scholarly journals Influence of sex and gonadal status of sheep on cortisol secretion in response to ACTH and on cortisol and LH secretion in response to stress: importance of different stressors

2002 ◽  
Vol 173 (1) ◽  
pp. 113-122 ◽  
Author(s):  
AI Turner ◽  
BJ Canny ◽  
RJ Hobbs ◽  
JD Bond ◽  
IJ Clarke ◽  
...  
Keyword(s):  
Sex Differences ◽  
Sex Difference ◽  
Restraint Stress ◽  
Cortisol Response ◽  
Blood Samples ◽  
Response To Stress ◽  
Lh Secretion ◽  
Gonadal Status ◽  
Major Mediator

There are sex differences in the response to stress and in the influence of stress on reproduction which may be due to gonadal steroids but the nature of these differences and the role of the gonads are not understood. We tested the hypotheses that sex and the presence/absence of gonads (gonadal status) will influence the cortisol response to injection of ACTH, insulin-induced hypoglycaemia and isolation/restraint stress, and that sex and gonadal status will influence the secretion of LH in response to isolation/restraint stress. Four groups of sheep were used in each of three experiments: gonad-intact rams, gonadectomised rams, gonad-intact ewes in the mid-luteal phase of the oestrous cycle and gonadectomised ewes. In Experiment 1 (n=4/group), jugular blood samples were collected every 10 min for 6 h; after 3 h, two animals in each group were injected (i.v.) with ACTH and the remaining two animals were injected (i.v.) with saline. Treatments were reversed 5 days later so that every animal received both treatments. Experiment 2 (n=4/group) used a similar schedule except that insulin was injected (i.v.) instead of ACTH. In Experiment 3 (n=5/group), blood samples were collected every 10 min for 16 h on a control day and again 2 weeks later when, after 8 h of sampling, all sheep were isolated and restrained for 8 h. Plasma cortisol was significantly (P<0.05) elevated following injection of ACTH or insulin and during isolation/restraint stress. There were no significant differences between the sexes in the cortisol response to ACTH. Rams had a greater (P<0.05) cortisol response to insulin-induced hypoglycaemia than ewes while ewes had a greater (P<0.05) cortisol response to isolation/restraint stress than rams. There was no effect of gonadal status on these parameters. Plasma LH was suppressed (P<0.05) in gonadectomised animals during isolation/restraint stress but was not affected in gonad-intact animals, and there were no differences between the sexes. Our results show that the sex that has the greater cortisol response to a stressor depends on the stressor imposed and that these sex differences are likely to be at the level of the hypothalamo-pituitary unit rather than at the adrenal gland. Since there was a sex difference in the cortisol response to isolation/restraint, the lack of a sex difference in the response of LH to this stress suggests that glucocorticoids are unlikely to be a major mediator of the stress-induced suppression of LH secretion.

scholarly journals A sex difference in the cortisol response to tail docking and ACTH develops between 1 and 8 weeks of age in lambs

2006 ◽  
Vol 188 (3) ◽  
pp. 443-449 ◽  
Author(s):  
A I Turner ◽  
B J Hosking ◽  
R A Parr ◽  
A J Tilbrook
Keyword(s):  
Sex Differences ◽  
Sex Difference ◽  
Stress Responses ◽  
Combined Treatment ◽  
Cortisol Response ◽  
Male And Female ◽  
Stage Of Development ◽  
Tail Docking ◽  
Response To Stress ◽  
Cortisol Responses

It is important to understand factors that may influence responses to stress, as these factors may also influence vulnerability to pathologies that can develop when stress responses are excessive or prolonged. It is clear that, in adults, the sex of an individual can influence the cortisol response to stress in a stressor specific manner. Nevertheless, the stage of development at which these sex differences emerge is unknown. We tested the hypothesis that there are sex differences in the cortisol response to tail docking and ACTH in lambs of 1 and 8 weeks of age. We also established cortisol responses in males when tail docking was imposed alone and in combination with castration at these ages. In experiment 1, 1 and 8 week old male and female lambs were subjected to sham handling, tail docking or, in males, a combination of tail docking and castration. In experiment 2, we administered ACTH (1.0 IU/kg) to male and female lambs at 1 and 8 weeks of age. There were significant cortisol responses to all treatments at both ages. Sex differences in the cortisol responses to tail docking and ACTH developed between 1 and 8 weeks of age, with females having greater responses than males. The data suggest that the mechanism for the sex difference in response to tail docking may involve the adrenal glands. At both ages, in males, the cortisol response to the combined treatment of tail docking and castration was significantly greater than that for tail docking alone.

scholarly journals Sex Differences in the Ovine Fetal Cortisol Response to Stress

2011 ◽  
Vol 69 (2) ◽  
pp. 118-122 ◽  
Author(s):  
Dino A Giussani ◽  
Andrew J W Fletcher ◽  
David S Gardner
Keyword(s):  
Sex Differences ◽  
Cortisol Response ◽  
Response To Stress ◽  
Ovine Fetal

scholarly journals Activation of the Hypothalamo-Pituitary-Adrenal Axis by Isolation and Restraint Stress during Lactation in Ewes: Effect of the Presence of the Lamb and Suckling

Endocrinology ◽  
2006 ◽  
Vol 147 (7) ◽  
pp. 3501-3509 ◽  
Author(s):  
A. J. Tilbrook ◽  
A. I. Turner ◽  
M. D. Ibbott ◽  
I. J. Clarke
Keyword(s):  
Hpa Axis ◽  
Restraint Stress ◽  
Cortisol Response ◽  
Blood Samples ◽  
Stress Control ◽  
Adrenal Axis ◽  
The Mean ◽  
Presence And Absence ◽  
Pituitary Adrenal Axis

We investigated the effect of the presence and absence of lambs and suckling by lambs to attenuate activation of the hypothalamo-pituitary-adrenal (HPA) axis to isolation and restraint stress in lactating sheep. In experiment 1, blood samples were collected every 10 min from nonlactating (n = 5) and lactating (n = 5) ewes for 4 h before and during stress. In experiment 2, ewes (n = 6) were allocated to 1) nonlactating, 2) lactating with lambs absent, 3) lactating with lambs present but unable to suckle, and 4) lactating with lambs present and able to suckle. Blood samples were collected over 8 h with no stress (control day) and for 4 h before and 4 h during stress (stress day). In experiment 1, the mean (±sem) cortisol concentrations increased significantly (P &lt; 0.05) in nonlactating ewes during stress but did not change in lactating ewes. In experiment 2, cortisol did not vary on the control day or pretreatment of the stress day but increased (P &lt; 0.05) during stress in all groups except lactating ewes with lambs present and able to suckle. The greatest cortisol response occurred in nonlactating ewes followed by lactating ewes with lambs absent and lactating ewes with lambs present but unable to suckle. During stress, the ACTH concentrations increased (P &lt; 0.05) in nonlactating ewes and lactating ewes with lambs absent but not in lactating ewes with lambs present. We conclude that the activity of the HPA axis during isolation and restraint is reduced in lactating ewes and that the presence of lambs increases this level of attenuation.

Sex differences in the effects of amiloride on formalin test nociception in mice

2006 ◽  
Vol 291 (2) ◽  
pp. R335-R342 ◽  
Author(s):  
Mona Lisa Chanda ◽  
Jeffrey S. Mogil
Keyword(s):  
Sex Differences ◽  
Sex Difference ◽  
Formalin Test ◽  
Testosterone Propionate ◽  
Nociceptive Behavior ◽  
Acid Sensing Ion Channels ◽  
Inflammatory Nociception ◽  
Dose Dependent ◽  
Tonic Phase

Amiloride is a nonspecific blocker of acid-sensing ion channels (ASICs) that have been recently implicated in the mediation of mechanical and chemical/inflammatory nociception. Preliminary data using a transgenic model are suggestive of sex differences in the role of ASICs. We report here that systemic administration of amiloride (10–70 mg/kg ip) produces a robust, dose-dependent blockade of late/tonic phase nociceptive behavior on the mouse formalin test (5%; 20 μl) in female but not male mice, completely abolishing the known sex difference in formalin test response. Adult gonadectomy produced a “switching” of sex differences in amiloride efficacy, with castrated males displaying an amiloride blockade and ovariectomized females rendered less sensitive to amiloride. Gonadectomized mice could be switched back to their intact status using chronic estrogen benzoate or testosterone propionate replacement via osmotic minipump (6 μg/day or 250 μg/day, respectively). It is unclear whether this striking sex difference is due to sex-specific involvement of ASICs in pain processing, but the present data represent one of the first demonstrations of pain-related sex differences with no obvious opioid involvement.

scholarly journals Sex differences in Alzheimer’s-related Tau biomarkers and a mediating effect of testosterone

2020 ◽  
Author(s):  
Erin Sundermann ◽  
Matthew S. Panizzon ◽  
Xu Chen ◽  
Murray Andrews ◽  
Douglas Galasko ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Differences ◽  
Sex Difference ◽  
Mediating Effect ◽  
Interactive Effects ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Before And After

Abstract Women show greater pathological Tau biomarkers than men along the Alzheimer’s disease (AD) continuum, particularly among apolipoprotein ε-E4 (APOE4) carriers; however, the reason for this sex difference in unknown. Sex differences often indicate an underlying role of sex hormones. We examined whether testosterone levels might influence this sex difference and the modifying role of APOE4 status. Analyses included 172 participants (25 cognitively normal, 97 mild cognitive impairment, 50 AD participants) from the Alzheimer’s Disease Neuroimaging Initiative (34% female, 54% APOE4+, aged 55–90). We examined the separate and interactive effects of plasma testosterone levels and APOE4 on cerebrospinal fluid phosphorylated-tau181 (p-Tau) levels in the overall sample, and the sex difference in p-Tau levels before and after adjusting for testosterone. A significant APOE4-by-testosterone interaction revealed that lower testosterone levels related to higher p-Tau levels among APOE4 carriers regardless of sex. As expected, women had higher p-Tau levels than men among APOE4 carriers only, yet this difference was eliminated upon adjustment for testosterone. Results suggest that testosterone is protective against p-Tau particularly among APOE4 carriers. The lower testosterone levels that typically characterize women may predispose them to pathological Tau, particularly among female APOE4 carriers.

scholarly journals Cortisol response to stress: The role of expectancy and anticipatory stress regulation

2020 ◽  
Vol 117 ◽  
pp. 104587 ◽  
Author(s):  
Matias M. Pulopulos ◽  
Chris Baeken ◽  
Rudi De Raedt
Keyword(s):  
Cortisol Response ◽  
Stress Regulation ◽  
Response To Stress

276. Sex difference in the effect of cortisol on the LH response of the pituitary to exogenous GnRH in hypothalamo-pituitary disconnected gonadectomised sheep

2005 ◽  
Vol 17 (9) ◽  
pp. 114
Author(s):  
C. A. Stackpole ◽  
I. J. Clarke ◽  
A. I. Turner ◽  
A. J. Tilbrook
Keyword(s):  
Sex Difference ◽  
Breeding Season ◽  
Sex Steroids ◽  
Present Experiment ◽  
Control Period ◽  
Plasma Concentrations ◽  
Saline Infusion ◽  
Sheep Model ◽  
Blood Samples ◽  
Lh Secretion

We have used the hypothalamo-pituitary disconnected (HPD) sheep model to investigate direct pituitary actions of cortisol to suppress LH secretion in response to exogenous GnRH. We previously observed that, during the non-breeding season, treatment with cortisol did not suppress the LH response to GnRH in HPD gonadectomised rams or ewes.1 In the present experiment, we tested the effect of cortisol on the LH response to exogenous GnRH in gonadectomised HPD sheep during the breeding season. Using a cross-over design, HPD gonadectomised Romney Marsh rams (n = 6) and ewes (n = 5) received a saline or cortisol (250 μg/kg/h) infusion for 30 h on each of two days, one week apart. All animals were treated with 125 ng i.v. injections of GnRH every 2 h during a 6h control period preceding the infusion and during the infusion. Jugular blood samples were taken during the control period and the first 6 h and last 6 h of the infusion (over 3 LH pulses). Mean plasma concentrations of LH and LH pulse amplitudes, driven by programmed GnRH injections, were similar in gonadectomised rams and ewes and there were no significant effects of saline infusion between the control periods or the saline infusion in either sex. The amplitude of LH pulses was significantly (P < 0.05) reduced in rams during the first 6 h of the cortisol infusion compared to the control period, but there were no effects of the cortisol infusion in ewes. These data show that, in the absence of sex steroids, there is a sex difference in the mechanism by which cortisol acts at the pituitary to reduce LH secretion in response to exogenous GnRH in HPD gonadectomized sheep during the breeding season. We conclude that the effect of cortisol to reduce secretion of LH involves an action on the pituitary, at least in gonadectomised rams. (1)Stackpole CA, Turner AI, Clarke IJ and Tilbrook AJ (2003) Biology of Reproduction 36(Supplement 1), 288.

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