scholarly journals Gender and Puberty Interact on the Stress-Induced Activation of Parvocellular Neurosecretory Neurons and Corticotropin-Releasing Hormone Messenger Ribonucleic Acid Expression in the Rat

Endocrinology ◽  
2005 ◽  
Vol 146 (1) ◽  
pp. 137-146 ◽  
Author(s):  
Victor Viau ◽  
Brenda Bingham ◽  
Jennifer Davis ◽  
Patricia Lee ◽  
Margaret Wong
Keyword(s):  
Paraventricular Nucleus ◽  
Cell Types ◽  
Female Rats ◽  
Male Rats ◽  
Messenger Ribonucleic Acid ◽  
Fos Protein ◽  
Male And Female Rats ◽  
Age Related ◽  
And Gender ◽  
Hpa Function

Individual variations in hypothalamic-pituitary-adrenal (HPA) function are most evident at or beyond the time of puberty, when marked changes in sex steroid release occur. To explore the nature by which gender differences in HPA function emerge we examined in prepubertal (∼30-d-old) and postpubertal (∼60-d-old) male and female rats HPA activity under basal conditions and in response to 30 min of restraint. Within the ACTH-regulating, medial parvocellular portion of the paraventricular nucleus, restraint-induced Fos protein and arginine vasopressin heteronuclear RNA were lower in 60- than in 30-d-old males. No such age-related shift in the response of these synaptic and transcriptional markers of cellular activation occurred in female rats. Basal CRH mRNA expression levels in the paraventricular nucleus increased with age in female but not male rats. Conversely, only male rats showed an age-related increase in basal CRH mRNA in the central amygdala, suggesting that neuronal and neurosecretory CRH-expressing cell types are subject to different pubertal and gender influences. We conclude that gonadal regulation of the HPA axis develops via distinct mechanisms in males and females. Puberty-related shifts in parvocellular neurosecretory function in males are emphasized by stress-induced shifts in neuronal activation, whereas biosynthetic alterations dominate in female rats.

Effects of trenbolone acetate and testosterone on growth and on plasma concentrations of corticosterone and ACTH in rats

1990 ◽  
Vol 126 (3) ◽  
pp. 461-466 ◽  
Author(s):  
M. N. Sillence ◽  
R. G. Rodway
Keyword(s):  
Weight Gain ◽  
Growth Response ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Male Rats ◽  
Adrenal Weight ◽  
Trenbolone Acetate ◽  
Male And Female Rats ◽  
Age Related ◽  
Old Rats

ABSTRACT The effects of trenbolone acetate (TBA) on growth and on plasma concentrations of corticosterone were examined in male and female rats. At 5 weeks of age, rats were injected with TBA (0·8 mg/kg) dissolved in peanut oil, or with oil alone, daily for 10 days. In female rats, TBA caused an increase in weight gain (20–38%), a reduction in adrenal weight (19%) and a reduction in plasma concentrations of corticosterone (55%). In contrast, TBA-treated male rats showed no significant increase in weight gain, no significant change in adrenal weight and no reduction in plasma concentrations of corticosterone. The mechanism by which adrenal activity was suppressed in TBA-treated female rats was examined and the response compared with that to testosterone. Female rats (8 weeks old) were injected daily either with oil vehicle, TBA (0·8 mg/kg) or testosterone propionate (0·8 mg/kg). Testosterone increased weight gain (24%), but the growth response to TBA treatment was significantly greater (97%). A reduction in plasma concentrations of corticosterone (45%) was again observed in response to TBA. However, testosterone increased plasma concentrations of corticosterone (52%) above those of control values. Neither androgen affected plasma concentrations of ACTH. Finally, the effects of TBA were examined in 6-week-old female rats, to characterize further the apparent age-related increase in responsiveness. The growth response of 6-week-old rats (60–74%) was intermediate between that seen in 5- and 8-week-old animals. It is concluded that part of the anabolic activity of TBA may be related to a reduction in circulating concentrations of corticosterone. The effect of TBA on corticosterone concentrations differs from that of the natural androgen, testosterone, and does not appear to be mediated by a reduction in plasma concentrations of ACTH. Journal of Endocrinology (1990) 126, 461–466

Effect of age and gender on thermoregulation

1989 ◽  
Vol 257 (4) ◽  
pp. R700-R704 ◽  
Author(s):  
R. B. McDonald ◽  
C. Day ◽  
K. Carlson ◽  
J. S. Stern ◽  
B. A. Horwitz
Keyword(s):  
Oxygen Consumption ◽  
Cold Exposure ◽  
Female Rats ◽  
Male Rats ◽  
Differential Heat ◽  
Independent Basis ◽  
Male And Female Rats ◽  
Brown Adipose ◽  
And Gender ◽  
Colonic Temperature

Previous investigations have shown that during cold exposure 24-mo-old male Fischer 344 (F344) rats do not thermoregulate as well as do 12-mo-old animals. To determine if this deficiency also occurs in female rats, we measured oxygen consumption (thermogenesis) and colonic temperature of male and female rats 5, 23, and 27 mo of age at rest and during 6 h of exposure to 6 degrees C. In addition, nonshivering thermogenesis (NST) was evaluated from the capacity of brown adipose tissue (BAT) mitochondria isolated from cold-exposed rats to bind guanosine 5'-diphosphate (GDP). Neither age nor gender had a significant effect on resting or cold-exposed oxygen consumption expressed on a mass-independent basis (l/kg body mass0.67) or on a lean body mass independent basis (l/kg lean body mass0.67). The drop in colonic temperature in response to cold was greater in the male rats. However, females exhibited increased BAT mass and relatively constant GDP binding with advancing age, whereas males showed decreased mass and GDP binding. Although the data suggest greater NST capacity in the female rats, rates of cold-induced oxygen consumption were similar in older female vs. male rats. Taken together, our data indicate that gender has a significant impact on thermoregulation and that, under the cold exposure conditions of the study, this effect involves differential heat conservation rather than heat production.

scholarly journals Developmental increases in plasma leptin binding activity and tissue Ob-Re mRNA expression in the rat

2005 ◽  
Vol 184 (3) ◽  
pp. 535-541 ◽  
Author(s):  
Jeremy T Smith ◽  
Peter J Mark ◽  
Brendan J Waddell
Keyword(s):  
Mrna Expression ◽  
Adult Life ◽  
Tissue Expression ◽  
Binding Activity ◽  
Female Rats ◽  
Male Rats ◽  
Target Cells ◽  
Male And Female Rats ◽  
Age Related ◽  
Plasma Leptin

Leptin’s actions are mediated via the long form of its receptor, Ob-Rb, but access to this receptor on target cells is also influenced by truncated leptin receptor isoforms Ob-Ra and Ob-Re. Plasma leptin binding activity is primarily attributed to Ob-Re, which can restrict leptin passage to extravascular tissue. In this study we investigated whether plasma leptin binding activity changes from fetal to adult life in male and female rats, and whether tissue expression of Ob-Re mRNA changes during development. Plasma leptin binding activity was low in the fetus and prepubertal rats but then increased in male rats by more than three-fold from pre- to post-puberty and by a further two-fold by 7 months of age. A more modest increase in plasma leptin binding activity was observed in females such that a clear sex difference became evident after puberty. There was also a reduction in hypothalamic Ob-Rb protein content between puberty and adult life in female rats. Combined with the higher levels of plasma leptin binding activity, this change in hypothalamic Ob-Rb expression is likely to lead to a more leptin-resistant state in aging females. To assess possible sources of circulating leptin binding activity, Ob-Re mRNA expression was measured by quantitative RT-PCR in several tissues from male rats soon after puberty and at 7 months of age. All tissues examined (testis, epididymis, adrenal, liver, adipose and spleen) expressed Ob-Re mRNA, and there was a dramatic, age-related increase in expression (> 300-fold) in the spleen. These data show that, in addition to the developmental increase in hypothalamic Ob-Rb expression previously reported, plasma leptin binding activity increases several fold from fetal to adult life in the rat. This suggests that the actions of leptin depend not only on its synthesis in adipose tissue and Ob-Rb expression in target cells, but also on factors that regulate tissue expression of Ob-Re and thus leptin transport within plasma.

scholarly journals Age-associated changes in excitation-contraction coupling are more prominent in ventricular myocytes from male rats than in myocytes from female rats

2010 ◽  
Vol 298 (2) ◽  
pp. H659-H670 ◽  
Author(s):  
Susan E. Howlett
Keyword(s):  
Sex Differences ◽  
Ventricular Myocytes ◽  
Contractile Function ◽  
Pulse Frequency ◽  
Female Rats ◽  
Male Rats ◽  
Cardiac Contractile Function ◽  
Ec Coupling ◽  
Male And Female Rats ◽  
Age Related

We evaluated effects of age on components of excitation-contraction (EC) coupling in ventricular myocytes from male and female rats to examine sex differences in mechanisms responsible for age-related contractile dysfunction. Myocytes were isolated from anesthetized young adult (∼3 mo) and aged (∼24 mo) Fischer 344 rats. Ca2+ concentrations and contractions were measured simultaneously (37°C, 2 Hz). Fractional shortening declined with age in males (6.7 ± 0.6% to 2.4 ± 0.4%; P < 0.05), as did peak Ca2+ transients (47.7 ± 4.6 to 28.1 ± 2.1 nM; P < 0.05) and Ca2+ current densities (−7.7 ± 0.7 to −6.2 ± 0.5 pA/pF; P < 0.05). Although sarcoplasmic reticulum (SR) Ca2+ content was similar regardless of age in males, EC coupling gain declined significantly with age to 55.8 ± 7.8% of values in younger males. In contrast with results in males, contraction and Ca2+ transient amplitudes were unaffected by age in females. Ca2+ current density declined with age in females (−7.5 ± 0.5 to −5.1 ± 0.7 pA/pF; P < 0.05), but SR Ca2+ content actually increased dramatically (49.0 ± 7.5 to 147.3 ± 28.5 nM; P < 0.05). Even so, EC coupling gain was not affected by age in female myocytes. Age also promoted hypertrophy of male myocytes more than female myocytes. Age and sex differences in EC coupling were largely maintained when conditioning pulse frequency was increased to 4 Hz. Contractions, Ca2+ transients, and EC coupling gain were also smaller in young females than in young males. Thus age-dependent changes are more prominent in myocytes from males than females. Increased SR Ca2+ content may compensate for reduced Ca2+ current to preserve contractile function in aged females, which may limit the detrimental effects of age on cardiac contractile function.

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.

Tyrosine kinase receptor alteration of renal vasoconstriction in rats is sex- and age-related

2012 ◽  
Vol 90 (10) ◽  
pp. 1372-1379 ◽  
Author(s):  
John C. Passmore ◽  
John T. Fleming ◽  
Suresh C. Tyagi ◽  
Jeff C. Falcone
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Inhibitors ◽  
Young Male ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Tyrosine Kinase Receptor ◽  
Middle Aged ◽  
Male And Female Rats ◽  
Age Related

Male rat renal blood vessels undergo reduced contraction to norepinephrine with aging. There is a greater renal vascular impairment in male compared with female rats. We investigated specific tyrosine kinase receptor inhibition of renal interlobar artery responsiveness to phenylephrine in male and female rats at specifically designated ages. Vessels from young male rats contracted much less to phenylephrine when the vessels were pretreated with the tyrosine kinase inhibitors Lavendustin A, HNMPA-(AM)3, or AG1478. Vessels from adult female rats pretreated with Lavendustin A showed no difference in contraction from control, but did demonstrate a slightly reduced contraction when pretreated with AG1478. Middle-aged male rat vessels treated with Lavendustin A demonstrated no inhibition, but the insulin and epidermal growth factor receptor (EGFR) antagonists both induced a decline in contraction. Vessels from aged male rats demonstrated no effect related to the 3 pretreatments. Middle-aged and aged female rats pretreated with any inhibitor demonstrated no inhibitor-dependent alterations. We conclude that maximum contraction of interlobar arteries from adult male rats is reduced when tyrosine kinase receptor activity is reduced. Female rats demonstrated much less inhibitor-related change of contraction.

Pars distalis cell quantification in normal adult male and female rats

1984 ◽  
Vol 101 (1) ◽  
pp. 87-NP ◽  
Author(s):  
M. O. Dada ◽  
G. T. Campbell ◽  
C. A. Blake
Keyword(s):  
Adult Male ◽  
Cell Types ◽  
Volume Density ◽  
Female Rats ◽  
Male Rats ◽  
Pars Distalis ◽  
Prolactin Cells ◽  
Male And Female ◽  
Gh Cells ◽  
Male And Female Rats

ABSTRACT We analysed cell types in the pars distalis of normal young adult male and female rats with respect to their percentages and the relative volumes they occupy. In male rats the percentages of the cell types were: prolactin 49·80, GH 22·67, LH 5·04, FSH 4·22, ACTH 2·93 and TSH 2·09, The volume densities were: prolactin 20·48, GH 20·95, LH 7·34, FSH 6·73, ACTH 3·75 and TSH 3·19. In female rats the percentages of the cell types were: prolactin 52·40, GH 20·30, LH 5·89, FSH 4·06, ACTH 2·53, TSH 2·40 and the volume densities were: prolactin 28·09, GH 20·86, LH 8·11, FSH 5·46, ACTH 3·49 and TSH 2·91. The percentages of pars distalis cells which did not stain with the antisera to the six classical hormones were 17·47 in male and 16·48 in female rats. The results suggest that (1) in both sexes the number (N) of prolactin cells > N of GH cells > N of gonadotrophs > N of TSH or ACTH cells, (2) the percentage of each cell type was similar in both sexes, (3) the volume density (Vv) of prolactin cells was greater than the Vv of GH cells in female but not in male rats and in both sexes the Vv of GH cells > the Vv of gonadotrophs > the Vv of TSH or ACTH cells, (4) in both sexes the volume (V) of prolactin cells < the V of GH cells < the V of gonadotrophs, the V of TSH cells or the V of ACTH cells, (5) the V of prolactin cells was greater in female than in male rats and (6) approximately 17% of the cells in the pars distalis of both sexes did not contain 'immunoreactive' prolactin, GH, LH, FSH, TSH or ACTH. J. Endocr. (1984) 101, 87–94

Daily exercise and gender influence arterial baroreflex regulation of heart rate and nerve activity

1996 ◽  
Vol 271 (5) ◽  
pp. H1840-H1848 ◽  
Author(s):  
C. Y. Chen ◽  
S. E. DiCarlo
Keyword(s):  
Heart Rate ◽  
Female Rats ◽  
Male Rats ◽  
Heart Weight ◽  
Arterial Baroreflex ◽  
Nerve Activity ◽  
Male And Female ◽  
Gender Influence ◽  
Male And Female Rats ◽  
And Gender

The influence of daily spontaneous running (DSR) and gender on the arterial baroreflex regulation of heart rate (HR) and lumbar sympathetic nerve activity (LSNA) was examined in 13 male [7 sedentary (SED) and 6 DSR] and 12 female (6 SED and 6 DSR) Sprague-Dawley rats. After 8-9 wk of DSR or SED control, all animals were chronically instrumented with right femoral venous and left carotid arterial catheters and electrodes around the lumbar sympathetic trunk. DSR resulted in an increase in heart weight-to-body weight ratio (P = 0.001) in male and female rats and resting bradycardia in male rats (P = 0.001). Arterial baroreflex function was examined by ramp increases (1.25 +/- 0.07 mmHg/s) and decreases (1.47 mmHg/s) in arterial pressure. DSR attenuated the arterial baroreflex regulation of LSNA in a similar manner in female and male rats. DSR reduced the range (32 and 29% for female and male rats, respectively), maximum (26 and 21% for female and male rats, respectively), and maximum gain (Gmax; 46 and 17% for female and male rats, respectively). In contrast, there was a gender influence on the arterial baroreflex regulation of HR. For example, SED female rats had a higher Gmax (40%) than SED male rats. Furthermore, DSR altered the arterial baroreflex regulation of HR differently in male and female rats. DSR female rats had a reduced Gmax (38%), range (25%), and maximum (12%), whereas DSR male rats had a reduced maximum (17%) and minimum (23%). These results demonstrate that DSR attenuated the arterial baroreflex regulation of LSNA in a similar manner in female and male rats. In contrast, DSR altered the arterial baroreflex regulation of HR differently in female and male rats.

Age- and gender-related changes in glucose homeostasis in glucocorticoid-treated rats

2014 ◽  
Vol 92 (10) ◽  
pp. 867-878 ◽  
Author(s):  
Cristiane dos Santos ◽  
Francielle Batista D. Ferreira ◽  
Luiz M. Gonçalves-Neto ◽  
Sebastião Roberto Taboga ◽  
Antonio Carlos Boschero ◽  
...  
Keyword(s):  
Body Mass ◽  
Glucose Intolerance ◽  
Glucose Homeostasis ◽  
Cell Mass ◽  
Female Rats ◽  
Male Rats ◽  
Dexamethasone Treatment ◽  
Age And Gender ◽  
Male And Female Rats ◽  
And Gender

The disruption to glucose homeostasis upon glucocorticoid (GC) treatment in adult male rats has not been fully characterized in older rats or in females. Thus, we evaluated the age- and gender-related changes in glucose homeostasis in GC-treated rats. We injected male and female rats at 3 months and 12 months of age with either dexamethasone (1.0 mg/kg body mass, intraperitoneally) or saline, daily for 5 days. All of the GC-treated rats had decreased body mass and food intake, and adrenal hypotrophy. Increased glycemia was observed in all of the GC-treated groups and only the 3-month-old female rats were not glucose intolerant. Dexamethasone treatment resulted in hyperinsulinemia and hypertriacylglyceridemia in all of the GC-treated rats. The glucose-stimulated insulin secretion (GSIS) was higher in all of the dexamethasone-treated animals, but it was less pronounced in the older animals. The β-cell mass was increased in the younger male rats treated with dexamethasone. We conclude that dexamethasone treatment induces glucose intolerance in both the 3- and 12-month-old male rats as well as hyperinsulinemia and augmented GSIS. Three-month-old female rats are protected from glucose intolerance caused by GC, whereas 12-month-old female rats developed the same complications that were present in 3- and 12-month-old male rats.

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.

Sign in / Sign up

Export Citation Format

Share Document