1
|
Janes TA, Ambrozio-Marques D, Fournier S, Joseph V, Soliz J, Kinkead R. Testosterone Supplementation Induces Age-Dependent Augmentation of the Hypoxic Ventilatory Response in Male Rats With Contributions From the Carotid Bodies. Front Physiol 2022; 12:781662. [PMID: 35002764 PMCID: PMC8741195 DOI: 10.3389/fphys.2021.781662] [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: 09/23/2021] [Accepted: 12/03/2021] [Indexed: 12/30/2022] Open
Abstract
Excessive carotid body responsiveness to O2 and/or CO2/H+ stimuli contributes to respiratory instability and apneas during sleep. In hypogonadal men, testosterone supplementation may increase the risk of sleep-disordered breathing; however, the site of action is unknown. The present study tested the hypothesis that testosterone supplementation potentiates carotid body responsiveness to hypoxia in adult male rats. Because testosterone levels decline with age, we also determined whether these effects were age-dependent. In situ hybridization determined that androgen receptor mRNA was present in the carotid bodies and caudal nucleus of the solitary tract of adult (69 days old) and aging (193–206 days old) male rats. In urethane-anesthetized rats injected with testosterone propionate (2 mg/kg; i.p.), peak breathing frequency measured during hypoxia (FiO2 = 0.12) was 11% greater vs. the vehicle treatment group. Interestingly, response intensity following testosterone treatment was positively correlated with animal age. Exposing ex vivo carotid body preparations from young and aging rats to testosterone (5 nM, free testosterone) 90–120 min prior to testing showed that the carotid sinus nerve firing rate during hypoxia (5% CO2 + 95% N2; 15 min) was augmented in both age groups as compared to vehicle (<0.001% DMSO). Ventilatory measurements performed using whole body plethysmography revealed that testosterone supplementation (2 mg/kg; i.p.) 2 h prior reduced apnea frequency during sleep. We conclude that in healthy rats, age-dependent potentiation of the carotid body’s response to hypoxia by acute testosterone supplementation does not favor the occurrence of apneas but rather appears to stabilize breathing during sleep.
Collapse
Affiliation(s)
- Tara A Janes
- Department of Physiology, Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada.,Department of Pediatrics, Québec Heart and Lung Institute, Université Laval, Québec, QC, Canada
| | | | - Sébastien Fournier
- Department of Surgery, Faculty of Medicine, Université Laval, Québec, QC, Canada
| | - Vincent Joseph
- Department of Pediatrics, Québec Heart and Lung Institute, Université Laval, Québec, QC, Canada
| | - Jorge Soliz
- Department of Pediatrics, Québec Heart and Lung Institute, Université Laval, Québec, QC, Canada
| | - Richard Kinkead
- Department of Pediatrics, Québec Heart and Lung Institute, Université Laval, Québec, QC, Canada
| |
Collapse
|
2
|
Tenorio-Lopes L, Kinkead R. Sex-Specific Effects of Stress on Respiratory Control: Plasticity, Adaptation, and Dysfunction. Compr Physiol 2021; 11:2097-2134. [PMID: 34107062 DOI: 10.1002/cphy.c200022] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
As our understanding of respiratory control evolves, we appreciate how the basic neurobiological principles of plasticity discovered in other systems shape the development and function of the respiratory control system. While breathing is a robust homeostatic function, there is growing evidence that stress disrupts respiratory control in ways that predispose to disease. Neonatal stress (in the form of maternal separation) affects "classical" respiratory control structures such as the peripheral O2 sensors (carotid bodies) and the medulla (e.g., nucleus of the solitary tract). Furthermore, early life stress disrupts the paraventricular nucleus of the hypothalamus (PVH), a structure that has emerged as a primary determinant of the intensity of the ventilatory response to hypoxia. Although underestimated, the PVH's influence on respiratory function is a logical extension of the hypothalamic control of metabolic demand and supply. In this article, we review the functional and anatomical links between the stress neuroendocrine axis and the medullary network regulating breathing. We then present the persistent and sex-specific effects of neonatal stress on respiratory control in adult rats. The similarities between the respiratory phenotype of stressed rats and clinical manifestations of respiratory control disorders such as sleep-disordered breathing and panic attacks are remarkable. These observations are in line with the scientific consensus that the origins of adult disease are often found among developmental and biological disruptions occurring during early life. These observations bring a different perspective on the structural hierarchy of respiratory homeostasis and point to new directions in our understanding of the etiology of respiratory control disorders. © 2021 American Physiological Society. Compr Physiol 11:1-38, 2021.
Collapse
Affiliation(s)
- Luana Tenorio-Lopes
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Richard Kinkead
- Département de Pédiatrie, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada
| |
Collapse
|
3
|
Azad P, Villafuerte FC, Bermudez D, Patel G, Haddad GG. Protective role of estrogen against excessive erythrocytosis in Monge's disease. Exp Mol Med 2021; 53:125-135. [PMID: 33473144 PMCID: PMC8080600 DOI: 10.1038/s12276-020-00550-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 11/12/2020] [Accepted: 11/19/2020] [Indexed: 01/29/2023] Open
Abstract
Monge's disease (chronic mountain sickness (CMS)) is a maladaptive condition caused by chronic (years) exposure to high-altitude hypoxia. One of the defining features of CMS is excessive erythrocytosis with extremely high hematocrit levels. In the Andean population, CMS prevalence is vastly different between males and females, being rare in females. Furthermore, there is a sharp increase in CMS incidence in females after menopause. In this study, we assessed the role of sex hormones (testosterone, progesterone, and estrogen) in CMS and non-CMS cells using a well-characterized in vitro erythroid platform. While we found that there was a mild (nonsignificant) increase in RBC production with testosterone, we observed that estrogen, in physiologic concentrations, reduced sharply CD235a+ cells (glycophorin A; a marker of RBC), from 56% in the untreated CMS cells to 10% in the treated CMS cells, in a stage-specific and dose-responsive manner. At the molecular level, we determined that estrogen has a direct effect on GATA1, remarkably decreasing the messenger RNA (mRNA) and protein levels of GATA1 (p < 0.01) and its target genes (Alas2, BclxL, and Epor, p < 0.001). These changes result in a significant increase in apoptosis of erythroid cells. We also demonstrate that estrogen regulates erythropoiesis in CMS patients through estrogen beta signaling and that its inhibition can diminish the effects of estrogen by significantly increasing HIF1, VEGF, and GATA1 mRNA levels. Taken altogether, our results indicate that estrogen has a major impact on the regulation of erythropoiesis, particularly under chronic hypoxic conditions, and has the potential to treat blood diseases, such as high altitude severe erythrocytosis.
Collapse
Affiliation(s)
- Priti Azad
- Department of Pediatrics, Division of Respiratory Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Francisco C Villafuerte
- Laboratorio de Fisiologia del Transporte de Oxigeno/Fisiología Comparada, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, San Martin de Porres, Lima 31, Peru
| | - Daniela Bermudez
- Laboratorio de Fisiologia del Transporte de Oxigeno/Fisiología Comparada, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, San Martin de Porres, Lima 31, Peru
| | - Gargi Patel
- Department of Pediatrics, Division of Respiratory Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Gabriel G Haddad
- Department of Pediatrics, Division of Respiratory Medicine, University of California, San Diego, La Jolla, CA, 92093, USA.
- Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093, USA.
- Rady Children's Hospital, San Diego, CA, 92123, USA.
| |
Collapse
|
4
|
Sex differences in breathing. Comp Biochem Physiol A Mol Integr Physiol 2019; 238:110543. [PMID: 31445081 DOI: 10.1016/j.cbpa.2019.110543] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 08/08/2019] [Accepted: 08/09/2019] [Indexed: 01/15/2023]
Abstract
Breathing is a vital behavior that ensures both the adequate supply of oxygen and the elimination of CO2, and it is influenced by many factors. Despite that most of the studies in respiratory physiology rely heavily on male subjects, there is much evidence to suggest that sex is an important factor in the respiratory control system, including the susceptibility for some diseases. These different respiratory responses in males and females may be related to the actions of sex hormones, especially in adulthood. These hormones affect neuromodulatory systems that influence the central medullary rhythm/pontine pattern generator and integrator, sensory inputs to the integrator and motor output to the respiratory muscles. In this article, we will first review the sex dependence on the prevalence of some respiratory-related diseases. Then, we will discuss the role of sex and gonadal hormones in respiratory control under resting conditions and during respiratory challenges, such as hypoxia and hypercapnia, and whether hormonal fluctuations during the estrous/menstrual cycle affect breathing control. We will then discuss the role of the locus coeruleus, a sexually dimorphic CO2/pH-chemosensitive nucleus, on breathing regulation in males and females. Next, we will highlight the studies that exist regarding sex differences in respiratory control during development. Finally, the few existing studies regarding the influence of sex on breathing control in non-mammalian vertebrates will be discussed.
Collapse
|
5
|
Tenorio-Lopes L, Henry MS, Marques D, Tremblay MÈ, Drolet G, Bretzner F, Kinkead R. Neonatal maternal separation opposes the facilitatory effect of castration on the respiratory response to hypercapnia of the adult male rat: Evidence for the involvement of the medial amygdala. J Neuroendocrinol 2017; 29. [PMID: 29063642 DOI: 10.1111/jne.12550] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 10/10/2017] [Accepted: 10/11/2017] [Indexed: 01/09/2023]
Abstract
Respiratory manifestations of panic disorder (PD) include a greater respiratory instability and enhanced responsiveness to CO2 compared to normal individuals. Although the prevalence of PD is approximately three times greater in women compared to men, the origins of this sexual dimorphism remain poorly understood. Similar to PD patients, adult female rats previously subjected to neonatal maternal separation (NMS) show an increase in their ventilatory response to CO2 . Because this effect of NMS is not observed in males, we hypothesised that testosterone prevents NMS-induced hyper-responsiveness to CO2 . Pups subjected to NMS were placed in an incubator for 3 h d-1 from postnatal days 3-12. Control pups remained undisturbed. At adulthood (8-10 weeks of age), rats were then subjected either to sham surgery or castration. Fourteen days later, breathing was measured at rest (room air) and during acute exposure to hypercapnia (5 and 10% CO2 for 10 minutes each) using plethysmography. To gain insight into the mechanisms involved, c-fos expression was used as an indicator of neuronal activation. Brains were collected following air or CO2 exposure for quantification of c-fos positive cells by immunohistochemistry in selected regions, including the paraventricular nucleus of the hypothalamus, the dorsomedial hypothalamus and the amygdalar complex. Castration produced a 100% increase of hyperventilatory response to 10% CO2 in control rats. Unexpectedly, castration had no effect on the hyperventilatory response of NMS rats. The intensity of the hypercapnic response was inversely correlated with c-fos expression in the medial amygdala. We conclude that testosterone prevents the hyper-responsiveness to CO2 , whereas NMS attenuates sensitivity to hormone withdrawal. We propose that an inhibitory influence from the medial amygdala contributes to this effect.
Collapse
Affiliation(s)
- L Tenorio-Lopes
- Department of Pediatrics, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - M S Henry
- Department of Molecular Medicine, Centre de Recherche du CHU de Québec-Université Laval, Axe Neurosciences, Université Laval, Québec, QC, Canada
| | - D Marques
- Departamento de Morfologia e Fisiologia Animal Fac. de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, Jaboticabal, Brazil
| | - M-È Tremblay
- Department of Molecular Medicine, Centre de Recherche du CHU de Québec-Université Laval, Axe Neurosciences, Université Laval, Québec, QC, Canada
| | - G Drolet
- Department of Molecular Medicine, Centre de Recherche du CHU de Québec-Université Laval, Axe Neurosciences, Université Laval, Québec, QC, Canada
| | - F Bretzner
- Department of Molecular Medicine, Centre de Recherche du CHU de Québec-Université Laval, Axe Neurosciences, Université Laval, Québec, QC, Canada
| | - R Kinkead
- Department of Pediatrics, Centre de Recherche de l'Institut Universitaire de Cardiologie et Pneumologie de Québec, Université Laval, Québec, QC, Canada
| |
Collapse
|
6
|
Rousseau JP, Tenorio-Lopes L, Baldy C, Janes TA, Fournier S, Kinkead R. On the origins of sex-based differences in respiratory disorders: Lessons and hypotheses from stress neuroendocrinology in developing rats. Respir Physiol Neurobiol 2017; 245:105-121. [DOI: 10.1016/j.resp.2017.03.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/28/2017] [Accepted: 03/31/2017] [Indexed: 12/31/2022]
|
7
|
Raff H, Hoeynck B, Jablonski M, Leonovicz C, Phillips JM, Gehrand AL. Insulin sensitivity, leptin, adiponectin, resistin, and testosterone in adult male and female rats after maternal-neonatal separation and environmental stress. Am J Physiol Regul Integr Comp Physiol 2017; 314:R12-R21. [PMID: 28877872 DOI: 10.1152/ajpregu.00271.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Care of premature infants often requires parental and caregiver separation, particularly during hypoxic and hypothermic episodes. We have established a neonatal rat model of human prematurity involving maternal-neonatal separation and hypoxia with spontaneous hypothermia prevented by external heat. Adults previously exposed to these neonatal stressors show a sex difference in the insulin and glucose response to arginine stimulation suggesting a state of insulin resistance. The current study used this cohort of adult rats to evaluate insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR)], plasma adipokines (reflecting insulin resistance states), and testosterone. The major findings were that daily maternal-neonatal separation led to an increase in body weight and HOMA-IR in adult male and female rats and increased plasma leptin in adult male rats only; neither prior neonatal hypoxia (without or with body temperature control) nor neonatal hypothermia altered subsequent adult HOMA-IR or plasma adiponectin. Adult male-female differences in plasma leptin were lost with prior exposure to neonatal hypoxia or hypothermia; male-female differences in resistin were lost in the adults that were exposed to hypoxia and spontaneous hypothermia as neonates. Exposure of neonates to daily hypoxia without spontaneous hypothermia led to a decrease in plasma testosterone in adult male rats. We conclude that neonatal stressors result in subsequent adult sex-dependent increases in insulin resistance and adipokines and that our rat model of prematurity with hypoxia without hypothermia alters adult testosterone dynamics.
Collapse
Affiliation(s)
- Hershel Raff
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute , Milwaukee, Wisconsin.,Departments of Medicine, Surgery, and Physiology, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Brian Hoeynck
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute , Milwaukee, Wisconsin
| | - Mack Jablonski
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute , Milwaukee, Wisconsin
| | - Cole Leonovicz
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute , Milwaukee, Wisconsin
| | - Jonathan M Phillips
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute , Milwaukee, Wisconsin
| | - Ashley L Gehrand
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute , Milwaukee, Wisconsin
| |
Collapse
|
8
|
Developmental plasticity in the neural control of breathing. Exp Neurol 2017; 287:176-191. [DOI: 10.1016/j.expneurol.2016.05.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/13/2016] [Accepted: 05/26/2016] [Indexed: 12/14/2022]
|
9
|
Lozo T, Komnenov D, Badr MS, Mateika JH. Sex differences in sleep disordered breathing in adults. Respir Physiol Neurobiol 2016; 245:65-75. [PMID: 27836648 DOI: 10.1016/j.resp.2016.11.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 10/26/2016] [Accepted: 11/02/2016] [Indexed: 02/06/2023]
Abstract
The prevalence of sleep disordered breathing is greater in men compared to women. This disparity could be due to sex differences in the diagnosis and presentation of sleep apnea, and the pathophysiological mechanisms that instigate this disorder. Women tend to report more non-typical symptoms of sleep apnea compared to men, and the presentation of apneic events are more prevalent in rapid compared to non-rapid eye movement sleep. In addition, there is evidence of sex differences in upper airway structure and mechanics and in neural mechanisms that impact on the control of breathing. The purpose of this review is to summarize the literature that addresses sex differences in sleep-disordered breathing, and to discuss the influence that upper airway mechanics, chemoreflex properties, and sex hormones have in modulating breathing during sleep in men and women.
Collapse
Affiliation(s)
- Tijana Lozo
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - Dragana Komnenov
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - M Safwan Badr
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Biomedical Engineering, Wayne State University Detroit, MI 48201, United States
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States.
| |
Collapse
|
10
|
Soliz J, Tam R, Kinkead R. Neonatal Maternal Separation Augments Carotid Body Response to Hypoxia in Adult Males but Not Female Rats. Front Physiol 2016; 7:432. [PMID: 27729873 PMCID: PMC5037225 DOI: 10.3389/fphys.2016.00432] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 09/12/2016] [Indexed: 12/20/2022] Open
Abstract
Perinatal exposure to adverse experiences disrupts brain development, including the brainstem network that regulates breathing. At adulthood, rats previously subjected to stress (in the form of neonatal maternal separation; NMS) display features reported in patients suffering from sleep disordered breathing, including an increased hypoxic ventilatory response and hypertension. This effect is also sex-specific (males only). Based on these observations, we hypothesized that NMS augments the carotid body's O2-chemosensitivity. Using an isolated and perfused ex vivo carotid body preparation from adult rats we compared carotid sinus nerve (CSN) responses to hypoxia and hypercapnia in carotid bodies harvested from adult rats that either experienced control conditions (no experimental manipulation) or were subjected to NMS (3 h/day from postnatal days 3 to 12). In males, the CSN response to hypoxia measured in preparations from NMS males was 1.5 fold higher than controls. In control rats, the female's response was similar to that of males; however, the increase in CSN activity measured in NMS females was 3.0 times lower than controls. The CSN response to hypercapnia was not influenced by stress or sex. We conclude that NMS is sufficient to have persistent and sex-specific effects on the carotid body's response to hypoxia. Because NMS also has sex-specific effects on the neuroendocrine response to stress, we propose that carotid body function is influenced by stress hormones. This, in turn, leads to a predisposition toward cardio-respiratory disorders.
Collapse
Affiliation(s)
| | | | - Richard Kinkead
- Department of Pediatrics, Centre de Recherche du CHU de Québec, Hôpital St-François d'Assise, Université LavalQuébec, QC, Canada
| |
Collapse
|
11
|
Montrezor LH, de Carvalho D, Dias MB, Anselmo-Franci JA, Bícego KC, Gargaglioni LH. Hypoxic and hypercapnic ventilatory responses in rats with polycystic ovaries. Respir Physiol Neurobiol 2015; 217:17-24. [DOI: 10.1016/j.resp.2015.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 06/20/2015] [Accepted: 06/21/2015] [Indexed: 01/11/2023]
|
12
|
Fournier S, Gulemetova R, Baldy C, Joseph V, Kinkead R. Neonatal stress affects the aging trajectory of female rats on the endocrine, temperature, and ventilatory responses to hypoxia. Am J Physiol Regul Integr Comp Physiol 2015; 308:R659-67. [PMID: 25652536 DOI: 10.1152/ajpregu.00418.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/28/2015] [Indexed: 11/22/2022]
Abstract
Human and animal studies on sleep-disordered breathing and respiratory regulation show that the effects of sex hormones are heterogeneous. Because neonatal stress results in sex-specific disruption of the respiratory control in adult rats, we postulate that it might affect respiratory control modulation induced by ovarian steroids in female rats. The hypoxic ventilatory response (HVR) of adult female rats exposed to neonatal maternal separation (NMS) is ∼30% smaller than controls (24), but consequences of NMS on respiratory control in aging female rats are unknown. To address this issue, whole body plethysmography was used to evaluate the impact of NMS on the HVR (12% O2, 20 min) of middle-aged (MA; ∼57 wk old) female rats. Pups subjected to NMS were placed in an incubator 3 h/day for 10 consecutive days (P3 to P12). Controls were undisturbed. To determine whether the effects were related to sexual hormone decline or aging per se, experiments were repeated on bilaterally ovariectomized (OVX) young (∼12 wk old) adult female rats. OVX and MA both reduced the HVR significantly in control rats but had little effect on the HVR of NMS females. OVX (but not aging) reduced the anapyrexic response in both control and NMS animals. These results show that hormonal decline decreases the HVR of control animals, while leaving that of NMS female animals unaffected. This suggests that neonatal stress alters the interaction between sex hormone regulation and the development of body temperature, hormonal, and ventilatory responses to hypoxia.
Collapse
Affiliation(s)
- Sébastien Fournier
- Department of Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Quebec, Canada
| | - Roumiana Gulemetova
- Department of Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Quebec, Canada
| | - Cécile Baldy
- Department of Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Quebec, Canada
| | - Vincent Joseph
- Department of Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Quebec, Canada
| | - Richard Kinkead
- Department of Pediatrics, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Quebec, Canada
| |
Collapse
|