1
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Haduch A, Bromek E, Kuban W, Basińska-Ziobroń A, Danek PJ, Alenina N, Bader M, Daniel WA. The effect of brain serotonin deficit (TPH2-KO) on the expression and activity of liver cytochrome P450 enzymes in aging male Dark Agouti rats. Pharmacol Rep 2023; 75:1522-1532. [PMID: 37848703 PMCID: PMC10661807 DOI: 10.1007/s43440-023-00540-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/19/2023]
Abstract
BACKGROUND Liver cytochrome P450 (CYP) greatly contributes to the metabolism of endogenous substances and drugs. Recent studies have demonstrated that CYP expression in the liver is controlled by the central nervous system via hormonal pathways. In particular, the expression of hepatic CYPs is negatively regulated by the brain serotoninergic system. The present study aimed to investigate changes in the function of the main liver drug-metabolizing CYP enzymes as a result of serotonin depletion in the brain of aging rats, caused by knockout of brain tryptophan hydroxylase gene (TPH2-KO). METHODS The hepatic CYP mRNA (qRT-PCR), protein level (Western blotting) and activity (HPLC), and serum hormone levels (ELISA) were measured in Dark Agouti wild-type (WT) male rats (mature 3.5-month-old and senescent 21-month-old) and in TPH2-KO senescent animals. RESULTS The expression/activity of the studied CYPs decreased with age in the liver of wild-type rats. The deprivation of serotonin in the brain of aging males decreased the mRNA level of most of the studied CYPs (CYP1A/2A/2B/3A), and lowered the protein level of CYP2C11 and CYP3A. In contrast, the activities of CYP2C11, CYP3A and CYP2C6 were increased. The expression of cytochrome b5 decreased in aging rats, but increased in TPH2-deficient senescent animals. The serum concentration of growth hormone declined in the aged and further dropped down in TPH2-deficient senescent rats. CONCLUSIONS Rat liver cytochrome P450 functions deteriorate with age, which may impair drug metabolism. The TPH2 knockout, which deprives brain serotonin, affects cytochrome P450 expression and activity differently in mature and senescent male rats.
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Affiliation(s)
- Anna Haduch
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland
| | - Ewa Bromek
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland
| | - Wojciech Kuban
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland
| | - Agnieszka Basińska-Ziobroń
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland
| | - Przemysław J Danek
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland
| | - Natalia Alenina
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Michael Bader
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
- Institute for Biology, University of Lübeck, Lübeck, Germany
- Charité University Medicine, Berlin, Germany
| | - Władysława A Daniel
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343, Kraków, Poland.
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2
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Yackle K. Transformation of Our Understanding of Breathing Control by Molecular Tools. Annu Rev Physiol 2023; 85:93-113. [PMID: 36323001 PMCID: PMC9918693 DOI: 10.1146/annurev-physiol-021522-094142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The rhythmicity of breath is vital for normal physiology. Even so, breathing is enriched with multifunctionality. External signals constantly change breathing, stopping it when under water or deepening it during exertion. Internal cues utilize breath to express emotions such as sighs of frustration and yawns of boredom. Breathing harmonizes with other actions that use our mouth and throat, including speech, chewing, and swallowing. In addition, our perception of breathing intensity can dictate how we feel, such as during the slow breathing of calming meditation and anxiety-inducing hyperventilation. Heartbeat originates from a peripheral pacemaker in the heart, but the automation of breathing arises from neural clusters within the brainstem, enabling interaction with other brain areas and thus multifunctionality. Here, we document how the recent transformation of cellular and molecular tools has contributed to our appreciation of the diversity of neuronal types in the breathing control circuit and how they confer the multifunctionality of breathing.
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Affiliation(s)
- Kevin Yackle
- Department of Physiology, University of California, San Francisco, California, USA;
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3
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Alonso L, Peeva P, Stasko S, Bader M, Alenina N, Winter Y, Rivalan M. Constitutive depletion of brain serotonin differentially affects rats' social and cognitive abilities. iScience 2023; 26:105998. [PMID: 36798444 PMCID: PMC9926123 DOI: 10.1016/j.isci.2023.105998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 09/30/2022] [Accepted: 01/12/2023] [Indexed: 01/19/2023] Open
Abstract
Central serotonin appears a promising transdiagnostic marker of psychiatric disorders and a modulator of some of their key behavioral symptoms. In adult male Tph2 -/- rats, constitutively lacking central serotonin, we tested individual's cognitive, social and non-social abilities and characterized group's social organization under classical and ethological testing conditions. Using unsupervised machine learning, we identified the functions most dependent on serotonin. Although serotonin depletion did not affect cognitive performances in classical testing, in the home-cage it induced compulsive aggression and sexual behavior, hyperactive and hypervigilant stereotyped behavior, reduced self-care and exacerbated corticosterone levels. This profile recalled symptoms of impulse control and anxiety disorders. Serotonin appeared essential for behavioral adaptation to dynamic social environments. Our animal model challenges the essential role of serotonin in decision-making, flexibility, impulsivity, and risk-taking. These findings highlight the importance of studying everyday life functions within the dynamic social living environment to model complexity in animal models.
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Affiliation(s)
- Lucille Alonso
- Humboldt-Universität zu Berlin, Berlin, Germany,Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Polina Peeva
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | | | - Michael Bader
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany,Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Natalia Alenina
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany,Corresponding author
| | - York Winter
- Humboldt-Universität zu Berlin, Berlin, Germany,Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Marion Rivalan
- Humboldt-Universität zu Berlin, Berlin, Germany,Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany,Corresponding author
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4
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Spinieli RL, Cornelius-Green J, Cummings KJ. A serotonin-deficient rat model of neurogenic hypertension: influence of sex and sympathetic vascular tone. J Neurophysiol 2022; 128:1199-1206. [PMID: 36169206 PMCID: PMC9621705 DOI: 10.1152/jn.00358.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/22/2022] [Accepted: 09/26/2022] [Indexed: 11/22/2022] Open
Abstract
Previously we showed that a loss of central nervous system (CNS) 5-hydroxytryptamine (5-HT) (tryptophan hydroxylase 2 knockout; TPH2-/-) leads to hypertension in male rats during wakefulness and REM sleep. Here, we tested the hypotheses that hypertension is also revealed in female TPH2-/- when sex hormones are controlled, and that the especially high arterial blood pressure (ABP) of male TPH2-/- rats is due to increased sympathetic vascular tone. The ABP of females was measured specifically during proestrus or estrus and again following ovariectomy. The ABP of males was measured before and after α-adrenergic blockade. Prior to ovariectomy, the ABP of female TPH2-/- rats was ∼3 mmHg higher than TPH2+/+ during REM sleep while in proestrus/estrus. This difference increased to ∼9 mmHg following ovariectomy (P = 0.047). Hypertension of female TPH2-/- was most obvious upon the transition to rapid eye movement (REM) sleep from the previous state (P < 0.0001). Mean arterial pressure (MAP) of male TPH2-/- rats was ∼14 mmHg higher than male TPH2+/+ (P = 0.02), a difference that was eliminated by α-adrenergic blockade. Male TPH2-/- had normal plasma levels of 5-HT, norepinephrine, and epinephrine, whereas plasma dopamine was reduced by 50% compared with TPH2+/+ (P < 0.0001). From these data, we conclude that: 1) a deficiency of CNS 5-HT leads to hypertension in males and females alike, although in females the effect is mild and possibly obscured by ovarian hormones; 2) hypertension in females, like males, is most apparent in REM sleep, indicating a neural origin, and 3) increased sympathetic vascular tone underlies the elevated ABP of TPH2-/- rats.NEW & NOTEWORTHY We show that hypertension is evident in female 5-HT-deficient TPH2-/- rats when sex hormones are controlled, an effect most evident upon the transition to REM sleep. In addition, our data strongly suggest that increased sympathetic vascular tone contributes to the hypertension present in this 5-HT-deficient model of neurogenic hypertension.
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Affiliation(s)
- Richard L Spinieli
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Jennifer Cornelius-Green
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Kevin J Cummings
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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5
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Meng X, Grandjean J, Sbrini G, Schipper P, Hofwijks N, Stoop J, Calabrese F, Homberg J. Tryptophan Hydroxylase 2 Knockout Male Rats Exhibit a Strengthened Oxytocin System, Are Aggressive, and Are Less Anxious. ACS Chem Neurosci 2022; 13:2974-2981. [PMID: 36197033 PMCID: PMC9585586 DOI: 10.1021/acschemneuro.2c00448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The central serotoninergic system is critical for stress responsivity and social behavior, and its dysregulations have been centrally implicated in virtually all neuropsychiatric disorders. Genetic serotonin depletion animal models could provide a tool to elucidate the causes and mechanisms of diseases and to develop new treatment approaches. Previously, mice lacking tryptophan hydroxylase 2 (Tph2) have been developed, showing altered behaviors and neurotransmission. However, the effect of congenital serotonin deficiency on emotional and social behavior in rats is still largely unknown, as are the underlying mechanisms. In this study, we used a Tph2 knockout (Tph2-/-) male rat model to study how the lack of serotonin in the rat brain affects anxiety-like and social behaviors. Since oxytocin is centrally implicated in these behaviors, we furthermore explored whether the effects of Tph2 knockout on behavior would relate to changes in the oxytocin system. We show that Tph2-/- rats display reduced anxiety-like behavior and a high level of aggression in social interactions. In addition, oxytocin receptor expression was increased in the infralimbic and prelimbic cortices, paraventricular nucleus, dorsal raphe nucleus, and some subregions of the hippocampus, which was paralleled by increased levels of oxytocin in the medial frontal cortex and paraventricular nucleus but not the dorsal raphe nucleus, central amygdala, and hippocampus. In conclusion, our study demonstrated reduced anxiety but exaggerated aggression in Tph2-/- male rats and reveals for the first time a potential involvement of altered oxytocin system function. Meanwhile, the research of oxytocin could be distinguished in almost any psychiatric disorder including anxiety and mental disorders. This research potentially proposes a new target for the treatment of such disorders, from a genetic serotonin deficiency aspect.
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Affiliation(s)
- Xianzong Meng
- Department
of Cognitive Neuroscience, Donders Institute for Brain, Cognition,
and Behaviour, Radboud University Medical
Centre, 6525 AJ Nijmegen, The Netherlands
| | - Joanes Grandjean
- Department
of Cognitive Neuroscience, Donders Institute for Brain, Cognition,
and Behaviour, Radboud University Medical
Centre, 6525 AJ Nijmegen, The Netherlands,Department
of Medical Imaging, Radboud University Medical
Centre, 6525 GA Nijmegen, The Netherlands
| | - Giulia Sbrini
- Department
of Pharmacological and Biomolecular Sciences, Università Degli Studi Di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Pieter Schipper
- Department
of Cognitive Neuroscience, Donders Institute for Brain, Cognition,
and Behaviour, Radboud University Medical
Centre, 6525 AJ Nijmegen, The Netherlands
| | - Nita Hofwijks
- Department
of Cognitive Neuroscience, Donders Institute for Brain, Cognition,
and Behaviour, Radboud University Medical
Centre, 6525 AJ Nijmegen, The Netherlands
| | - Jesse Stoop
- Department
of Cognitive Neuroscience, Donders Institute for Brain, Cognition,
and Behaviour, Radboud University Medical
Centre, 6525 AJ Nijmegen, The Netherlands
| | - Francesca Calabrese
- Department
of Pharmacological and Biomolecular Sciences, Università Degli Studi Di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Judith Homberg
- Department
of Cognitive Neuroscience, Donders Institute for Brain, Cognition,
and Behaviour, Radboud University Medical
Centre, 6525 AJ Nijmegen, The Netherlands,
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6
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Mouradian GC, Liu P, Nakagawa P, Duffy E, Gomez Vargas J, Balapattabi K, Grobe JL, Sigmund CD, Hodges MR. Patch-to-Seq and Transcriptomic Analyses Yield Molecular Markers of Functionally Distinct Brainstem Serotonin Neurons. Front Synaptic Neurosci 2022; 14:910820. [PMID: 35844900 PMCID: PMC9280690 DOI: 10.3389/fnsyn.2022.910820] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/10/2022] [Indexed: 01/22/2023] Open
Abstract
Acute regulation of CO2 and pH homeostasis requires sensory feedback from peripheral (carotid body) and central (central) CO2/pH sensitive cells - so called respiratory chemoreceptors. Subsets of brainstem serotonin (5-HT) neurons in the medullary raphe are CO2 sensitive or insensitive based on differences in embryonic origin, suggesting these functionally distinct subpopulations may have unique transcriptional profiles. Here, we used Patch-to-Seq to determine if the CO2 responses in brainstem 5-HT neurons could be correlated to unique transcriptional profiles and/or unique molecular markers and pathways. First, firing rate changes with hypercapnic acidosis were measured in fluorescently labeled 5-HT neurons in acute brainstem slices from transgenic, Dahl SS (SSMcwi) rats expressing T2/ePet-eGFP transgene in Pet-1 expressing (serotonin) neurons (SS ePet1-eGFP rats). Subsequently, the transcriptomic and pathway profiles of CO2 sensitive and insensitive 5-HT neurons were determined and compared by single cell RNA (scRNAseq) and bioinformatic analyses. Low baseline firing rates were a distinguishing feature of CO2 sensitive 5-HT neurons. scRNAseq of these recorded neurons revealed 166 differentially expressed genes among CO2 sensitive and insensitive 5-HT neurons. Pathway analyses yielded novel predicted upstream regulators, including the transcription factor Egr2 and Leptin. Additional bioinformatic analyses identified 6 candidate gene markers of CO2 sensitive 5-HT neurons, and 2 selected candidate genes (CD46 and Iba57) were both expressed in 5-HT neurons determined via in situ mRNA hybridization. Together, these data provide novel insights into the transcriptional control of cellular chemoreception and provide unbiased candidate gene markers of CO2 sensitive 5-HT neurons. Methodologically, these data highlight the utility of the patch-to-seq technique in enabling the linkage of gene expression to specific functions, like CO2 chemoreception, in a single cell to identify potential mechanisms underlying functional differences in otherwise similar cell types.
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Affiliation(s)
- Gary C. Mouradian
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, United States,*Correspondence: Gary C. Mouradian Jr.,
| | - Pengyuan Liu
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Pablo Nakagawa
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Erin Duffy
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Javier Gomez Vargas
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Kirthikaa Balapattabi
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Justin L. Grobe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States,Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, United States,Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Curt D. Sigmund
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, United States,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Matthew R. Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, United States,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, United States
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7
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Patil CN, Ritter ML, Wackman KK, Oliveira V, Balapattabi K, Grobe CC, Brozoski DT, Reho JJ, Nakagawa P, Mouradian GC, Kriegel AJ, Kwitek AE, Hodges MR, Segar JL, Sigmund CD, Grobe JL. Cardiometabolic effects of DOCA-salt in male C57BL/6J mice are variably dependent on sodium and nonsodium components of diet. Am J Physiol Regul Integr Comp Physiol 2022; 322:R467-R485. [PMID: 35348007 PMCID: PMC9054347 DOI: 10.1152/ajpregu.00017.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/14/2022] [Accepted: 03/23/2022] [Indexed: 01/22/2023]
Abstract
Hypertension characterized by low circulating renin activity accounts for roughly 25%-30% of primary hypertension in humans and can be modeled experimentally via deoxycorticosterone acetate (DOCA)-salt treatment. In this model, phenotypes develop in progressive phases, although the timelines and relative contributions of various mechanisms to phenotype development can be distinct between laboratories. To explore interactions among environmental influences such as diet formulation and dietary sodium (Na) content on phenotype development in the DOCA-salt paradigm, we examined an array of cardiometabolic endpoints in young adult male C57BL/6J mice during sham or DOCA-salt treatments when mice were maintained on several common, commercially available laboratory rodent "chow" diets including PicoLab 5L0D (0.39% Na), Envigo 7913 (0.31% Na), Envigo 2920x (0.15% Na), or a customized version of Envigo 2920x (0.4% Na). Energy balance (weight gain, food intake, digestive efficiency, and energy efficiency), fluid and electrolyte homeostasis (fluid intake, Na intake, fecal Na content, hydration, and fluid compartmentalization), renal functions (urine production rate, glomerular filtration rate, urine Na excretion, renal expression of renin, vasopressin receptors, aquaporin-2 and relationships among markers of vasopressin release, aquaporin-2 shedding, and urine osmolality), and blood pressure, all exhibited changes that were subject to interactions between diet and DOCA-salt. Interestingly, some of these phenotypes, including blood pressure and hydration, were dependent on nonsodium dietary components, as Na-matched diets resulted in distinct phenotype development. These findings provide a broad and robust illustration of an environment × treatment interaction that impacts the use and interpretation of a common rodent model of low-renin hypertension.
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Affiliation(s)
- Chetan N Patil
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - McKenzie L Ritter
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Kelsey K Wackman
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Vanessa Oliveira
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | | | - Connie C Grobe
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Daniel T Brozoski
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - John J Reho
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Pablo Nakagawa
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Gary C Mouradian
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Alison J Kriegel
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cancer Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Anne E Kwitek
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jeffrey L Segar
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Curt D Sigmund
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Justin L Grobe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, Wisconsin
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
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8
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Haduch A, Danek PJ, Kuban W, Pukło R, Alenina N, Gołębiowska J, Popik P, Bader M, Daniel WA. Cytochrome P450 2D (CYP2D) enzyme dysfunction associated with aging and serotonin deficiency in the brain and liver of female Dark Agouti rats. Neurochem Int 2022; 152:105223. [PMID: 34780807 DOI: 10.1016/j.neuint.2021.105223] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 12/18/2022]
Abstract
Among the enzymes that support brain metabolism, cytochrome P450 (CYP) enzymes occupy an important place. These enzymes catalyze the biotransformation pathways of neuroactive endogenous substrates (neurosteroids, neurotransmitters) and are necessary for the detoxification processes. The aim of the present study was to assess changes in the CYP2D activity and protein level during the aging process and as a result of serotonin deficiency in the female brain. The CYP2D activity was measured in brain and liver microsomes of Dark Agouti wild type (WT) female rats (mature 15-week-old and senescent 18-month-old rats) and in tryptophan hydroxylase 2 (TPH2)-deficient senescent female rats. The CYP2D activity in mature WT Dark Agouti females was independent of the changing phases of the estrous cycle. In senescent WT females rats, the CYP2D activity and protein level were decreased in the cerebral cortex, hippocampus, cerebellum and liver, but increased in the brain stem. In the other examined structures (frontal cortex, hypothalamus, thalamus, striatum), the enzyme activity did not change. In aging TPH2-deficient females, the CYP2D activity and protein levels were decreased in the frontal cortex, hypothalamus and brain stem (activity only), remaining unchanged in other brain structures and liver, relative to senescent WT females. In summary, the aging process and TPH2 deficit affect the CYP2D activity and protein level in female rats, which may have a negative impact on the compensatory capacity of CYP2D in the synthesis of serotonin and dopamine in cerebral structures involved in cognitive and emotional functions. In the liver, the CYP2D-catalyzed drug metabolism may be diminished in elderly females. The results in female rats are compared with those obtained previously in males. It is concluded that aging and serotonin deficiency exert sex-dependent effects on brain CYP2D, which seem to be less favorable in females concerning CYP2D-mediated neurotransmitter synthesis, but beneficial regarding slower neurosteroid metabolism.
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Affiliation(s)
- Anna Haduch
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Przemysław J Danek
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Wojciech Kuban
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Renata Pukło
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Natalia Alenina
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany; Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Joanna Gołębiowska
- Department of Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Piotr Popik
- Department of Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Michael Bader
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany; Institute for Biology, University of Lübeck, Germany; Charité University Medicine, Berlin, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Germany
| | - Władysława A Daniel
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland.
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9
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Mordhorst A, Dhandapani P, Matthes S, Mosienko V, Rothe M, Todiras M, Self J, Schunck WH, Schütz A, Bader M, Alenina N. Phenylalanine hydroxylase contributes to serotonin synthesis in mice. FASEB J 2021; 35:e21648. [PMID: 33993565 DOI: 10.1096/fj.202100366r] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 04/11/2021] [Accepted: 04/21/2021] [Indexed: 12/31/2022]
Abstract
Serotonin is an important signaling molecule in the periphery and in the brain. The hydroxylation of tryptophan is the first and rate-limiting step of its synthesis. In most vertebrates, two enzymes have been described to catalyze this step, tryptophan hydroxylase (TPH) 1 and 2, with expression localized to peripheral and neuronal cells, respectively. However, animals lacking both TPH isoforms still exhibit about 10% of normal serotonin levels in the blood demanding an additional source of the monoamine. In this study, we provide evidence by the gain and loss of function approaches in in vitro and in vivo systems, including stable-isotope tracing in mice, that phenylalanine hydroxylase (PAH) is a third TPH in mammals. PAH contributes to serotonin levels in the blood, and may be important as a local source of serotonin in organs in which no other TPHs are expressed, such as liver and kidney.
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Affiliation(s)
- Alexander Mordhorst
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany.,Charite - University Medicine, Berlin, Germany
| | - Priyavathi Dhandapani
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Susann Matthes
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Valentina Mosienko
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | | | - Mihail Todiras
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.,Nicolae Testemiţanu State University of Medicine and Pharmacy, Chișinău, Moldova
| | - Julie Self
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Wolf-Hagen Schunck
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Anja Schütz
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Michael Bader
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany.,Charite - University Medicine, Berlin, Germany.,Institute for Biology, University of Lübeck, Lübeck, Germany
| | - Natalia Alenina
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany.,Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia.,Institute of Cytology, Russian Academy of Science, St. Petersburg, Russia
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10
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Mouradian GC, Kilby M, Alvarez S, Kaplan K, Hodges MR. Mortality and ventilatory effects of central serotonin deficiency during postnatal development depend on age but not sex. Physiol Rep 2021; 9:e14946. [PMID: 34228894 PMCID: PMC8259800 DOI: 10.14814/phy2.14946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 11/24/2022] Open
Abstract
Serotonin (5-HT) influences brain development and has predominantly excitatory neuromodulatory effects on the neural respiratory control circuitry. Infants that succumb to sudden infant death syndrome (SIDS) have reduced brainstem 5-HT levels and Tryptophan hydroxylase 2 (Tph2). Furthermore, there are age- and sex-dependent risk factors associated with SIDS. Here we utilized our established Dark Agouti transgenic rat lacking central serotonin KO to test the hypotheses that CNS 5-HT deficiency leads to: (1) high mortality in a sex-independent manner, (2) age-dependent alterations in other CNS aminergic systems, and (3) age-dependent impairment of chemoreflexes during post-natal development. KO rat pups showed high neonatal mortality but not in a sex-dependent manner and did not show altered hypoxic or hypercapnic ventilatory chemoreflexes. However, KO rat pups had increased apnea-related metrics during a specific developmental age (P12-16), which were preceded by transient increases in dopaminergic system activity (P7-8). These results support and extend the concept that 5-HT per se is a critical factor in supporting respiratory control during post-natal development.
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Affiliation(s)
- Gary C. Mouradian
- Department of PhysiologyMedical College of WisconsinMilwaukeeWIUSA
- Neuroscience Research CenterMedical College of WisconsinMilwaukeeWIUSA
| | - Madeline Kilby
- Department of PhysiologyMedical College of WisconsinMilwaukeeWIUSA
| | - Santiago Alvarez
- Department of PhysiologyMedical College of WisconsinMilwaukeeWIUSA
| | - Kara Kaplan
- Department of PhysiologyMedical College of WisconsinMilwaukeeWIUSA
| | - Matthew R. Hodges
- Department of PhysiologyMedical College of WisconsinMilwaukeeWIUSA
- Neuroscience Research CenterMedical College of WisconsinMilwaukeeWIUSA
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11
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Haduch A, Pukło R, Alenina N, Nikiforuk A, Popik P, Bader M, Daniel WA. The effect of ageing and cerebral serotonin deficit on the activity of cytochrome P450 2D (CYP2D) in the brain and liver of male rats. Neurochem Int 2020; 141:104884. [PMID: 33091481 DOI: 10.1016/j.neuint.2020.104884] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 10/09/2020] [Accepted: 10/14/2020] [Indexed: 12/29/2022]
Abstract
Brain cytochrome P450 (CYP) contributes to the local metabolism of endogenous substrates and drugs. The aim of present study was to ascertain whether the cytochrome P450 2D (CYP2D) activity changes with ageing and in cerebral serotonin deficit. Kinetics of 5-methoxytryptamine O-demethylation to serotonin was studied and the CYP2D activity was measured in brain and liver microsomes of Dark Agouti wild type (WT) rats (mature 3.5-month-old and senescent 21-month-old rats) and in tryptophan hydroxylase 2 (TPH2)-deficient senescent rats. The CYP2D activity and protein level decreased in the frontal cortex of senescent WT rats, but increased in senescent TPH2-deficient rats (compared to senescent WT). In contrast, in the hippocampus, hypothalamus and striatum the CYP2D activity/protein level increased with ageing, but did not change in senescent TPH2-deficient animals (compared to senescent WT). The activity and protein level of liver CYP2D was lower in senescent WT rats than in the mature animals and further decreased in senescent TPH2-deficient rats. In conclusion, ageing and TPH2-deficit affect the CYP2D activity and protein level, which may have a positive impact on neurotransmitter synthesis in brain structures involved in cognitive, emotional or motor functions, but a negative effect on drug metabolism in the liver.
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Affiliation(s)
- Anna Haduch
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Renata Pukło
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Natalia Alenina
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Germany
| | - Agnieszka Nikiforuk
- Department of Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Piotr Popik
- Department of Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Michael Bader
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany; German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Germany; Institute for Biology, University of Lübeck, Germany; Charité University Medicine, Berlin, Germany
| | - Władysława A Daniel
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland.
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12
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Magnusson JL, Emter CA, Cummings KJ. Sex- and age-based differences in the effect of central serotonin on arterial blood pressure regulation. J Appl Physiol (1985) 2020; 129:1310-1323. [PMID: 32909922 DOI: 10.1152/japplphysiol.00414.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Medullary serotonin (5-hydroxytryptamine; 5-HT) neurons project to multiple autonomic nuclei in the central nervous system (CNS). Infant rats lacking 5-HT have low arterial blood pressure (ABP) in quiet sleep, but the role of 5-HT in ABP regulation across vigilance states in adults has not been studied. We hypothesized that in adults, CNS 5-HT deficiency leads to hypotension mainly in quiet wakefulness (QW) and non-rapid eye movement (NREM) sleep, when 5-HT neurons are active. We tested male and female tryptophan hydroxylase 2 knockout rats (TPH2-/-), specifically deficient in CNS 5-HT, and wild-type (TPH2+/+) controls at 2-3, 5-8, and 12-13 mo of age. Compared with TPH2+/+, mean arterial pressure of 5-8- and 12-13-mo-old (middle-aged) male TPH2-/- rats was significantly elevated (∼10 mmHg) in QW and rapid eye movement (REM) sleep. Middle-aged male TPH2-/- rats also had more frequent extreme hypertensive events during prolonged episodes of REM sleep. Female TPH2-/- had normal ABP. The low- and very-low-frequency components of systolic ABP variability were significantly higher in middle-aged male, but not female, TPH2-/- rats compared with in TPH2+/+ rats, suggesting elevated sympathetic vascular tone in male TPH2-/- rats. However, the hypertension of male TPH2-/- rats was not ameliorated by ganglionic blockade. Hearts and lungs of middle-aged male TPH2-/- rats were significantly heavier than those of TPH2+/+ rats. We show that a loss of CNS 5-HT leads to high ABP only in middle-aged males during wakefulness and REM sleep, possibly due to increased vascular tone. It should be investigated whether elevated ventricular afterload associated with CNS 5-HT deficiency initiates cardiac remodeling or alters pulmonary hemodynamics.NEW & NOTEWORTHY The role of serotonin in arterial blood pressure (ABP) regulation across states of vigilance is unknown. We hypothesized that adult rats devoid of CNS serotonin (TPH2-/-) have low ABP in wakefulness and NREM sleep, when serotonin neurons are active. However, TPH2-/- rats experience higher ABP than TPH2+/+ rats in wakefulness and REM only, a phenotype present only in older males and not females. CNS serotonin may be critical for preventing high ABP in males with aging.
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Affiliation(s)
- Jennifer L Magnusson
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
| | - Craig A Emter
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri
| | - Kevin J Cummings
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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13
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Sbrini G, Brivio P, Peeva PM, Todiras M, Bader M, Alenina N, Calabrese F. The Absence of Serotonin in the Brain Alters Acute Stress Responsiveness by Interfering With the Genomic Function of the Glucocorticoid Receptors. Front Cell Neurosci 2020; 14:128. [PMID: 32547368 PMCID: PMC7278285 DOI: 10.3389/fncel.2020.00128] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/17/2020] [Indexed: 12/29/2022] Open
Abstract
Alterations in serotonergic transmission have been related to a major predisposition to develop psychiatric pathologies, such as depression. We took advantage of tryptophan hydroxylase (TPH) 2 deficient rats, characterized by a complete absence of serotonin in the brain, to evaluate whether a vulnerable genotype may influence the reaction to an acute stressor. In this context, we investigated if the glucocorticoid receptor (GR) genomic pathway activation was altered by the lack of serotonin in the central nervous system. Moreover, we analyzed the transcription pattern of the clock genes that can be affected by acute stressors. Adult wild type (TPH2+/+) and TPH2-deficient (TPH2-/-) male rats were sacrificed after exposure to one single session of acute restraint stress. Protein and gene expression analyses were conducted in the prefrontal cortex (PFC). The acute stress enhanced the translocation of GRs in the nucleus of TPH2+/+ animals. This effect was blunted in TPH2-/- rats, suggesting an impairment of the GR genomic mechanism. This alteration was mirrored in the expression of GR-responsive genes: acute stress led to the up-regulation of GR-target gene expression in TPH2+/+, but not in TPH2-/- animals. Finally, clock genes were differently modulated in the two genotypes after the acute restraint stress. Overall our findings suggest that the absence of serotonin within the brain interferes with the ability of the HPA axis to correctly modulate the response to acute stress, by altering the nuclear mechanisms of the GR and modulation of clock genes expression.
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Affiliation(s)
- Giulia Sbrini
- Department of Pharmacological and Biomolecular Sciences, Università Degli Studi di Milano, Milan, Italy
| | - Paola Brivio
- Department of Pharmacological and Biomolecular Sciences, Università Degli Studi di Milano, Milan, Italy
| | - Polina Mineva Peeva
- Cardiovascular and Metabolic Diseases, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | - Mihail Todiras
- Cardiovascular and Metabolic Diseases, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | - Michael Bader
- Cardiovascular and Metabolic Diseases, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany.,Charite-University Medicine, Berlin, Germany
| | - Natalia Alenina
- Cardiovascular and Metabolic Diseases, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany.,Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Francesca Calabrese
- Department of Pharmacological and Biomolecular Sciences, Università Degli Studi di Milano, Milan, Italy
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14
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Cummings KJ, Leiter JC. Take a deep breath and wake up: The protean role of serotonin preventing sudden death in infancy. Exp Neurol 2020; 326:113165. [PMID: 31887304 PMCID: PMC6956249 DOI: 10.1016/j.expneurol.2019.113165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 12/14/2019] [Accepted: 12/26/2019] [Indexed: 01/24/2023]
Abstract
Recordings from infants who died suddenly and unexpectedly demonstrate the occurrence of recurring apneas, ineffective gasping, and finally, failure to restore eupnea and arouse prior to death. Immunohistochemical and autoradiographic data demonstrate a constellation of serotonergic defects in the caudal raphe nuclei in infants who died of Sudden Infant Death Syndrome (SIDS). The purpose of this review is to synthesize what is known about adaptive responses of the infant to severely hypoxic conditions, which unleash a flood of neuromodulators that inhibit cardiorespiratory function, thermogenesis, and arousal and the emerging role of serotonin, which combats this cardiorespiratory inhibition to foster autoresuscitation, eupnea, and arousal to ensure survival following an hypoxic episode. The laryngeal and carotid body chemoreflexes are potent in newborns and infants, and both reflexes can induce apnea and bradycardia, which may be adaptive initially, but must be terminated if an infant is to survive. Serotonin has a unique ability to touch on each of the processes that may be required to recover from hypoxic reflex apnea: gasping, the restoration of heart rate and blood pressure, termination of apneas and, eventually, stimulation of eupnea and arousal. Recurrent apneic events, bradycardia, ineffective gasping and a failure to terminate apneas and restore eupnea are observed in animals harboring defects in the caudal serotonergic system models - all of these phenotypes are reminiscent of and compatible with the cardiorespiratory recordings made in infants who subsequently died of SIDS. The caudal serotonergic system provides an organized, multi-pronged defense against reflex cardiorespiratory inhibition and the hypoxia that accompanies prolonged apnea, bradycardia and hypotension, and any deficiency of caudal serotonergic function will increase the propensity for sudden unexplained infant death.
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Affiliation(s)
- Kevin J Cummings
- Department of Biomedical Sciences, University of Missouri-Columbia, Dalton Cardiovascular Research Center, 134 Research Park Drive, Columbia, MO 65203, USA
| | - James C Leiter
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, One Rope Ferry Road, Hanover, NH 03755, USA.
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15
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Abstract
The rate-limiting enzyme in serotonin synthesis is tryptophan hydroxylase (TPH). There are two independent serotonin systems in the body characterized by two isoforms of TPH, TPH1 and TPH2. While TPH2 synthesizes serotonin in the brain, TPH1 is expressed in the gut and in other peripheral tissues and supplies platelets in the circulation with serotonin. This duality of the serotonin system is enforced by the blood-brain barrier which is impermeable for serotonin. In the brain serotonin acts as neurotransmitter and is a main target for the treatment of psychiatric disorders. In the periphery it is released by platelets at the site of activation and elicits numerous physiological effects. TPH1 deficient mice were shown to be protected from diverse diseases including hemostatic, inflammatory, fibrotic, gastrointestinal, and metabolic disorders and therefore serotonin synthesis inhibition emerged as a reasonable therapeutic paradigm. Recently the first TPH inhibitor, telotristat ethyl, came on the market for the treatment of carcinoid syndrome. This review summarizes the state of development and the therapeutic opportunities of such compounds.
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Affiliation(s)
- Michael Bader
- Max-Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Str. 10, 13125 Berlin-Buch, Germany; University of Lübeck, Institute for Biology, Ratzeburger Allee 160, 23562 Lübeck, Germany; Charité University Medicine, Charitéplatz 1, 10117 Berlin, Germany; German Center for Cardiovascular Research (DZHK), Partner Site, Berlin, Germany.
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16
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Cummings KJ, Hodges MR. The serotonergic system and the control of breathing during development. Respir Physiol Neurobiol 2019; 270:103255. [PMID: 31362064 DOI: 10.1016/j.resp.2019.103255] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/28/2019] [Accepted: 07/12/2019] [Indexed: 01/26/2023]
Abstract
Serotonin (5-hydroxytryptamine 5-HT) was first discovered in the late 1940's as an endogenous bioactive amine capable of inducing vasoconstriction, and in the mid-1950's was found in the brain. It was in these early years that some of the first demonstrations were made regarding a role for brain 5-HT in neurological function and behavior, including data implicating reduced brain levels of 5-HT in clinical depression. Since that time, advances in molecular biology and physiological approaches in basic science research have intensely focused on 5-HT in the brain, and the many facets of its role during embryonic development, post-natal maturation, and neural function in adulthood continues to be established. This review focuses on what is known about the developmental roles for the 5-HT system, which we define as the neurons producing 5-HT along with pre-and post-synaptic receptors, in a vital homeostatic motor behavior - the control of breathing. We will cover what is known about the embryonic origins and fate specification of 5-HT neurons, and how the 5-HT system influences pre- and post-natal maturation of the ventilatory control system. In addition, we will focus on the role of the 5-HT system in specific respiratory behaviors during fetal, neonatal and postnatal development, and the relevance of dysfunction in this system in respiratory-related human pathologies including Sudden Infant Death Syndrome (SIDS).
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Affiliation(s)
- Kevin J Cummings
- Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211, USA; Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA.
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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17
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Matthes S, Mosienko V, Popova E, Rivalan M, Bader M, Alenina N. Targeted Manipulation of Brain Serotonin: RNAi-Mediated Knockdown of Tryptophan Hydroxylase 2 in Rats. ACS Chem Neurosci 2019; 10:3207-3217. [PMID: 30977636 DOI: 10.1021/acschemneuro.8b00635] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the biosynthesis of the biogenic monoamine serotonin (5-hydroxytryptamine, 5-HT). Two existing TPH isoforms are responsible for the generation of two distinct serotonergic systems in vertebrates. TPH1, predominantly expressed in the gastrointestinal tract and pineal gland, mediates 5-HT biosynthesis in non-neuronal tissues, while TPH2, mainly found in the raphe nuclei of the brain stem, is accountable for the production of 5-HT in the brain. Neuronal 5-HT is a key regulator of mood and behavior and its deficiency has been implicated in a variety of neuropsychiatric disorders, e.g., depression and anxiety. To gain further insights into the complexity of central 5-HT modulations of physiological and pathophysiological processes, a new transgenic rat model, allowing an inducible gene knockdown of Tph2, was established based on doxycycline-inducible shRNA-expression. Biochemical phenotyping revealed a functional knockdown of Tph2 mRNA expression following oral doxycycline administration, with subsequent reductions in the corresponding levels of TPH2 enzyme expression and activity. Transgenic rats showed also significantly decreased tissue levels of 5-HT and its degradation product 5-Hydroxyindoleacetic acid (5-HIAA) in the raphe nuclei, hippocampus, hypothalamus, and cortex, while peripheral 5-HT concentrations in the blood remained unchanged. In summary, this novel transgenic rat model allows inducible manipulation of 5-HT biosynthesis specifically in the brain and may help to elucidate the role of 5-HT in the pathophysiology of affective disorders.
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Affiliation(s)
- Susann Matthes
- Max-Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Straße 10, 13125 Berlin-Buch, Germany
- Institute for Biology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Valentina Mosienko
- Max-Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Straße 10, 13125 Berlin-Buch, Germany
- College of Medicine and Health, Institute of Biomedical and Clinical Sciences, University of Exeter, Hatherly Building, Prince of Wales Rd., EX4 4PS Exeter, United Kingdom
| | - Elena Popova
- Max-Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Straße 10, 13125 Berlin-Buch, Germany
| | - Marion Rivalan
- Charité University Medicine, Charitéplatz 1, 10117 Berlin, Germany
| | - Michael Bader
- Max-Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Straße 10, 13125 Berlin-Buch, Germany
- Institute for Biology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
- Charité University Medicine, Charitéplatz 1, 10117 Berlin, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, 13316 Berlin, Germany
- Berlin Institute of Health (BIH), Anna-Louisa-Karsch-Straße 2, 10178 Berlin, Germany
| | - Natalia Alenina
- Max-Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Straße 10, 13125 Berlin-Buch, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, 13316 Berlin, Germany
- Institute of Translational Biomedicine, St. Petersburg State University, Saint Petersburg 199034, Russia
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18
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Peeters DG, de Boer SF, Terneusen A, Newman-Tancredi A, Varney MA, Verkes RJ, Homberg JR. Enhanced aggressive phenotype of Tph2 knockout rats is associated with diminished 5-HT1A receptor sensitivity. Neuropharmacology 2019; 153:134-141. [DOI: 10.1016/j.neuropharm.2019.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/18/2019] [Accepted: 05/05/2019] [Indexed: 11/28/2022]
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19
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Pratelli M, Pasqualetti M. Serotonergic neurotransmission manipulation for the understanding of brain development and function: Learning from Tph2 genetic models. Biochimie 2019; 161:3-14. [DOI: 10.1016/j.biochi.2018.11.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/24/2018] [Indexed: 01/04/2023]
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20
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Mouradian GC, Alvarez-Argote S, Gorzek R, Thuku G, Michkalkiewicz T, Wong-Riley MTT, Konduri GG, Hodges MR. Acute and chronic changes in the control of breathing in a rat model of bronchopulmonary dysplasia. Am J Physiol Lung Cell Mol Physiol 2019; 316:L506-L518. [PMID: 30652496 PMCID: PMC6459293 DOI: 10.1152/ajplung.00086.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 01/09/2019] [Accepted: 01/14/2019] [Indexed: 12/15/2022] Open
Abstract
Infants born very prematurely (<28 wk gestation) have immature lungs and often require supplemental oxygen. However, long-term hyperoxia exposure can arrest lung development, leading to bronchopulmonary dysplasia (BPD), which increases acute and long-term respiratory morbidity and mortality. The neural mechanisms controlling breathing are highly plastic during development. Whether the ventilatory control system adapts to pulmonary disease associated with hyperoxia exposure in infancy remains unclear. Here, we assessed potential age-dependent adaptations in the control of breathing in an established rat model of BPD associated with hyperoxia. Hyperoxia exposure ( FI O 2 ; 0.9 from 0 to 10 days of life) led to a BPD-like lung phenotype, including sustained reductions in alveolar surface area and counts, and modest increases in airway resistance. Hyperoxia exposure also led to chronic increases in room air and acute hypoxic minute ventilation (V̇e) and age-dependent changes in breath-to-breath variability. Hyperoxia-exposed rats had normal oxygen saturation ( S p O 2 ) in room air but greater reductions in S p O 2 during acute hypoxia (12% O2) that were likely due to lung injury. Moreover, acute ventilatory sensitivity was reduced at P12 to P14. Perinatal hyperoxia led to greater glial fibrillary acidic protein expression and an increase in neuron counts within six of eight or one of eight key brainstem regions, respectively, controlling breathing, suggesting astrocytic expansion. In conclusion, perinatal hyperoxia in rats induced a BPD-like phenotype and age-dependent adaptations in V̇e that may be mediated through changes to the neural architecture of the ventilatory control system. Our results suggest chronically altered ventilatory control in BPD.
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Affiliation(s)
- Gary C Mouradian
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
| | | | - Ryan Gorzek
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Gabriel Thuku
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Teresa Michkalkiewicz
- Department of Pediatrics, Medical College of Wisconsin , Milwaukee, Wisconsin
- Children's Research Institute, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Margaret T T Wong-Riley
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Girija Ganesh Konduri
- Department of Pediatrics, Medical College of Wisconsin , Milwaukee, Wisconsin
- Children's Research Institute, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
- Neuroscience Research Center, Medical College of Wisconsin , Milwaukee, Wisconsin
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21
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Davis MR, Magnusson JL, Cummings KJ. Increased central cholinergic drive contributes to the apneas of serotonin-deficient rat pups during active sleep. J Appl Physiol (1985) 2019; 126:1175-1183. [PMID: 30763168 DOI: 10.1152/japplphysiol.00909.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Infant rat pups lacking central nervous system (CNS) serotonin (5-hydroxytryptamine; 5-HT) have unstable breathing during prolonged periods of active sleep. Given that cholinergic neurons are drivers of active sleep and project to respiratory patterning regions in the brainstem, we hypothesized that 5-HT preserves respiratory stability in active sleep by dampening central cholinergic drive. We used whole-body plethysmography coupled with nuchal electromyography to monitor the breathing pattern of 2-wk-old tryptophan hydroxylase 2 (TPH2)+/+ and TPH2-deficient (TPH2-/-) pups in active sleep, before and after muscarinic blockade. For the group 1 experiment we injected methylatropine (Ap-M), a CNS-impermeant form of atropine, followed ~30 min later by an injection of atropine sulfate (Ap-S), the CNS-permeant form (both 1 mg/kg, 10 μl bolus iv); both injections occurred within an active sleep episode. We analyzed the effect of each drug on the coefficient of variation of the respiratory period (CV-P) during active sleep. For the group 2 experiment rats were cycled through several episodes of active and quiet sleep before administration of Ap-S (1 mg/kg, 200 μl ip) or vehicle. We assessed the effect of Ap-S on the apnea indices of both genotypes during quiet and active sleep. In group 1 Ap-S significantly reduced the CV-P of TPH2-/- pups (P = 0.03), an effect not observed in TPH2+/+ pups or following Ap-M. In group 2 the apnea index of TPH2-/- pups was significantly reduced following Ap-S injection (P = 0.04), whereas the apnea index of TPH2+/+ littermates was unaffected (P = 0.58). These findings suggest that central 5-HT reduces apnea and stabilizes breathing by reducing cholinergic signaling through muscarinic receptors. NEW & NOTEWORTHY Serotonin in the central nervous system (CNS) is necessary for maintaining the stability of breathing in the early postnatal period, particularly during active sleep. Here we show that the administration of atropine to the CNS selectively stabilizes the respiratory pattern of tryptophan hydroxylase 2-deficient rat pups and reduces their apneas. This suggests that CNS serotonin stabilizes breathing at least in part by reducing central cholinergic drive.
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Affiliation(s)
- Marina R Davis
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri , Columbia, Missouri
| | - Jennifer L Magnusson
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri , Columbia, Missouri
| | - Kevin J Cummings
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri , Columbia, Missouri
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Brivio P, Sbrini G, Peeva P, Todiras M, Bader M, Alenina N, Calabrese F. TPH2 Deficiency Influences Neuroplastic Mechanisms and Alters the Response to an Acute Stress in a Sex Specific Manner. Front Mol Neurosci 2018; 11:389. [PMID: 30425618 PMCID: PMC6218558 DOI: 10.3389/fnmol.2018.00389] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 10/04/2018] [Indexed: 01/13/2023] Open
Abstract
Dysregulations of the central serotoninergic system have been implicated in several psychopathologies, characterized by different susceptibility between males and females. We took advantage of tryptophan hydroxylase 2 (TPH2) deficient rats, lacking serotonin specifically in the brain, to investigate whether a vulnerable genotype can be associated with alterations of neuronal plasticity from the early stage of maturation of the brain until adulthood. We found a significant increase, in both gene and protein expression, of the neurotrophin brain-derived neurotrophic factor (BDNF), in the prefrontal cortex (PFC) of adult TPH2-deficient (TPH2−/−) male and female rats in comparison to wild type (TPH2+/+) counterparts. Interestingly, a development-specific pattern was observed during early postnatal life: whereas the increase in Bdnf expression, mainly driven by the modulation of Bdnf isoform IV was clearly visible after weaning at postnatal day (pnd) 30 in both sexes of TPH2−/− in comparison to TPH2+/+ rats, at early stages (pnd1 and pnd10) Bdnf expression levels did not differ between the genotypes, or even were downregulated in male TPH2−/− animals at pnd10. Moreover, to establish if hyposerotonergia may influence the response to a challenging situation, we exposed adult rats to an acute stress. Although the pattern of corticosterone release was similar between the genotypes, neuronal activation in response to stress, quantified by the expression of the immediate early genes activity regulated cytoskeleton associated protein (Arc) and Fos Proto-Oncogene (cFos), was blunted in both sexes of animals lacking brain serotonin. Interestingly, although upregulation of Bdnf mRNA levels after stress was observed in both genotypes, it was less pronounced in TPH2−/− in comparison to TPH2+/+ rats. In summary, our results demonstrated that serotonin deficiency affects neuroplastic mechanisms following a specific temporal pattern and influences the response to an acute stress.
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Affiliation(s)
- Paola Brivio
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Giulia Sbrini
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Polina Peeva
- Cardiovascular and Metabolic Diseases, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | - Mihail Todiras
- Cardiovascular and Metabolic Diseases, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | - Michael Bader
- Cardiovascular and Metabolic Diseases, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany.,Charite-University Medicine, Berlin, Germany
| | - Natalia Alenina
- Cardiovascular and Metabolic Diseases, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany.,Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Francesca Calabrese
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
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23
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Magnusson JL, Cummings KJ. Central serotonin and the control of arterial blood pressure and heart rate in infant rats: influence of sleep state and sex. Am J Physiol Regul Integr Comp Physiol 2017; 314:R313-R321. [PMID: 29046318 DOI: 10.1152/ajpregu.00321.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sudden infant death syndrome (SIDS) is associated with serotonin (5-HT) neuron abnormalities. There is evidence of autonomic dysfunction during sleep in infants eventually succumbing to SIDS, as well as cardiovascular collapse before death. Neonatal rodents deficient in central 5-HT display hypotension and bradycardia. We hypothesized that central 5-HT reduces cardiac vagal tone and increases sympathetic vascular tone and, given the firing pattern of 5-HT neurons, that these effects are greater in quiet sleep (QS) than in active sleep (AS). We tested these hypotheses using 2-wk-old male and female rat pups lacking tryptophan hydroxylase-2 ( TPH2-/-) and wild-type (WT) littermates. Arterial blood pressure (ABP) and heart rate (HR) were measured over 3 h during periods of QS and AS. We also gave atropine or atenolol (each 1 mg/kg iv), or phentolamine (5, 50, and 500 μg/kg iv) to separate groups to assess the effects 5-HT deficiency on autonomic tone to the heart or sympathetic vascular tone, respectively. Compared with WT, male and female TPH2-/- pups had reduced ABP in QS but not in AS. Atropine induced a greater HR increase in female TPH2-/- than in female WT pups, an effect absent in male TPH2-/- pups. Both genotypes experienced the same atenolol-induced drop in HR. In males only, phentolamine induced a smaller decrease in the ABP of TPH2-/- pups compared with WT. These data suggest that central 5-HT maintains ABP in QS, and HR in both states. In males, central 5-HT facilitates sympathetic vascular tone, and in females it reduces cardiac vagal drive.
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Affiliation(s)
- Jennifer L Magnusson
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri , Columbia, Missouri
| | - Kevin J Cummings
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri , Columbia, Missouri
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24
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Young JO, Geurts A, Hodges MR, Cummings KJ. Active sleep unmasks apnea and delayed arousal in infant rat pups lacking central serotonin. J Appl Physiol (1985) 2017; 123:825-834. [PMID: 28775068 DOI: 10.1152/japplphysiol.00439.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/31/2017] [Accepted: 07/31/2017] [Indexed: 11/22/2022] Open
Abstract
Sudden infant death syndrome (SIDS), occurring during sleep periods, is highly associated with abnormalities within serotonin (5-HT) neurons, including reduced 5-HT. There is evidence that future SIDS cases experience more apnea and have abnormal arousal from sleep. In rodents, a loss of 5-HT neurons is associated with apnea in early life and, in adulthood, delayed arousal. As the activity of 5-HT neurons changes with vigilance state, we hypothesized that the degree of apnea and delayed arousal displayed by rat pups specifically lacking central 5-HT varies with state. Two-week-old tryptophan hydroxylase 2-deficient (TPH2-/-) and wild-type (WT) rat pups were placed in plethysmographic chambers supplied with room air. At the onset of active (AS) or quiet (QS) sleep, separate groups of rats were exposed to hypercapnia (5% CO2) or mild hypoxia (~17% O2) or maintained in room air. Upon arousal, rats received room air. Apnea indexes and latencies to spontaneous arousal from AS and QS were determined for pups exposed only to room air. Arousal latencies were also calculated for TPH2-/- and WT pups exposed to hypoxia or hypercapnia. Compared with WT, TPH2-/- pups hypoventilated in all states but were profoundly more apneic solely in AS. TPH2-/- pups had delayed arousal in response to increasing CO2, and AS selectively delayed the arousal of TPH2-/- pups, irrespective of the gas they breathed. Thus infants who are deficient in CNS 5-HT may be at increased risk for SIDS in AS because of increased apnea and delayed arousal compared with QS.NEW & NOTEWORTHY Sudden infant death syndrome (SIDS) occurs during sleep and is associated with central serotonin (5-HT) deficiency. We report that rat pups deficient in central 5-HT (TPH2-/-) are profoundly more apneic in active sleep (AS) but not quiet sleep (QS). Unlike control pups, the arousal of TPH2-/- pups in air, CO2, and hypoxia was delayed in AS compared with QS. Thus for infants deficient in central 5-HT, the risk of SIDS may be higher in AS than in QS.
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Affiliation(s)
- Jacob O Young
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri; and
| | - Aron Geurts
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Kevin J Cummings
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri; and
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25
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Abstract
Although serotonin neurotransmission has been implicated in several neurodevelopmental and psychological disorders, the factors that drive dysfunction of the serotonin system are poorly understood. Current research regarding the serotonin system revolves around its dysfunction in neuropsychiatric disorders, but there is no database collating genetic mutations that result in serotonin abnormalities. To bridge this gap, we developed a list of genes in mice that, when perturbed, result in altered levels of serotonin either in brain or blood. Due to the intrinsic limitations of search, the current list should be considered a preliminary subset of all relevant cases. Nevertheless, it offered an opportunity to gain insight into what types of genes have the potential to impact serotonin by using gene ontology (GO). This analysis found that genes associated with monoamine metabolism were more often associated with increases in brain serotonin than decreases. Speculatively, this could be because several pathways (and therefore many genes) are responsible for the clearance and metabolism of serotonin whereas only one pathway (and therefore fewer genes) is directly involved in the synthesis of serotonin. Another contributor could be cross talk between monoamine systems such as dopamine. In contrast, genes that were associated with decreases in brain serotonin were more likely linked to a developmental process. Sensitivity of serotonin neurons to developmental perturbations could be due to their complicated neuroanatomy or possibly they may be negatively regulated by dysfunction of their innervation targets. Thus, these observations suggest hypotheses regarding the mechanisms underlying the vulnerability of brain serotonin neurotransmission.
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Affiliation(s)
- Richard C. Tenpenny
- Department of Anesthesiology, Perioperative, and Pain
Medicine, Boston Children’s Hospital and Department of Anesthesia,
Harvard Medical School, 300 Longwood
Avenue, Boston, Massachusetts 02115, United States
| | - Kathryn G. Commons
- Department of Anesthesiology, Perioperative, and Pain
Medicine, Boston Children’s Hospital and Department of Anesthesia,
Harvard Medical School, 300 Longwood
Avenue, Boston, Massachusetts 02115, United States
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