were collected during the a.m. milking on d -4, 14, and 35. Milk production was not affected by QN during the treatment period but was increased during the DOMP and posttreatment periods in the QN cows. With respect to milk composition, the treatments affected only the protein content, which was greater in the QN cows during the treatment period. Blood PRL concentration declined during QN injections and was lower in the QN cows than in the control cows between d 5 and 14. The basal concentration of PRL was increased by DOMP injections during the DOMP and posttreatment periods but was not affected by previous QN injections. Prolactin concentration in milk was not affected by the QN treatments but was increased by DOMP injections during the DOMP and posttreatment periods. Milking-induced PRL release was decreased by QN on d 14. On d 35, milking did not induce a significant release of PRL above the baseline for both treatments. In conclusion, the results of this experiment support the contention that the mammary gland's responsiveness to PRL is modulated by the previous level of the hormone.
Collapse
Affiliation(s)
- J J Tong
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang Province, P. R. China 150030
| | - I M Thompson
- Sherbrooke Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada J1M 0C8
| | - X Zhao
- Department of Animal Science, McGill University, Sainte-Anne-de-Bellevue, Quebec, Canada H9X 3V9
| | - P Lacasse
- Sherbrooke Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada J1M 0C8.
| |
Collapse
|
14
|
Pennacchio GE, Neira FJ, Soaje M, Jahn GA, Valdez SR. Effect of hyperthyroidism on circulating prolactin and hypothalamic expression of tyrosine hydroxylase, prolactin signaling cascade members and estrogen and progesterone receptors during late pregnancy and lactation in the rat. Mol Cell Endocrinol 2017; 442:40-50. [PMID: 27919641 DOI: 10.1016/j.mce.2016.11.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 11/30/2016] [Accepted: 11/30/2016] [Indexed: 11/18/2022]
Abstract
Hyperthyroidism (HyperT) compromises pregnancy and lactation, hindering suckling-induced PRL release. We studied the effect of HyperT on hypothalamic mRNA (RT-qPCR) and protein (Western blot) expression of tyrosine hydroxylase (TH), PRL receptor (PRLR) and signaling pathway members, estrogen-α (ERα) and progesterone (PR) receptors on late pregnancy (days G19, 20 and 21) and early lactation (L2) in rats. HyperT advanced pre-partum PRL release, reduced circulating PRL on L2 and increased TH mRNA (G21 and L2), p-TH, PRLR mRNA, STAT5 protein (G19 and L2), PRLR protein (G21) and CIS protein (G19). PRs mRNAs and protein decreased on G19 but afterwards PRA mRNA (G20), PRB mRNA (G21) and PRA mRNA and protein (L2) increased. ERα protein increased on G19 and decreased on G20. Thus, the altered hypothalamic PRLR, STAT5, PR and ERα expression in hyperthyroid rats may induce elevated TH expression and activation, that consequently, elevate dopaminergic tone during lactation, blunting suckling-induced PRL release and litter growth.
Collapse
Affiliation(s)
- Gisela E Pennacchio
- Laboratorio de Reproducción y Lactancia, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), CCT-CONICET Mendoza, Argentina; Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina.
| | - Flavia J Neira
- Laboratorio de Reproducción y Lactancia, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), CCT-CONICET Mendoza, Argentina
| | - Marta Soaje
- Laboratorio de Reproducción y Lactancia, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), CCT-CONICET Mendoza, Argentina; Instituto de Fisiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Graciela A Jahn
- Laboratorio de Reproducción y Lactancia, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), CCT-CONICET Mendoza, Argentina
| | - Susana R Valdez
- Laboratorio de Reproducción y Lactancia, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU), CCT-CONICET Mendoza, Argentina; Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina.
| |
Collapse
|
15
|
Furigo IC, Ramos-Lobo AM, Frazão R, Donato J. Brain STAT5 signaling and behavioral control. Mol Cell Endocrinol 2016; 438:70-76. [PMID: 27118133 DOI: 10.1016/j.mce.2016.04.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 04/19/2016] [Accepted: 04/22/2016] [Indexed: 02/06/2023]
Abstract
Several growth factors and cytokines recruit the signal transducer and activator of transcription 5 (STAT5) signaling pathway to control cell proliferation, differentiation and apoptosis. Nonetheless, the importance of this transcription factor for brain functions is still poorly understood. Because some STAT5-inducing hormones, such as prolactin and leptin, act in the brain to regulate the expression of motivated behaviors, this signaling pathway is likely involved in behavioral modulation. Therefore, the objective of the present review was to summarize and discuss the available data regarding the possible role of central STAT5 signaling in the regulation of brain functions, especially on behavioral control. We discussed studies that investigated the importance of STAT5 signaling in the regulation of maternal and feeding behaviors. Additionally, we highlighted other behaviors that could be potentially affected by STAT5 signaling. This knowledge may help to understand how motivated behaviors are regulated at the cellular level.
Collapse
Affiliation(s)
- Isadora C Furigo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Angela M Ramos-Lobo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Renata Frazão
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, 05508-900, Brazil
| | - J Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, 05508-000, Brazil.
| |
Collapse
|
16
|
Lacasse P, Ollier S, Lollivier V, Boutinaud M. New insights into the importance of prolactin in dairy ruminants. J Dairy Sci 2016; 99:864-74. [DOI: 10.3168/jds.2015-10035] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/08/2015] [Indexed: 12/16/2022]
|
17
|
Lacasse P, Ollier S. The dopamine antagonist domperidone increases prolactin concentration and enhances milk production in dairy cows. J Dairy Sci 2015; 98:7856-64. [PMID: 26298751 DOI: 10.3168/jds.2015-9865] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 07/06/2015] [Indexed: 11/19/2022]
Abstract
In previous studies, our team showed that the inhibition of prolactin (PRL) secretion by the dopamine agonist quinagolide reduces milk production in dairy cows. The objective of this study was to determine the effects of administration of a dopamine antagonist on basal and milking-induced PRL concentrations in blood and on milk production during positive energy balance and feed restriction in dairy cows. Eighteen mid-lactation Holstein cows received daily s.c. injections of either domperidone (300 mg, DOMP, n=9) or the vehicle, canola oil (CTL, n=9), for 5 wk. During wk 5, all cows were fed at 65% of their dry matter intake in the previous week. Blood and milk samples were collected before (for blood) and during (for milk) the a.m. milking thrice weekly from d -9 to 41 (8d after the last injection). In addition, blood samples were collected during the a.m. milking on d -1 (before the first injection), and on d 1, 28, and 34. Basal PRL concentration was similar in both groups before the start of the treatments. Domperidone injections caused a gradual increase in basal PRL concentration. Feed restriction reduced basal PRL concentration in both the CTL and DOMP cows, but PRL concentration remained higher in the DOMP cows. Prolactin concentration remained elevated in the DOMP cows 7d after the last injection. The milk concentration of PRL increased during the DOMP treatment, but the increase was smaller than that observed in serum. In the CTL cows, the milking-induced PRL release above the premilking concentration was similar on d -1, 1, and 28 but was reduced during feed restriction. In the DOMP cows, the milking-induced PRL release was similar on d -1 and 1 but was reduced on d 28 and 34. Milk production was similar for both groups before the treatments started but was greater in the DOMP cows during the treatment period, at 2.9 ± 0.6 and 2.4 ± 0.6 kg/d greater during wk 3 and 4 of treatment, respectively. Milk production declined in both groups during feed restriction but remained higher in the DOMP cows. Milk production became similar again for both groups after the last injection. In addition, dry matter intake was increased by DOMP. These results support the hypothesis that PRL is galactopoietic in dairy cattle.
Collapse
Affiliation(s)
- P Lacasse
- Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada J1M 0C8.
| | - S Ollier
- Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada J1M 0C8
| |
Collapse
|
18
|
Abstract
The hypothalamic control of prolactin secretion is different from other anterior pituitary hormones, in that it is predominantly inhibitory, by means of dopamine from the tuberoinfundibular dopamine neurons. In addition, prolactin does not have an endocrine target tissue, and therefore lacks the classical feedback pathway to regulate its secretion. Instead, it is regulated by short loop feedback, whereby prolactin itself acts in the brain to stimulate production of dopamine and thereby inhibit its own secretion. Finally, despite its relatively simple name, prolactin has a broad range of functions in the body, in addition to its defining role in promoting lactation. As such, the hypothalamo-prolactin axis has many characteristics that are quite distinct from other hypothalamo-pituitary systems. This review will provide a brief overview of our current understanding of the neuroendocrine control of prolactin secretion, in particular focusing on the plasticity evident in this system, which keeps prolactin secretion at low levels most of the time, but enables extended periods of hyperprolactinemia when necessary for lactation. Key prolactin functions beyond milk production will be discussed, particularly focusing on the role of prolactin in inducing adaptive responses in multiple different systems to facilitate lactation, and the consequences if prolactin action is impaired. A feature of this pleiotropic activity is that functions that may be adaptive in the lactating state might be maladaptive if prolactin levels are elevated inappropriately. Overall, my goal is to give a flavour of both the history and current state of the field of prolactin neuroendocrinology, and identify some exciting new areas of research development.
Collapse
Affiliation(s)
- David R Grattan
- Centre for Neuroendocrinology and Department of AnatomyUniversity of Otago, PO Box 913, Dunedin 9054, New ZealandMaurice Wilkins Centre for Molecular BiodiscoveryAuckland, New Zealand Centre for Neuroendocrinology and Department of AnatomyUniversity of Otago, PO Box 913, Dunedin 9054, New ZealandMaurice Wilkins Centre for Molecular BiodiscoveryAuckland, New Zealand
| |
Collapse
|
19
|
van-Hover C, Li C. Stress-activated afferent inputs into the anterior parvicellular part of the paraventricular nucleus of the hypothalamus: Insights into urocortin 3 neuron activation. Brain Res 2015; 1611:29-43. [PMID: 25779038 PMCID: PMC4441854 DOI: 10.1016/j.brainres.2015.03.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 02/06/2015] [Accepted: 03/05/2015] [Indexed: 01/03/2023]
Abstract
Urocortin 3 (Ucn 3) is a member of the corticotropin-releasing factor family, which plays a major role in coordinating stress responses. Ucn 3 neurons in the anterior parvicellular part of the paraventricular nucleus of the hypothalamus (PVHap) provide prominent input into the ventromedial nucleus of the hypothalamus (VMH), a well known satiety center, where Ucn 3 acts to suppress feeding and modulate blood glucose levels. In the present study, we first determined that Ucn 3 expression in the PVHap was stimulated by acute restraint stress. We then performed retrograde tracing with fluorogold (FG) combined with immunohistochemistry for Fos as a marker for neuronal activation after restraint stress to determine the stress-activated afferent inputs into the PVHap. Substantial numbers of FG/Fos double labeled cells were found in the bed nucleus of the stria terminalis, the lateral septal nucleus, the medial amygdala, and a number of nuclei in the hypothalamus including the VMH, the arcuate nucleus, the posterior nucleus, and the ventral premammillary nucleus. In the brainstem, FG/Fos positive cells were found in the periaqueductal gray, the nucleus of the solitary tract, and the ventrolateral medulla. In conclusion, the present study showed that acute stress rapidly stimulates Ucn 3 expression in the PVHap and identified specific stress-sensitive brain areas that project to the PVHap. These areas are potentially important in mediating the stress-induced activation of Ucn 3 neurons in the PVHap.
Collapse
Affiliation(s)
- Christine van-Hover
- Department of Pharmacology and Neuroscience, University of Virginia Health System, P.O. Box 800735 1300 Jefferson Park Avenue, Charlottesville, VA 22908, United States
| | - Chien Li
- Department of Pharmacology and Neuroscience, University of Virginia Health System, P.O. Box 800735 1300 Jefferson Park Avenue, Charlottesville, VA 22908, United States.
| |
Collapse
|
20
|
Buonfiglio DC, Ramos-Lobo AM, Silveira MA, Furigo IC, Hennighausen L, Frazão R, Donato J. Neuronal STAT5 signaling is required for maintaining lactation but not for postpartum maternal behaviors in mice. Horm Behav 2015; 71:60-8. [PMID: 25896118 PMCID: PMC6282758 DOI: 10.1016/j.yhbeh.2015.04.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Revised: 04/04/2015] [Accepted: 04/10/2015] [Indexed: 12/17/2022]
Abstract
Prolactin and placental lactogens control mammary development and lactation as well as play an important role in maternal behaviors. However, the molecular mechanisms in the brain responsible for this regulation remain largely unknown. Therefore, the present study investigated whether Signal Transducer and Activator of Transcription 5 (STAT5) signaling in the brain, the key transcriptional factor recruited by prolactin receptor and other hormones, is required for postpartum maternal behavior, maintenance of lactation and offspring growth. Neuronal ablation of STAT5 impaired the control of prolactin secretion and reduced the hypothalamic expression of suppressors of cytokine signaling (i.e., SOCS3 and CISH). In addition, neuronal STAT5 deletion attenuated the hyperphagia commonly observed during lactation by decreasing the hypothalamic expression of orexigenic neurotransmitters such as the neuropeptide Y and agouti-related protein. The lower food intake of lactating neuron-specific STAT5 knockout females resulted in reduced milk production and offspring growth. Unexpectedly, postpartum maternal behavior expression was not impaired in neuron-specific STAT5 knockout females. On the contrary, the latency to retrieve and group the pups into the nest was reduced in mutant dams. Finally, we demonstrated that approximately 30% of recorded neurons in the medial preoptic area were acutely depolarized by prolactin suggesting that fast STAT5-independent signaling pathways may be involved in the regulation of maternal behaviors. Overall, our results revealed important information about the molecular mechanisms recruited by hormones to orchestrate the activation of neural circuitries engaged in the induction of maternal care.
Collapse
Affiliation(s)
- Daniella C Buonfiglio
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-000, Brazil
| | - Angela M Ramos-Lobo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-000, Brazil
| | - Marina A Silveira
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-900, Brazil
| | - Isadora C Furigo
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-000, Brazil
| | - Lothar Hennighausen
- Laboratory of Genetics and Physiology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Renata Frazão
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-900, Brazil
| | - Jose Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP 05508-000, Brazil.
| |
Collapse
|
21
|
Lacasse P, Ollier S. Effect of premilking stimulation and milking frequency on milking-induced prolactin release in lactating dairy cows. Domest Anim Endocrinol 2014; 47:47-54. [PMID: 24388184 DOI: 10.1016/j.domaniend.2013.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 11/19/2013] [Accepted: 11/24/2013] [Indexed: 11/16/2022]
Abstract
Four experiments were conducted to investigate the factors controlling prolactin (PRL) release at milking. Each experiment used 9 dairy cows in mid-lactation in a 3 × 3 Latin square design. Experiment 1 evaluated the effect of premilking stimulation. The milking unit was attached after 0, 20, or 120 s of manual stimulation. Blood samples were collected from 20 min before to 60 min after milking-unit attachment. The peak value and total PRL release (area under the curve) were not affected by the treatments, but the 120-s stimulation hastened PRL release. Stimulation (20 or 120 s) increased the β-endorphin peak value (P = 0.02), but the magnitudes of PRL and β-endorphin releases were not correlated. Experiment 2 evaluated the effect of milking frequency. Cows were milked twice, at 7 AM and 7 PM; 3 times, at 7 AM, 1 PM, and 7 PM; or 7 times, at 7 AM, 9 AM, 11 AM, 1 PM, 3 PM, 5 PM, and 7 PM. The amount of PRL released at the 7 PM milking decreased as the number of milkings increased (P < 0.01), and peak values were smaller with 7 milkings than with 2 and 3 milkings (P < 0.05). Beta-endorphin release was not affected by milking frequency and not correlated with the magnitude of PRL release. Experiment 3 evaluated the effect of manual stimulation between milkings on milking-induced PRL release. Cows received no stimulation; 5 stimulations (5 min each), at 9 AM, 11 AM, 1 PM, 3 PM, and 5 PM; or 1 stimulation at 5 PM. Manual stimulation reduced (P < 0.5) the amount of PRL released and the maximum PRL concentration at the 7 PM milking, but no difference were found between 1 and 5 stimulations. Manual stimulation did not affect the amount of cortisol released but did impair milk ejection. Experiment 4 evaluated the effect of milking frequency on the PRL release induced by manual stimulation. Cows were milked at 7 AM only; at 7 AM, 9 AM, 11 AM, 1 PM, 3 PM, and 5 PM; or at 7 AM and 5 PM. All cows then received manual stimulation at 7 PM. Milking every 2 h or once 2 h before manual stimulation reduced the amount of PRL released and the maximum PRL concentration but did not affect cortisol release. In conclusion, the length of premilking stimulation has no significant effect on milking-induced PRL release, but increasing milking frequency reduces the amount of PRL released at milking. This effect is due not to the number of milkings or the amount of milk harvested during the milking but to the interval since the preceding milking.
Collapse
Affiliation(s)
- P Lacasse
- Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec J1M 0C8, Canada.
| | - S Ollier
- Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec J1M 0C8, Canada
| |
Collapse
|
22
|
Romanò N, Yip SH, Hodson DJ, Guillou A, Parnaudeau S, Kirk S, Tronche F, Bonnefont X, Le Tissier P, Bunn SJ, Grattan DR, Mollard P, Martin AO. Plasticity of hypothalamic dopamine neurons during lactation results in dissociation of electrical activity and release. J Neurosci 2013; 33:4424-33. [PMID: 23467359 PMCID: PMC6704969 DOI: 10.1523/jneurosci.4415-12.2013] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 01/09/2013] [Accepted: 01/14/2013] [Indexed: 11/21/2022] Open
Abstract
Tuberoinfundibular dopamine (TIDA) neurons are the central regulators of prolactin (PRL) secretion. Their extensive functional plasticity allows a change from low PRL secretion in the non-pregnant state to the condition of hyperprolactinemia that characterizes lactation. To allow this rise in PRL, TIDA neurons are thought to become unresponsive to PRL at lactation and functionally silenced. Here we show that, contrary to expectations, the electrical properties of the system were not modified during lactation and that the neurons remained electrically responsive to a PRL stimulus, with PRL inducing an acute increase in their firing rate during lactation that was identical to that seen in non-pregnant mice. Furthermore, we show a long-term organization of TIDA neuron electrical activity with an harmonization of their firing rates, which remains intact during lactation. However, PRL-induced secretion of dopamine (DA) at the median eminence was strongly blunted during lactation, at least in part attributable to lack of phosphorylation of tyrosine hydroxylase, the key enzyme involved in DA synthesis. We therefore conclude that lactation, rather than involving electrical silencing of TIDA neurons, represents a condition of decoupling between electrical activity at the cell body and DA secretion at the median eminence.
Collapse
Affiliation(s)
- Nicola Romanò
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France
- INSERM, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Siew H. Yip
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand
| | - David J. Hodson
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France
- INSERM, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
- Department of Medicine, Section of Cell Biology, Division of Diabetes Endocrinology and Metabolism, Imperial College London, London SW7 2AZ, United Kingdom
| | - Anne Guillou
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France
- INSERM, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Sébastien Parnaudeau
- National Center of Scientific Research, Coeducational Research Unit 7224, Molecular Genetics, Neurophysiology, and Behavior, F-75005 Paris, France
- National Institute of Health and Medical Research, Unit 952, F-75005 Paris, France, and
| | - Siobhan Kirk
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand
| | - François Tronche
- National Center of Scientific Research, Coeducational Research Unit 7224, Molecular Genetics, Neurophysiology, and Behavior, F-75005 Paris, France
- Pierre et Marie Curie University, F-75005, Paris, France
- National Institute of Health and Medical Research, Unit 952, F-75005 Paris, France, and
| | - Xavier Bonnefont
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France
- INSERM, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Paul Le Tissier
- Neural Development Unit, Institute of Child Health, London WC1E 6BT, United Kingdom
| | - Stephen J. Bunn
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand
| | - Dave R. Grattan
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand
| | - Patrice Mollard
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France
- INSERM, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| | - Agnès O. Martin
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, F-34000 Montpellier, France
- INSERM, U661, F-34000 Montpellier, France
- Universités de Montpellier 1 & 2, UMR-5203, F-34000 Montpellier, France
| |
Collapse
|
23
|
Newbern D, Freemark M. Placental hormones and the control of maternal metabolism and fetal growth. Curr Opin Endocrinol Diabetes Obes 2011; 18:409-16. [PMID: 21986512 DOI: 10.1097/med.0b013e32834c800d] [Citation(s) in RCA: 305] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW To examine the roles of the placental and pituitary hormones in the control of maternal metabolism and fetal growth. RECENT FINDINGS In addition to promoting growth of maternal tissues, placental growth hormone (GH-V) induces maternal insulin resistance and thereby facilitates the mobilization of maternal nutrients for fetal growth. Human placental lactogen (hPL) and prolactin increase maternal food intake by induction of central leptin resistance and promote maternal beta-cell expansion and insulin production to defend against the development of gestational diabetes mellitus. The effects of the lactogens are mediated by diverse signaling pathways and are potentiated by glucose. Pathologic conditions of pregnancy are associated with dysregulation of GH-V and hPL gene expression. SUMMARY The somatogenic and lactogenic hormones of the placenta and maternal pituitary gland integrate the metabolic adaptations of pregnancy with the demands of fetal and neonatal development. Dysregulation of placental growth hormone and/or placental lactogen in pathologic conditions of pregnancy may adversely impact fetal growth and postnatal metabolic function.
Collapse
Affiliation(s)
- Dorothee Newbern
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina 27710, USA.
| | | |
Collapse
|
24
|
Lacasse P, Lollivier V, Bruckmaier RM, Boisclair YR, Wagner GF, Boutinaud M. Effect of the prolactin-release inhibitor quinagolide on lactating dairy cows. J Dairy Sci 2011; 94:1302-9. [PMID: 21338795 DOI: 10.3168/jds.2010-3649] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Accepted: 11/17/2010] [Indexed: 11/19/2022]
Abstract
In most mammals, prolactin (PRL) is essential for maintaining lactation, and yet the short-term suppression of PRL during established lactation by bromocriptine has produced inconsistent effects on milk yield in cows and goats. To assess the effect of the long-term inhibition of PRL release in lactating dairy cows, 5 Holstein cows in early lactation received daily intramuscular injections of 1mg of the PRL-release inhibitor quinagolide for 9 wk. Four control cows received the vehicle (water) only. During the last week of the treatments, one udder half was milked once a day (1×) and the other twice a day (2×). Blood samples were harvested at milking in wk -1, 1, 4, and 8. The daily injections of quinagolide reduced milking-induced PRL release but not the basal PRL concentration. Quinagolide induced a faster decline in milk production, which was about 5.3 kg/d lower in the quinagolide-treated cows during the last 4 wk of treatment. During wk 9, the inhibition of milk production by quinagolide was maintained in the udder half that was milked 2× but not in the half milked 1×. Milk production was significantly correlated with the quantity of PRL released at milking. Quinagolide did not affect the release of oxytocin at milking. Serum concentration of insulin-like growth factor-1 was not affected by treatment or correlated with milk production. Serum concentrations of leptin and the calciotropic hormone stanniocalcin were not affected by the treatment. In conclusion, the chronic administration of the PRL-release inhibitor quinagolide decreases milk production in dairy cows. The effect is likely the result of the reduced release of milking-induced PRL and is modulated at the level of the gland by milking frequency.
Collapse
Affiliation(s)
- P Lacasse
- Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, PO Box 90 STN Lennoxville, Sherbrooke, Quebec, Canada J1M 1Z3.
| | | | | | | | | | | |
Collapse
|
25
|
Crawford JL, McLeod BJ, Eckery DC. The hypothalamic-pituitary-ovarian axis and manipulations of the oestrous cycle in the brushtail possum. Gen Comp Endocrinol 2011; 170:424-48. [PMID: 21074534 DOI: 10.1016/j.ygcen.2010.10.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 10/31/2010] [Indexed: 11/23/2022]
Abstract
The main purpose of this review is to provide a comprehensive update on what is known about the regulatory mechanisms of the hypothalamic-pituitary-ovarian axis in the brushtail possum, and to report on the outcomes of attempts made to manipulate by hormonal means, these processes in the possum. Over the last 15 years, several unique features of possum reproductive physiology have been discovered. These include an extended follicular phase despite elevated concentrations of FSH during the luteal phase, and early expression of LH receptors on granulosa cells of small antral follicles, suggesting a different mechanism for the selection of a dominant follicle. The use of routine synchronisation protocols that are effective in eutherians has failed to be effective in possums, and so the ability to reliably synchronise oestrus in this species remains a challenge.
Collapse
Affiliation(s)
- Janet L Crawford
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
| | | | | |
Collapse
|
26
|
Speakman JR, Król E. Limits to sustained energy intake. XIII. Recent progress and future perspectives. J Exp Biol 2011; 214:230-41. [DOI: 10.1242/jeb.048603] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Summary
Several theories have been proposed to explain limits on the maximum rate at which animals can ingest and expend energy. These limits are likely to be intrinsic to the animal, and potentially include the capacity of the alimentary tract to assimilate energy – the ‘central limitation’ hypothesis. Experimental evidence from lactating mice exposed to different ambient temperatures allows us to reject this and similar ideas. Two alternative ideas have been proposed. The ‘peripheral limitation’ hypothesis suggests that the maximal sustained energy intake reflects the summed demands of individual tissues, which have their own intrinsic limitations on capacity. In contrast, the ‘heat dissipation limit’ (HDL) theory suggests that animals are constrained by the maximal capacity to dissipate body heat. Abundant evidence in domesticated livestock supports the HDL theory, but data from smaller mammals are less conclusive. Here, we develop a novel framework showing how the HDL and peripheral limitations are likely to be important in all animals, but to different extents. The HDL theory makes a number of predictions – in particular that there is no fixed limit on sustained energy expenditure as a multiple of basal metabolic rate, but rather that the maximum sustained scope is positively correlated with the capacity to dissipate heat.
Collapse
Affiliation(s)
- John R. Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK
| | - Elżbieta Król
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK
- Mammal Research Institute PAS, 17-230 Białowieża, Poland
| |
Collapse
|
27
|
The neuroendocrine basis of lactation-induced suppression of GnRH: role of kisspeptin and leptin. Brain Res 2010; 1364:139-52. [PMID: 20727862 DOI: 10.1016/j.brainres.2010.08.038] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/11/2010] [Accepted: 08/12/2010] [Indexed: 11/22/2022]
Abstract
Lactation is an important physiological model of the integration of energy balance and reproduction, as it involves activation of potent appetitive neuropeptide systems coupled to a profound inhibition of pulsatile GnRH/LH secretion. There are multiple systems that contribute to the chronic hyperphagia of lactation: 1) suppression of the metabolic hormones, leptin and insulin, 2) activation of hypothalamic orexigenic neuropeptide systems NPY, AGRP, orexin (OX) and melanin concentrating hormone (MCH), 3) special induction of NPY expression in the dorsomedial hypothalamus, and 4) suppression of anorexigenic systems POMC and CART. These changes ensure adequate energy intake to meet the metabolic needs of milk production. There is significant overlap in all of the systems that regulate food intake with the regulation of GnRH, suggesting there could be several redundant factors acting to suppress GnRH/LH during lactation. In addition to an overall increase in inhibitory tone acting directly on GnRH cell bodies that is brought about by increases in orexigenic systems, there are also effects at the ARH to disrupt Kiss1/neurokinin B/dynorphin neuronal function through inhibition of Kiss1 and NKB. These changes could lead to an increase in inhibitory auto-regulation of the Kiss1 neurons and a possible disruption of pulsatile GnRH release. While the low levels of leptin and insulin contribute to the changes in ARH appetitive systems, they do not appear to contribute to the suppression of ARH Kiss1 or NKB. The inhibition of Kiss1 may be the key factor in the suppression of GnRH during lactation, although the mechanisms responsible for its inhibition are unknown.
Collapse
|
28
|
Anderson GM, Kieser DC, Steyn FJ, Grattan DR. Hypothalamic prolactin receptor messenger ribonucleic acid levels, prolactin signaling, and hyperprolactinemic inhibition of pulsatile luteinizing hormone secretion are dependent on estradiol. Endocrinology 2008; 149:1562-70. [PMID: 18162529 DOI: 10.1210/en.2007-0867] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hyperprolactinemia can reduce fertility and libido. Although central prolactin actions are thought to contribute to this, the mechanisms are poorly understood. We first tested whether chronic hyperprolactinemia inhibited two neuroendocrine parameters necessary for female fertility: pulsatile LH secretion and the estrogen-induced LH surge. Chronic hyperprolactinemia induced by the dopamine antagonist sulpiride caused a 40% reduction LH pulse frequency in ovariectomized rats, but only in the presence of chronic low levels of estradiol. Sulpiride did not affect the magnitude of a steroid-induced LH surge or the percentage of GnRH neurons activated during the surge. Estradiol is known to influence expression of the long form of prolactin receptors (PRL-R) and components of prolactin's signaling pathway. To test the hypothesis that estrogen increases PRL-R expression and sensitivity to prolactin, we next demonstrated that estradiol greatly augments prolactin-induced STAT5 activation. Lastly, we measured PRL-R and suppressor of cytokine signaling (SOCS-1 and -3 and CIS, which reflect the level of prolactin signaling) mRNAs in response to sulpiride and estradiol. Sulpiride induced only SOCS-1 in the medial preoptic area, where GnRH neurons are regulated, but in the arcuate nucleus and choroid plexus, PRL-R, SOCS-3, and CIS mRNA levels were also induced. Estradiol enhanced these effects on SOCS-3 and CIS. Interestingly, estradiol also induced PRL-R, SOCS-3, and CIS mRNA levels independently. These data show that GnRH pulse frequency is inhibited by chronic hyperprolactinemia in a steroid-dependent manner. They also provide evidence for estradiol-dependent and brain region-specific regulation of PRL-R expression and signaling responses by prolactin.
Collapse
Affiliation(s)
- Greg M Anderson
- Centre for Neuroendocrinology and Department of Anatomy and Structural Biology, University of Otago School of Medical Sciences, Dunedin, New Zealand.
| | | | | | | |
Collapse
|
29
|
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.
Collapse
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
| | | |
Collapse
|
30
|
Grattan DR, Jasoni CL, Liu X, Anderson GM, Herbison AE. Prolactin regulation of gonadotropin-releasing hormone neurons to suppress luteinizing hormone secretion in mice. Endocrinology 2007; 148:4344-51. [PMID: 17569755 DOI: 10.1210/en.2007-0403] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hyperprolactinemia causes infertility, but the mechanisms involved are not known. The present study aimed to determine whether and how prolactin may influence LH secretion in the adult female mouse. Using ovariectomized, estrogen-treated (OVX+E) mice, we found that 7 d of intracerebroventricular prolactin potently suppressed serum LH levels (P < 0.05). To examine whether this central action of prolactin may involve the GnRH neurons, the effects of acute and chronic prolactin on cAMP response element-binding protein phosphorylation (pCREB) in GnRH neurons were examined using dual-label immunocytochemistry. In diestrous and OVX+E mice, a single sc injection of ovine prolactin resulted in a significant (P < 0.05) doubling of the number of GnRH neurons expressing pCREB. OVX+E mice treated with five injections of ovine prolactin over 48 h showed a 4-fold increase in the number of GnRH neurons with pCREB. To determine whether GnRH neurons might be regulated directly by prolactin, we examined prolactin receptor (PRL-R) mRNA expression in green fluorescent protein-tagged GnRH neurons by single-cell RT-PCR. As a positive control, PRL-R mRNA was measured in arcuate dopaminergic neurons obtained from green fluorescent protein-tagged tyrosine hydroxylase neurons. Three of 23 GnRH neurons (13%) were identified to express PRL-R transcripts, whereas nine of 11 arcuate dopaminergic neurons (82%) were found to coexpress PRL-R mRNA. These data demonstrate that prolactin suppresses LH levels in the mouse, as it does in other species, and indicate that it acts centrally to regulate intracellular signaling within GnRH neurons. This is likely to occur, at least in part, through the direct regulation of a subpopulation of GnRH neurons.
Collapse
Affiliation(s)
- David R Grattan
- Centre for Neuroendocrinology, Department of Anatomy and Structural Biology, University of Otago, P.O. Box 913, Dunedin 9054, New Zealand.
| | | | | | | | | |
Collapse
|
31
|
Crowley WR, Ramoz G, Torto R, Keefe KA, Wang JJ, Kalra SP. Neuroendocrine actions and regulation of hypothalamic neuropeptide Y during lactation. Peptides 2007; 28:447-52. [PMID: 17241697 PMCID: PMC2581809 DOI: 10.1016/j.peptides.2006.09.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Accepted: 09/07/2006] [Indexed: 11/26/2022]
Abstract
The expression of neuropeptide Y (NPY) and its co-messenger, agouti-related peptide (AgRP), in arcuate neurons of the hypothalamus is increased during lactation in rats. Our research has been addressing the questions of the physiological actions of these peptides during lactation and the physiological signals associated with lactation that result in increased expression of their genes. Our studies indicate that NPY and AgRP exert pleiotropic actions during lactation that help integrate neuroendocrine regulation of energy balance with controls over anterior and posterior pituitary hormone secretion. Further, reciprocal signaling to the NPY/AgRP system by leptin and ghrelin is responsible for the changes in expression of these hypothalamic peptides in lactating animals, and thus, may contribute to regulation of food intake and the various neuroendocrine adaptations of lactation.
Collapse
Affiliation(s)
- W R Crowley
- Department of Pharmacology and Toxicology, University of Utah Health Sciences Center, Salt Lake City, UT 84112, USA.
| | | | | | | | | | | |
Collapse
|
32
|
Kokay IC, Grattan DR. Expression of mRNA for prolactin receptor (long form) in dopamine and pro-opiomelanocortin neurones in the arcuate nucleus of non-pregnant and lactating rats. J Neuroendocrinol 2005; 17:827-35. [PMID: 16280030 DOI: 10.1111/j.1365-2826.2005.01374.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Under most conditions, prolactin secretion from the pituitary gland is subject to negative-feedback regulation. Prolactin stimulates dopamine release from tuberoinfundibular (TIDA) neurones in the arcuate nucleus of the hypothalamus, which in turn suppresses the production of prolactin. However, during late pregnancy and continuing into lactation, this feedback mechanism becomes less responsive to prolactin and, as a result, a hyperprolactinaemic state develops. We investigated whether long-form prolactin receptor (PRL-R(L)) mRNA is present on TIDA neurones in nonpregnant and lactating rats. In addition, we examined whether PRL-R(L) mRNA is colocalized on hypothalamic pro-opiomelanocortin (POMC) neurones. Dual-label in situ hybridizations using an (35)S-labelled cRNA probe specific for long-form PRL-R, together with a digoxigenin-labelled RNA probe that encoded either tyrosine hydroxylase (TH) or POMC mRNA, were performed on brain sections. In both nonpregnant and lactating rats, the majority of TH mRNA-positive cells (> 90%) were found to express long-form PRL-R mRNA. In sections from nonpregnant rats, few non-TH positive cells expressed PRL-R(L) mRNA. By contrast, during lactation, the proportion of PRL-R(L) mRNA-positive cells that were not TH mRNA-positive increased to approximately 70%. Only a small number of neurones in this subpopulation of PRL-R(L) mRNA-positive neurones were found to be positive for POMC mRNA. These data show that the loss of responsiveness to prolactin occurring during lactation is not due to down regulation of long-form PRL-R gene expression on TIDA neurones. Moreover, the persistent expression of PRL-R(L) in arcuate neuroendocrine circuits suggests that PRL-R-mediated signalling continues to be important in these neurones during lactation.
Collapse
Affiliation(s)
- I C Kokay
- Centre for Neuroendocrinology and Department of Anatomy and Structural Biology, University of Otago, Dunedin, New Zealand.
| | | |
Collapse
|
33
|
Chen P, Smith MS. Suckling-induced activation of neuronal input to the dorsomedial nucleus of the hypothalamus: possible candidates for mediating the activation of DMH neuropeptide Y neurons during lactation. Brain Res 2003; 984:11-20. [PMID: 12932835 DOI: 10.1016/s0006-8993(03)02999-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Activation of the neuropeptide Y (NPY) neuronal system in the dorsomedial nucleus of the hypothalamus (DMH) during lactation in the rat is in part due to neural impulses arising from the suckling stimulus. However, the afferent neuronal input to the DMH that is activated during lactation and is responsible for activation of NPY neurons is currently unknown. Previously, using cFos as a marker for neuronal activation, we identified several brain areas in the lactating animals that were activated by the suckling stimulus. Thus, the objective of the present study was to determine if any of these suckling activated areas project directly to the DMH. The retrograde tracer, fluorogold (FG), was injected into the DMH on day 4 postpartum. FG-injected lactating rats were then deprived of their eight-pup litters on day 9 postpartum, and 48 h later, the pups were returned to the females to reinitiate the suckling stimulus for 90 min and induce cFos expression. The animals were then perfused and the brains were subjected to double-label immunohistochemistry to visualize both FG- and cFos-positive cells. Substantial numbers of FG/cFos double-labeled cells were found in forebrain regions, including the preoptic area, lateral septal nucleus, ventral subiculum, and supramammillary nucleus, and in brainstem regions, including the lateral parabrachial nucleus, periaqeductal gray, and ventrolateral medulla. In conclusion, these areas are potentially important candidates for mediating the activation of the NPY neuronal system in the DMH during lactation.
Collapse
Affiliation(s)
- Peilin Chen
- Division of Neuroscience, Oregon National Primate Research Center, Department of Physiology and Pharmacology, Oregon Health and Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA
| | | |
Collapse
|
34
|
García MC, López M, Gualillo O, Seoane LM, Diéguez C, Señarís RM. Hypothalamic levels of NPY, MCH, and prepro-orexin mRNA during pregnancy and lactation in the rat: role of prolactin. FASEB J 2003; 17:1392-400. [PMID: 12890692 DOI: 10.1096/fj.02-0933com] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Pregnancy and lactation provide excellent models of physiological hyperphagia and hyperprolactinemia. To identify possible factors associated with the increased feeding in these situations, we measured hypothalamic mRNA levels of three orexigenic neuropeptides--NPY, MCH, and orexins--in nonpregnant, pregnant, and lactating rats by in situ hybridization. NPY mRNA content in the arcuate nucleus was significantly increased during pregnancy and lactation. However, MCH and prepro-orexin expression was decreased in both states. 48 or 72 h of fasting in pregnant and lactating rats further elevated NPY mRNA levels and increased the low MCH mRNA content. Surprisingly, no effect was observed in prepro-orexin mRNA levels. Finally, we investigated the possible effect of high PRL levels on these orexigenic signals using a model of hyperprolactinemia induced by pituitary graft. NPY mRNA content was unchanged, but MCH and prepro-orexin mRNA levels were significantly decreased. Our results suggest that the increased NPY expression might be partly responsible for the hyperphagia observed during pregnancy and lactation. MCH and prepro-orexin may be involved in the adaptation of other homeostatic mechanisms and their decreased levels in these physiological settings could be mediated by the elevated circulating PRL levels.
Collapse
Affiliation(s)
- M C García
- Department of Physiology, Faculty of Medicine, University of Santiago de Compostela, R/San Francisco s/n, 15782 Santiago de Compostela, Spain
| | | | | | | | | | | |
Collapse
|
35
|
Berghorn KA, Le WW, Sherman TG, Hoffman GE. Suckling stimulus suppresses messenger RNA for tyrosine hydroxylase in arcuate neurons during lactation. J Comp Neurol 2001; 438:423-32. [PMID: 11559898 DOI: 10.1002/cne.1325] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Tyrosine hydroxylase (TH) mRNA in tuberoinfundibular dopamine (TIDA) neurons is suppressed during lactation but rebounds upon pup removal. A time course of TH mRNA changes after pup removal revealed three phases: (1) a nuclear phase (evident 1.5 hours after pup removal, maximal at 3 hours) with TH mRNA appearing in 1 or 2 nuclear loci with little or no change in cytoplasmic mRNA; (2) a cytoplasmic phase (noted 6 hours after pup removal, peaked 12-24 hours) with a significant increase in total TH mRNA levels mainly in the cytoplasm; and (3) a stabilization phase (24-48 hours after pup removal) when nuclear signals were low and cytoplasmic RNA showed a slight decline with extension of RNA clusters into the cell dendrites. In rats whose pups could suckle only on one side, TH was up-regulated only on the side contralateral to nipple blockade. These data indicate that after suckling terminates, TH up-regulation is evident at 1.5 hours, but 6 hours is needed before the cells transport sufficient mRNA into the cytoplasm. The rapid signaling of TH up-regulation stems from the fact that the TIDA neurons respond to neural signals from termination of suckling.
Collapse
Affiliation(s)
- K A Berghorn
- Laboratory for Pregnancy and Newborn Research, Department of Physiology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
| | | | | | | |
Collapse
|
36
|
Andrews ZB, Kokay IC, Grattan DR. Dissociation of prolactin secretion from tuberoinfundibular dopamine activity in late pregnant rats. Endocrinology 2001; 142:2719-24. [PMID: 11356724 DOI: 10.1210/endo.142.6.8196] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study investigated whether the PRL surge that precedes parturition is accompanied by a decrease in activity of hypothalamic tuberoinfundibular dopamine (TIDA) neurons, as occurs during the PRL surges of early pregnancy. Serial blood samples were collected at regular intervals during early and late pregnancy via chronic indwelling jugular cannulae, and concentrations of plasma PRL were determined by RIA. In addition, pregnant rats were killed at either 1200 and 0300 h on different days throughout pregnancy. Levels of TIDA neuronal activity were estimated using concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) in the median eminence as an index of dopamine metabolism. During early pregnancy, plasma PRL concentrations showed characteristic diurnal and nocturnal surges peaking at 1700 and 0300 h, respectively, whereas during late pregnancy, there was a broad nocturnal surge throughout the night preceding parturition. During early pregnancy, DOPAC was elevated at 1200 h, associated with suppressed plasma PRL, whereas at 0300 h, during the nocturnal PRL surge, DOPAC was significantly reduced (P < 0.05). On the last day of pregnancy DOPAC levels were significantly reduced at both 1200 and 0300 h compared with those at 1200 h in early pregnancy regardless of the PRL concentration. This experiment was repeated with additional groups to further characterize the timing of the fall in TIDA activity during late pregnancy. DOPAC concentrations were elevated throughout the second half of pregnancy, then fell significantly between 0300-1200 h on day 21, approximately 36 h before parturition. As in the previous experiment, the timing of changes in DOPAC concentrations in the median eminence was dissociated from the antepartum PRL surge. These data indicate that the regulation of PRL secretion during late pregnancy is different from that of early pregnancy. Despite the prolonged reduction in activity of TIDA neurons during late pregnancy, PRL secretion still occurs as a nocturnal surge, suggesting that dopamine is not the only regulator of PRL secretion at this time.
Collapse
Affiliation(s)
- Z B Andrews
- Department of Anatomy and Structural Biology and Neuroscience Research Center, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | | | | |
Collapse
|
37
|
Strader AD, Buntin JD. Neuropeptide-Y: a possible mediator of prolactin-induced feeding and regulator of energy balance in the ring dove (Streptopelia risoria). J Neuroendocrinol 2001; 13:386-92. [PMID: 11264727 DOI: 10.1046/j.1365-2826.2001.00642.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Although neuropeptide-Y (NPY) has been widely reported to be a potent stimulator of feeding activity and regulator of energy homeostasis, most of the supportive evidence for such effects has been gathered in mammalian species. This study characterized the orexigenic potency of NPY in an avian species, the ring dove, and measured changes in hypothalamic NPY-immunoreactive (NPY-ir) cell numbers in response to energy state fluctuations or intracranial administration of the potent orexigenic hormone prolactin. Food intake was significantly elevated in male doves at 1 h after intracerebroventricular (i.c.v.) injection of 0.25 and 0.5 microg NPY but not after injection of a higher dose (1.0 microg). In time course studies, food intake was increased at 1 h after i.c.v. injection of 0.5 microg NPY but was not elevated at 2, 3, or 4 h. The number of NPY-ir cell bodies in the infundibular region of the dove hypothalamus increased two to four-fold following acute food deprivation, chronic food restriction, or repeated i.c.v. injections of prolactin. No additive effects were observed when food restriction and prolactin treatment were combined. These findings suggest that NPY is involved in energy homeostasis in doves and are consistent with the hypothesis that prolactin-induced hyperphagia is mediated in part by NPY.
Collapse
Affiliation(s)
- A D Strader
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | | |
Collapse
|
38
|
Speth RC, Smith MS, Grove KL. Lactation decreases angiotensinogen mRNA expression in the midcaudal arcuate nucleus of the rat brain. Am J Physiol Regul Integr Comp Physiol 2001; 280:R1169-76. [PMID: 11247841 DOI: 10.1152/ajpregu.2001.280.4.r1169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In lactating rats, ANG II receptor binding in the arcuate nucleus (ARH) and median eminence is decreased. To further evaluate brain angiotensinergic activity during lactation, we assessed angiotensinogen (AON) mRNA by in situ hybridization in forebrains of day 10 or 11 postpartum lactating and diestrous rats. AON mRNA was abundantly expressed in the ARH, preoptic, suprachiasmatic, supraoptic, paraventricular, and dorsomedial hypothalamic nuclei, and other regions, similar to that reported in male rat brains. AON mRNA levels were decreased 27% in the midcaudal ARH of lactating rats but did not differ between lactating or diestrous rats in any of the other brain areas examined. Immunofluorescence for AON and glial fibrillary acidic protein or tyrosine hydroxylase confirmed that the AON immunoreactivity in the ARH was limited to astrocytes. Confocal microscopy revealed close appositions of AON-positive astrocytes to dopaminergic neurons in the ARH. The decrease in AON mRNA in the midcaudal ARH during lactation coupled with decreased ARH ANG II receptor binding suggests that lactating rats are less subject to ANG II-mediated inhibition of prolactin secretion.
Collapse
Affiliation(s)
- R C Speth
- Division of Neuroscience, Oregon Regional Primate Research Center, Oregon Health Sciences University, Beaverton, OR 97006, USA.
| | | | | |
Collapse
|
39
|
Pi X, Voogt JL. Mechanisms for suckling-induced changes in expression of prolactin receptor in the hypothalamus of the lactating rat. Brain Res 2001; 891:197-205. [PMID: 11164823 DOI: 10.1016/s0006-8993(00)03212-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The present study aimed to investigate whether increased expression of prolactin receptor (PRL-R) during lactation is caused by suckling-induced hyperprolactinemia or the suckling stimulus itself. Three groups (n=7) of mid-lactating rats were used. Each rat received 3 days of s.c. injection of vehicle or drug before sacrifice on lactation day 10. Rats in the control group received vehicle only and were suckled by pups. The second group received bromocriptine to suppress PRL levels and were suckled by pups. The third group of rats received haloperidol (high PRL) and were deprived of pups. Plasma PRL levels were measured. Animals were perfused with 2% paraformaldehyde for immunofluorescent study. Results showed that PRL-R immunoreactivity in the ventrolateral preoptic, ventromedial preoptic, and ventromedial hypothalamic nuclei was significantly increased in the bromocriptine-treated group compared to the control group, indicating PRL-R expression in these areas may be inhibited by hyperprolactinemia in the presence of the suckling stimulus. The PRL-R in the lateroanterior, ventrolateral and paraventricular nuclei was significantly decreased in the haloperidol-treated group compared to the control group, suggesting that the PRL-R in these areas is most likely regulated by the suckling stimulus itself. The PRL-R in the arcuate nucleus was significantly increased in bromocriptine-treated rats and decreased in haloperidol-treated rats, suggesting that the PRL-R in this nucleus is regulated by mechanisms related to both the stimulus of suckling itself and suckling-induced hyperprolactinemia. These results support the hypothesis that expression of PRL-R in discrete hypothalamic nuclei is differentially regulated by either PRL and/or suckling.
Collapse
Affiliation(s)
- X Pi
- Department of Molecular and Integrative Physiology, Kansas University Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160-7401, USA
| | | |
Collapse
|
40
|
Kameda Y, Miura M, Nishimaki T. Localization of neuropeptide Y mRNA and peptide in the chicken hypothalamus and their alterations after food deprivation, dehydration, and castration. J Comp Neurol 2001. [DOI: 10.1002/cne.1074] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
41
|
Speth RC, Barry WT, Smith MS, Grove KL. A comparison of brain angiotensin II receptors during lactation and diestrus of the estrous cycle in the rat. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:R904-9. [PMID: 10484510 DOI: 10.1152/ajpregu.1999.277.3.r904] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During lactation there are many dramatic alterations in the hypothalamic-pituitary (HP) axis, as well as an increased demand for food and water. The renin-angiotensin system (RAS) is one of the major mediators of the HP axis. This study examined the receptors for ANG II in the rat brain during lactation and diestrus. Compared with diestrus, lactating rats had significant decreases in ANG II receptor binding in several forebrain regions, most notably in the arcuate nucleus/median eminence, dorsomedial hypothalamic nucleus (DMH), and lateral hypothalamic area (LHA). In contrast, there was an increase in ANG II receptor binding in the preoptic area during lactation. These significant changes in ANG II binding in the brain during lactation support the hypothesis that changes in the RAS may contribute to the dramatic changes in the HP axis during lactation. In addition, the significant reduction in ANG II binding in the DMH and LHA may be indicative of a role in the regulation of food intake, a function only recently associated with the RAS.
Collapse
Affiliation(s)
- R C Speth
- Department of Veterinary Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington 99164, USA
| | | | | | | |
Collapse
|
42
|
Chen P, Li C, Haskell-Luevano C, Cone RD, Smith MS. Altered expression of agouti-related protein and its colocalization with neuropeptide Y in the arcuate nucleus of the hypothalamus during lactation. Endocrinology 1999; 140:2645-50. [PMID: 10342854 DOI: 10.1210/endo.140.6.6829] [Citation(s) in RCA: 71] [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
During lactation, the levels of neuropeptide Y (NPY), which plays an important role in mediating food intake, are significantly elevated in a number of hypothalamic areas, including the arcuate nucleus (ARH). To identify additional hypothalamic systems that might be important in mediating the increase in food intake and alterations in energy homeostasis during lactation, the present studies examined the expression of agouti-related protein (AGRP), a recently described homologue of the skin agouti protein. AGRP is found in the hypothalamus and has been suggested to play an important role in the regulation of food intake. In the first experiment, animals were studied during diestrus of the estrous cycle, a stage of the cycle when estrogen levels are basal and similar to lactation, or during days 12-13 postpartum. Lactating animals had their litters adjusted to eight pups on day 2 postpartum. Brain tissue sections were used to measure AGRP messenger RNA (mRNA) levels by in situ hybridization. AGRP mRNA signal was found mostly in the ventromedial portion of the ARH, which has been shown to contain a high density of NPY neurons. A significant increase in AGRP mRNA content was observed in the mid- to caudal portion of the ARH of lactating animals compared with diestrous females. No difference was found in the rostral portion of the ARH. In the second experiment, double-label in situ hybridization for AGRP and NPY was performed in lactating animals to determine the extent of colocalization of the two peptides in the ARH, using 35S-labeled and digoxigenin-labeled antisense complementary RNA probes. It was found that almost all of the NPY-positive neurons throughout the ARH also expressed AGRP mRNA signal. Furthermore, AGRP expression was confined almost exclusively to NPY-positive neurons. Thus, the present study showed that during lactation, AGRP gene expression was significantly elevated in a subset of the AGRP neurons in the ARH. The high degree of colocalization of AGRP and NPY, coupled with previous reports from our laboratory demonstrating increased NPY expression in the ARH in response to suckling, suggests that AGRP and NPY are coordinately regulated and may be involved in the increase in food intake during lactation.
Collapse
Affiliation(s)
- P Chen
- Division of Neuroscience, Oregon Regional Primate Research Center, Beaverton 97006, USA
| | | | | | | | | |
Collapse
|