scholarly journals An afferent explanation for sexual dimorphism in the aortic baroreflex of rat

2014 ◽  
Vol 307 (6) ◽  
pp. H910-H921 ◽  
Author(s):  
Grace C. Santa Cruz Chavez ◽  
Bai-Yan Li ◽  
Patricia A. Glazebrook ◽  
Diana L. Kunze ◽  
John H. Schild
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Cross Sectional ◽  
Electrophysiological Properties ◽  
Depressor Response ◽  
Aortic Depressor Nerve ◽  
Functional Aspects ◽  
Compound Action Potentials ◽  
Experimental Protocols ◽  
Aortic Baroreceptors

Sex differences in baroreflex (BRx) function are well documented. Hormones likely contribute to this dimorphism, but many functional aspects remain unresolved. Our lab has been investigating a subset of vagal sensory neurons that constitute nearly 50% of the total population of myelinated aortic baroreceptors (BR) in female rats but less than 2% in male rats. Termed “Ah,” this unique phenotype has many of the nonoverlapping electrophysiological properties and chemical sensitivities of both myelinated A-type and unmyelinated C-type BR afferents. In this study, we utilize three distinct experimental protocols to determine if Ah-type barosensory afferents underlie, at least in part, the sex-related differences in BRx function. Electron microscopy of the aortic depressor nerve (ADN) revealed that female rats have less myelin ( P < 0.03) and a smaller fiber cross-sectional area ( P < 0.05) per BR fiber than male rats. Electrical stimulation of the ADN evoked compound action potentials and nerve conduction profiles that were markedly different ( P < 0.01, n = 7 females and n = 9 males). Selective activation of ADN myelinated fibers evoked a BRx-mediated depressor response that was 3–7 times greater in female ( n = 16) than in male ( n = 17) rats. Interestingly, the most striking hemodynamic difference was functionally dependent upon the rate of myelinated barosensory fiber activation. Only 5–10 Hz of stimulation evoked a rapid, 20- to 30-mmHg reduction in arterial pressure of female rats, whereas rates of 50 Hz or higher were required to elicit a comparable depressor response from male rats. Collectively, our experimental results are suggestive of an alternative myelinated baroreceptor afferent pathway in females that may account for, at least in part, the noted sex-related differences in autonomic control of cardiovascular function.

Role of estrogens and age in flow-mediated outward remodeling of rat mesenteric resistance arteries

2014 ◽  
Vol 307 (4) ◽  
pp. H504-H514 ◽  
Author(s):  
K. Tarhouni ◽  
M. L. Freidja ◽  
A. L. Guihot ◽  
E. Vessieres ◽  
L. Grimaud ◽  
...  
Keyword(s):  
Blood Flow ◽  
Female Rats ◽  
Male Rats ◽  
Resistance Arteries ◽  
Cross Sectional ◽  
Male And Female ◽  
Male And Female Rats ◽  
Arterial Contractility

In resistance arteries, a chronic increase in blood flow induces hypertrophic outward remodeling. This flow-mediated remodeling (FMR) is absent in male rats aged 10 mo and more. As FMR depends on estrogens in 3-mo-old female rats, we hypothesized that it might be preserved in 12-mo-old female rats. Blood flow was increased in vivo in mesenteric resistance arteries after ligation of the side arteries in 3- and 12-mo-old male and female rats. After 2 wk, high-flow (HF) and normal-flow (NF) arteries were isolated for in vitro analysis. Arterial diameter and cross-sectional area increased in HF arteries compared with NF arteries in 3-mo-old male and female rats. In 12-mo-old rats, diameter increased only in female rats. Endothelial nitric oxide synthase expression and endothelium-mediated relaxation were higher in HF arteries than in NF arteries in all groups. ERK1/2 phosphorylation, NADPH oxidase subunit expression levels, and arterial contractility to KCl and to phenylephrine were greater in HF vessels than in NF vessels in 12-mo-old male rats only. Ovariectomy in 12-mo-old female rats induced a similar pattern with an increased contractility without diameter increase in HF arteries. Treatment of 12-mo-old male rats and ovariectomized female rats with hydralazine, the antioxidant tempol, or the angiotensin II type 1 receptor blocker candesartan restored HF remodeling and normalized arterial contractility in HF vessels. Thus, we found that FMR of resistance arteries remains efficient in 12-mo-old female rats compared with age-matched male rats. A balance between estrogens and vascular contractility might preserve FMR in mature female rats.

Aging and fluid homeostasis in rats

1997 ◽  
Vol 273 (4) ◽  
pp. R1441-R1450 ◽  
Author(s):  
Neil E. Rowland ◽  
Annie Morien ◽  
Mircea Garcea ◽  
Melvin J. Fregly
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Acute Administration ◽  
Salt Appetite ◽  
Sprague Dawley ◽  
Cross Sectional ◽  
Aging Rats ◽  
Fluid Homeostasis ◽  
Male And Female Rats ◽  
Age Related

The capacity of aging rats to defend body fluid homeostasis in response to a variety of dipsogenic and natriorexigenic stimuli was assessed. Male and female rats of both the Fischer 344 (FR) and Sprague-Dawley (SD) strains were used and tested at target ages of ∼5, 10, 15, and 20 mo in both longitudinal and cross-sectional studies. There were no consistent age-related declines in water intake in response to water deprivation or acute administration of hypertonic NaCl; angiotensin (ANG) I, II, III; or isoproterenol. Likewise, there were no major impairments in either urinary excretion of the hypertonic NaCl load or excretion of water or hypotonic NaCl loads, although the latter were excreted more slowly in the older cohorts. The preference/aversion functions for NaCl solutions differed between SD and FR rats, but did not change with age except in male FR rats that lost their aversion to dilute NaCl at 20 mo of age. Intake of hypotonic NaCl solution after acute sodium depletion (furosemide treatment) showed a partial decline with age, and the older rats sustained larger estimated sodium deficits after a 6-h repletion period. A more complete age-related decline was observed in the intake of hypertonic NaCl stimulated by chronic dietary administration of a kininase II inhibitor (ramipril). Male rats of 15–20 mo of age showed no ramipril-induced sodium appetite. Brain ANG II receptor density, determined by autoradiography, declined by almost 50% in the paraventricular nucleus at 20 mo of age and declined slightly in the organum vasculosum laminae terminalis but did not decline in either the supraoptic nucleus or subfornical organ. Thus the major deficits in fluid intake in aging rats are related to salt appetite; the mechanism was not identified definitively.

scholarly journals Sex Differences and Similarities in Hippocampal Cellular Proliferation and the Number of Immature Neurons during Adolescence in Rats

2019 ◽  
Vol 41 (1-2) ◽  
pp. 132-138 ◽  
Author(s):  
Alina Siddiqui ◽  
Russell D. Romeo
Keyword(s):  
Sex Differences ◽  
Dentate Gyrus ◽  
Cellular Proliferation ◽  
Female Rats ◽  
Male Rats ◽  
Ki 67 ◽  
Cross Sectional ◽  
Male And Female Rats ◽  
Immature Neurons ◽  
Males And Females

Adolescence is associated with significant reductions in hippocampal cellular proliferation and neurogenesis, the physiological and behavioral implications of which are unclear. Though sex differences exist in these proliferative processes in adulthood, relatively little is known about the role sex plays in these adolescent-related changes. To address this gap, we examined cross-sectional area of the dentate gyrus and cellular proliferation, as measured by Ki-67 immunohistochemistry, in pre- (30 days), mid- (45 days), and post-adolescent (70 days) male and female rats. We also investigated the number of immature neurons using doublecortin (DCX) immunohistochemistry in pre- and post-adolescent males and females. Despite increases in the size of the dentate gyrus during adolescence, we found significant adolescent-related decreases in hippocampal proliferation in both males and females, with a more dramatic decrease in males, indicating both age- and sex-dependent changes in the dentate gyrus. We also found an adolescent-related decline in the number of immature neurons in the dentate gyrus of male rats and a female-biased sex difference in the number of immature neurons in adults. Given these significant changes in the dentate gyrus, these data suggest that this period in development might be particularly sensitive to internal and external factors known to modulate neurogenesis, with potential sex-specific neurobehavioral ramifications.

Acute fasting and fiber number in rat soleus muscle

1982 ◽  
Vol 53 (5) ◽  
pp. 1234-1238 ◽  
Author(s):  
D. Parsons ◽  
M. Riedy ◽  
R. L. Moore ◽  
P. D. Gollnick
Keyword(s):  
Body Weight ◽  
Soleus Muscle ◽  
Female Rats ◽  
Male Rats ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Weight Losses ◽  
Male And Female Rats ◽  
Fiber Number ◽  
Experimental Treatments

The influence of fasting on fiber number in the soleus muscle (SM) of weanling male and female rats was investigated. For female rats, comparisons were made among groups of animals fed normally, rats fasted and then fed until prefast body weight was regained, and animals that grew to maturity. For male rats, comparisons were made only between control and fasted groups. Prior to the experimental treatments the SM was surgically removed from one leg. There was a 40% loss in body weight after fasting. Although major weight losses occurred in most muscles and organs, there was no change in the SM. Over the same period SM weight increased 31% in normal animals. Total fiber number (direct counts after nitric acid digestion) was unaltered by the treatments. Although wide variation existed between animals, total fiber number between legs for the same animal was closely correlated (r = 0.98). SM weight for male rats calculated from fiber length, cross-sectional area, and total fiber number could account for from 91 to 99% of the total muscle weight. There was no change in fiber number from weaning to maturity. It is concluded that fiber number is unchanged by fasting or during normal maturation.

Perinatal activation of ERα and ERβ but not GPER-1 masculinizes female rat caudate-putamen medium spiny neuron electrophysiological properties

2021 ◽  
Author(s):  
Jinyan Cao ◽  
John Meitzen
Keyword(s):  
Developmental Process ◽  
Medium Spiny Neuron ◽  
Female Rats ◽  
Male Rats ◽  
Intrinsic Excitability ◽  
Inward Rectification ◽  
Female Rat ◽  
Caudate Putamen ◽  
Electrophysiological Properties ◽  
Receptor Agonists

Exposure to steroid sex hormones such as 17β-estradiol (estradiol) during early life potentially permanently masculinize neuron electrophysiological phenotype. In rodents, one crucial component of this developmental process occurs in males, with estradiol aromatized in the brain from testes-sourced testosterone. However, it is unknown whether most neuron electrophysiological phenotypes are altered by this early masculinization process, including medium spiny neurons (MSNs) of the rat caudate-putamen. MSNs are the predominant and primary output neurons of the caudate-putamen, and exhibit increased intrinsic excitability in females compared to males. Here we hypothesize that since perinatal estradiol exposure occurs in males, then a comparable exposure in females to estradiol or its receptor agonists would be sufficient to induce masculinization. To test this hypothesis, we injected perinatal female rats with estradiol or its receptor agonists and then later assessed MSN electrophysiology. Female and male rats on postnatal day 0 and 1 were systemically injected with either vehicle, estradiol, the ERα agonist PPT, the ERβ agonist DPN, or the GPER-1 agonist G1. On postnatal days 19±2 MSN electrophysiological properties were assessed using whole-cell patch clamp recordings. Estradiol exposure abolished increased intrinsic excitability in female compared to male MSNs. Exposure to either an ERα or ERβ agonist masculinized female MSN evoked action potential firing rate properties, while exposure to an ERβ agonist masculinized female MSN inward rectification properties. Exposure to ER agonists minimally impacted male MSN electrophysiological properties. These findings indicate that perinatal estradiol exposure masculinizes MSN electrophysiological phenotype via activation of ERα and ERβ.

scholarly journals Sex differences in the inflammatory mediator-induced sensitization of dural afferents

2011 ◽  
Vol 106 (4) ◽  
pp. 1662-1668 ◽  
Author(s):  
N. N. Scheff ◽  
M. S. Gold
Keyword(s):  
Sex Difference ◽  
Inflammatory Mediator ◽  
Sodium Current ◽  
Adult Population ◽  
Female Rats ◽  
Male Rats ◽  
Sprague Dawley ◽  
Electrophysiological Properties ◽  
Male And Female Rats ◽  
Dural Afferents

Approximately 20% of the adult population suffers from migraine. This debilitating pain disorder is three times more prevalent in women than in men. To begin to evaluate the underlying mechanisms that may contribute to this sex difference, we tested the hypothesis that there is a sex difference in the inflammatory mediator (IM)-induced sensitization of dural afferents. Acutely dissociated retrogradely labeled dural afferents from adult Sprague-Dawley rats were examined with whole cell patch-clamp recordings. Baseline passive and active electrophysiological properties of dural afferents from both sexes were comparable. However, while IM-induced increases in the excitability of dural afferents from male and female rats were also comparable, the proportion of dural afferents from female rats sensitized by IM (∼100%) was significantly greater than that of dural afferents from male rats (∼50%). This appeared to be due to differences downstream of IM receptors, as tetrodotoxin-resistant sodium current was increased by IM in a majority of male dural afferents (13/14). These data indicate that there are both quantitative and qualitative differences in the IM-induced sensitization of dural afferents that may contribute to the sex difference in the manifestation of migraine.

INDUCTION OF GOITRE BY PTU OR KClO4 IN MALE AND FEMALE RATS. EFFECT OF GONADECTOMY

1973 ◽  
Vol 74 (1) ◽  
pp. 88-104 ◽  
Author(s):  
T. Jolín ◽  
M. J. Tarin ◽  
M. D. Garcia
Keyword(s):  
Iodine Content ◽  
High Plasma ◽  
Disc Electrophoresis ◽  
Female Rats ◽  
Male Rats ◽  
Adult Rats ◽  
Male And Female ◽  
Glucose Levels ◽  
Male And Female Rats ◽  
Tsh Levels

ABSTRACT Male and female rats of varying ages were placad on a low iodine diet (LID) plus KClO4 or 6-propyl-2-thiouracil (PTU) or on the same diet supplemented with I (control rats). Goitrogenesis was also induced with LID plus PTU in gonadectomized animals of both sexes. The weight of the control and goitrogen treated animals, and the weight and iodine content of their thyroids were determined, as well as the plasma PBI, TSH, insulin and glucose levels. The pituitary GH-like protein content was assessed by disc electrophoresis on polyacrylamide gels. If goitrogenesis was induced in young rats of both sexes starting with rats of the same age, body weight (B.W.) and pituitary growth hormone (GH) content, it was found that both the males and females developed goitres of the same size. On the contrary, when goitrogenesis was induced in adult animals, it was found that male rats, that had larger B.W. and pituitary GH content than age-paired females, developed larger goitres. However, both male and female rats were in a hypothyroid condition of comparable degree as judged by the thyroidal iodine content and the plasma PBI and TSH levels. When all the data on the PTU or KClO4-treated male and female rats of varying age and B.W. were considered together, it was observed that the weights of the thyroids increased proportionally to B.W. However, a difference in the slope of the regression of the thyroid weight over B.W. was found between male and female rats, due to the fact that adult male rats develop larger goitres than female animals. In addition, in the male rats treated with PTU, gonadectomy decreased the B.W., pituitary content of GH-like protein and, concomitantly, the size of the goitre decreased; an opposite effect was induced by ovariectomy on the female animals. However, when goitrogenesis was induced in weight-paired adult rats of both sexes, the male animals still developed larger goitres than the females. Among all the parameters studied here, the only ones which appeared to bear a consistent relationship with the size of the goitres in rats of different sexes, treated with a given goitrogen, were the rate of body growth and the amount of a pituitary GH-like protein found before the onset of the goitrogen treatment. Moreover, though the pituitary content of the GH-like protein decreased as a consequence of goitrogen treatment, it was still somewhat higher in male that in female animals. The present results suggest that GH may somehow be involved in the mechanism by which male and female rats on goitrogens develop goitres of different sizes, despite equally high plasma TSH levels.

OXYDATION DES ANABOLIKUMS 1-METHYL-ANDROST-1-EN-17β-OL-3-ON MIT WASSERSTOFFTRANSFER AUF ÖSTRON

1971 ◽  
Vol 67 (3) ◽  
pp. 517-530 ◽  
Author(s):  
Martin Wenzel
Keyword(s):  
Rat Liver ◽  
Anabolic Steroid ◽  
Female Rats ◽  
Male Rats ◽  
Female Rat ◽  
Liver Slices ◽  
Androgen Effects ◽  
Biochemical Difference

ABSTRACT With the aid of metenolon-17α-T a tritium-transfer to oestrone in rat liver slices was demonstrated. This tritium-transfer from metenolon17α-T to oestrone yielding tritium-labelled oestradiol had a higher efficiency in male than in female rat liver. Correspondingly in the presence of metenolon the relation of oestrone to oestradiol is changed more in male than in female rat liver. Looking for biochemical differences between the anabolic steroid metenolon and testosterone the oxydation at C17 was measured in different organs of the rat using 17α-T-labelled steroids. The highest oxydation rate was found for both steroids in the liver. In the sexual organs of male rats the oxydation rate of testosterone was 50–10 times higher than that of the anabolic steroid. This difference was less in sexual organs of female rats. This result of a greater biochemical difference between both steroids in males than in females leads to the question, whether the dissociation between the anabolic and the androgen effects is higher in males than in females.

The effect of dexamethasone on mucosal immunity of uterine tissue during pregnancy in rat

2019 ◽  
Vol 20 (1) ◽  
pp. 75-84
Keyword(s):  
Early Pregnancy ◽  
Histopathological Examination ◽  
Early Period ◽  
Interleukin 10 ◽  
Treated Group ◽  
Female Rats ◽  
Male Rats ◽  
Mrna Levels ◽  
Uterine Tissue ◽  
Leukocytic Infiltration

Disturbances in early pregnancy immunity affect embryo development, endometrial receptivity, placental development, fetal growth and lead to subfertility, dexamethasone is a synthetic glucocorticoid used for treatment of various complications. Immune cells and cytokines were examined during the early pregnancy in twenty-four female rats and six male rats for mating. Rats were grouped into two group control and dexamethasone treated by a dose of 50µgm/kgm body weight daily starting from one week before mating and persisted for one week after pregnancy. Blood samples were collected from each rat at 5hrs and at 1,3,7 day of pregnancy. Extracted RNA was subjected to real time PCR to determine mRNA levels for immune related genes interleukin1a(IL1A) and interleukin 10(IL10). Histopathological examination was done to uterus in order to detect leukocyte infiltration in uterine tissue. Results showed that significant increase in white blood cell count mainly eosinophil at 5hrs and lymphocyte at three and seven day of pregnancy of dexamethasone treated group. Moreover, TNF, C-reactive protein and progesterone were increased mainly at seven day of pregnancy of dexamethasone treated group. Similarly, interleukin 1alpha and interleukin 10 significantly increased at 5hrs and one day of pregnancy of dexamethasone treated group. In contrast, serum levels of total antioxidant capacity and estrogen were decreased significantly at 5hrs and seven day in dexamethasone treated group. Histopathological examination of uterus revealed leukocytic infiltration especially neutrophil and few eosinophils at five hours and one day of gestation then eosinophil become absent at 3day and seven day of dexamethasone group. Epithelial height and uterine gland diameter significantly increased at 5hrs, three day and seven days of gestation of dexamethasone treated group. The present investigation demonstrated that using of dexamethasone by dose of 50µgm/kgm during early pregnancy had a conflicting impact on some immune cytokines and parameters and may reflect a harmful response of immune system toward early period of pregnancy

Female rats display higher methamphetamine-primed reinstatement and c-Fos immunoreactivity than male rats

2021 ◽  
pp. 173089
Author(s):  
Steven T. Pittenger ◽  
Shinnyi Chou ◽  
Nathen J. Murawski ◽  
Scott T. Barrett ◽  
Olivia Loh ◽  
...  
Keyword(s):  
Female Rats ◽  
Male Rats
Sign in / Sign up

Export Citation Format

Share Document