scholarly journals Sex-specific Stress and Behavioural Responses to Human Experimenters in Rats

2021 ◽  
Author(s):  
Jamshid Faraji ◽  
Mirela Ambeskovic ◽  
Nevyn Sauter ◽  
Jaxson Toly ◽  
Kera Whitten ◽  
...  
Keyword(s):  
Stress Hormones ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Male Rat ◽  
Preclinical Research ◽  
Behavioural Responses ◽  
Human Male ◽  
Male Experimenter ◽  
Cutaneous Temperature ◽  
Induced Changes

AbstractThe sex of the experimenter may cause stress in animal models and be a major confounding factor in preclinical research. We studied the effects of the sex of the experimenter on female and male rat anxiety behaviours using thigmotaxis in the open field test, anxiety-induced changes in brain and back temperature using infra-red thermography, and alterations in plasma concentrations of stress hormones, corticosterone and oxytocin. Female rats displayed consistently exacerbated anxiety-related behaviours along with increased infrared cutaneous temperature during repeated exposure to male experimenters. Experimental stress further intensified thermal responses to a male experimenter, especially in female rats. These behavioural responses to a male experimenter in females were associated with higher circulating corticosterone and lower oxytocin levels. Similar responses were induced by a T-shirt worn by a human male. These findings suggest that emotional and physiological responses of female rats to a male experimenter are influenced by visual and olfactory cues. These results emphasize the need to standardize and report experimenter sex throughout a study to avoid ambiguity in interpretation of the results.

EFFECTS OF TAMOXIFEN ON PLASMA CONCENTRATIONS OF TESTOSTERONE AND GONADOTROPHINS IN THE MALE RAT

1978 ◽  
Vol 79 (2) ◽  
pp. 239-240 ◽  
Author(s):  
A. BARTKE ◽  
M. MASON ◽  
S. DALTERIO ◽  
F. BEX
Keyword(s):  
Plasma Concentration ◽  
Chronic Treatment ◽  
Plasma Concentrations ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Male Rat ◽  
Accessory Reproductive Glands ◽  
Direct Inhibitory Effect ◽  
Testicular Steroidogenesis ◽  
Male Accessory Reproductive Glands

Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545, U.S.A. (Received 2% March 1978) Tamoxifen (trans 1-(p-β-dimethylaminoethoxyphenyl)-1,2-diphenylbut-1-ene; ICI 46,474) is both a potent antioestrogen and a weak oestrogen (Harper & Walpole, 1967) and is thought to act by inhibiting the binding of oestradiol to its cytoplasmic receptor (Jordan & Koerner, 1975). Chronic treatment with tamoxifen causes atrophy of the male accessory reproductive glands and the testicular germinal epithelium in the rat (Harper & Walpole, 1967) and the dog (M. Mason, unpublished data), as well as depression of the plasma concentration of testosterone in the latter species (M. Mason & A. Bartke, unpublished data). A direct inhibitory effect of tamoxifen on testicular steroidogenesis was suspected because treatment of female rats with tamoxifen increases, rather than decreases, the plasma concentration of luteinizing hormone (LH; Watson, Anderson, Alam, O'Grady & Heald, 1975). The possibility that an antioestrogen might act directly is of interest since

Effects of ageing and exogenous melatonin on pituitary responsiveness to GnRH in rats

Reproduction ◽  
2000 ◽  
pp. 151-156 ◽  
Author(s):  
E Diaz ◽  
D Pazo ◽  
AI Esquifino ◽  
B Diaz
Keyword(s):  
Body Weight ◽  
Reproductive System ◽  
Plasma Concentrations ◽  
Pituitary Hormones ◽  
Female Rats ◽  
Control Groups ◽  
Melatonin Treatment ◽  
Exogenous Melatonin ◽  
Reproductive Axis ◽  
Effect Of Age

The effect of age and melatonin on the activity of the neuroendocrine reproductive system was studied in young cyclic (3-5 months-old), and old acyclic (23-25 month-old) female rats. Pituitary responsiveness to a bolus of GnRH (50 ng per 100 g body weight) was assessed at both reproductive stages in control and melatonin-treated (150 micrograms melatonin per 100 g body weight each day for 1 month) groups. After this experiment, female rats were treated for another month to study the influence of ageing and melatonin on the reproductive axis. Plasma LH, FSH, prolactin, oestradiol and progesterone were measured. A positive LH response to GnRH was observed in both control groups (cyclic and acyclic). However, a response of greater magnitude was observed in old acyclic rats. Melatonin treatment reduced this increased response in acyclic rats and produced a pituitary responsiveness similar to that of young cyclic rats. FSH secretion was independent of GnRH administration in all groups, indicating desynchronization between LH and FSH secretion in response to GnRH in young animals and during senescence. No effect on prolactin was observed. Significantly higher LH (3009.11 +/- 1275.08 pg ml(-1); P < 0.05) and FSH concentrations (5879.28 +/- 1631.68 pg ml(-1); P < 0.01) were seen in acyclic control rats. After melatonin treatment, LH (811.11 +/- 89.71 pg ml(-1)) and FSH concentrations (2070 +/- 301.62 pg ml(-1)) decreased to amounts similar to those observed in young cyclic rats. However, plasma concentrations of oestradiol and progesterone were not reduced. In conclusion, the results of the present study indicate that, during ageing, the effect of melatonin is exerted primarily at the hypothalamo-pituitary axis rather than on the ovary. Melatonin restored the basal concentrations of pituitary hormones and pituitary responsiveness to similar values to those observed in young rats.

Sexual Behavior is Enhanced by Regular, Repeated Mating from Young Adulthood to Middle Age in Female Long-Evans Rats

2020 ◽  
Vol 13 (2) ◽  
pp. 169-177
Author(s):  
Fay A. Guarraci ◽  
Chantal M.F. Gonzalez ◽  
Devon Lucero ◽  
Lourdes K. Davis ◽  
Sarah H. Meerts
Keyword(s):  
Sexual Behavior ◽  
Mating Behavior ◽  
Preference Test ◽  
Sexual History ◽  
Female Rats ◽  
Male Rat ◽  
Female Rat ◽  
Repeated Mating ◽  
First Time ◽  
Mating Tests

Background: Aging is associated neuroendocrine changes in women. Animals can be used to model these changes, as well as changes in reproductive behavior. Objective: The current study was designed to characterize mating behavior across age and assess the effects of age and sexual history on mating behavior. Methods: Sexual motivation was assessed using the partner-preference test, in which a female rat is given the choice to interact with a same-sex conspecific or a sexually-vigorous male rat, with which she can mate. Results: Across repeated mating tests (2-12 months of age), female rats spent more time with the male, displayed more solicitation behaviors, were less likely to leave the male after mounts, but visited both stimulus animals less frequently. Comparing a separate group of age-matched, hormoneyoked female rats mated for the first time at 12 months of age to female rats mated for the first time at 2 months of age showed that the 12 month rats visited both stimulus animals less, were less likely to leave the male after mounts, took longer to return to the male after mounts, and displayed fewer solicitation behaviors than their younger counterparts. Relative to middle-aged female rats once they were sexually experienced, 12 month naïve rats spent less time with the male, were more likely to leave the male after mounts, and displayed fewer solicitation behaviors. Furthermore, 12 month naïve rats failed to discriminate between the stimulus animals, visiting both stimulus animals at the same rate unlike 2 month naïve or 12 month experienced rats. Conclusion: Taken together, these results suggest that aging affects some measures of sexual behavior, but most effects of age can be mitigated by regular, repeated mating.

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

scholarly journals Increased bioactivation of dihaloalkanes in rat liver due to induction of class Theta glutathione S-transferase T1-1

1998 ◽  
Vol 335 (3) ◽  
pp. 619-630 ◽  
Author(s):  
Philip J. SHERRATT ◽  
Margaret M. MANSON ◽  
Anne M. THOMSON ◽  
Erna A. M. HISSINK ◽  
Gordon E. NEAL ◽  
...  
Keyword(s):  
Western Blotting ◽  
Rat Liver ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Female Rat ◽  
Glutathione S Transferase ◽  
Chemopreventive Agents ◽  
Cytoplasmic Staining ◽  
Potent Inducer

A characteristic feature of the class Theta glutathione S-transferase (GST) T1-1 is its ability to activate dichloromethane and dibromoethane by catalysing the formation of mutagenic conjugates. The level of the GSTT1 subunit within tissues is an important determinant of susceptibility to the carcinogenic effects of these dihaloalkanes. In the present study it is demonstrated that hepatic GST activity towards these compounds can be elevated significantly in female and male Fischer-344 rats by feeding these animals on diets supplemented with cancer chemopreventive agents. Immunoblotting experiments showed that increased activity towards the dihaloalkanes is associated with elevated levels of the GSTT1 subunit in rat liver. Sex-specific effects were observed in the induction of GSTT1 protein. Amongst the chemopreventive agents tested, indole-3-carbinol proved to be the most potent inducer of hepatic GSTT1 in male rats (6.2-fold), whereas coumarin was the most potent inducer of this subunit in the livers of female rats (3.5-fold). Phenobarbital showed significant induction of GSTT1 only in male rat liver and had little effect in female rat liver. Western blotting showed that class Alpha, Mu and Pi GST subunits are not co-ordinately induced with GSTT1, indicating that the expression of GSTT1 is determined, at least in part, by mechanisms distinct from those that regulate levels of other transferases. The increase in amount of hepatic GSTT1 protein was also reflected by an increase in the steady-state level of mRNA in response to treatment with chemopreventive agents and model inducers. Immunohistochemical detection of GSTT1 in rat liver supported the Western blotting data, but showed, in addition to cytoplasmic staining, significant nuclear localization of the enzyme in hepatocytes from some treated animals, including those fed on an oltipraz-containing diet. Significantly, the hepatic level of cytochrome P-450 2E1, an enzyme which offers a detoxification pathway for dihaloalkanes, was unchanged by the various inducing agents studied. It is concluded that the induction of GSTT1 by dietary components and its localization within cells are important factors that should be considered when assessing the risk dihaloalkanes pose to human health.

PLASMA PROLACTIN AND PROGESTERONE RESPONSES TO MATING ARE ALTERED IN AGED RATS

1981 ◽  
Vol 90 (2) ◽  
pp. 179-191 ◽  
Author(s):  
S. HENDRICKS ◽  
C. A. BLAKE
Keyword(s):  
Plasma Concentrations ◽  
External Jugular Vein ◽  
Female Rats ◽  
Plasma Prolactin ◽  
Aged Rats ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Plasma Progesterone ◽  
The One ◽  
The Right

The effects of varying amounts of copulatory stimulation on patterns of plasma concentrations of prolactin and progesterone were evaluated in 3- and 12-month-old female rats. The 12-month-old group included rats which still exhibited oestrous cycles and rats in persistent vaginal oestrus (PVO). The extent of copulatory stimulation was defined by the number of intromissions received during mating: ≤5,15 or > 50. Blood samples were drawn over the 8 days after mating through a cannula inserted into the right external jugular vein. Plasma from the samples was assayed for prolactin and progesterone. In aged but still cyclic rats, pregnancy rates were positively correlated with the number of intromissions received during mating. Only one rat in PVO became pregnant. All animals which became pregnant and rats in PVO which, after mating, exhibited a disruption of the pattern of PVO, showed the nocturnal surge of plasma prolactin characteristic of pregnant and pseudopregnant rats. While these surges persisted until day 8 after mating in pregnant animals, they were absent by this time in the rats in PVO. Prolactin surges were present in some but not all of the aged rats which did not become pregnant. Progesterone concentrations were raised in all pregnant animals except the one pregnant rat in PVO and, while not related to the number of intromissions, concentrations were higher 8 days after mating in young compared with those in aged pregnant rats. Plasma progesterone was low in rats in PVO regardless of disruption of the pattern of PVO. We have concluded that the failure of limited copulatory stimulation to induce pregnancy in older rats results, at least in part, from its failure to initiate nocturnal prolactin surges. Nevertheless, our data suggest that matings which are not experimentally limited should provide ample stimulation to establish such surges. Although reduced plasma concentrations of prolactin and progesterone at pro-oestrus and reduced plasma progesterone through part of gestation may contribute to decreasing fertility in aged rats, other unidentified factors appear to be involved in mediating the capacity of extensive copulatory stimulation to induce pregnancy in these animals.

scholarly journals EFFECT OF YOHIMBINE ON CLOMIPRAMINE-INDUCED SEXUAL DYSFUNCTION IN MALE RATS

2017 ◽  
Vol 10 (2) ◽  
pp. 92
Author(s):  
Devangam Sheshadri Shekar
Keyword(s):  
Sexual Behavior ◽  
Sexual Dysfunction ◽  
Histopathological Examination ◽  
Red Light ◽  
Female Rats ◽  
Male Rats ◽  
Male Rat ◽  
Testicular Damage

Object: The present investigation has been carried out to find out the effect of yohimbine on clomipramine-induced sexual dysfunction in male rats.Methods: The male rats were treated with clomipramine and yohimbine simultaneously for 60 days. During the treatment, all the male rats werechallenged with the female rats which are in estrous phase and their sexual behavior was observed under dim red light. Half of the animals in each group and remaining on 60 day were sacrificed, blood was collected and serum separated. Testis was collected and preserved in 10% formalin forsubsequent histopathological examination. thResults: The study reveals that yohimbine failed to antagonize the clomipramine-induced sexual dysfunction in male rats in all aspects, except thepartial improvement in the sexual behavior.Conclusion: Yohimbine a well-known aphrodisiac failed to antagonize the clomipramine-induced sexual dysfunction in male rats. The decrease intestosterone levels, a decrease in spermatozoa count were continued even in the presence of yohimbine except improvement in the sexual behaviorparameters. Hence, yohimbine could not be a safe antidote against clomipramine-induced sexual dysfunction in male rats.Keywords: Yohimbine, Clomipramine, Testosterone, Male rat sexual competence, Testicular damage.

scholarly journals Impact of Gender and Age on Hyperthermia-Induced Changes in Respiration of Liver Mitochondria

Medicina ◽  
2018 ◽  
Vol 54 (4) ◽  
pp. 62 ◽  
Author(s):  
Giedrė Šilkūnienė ◽  
Rasa Žūkienė ◽  
Zita Naučienė ◽  
Laima Degutytė-Fomins ◽  
Vida Mildažienė
Keyword(s):  
Thermal Inactivation ◽  
Liver Mitochondria ◽  
Female Rats ◽  
Ros Generation ◽  
Age Group ◽  
Male And Female Rats ◽  
Gender And Age ◽  
Induced Changes ◽  
Gender Dependence ◽  
Malate Oxidation

Aim: This study aimed to compare hyperthermia-induced changes in respiration and generation of reactive oxygen species (ROS) in liver mitochondria derived from animals of different gender and age. Methods: The effects of hyperthermia (40–47 °C) on oxidation of different substrates and ROS production were estimated in mitochondria isolated from the liver of male and female rats of the 1–1.5, 3–4, or 6–7 months age. Results: Gender-dependent differences in response of respiration to hyperthermia were the highest at 3–4 months of age, less so at 6–7 months of age, and only minor at juvenile age. Mild hyperthermia (40–42 °C) stimulated pyruvate + malate oxidation in mitochondria of females, but inhibited in mitochondria of males in the 3–4 month age group. The resistance of mitochondrial membrane to hyperthermia was the highest at 3–4 month males, and the lowest in the 6–7 month age group. Inhibition of glutamate + malate oxidation by hyperthermia was caused by thermal inactivation of glutamate dehydrogenase. ROS generation at 37 °C was higher at 1–1.5 month of age, but the increase in ROS generation with rise in temperature in this age group was the smallest, and the strongest in 6–7 month old animals of both genders. Conclusions: The response to hyperthermia varies during the first 6–7 months of life of experimental animals: stronger gender dependence is characteristic at 3–4 months of age, while mitochondria from 6–7 months animals are less resistant to hyperthermia.

High-fat diet induced changes in lumbar vertebra of the male rat offsprings

2016 ◽  
Vol 118 (7) ◽  
pp. 711-721 ◽  
Author(s):  
Zeljka Peric Kacarevic ◽  
Darija Snajder ◽  
Andela Maric ◽  
Nikola Bijelic ◽  
Olga Cvijanovic ◽  
...  
Keyword(s):  
High Fat Diet ◽  
Lumbar Vertebra ◽  
Male Rat ◽  
High Fat ◽  
Induced Changes

Influence of carnitine supplementation on muscle substrate and carnitine metabolism during exercise

1988 ◽  
Vol 64 (6) ◽  
pp. 2394-2399 ◽  
Author(s):  
M. Soop ◽  
O. Bjorkman ◽  
G. Cederblad ◽  
L. Hagenfeldt ◽  
J. Wahren
Keyword(s):  
Prolonged Exercise ◽  
Carnitine Supplementation ◽  
Bicycle Exercise ◽  
Plasma Carnitine ◽  
Human Male ◽  
Carnitine Metabolism ◽  
Exercise Induced ◽  
Induced Changes ◽  
Male Subjects ◽  
Free Plasma

We examined 1) the effect of L-carnitine supplementation on free fatty acid (FFA) utilization during exercise and 2) exercise-induced alterations in plasma levels and skeletal muscle exchange of carnitine. Seven moderately trained human male subjects serving as their own controls participated in two bicycle exercise sessions (120 min, 50% of VO2max). The second exercise was preceded by 5 days of oral carnitine supplementation (CS; 5 g daily). Despite a doubling of plasma carnitine levels, with CS, there were no effects on exercise-induced changes in arterial levels and turnover of FFA, the relation between leg FFA inflow and FFA uptake, or the leg exchange of other substrates. Heart rate during exercise after CS decreased 7–8%, but O2 uptake was unchanged. Exercise before CS induced a fall from 33.4 +/- 1.6 to 30.8 +/- 1.0 (SE) mumol/l in free plasma carnitine despite a release (2.5 +/- 0.9 mumol/min) from the leg. Simultaneously, acylated plasma carnitine rose from 5.0 +/- 1.0 to 14.2 +/- 1.4 mumol/l, with no evidence of leg release. Consequently, total plasma carnitine increased. We concluded that in healthy subjects CS does not influence muscle substrate utilization either at rest or during prolonged exercise and that free carnitine released from muscle during exercise is presumably acylated in the liver and released to plasma.

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