scholarly journals The Disruptive Effects of Estrogen Removal Before Puberty on Risk for Binge Eating in Female Rats

2020 ◽  
Vol 8 (5) ◽  
pp. 839-856 ◽  
Author(s):  
Kelly L. Klump ◽  
Elaine B. Sinclair ◽  
Britny A. Hildebrandt ◽  
Deborah A. Kashy ◽  
Shannon O’Connor ◽  
...  
Keyword(s):  
Animal Model ◽  
Binge Eating ◽  
Brain Development ◽  
Causal Effects ◽  
Female Rats ◽  
Adult Females ◽  
Ovx Rats ◽  
Adolescent Brain Development ◽  
Intact Rats

Recent research suggests that estrogen is protective against binge eating in adult females and that pubertal estrogen may be critical for these effects. Nonetheless, to date, no study has examined the role of pubertal estrogen in adult binge-eating phenotypes in females, potentially because of difficulties experimentally manipulating estrogen in humans to examine causal effects. We used a novel animal model to examine whether estrogen removal before puberty (via prepubertal ovariectomy, or P-OVX) increased rates of binge-eating-prone (BEP) phenotypes in adulthood in female rats. Seventy-seven P-OVX rats and 79 intact rats were followed from prepuberty into adulthood and phenotyped for BEP status in adulthood. Results showed significantly increased rates (~2–8 times higher) of adult BEP phenotypes in P-OVX compared with intact rats. Findings confirm that estrogen removal substantially increases later risk for binge eating in females, potentially by disrupting typical adolescent brain development.

POSITIVE FEEDBACK ACTION OF OESTRADIOL ON GONADOTROPHIN RELEASE IN 15 DAY OLD FEMALE RATS

1977 ◽  
Vol 86 (2) ◽  
pp. 263-272 ◽  
Author(s):  
J. Kronibus ◽  
W. Wuttke
Keyword(s):  
Column Chromatography ◽  
Positive Feedback ◽  
Female Rats ◽  
Intact Control ◽  
Partial Separation ◽  
Ovx Rats ◽  
Serum Lh ◽  
The Mean ◽  
Intact Rats

ABSTRACT Female rats were ovariectomized (ovx), adrenalectomized (adx) or both (adx-ovx) on day 8 after birth. The serum gonadotrophin concentrations on day 15 were higher in ovx and adx-ovx rats than in sham-operated or untreated controls of the same age. Intact animals on day 15 had higher LH and FSH levels compared with adult, dioestrous levels, and a number of LH peaks were observed. After partial separation of oestradiol (LH 20 column chromatography) from other lipid substances which interfere with the radioimmunoassay for oestradiol, levels of oestradiol were undetectable in ovx and in adx-ovx animals on day 15 but concentrations were relatively high in intact or adx rats. To test whether the high gonadotrophin concentrations in 15-day-old intact rats were due to a positive feedback action of oestradiol, silastic tubes containing different amounts of oestradiol were implanted on day 8 at the time of adrenalectomy and ovariectomy. The mean serum LH and FSH concentrations were increased on day 15 in those animals in which silastic tube implantation resulted in physiological oestradiol levels. These elevated gonadotrophin values were due to a number of peak levels. Injection of 600 μg progesterone on day 15, 8 h before decapitation resulted in high FSH levels in all the implanted animals, whereas LH levels were still variable from one animal to another. This situation is very similar to that in intact control rats and it is concluded that the hypothalamo-pituitary axis in 15-day-old female rats reacts to an oestrogenic stimulus followed by a progestational reaction as does the adult "gonadostat". This would account for the premature, pre-ovulatory type of LH peaks.

Hypothalamic obesity in female rats in absence of vagally mediated hyperinsulinemia

1980 ◽  
Vol 239 (6) ◽  
pp. E437-E441 ◽  
Author(s):  
B. M. King ◽  
G. R. Phelps ◽  
L. A. Frohman
Keyword(s):  
Fasting Glucose ◽  
Insulin Response ◽  
Female Rats ◽  
Oral Glucose ◽  
Fasting Insulin ◽  
Hypothalamic Obesity ◽  
Glucose Levels ◽  
Rapid Absorption ◽  
Intact Rats

In order to assess the role of vagally mediated hyperinsulinemia in hypothalamic obesity, plasma insulin and glucose levels were assayed in vagotomized and sham-vagotomized female rats after a 6-h fast and after a measured glucose meal both before and 10–14 days after ventromedial hypothalamic (VMH) lesions. Both groups displayed similar gains in body weight in the first 10 days after VMH lesions, but only the sham-vagotomized VMH-lesioned animals displayed elevated fasting insulin levels. Fasting glucose levels did not differ either before or after the lesion. The insulin response to oral glucose was increased in VMH rats, both in vagotomized and sham-vagotomized animals, and it is concluded that the hyperresponsiveness to oral glucose is independent of vagal mediation. Vagotomy markedly exaggerated the glucose and insulin response to oral glucose loading in both intact rats and rats with VMH lesions, probably as a result of more rapid absorption of glucose from the intestine. It is concluded that the fasting hyperinsulinemia that is characteristic of VMH animals is under vagal control and that its elimination does not prevent the development of obesity.

scholarly journals Male gender increases sensitivity to proteinuria induced by mild NOS inhibition in rats: role of sex hormones

2000 ◽  
Vol 279 (4) ◽  
pp. F664-F670 ◽  
Author(s):  
A. Marjan G. Verhagen ◽  
Diana M. A. Attia ◽  
Hein A. Koomans ◽  
Jaap A. Joles
Keyword(s):  
Nitric Oxide ◽  
Sex Hormones ◽  
Oxide System ◽  
Female Rats ◽  
Male Rats ◽  
Time Control ◽  
Ovx Rats ◽  
Increased Sensitivity ◽  
Dose Dependent Increase

Men are at greater risk for renal injury than women. We studied whether male rats are more sensitive to the hypertensive and proteinuric effects of chronic nitric oxide sythase (NOS) inhibition than female rats. In addition, we studied whether androgens or estrogens are responsible for differences in sensitivity to proteinuria induced by chronic NOS inhibition. Females and males were treated with 10, 20, 30, and 100 mg/l N ω-nitro-l-arginine (l-NNA) during 24 wk. Systolic blood pressure (SBP) and proteinuria were measured regularly and compared with time-control measurements in control females and males. In females and males treatment with 10 mg/l l-NNA had no effect on SBP or proteinuria. Treatment with 20, 30, and 100 mg/l l-NNA resulted in a dose-dependent increase in SBP that was similar in males and females. However, females treated with 20 and 30 mg/ll-NNA were resistant to the development of proteinuria: maximum values were 16 ± 7 and 46 ± 21, respectively, vs. 16 ± 3 mg/day in controls, whereas males treated with those doses showed an increase in proteinuria [139 ± 35 ( P< 0.05) and 318 ± 82 ( P < 0.01), respectively, vs. 55 ± 11 mg/day in controls]. Treatment with 100 mg/ll-NNA increased proteinuria similarly in both females and males. To study the role of sex hormones in differences in sensitivity to proteinuria induced by mild chronic NOS inhibition, treatment with 20 mg/l l-NNA was repeated in ovariectomized (Ovx) and orchidectomized rats. Ovariectomy did not affect the increase in SBP caused by 20 mg/l l-NNA, but, in contrast to intact females, this dose of l-NNA did cause Ovx rats to develop proteinuria (51 ± 16 vs. 16 ± 7 mg/day in control Ovx rats; P < 0.05). Orchidectomy completely prevented the increased SBP as well as proteinuria induced by 20 mg/ll-NNA in male rats. In conclusion, male rats are more sensitive than female rats to develop proteinuria induced by mild chronic NOS inhibition. Estrogens provide some protection in females, whereas androgens are responsible for the increased sensitivity of male rats to proteinuria induced by mild chronic NOS inhibition. Risk factors associated with a compromised nitric oxide system may be more detrimental to the kidney in men than in women.

scholarly journals Induction of experimental mammary carcinogenesis in rats with 7,12-dimethylbenz(a)anthracene

2004 ◽  
Vol 59 (5) ◽  
pp. 257-261 ◽  
Author(s):  
Alfredo Carlos S. D. Barros ◽  
Elisa Naomi K. Muranaka ◽  
Lincon Jo Mori ◽  
Christina Helena T. Pelizon ◽  
Kyoshi Iriya ◽  
...  
Keyword(s):  
Animal Model ◽  
Light Microscopy ◽  
Breast Tumor ◽  
Mammary Carcinogenesis ◽  
Mammary Glands ◽  
Female Rats ◽  
Histopathological Analysis ◽  
Breast Carcinomas ◽  
Sprague Dawley

PURPOSE: To test an experimental model of chemical mammary carcinogenesis induction in rats. METHODS: Twenty young virgin Sprague-Dawley female rats, aged 47 days, received 20 mg of 7,12-dimethylbenz(a)anthracene (DMBA) intragastrically by gavage. Afterwards, at 8 and 13 weeks, their mammary glands were examined. At the end of the experiment, the animals were sacrificed, and the mammary tumors were measured and weighed. Tumor fragments were analyzed using light microscopy. RESULTS: Eight weeks after DMBA injection, 16 rats presented at least 1 breast tumor (80%). After 13 weeks, all of them (100%) developed breast carcinomas that were confirmed by histopathological analysis. CONCLUSION: This experimental animal model of chemical mammary induced carcinogenesis is feasible and can be used in further experiments on the role of tumorigenic biomodulator substances.

scholarly journals Modulation of responses to stress by estradiol benzoate and selective estrogen receptor agonists

2010 ◽  
Vol 205 (3) ◽  
pp. 253-262 ◽  
Author(s):  
Lidia I Serova ◽  
Heather A Harris ◽  
Shreekrishna Maharjan ◽  
Esther L Sabban
Keyword(s):  
Gene Expression ◽  
Estrogen Receptor ◽  
Hpa Axis ◽  
Immobilization Stress ◽  
Estradiol Benzoate ◽  
Female Rats ◽  
Reduced Body ◽  
Ovx Rats ◽  
Selective Agonists

Previously, pretreatment with estradiol benzoate (EB) was found to modulate the response of hypothalamic–pituitary–adrenal (HPA) axis and gene expression in several catecholaminergic neuronal locations in ovariectomized (OVX) rats exposed to single immobilization stress (IMO). Here, we investigated the role of estrogen receptor (ER) subtypes, using selective agonists for ERα (propyl pyrazole triol, PPT) or ERβ (WAY-200070) in two major central noradrenergic systems and the HPA axis after exposure to single and repeated IMO. OVX female rats received 21 daily injections of either EB (25 μg/kg), PPT (10 mg/kg), WAY-200070 (10 mg/kg), or vehicle. Injections of EB and PPT, but not WAY-200070, elicited reduced body weight and increased uterine weight, showing their selectivity. Both EB and PPT increased corticosterone levels about two- to threefold, but prevented any further rise with either single or repeated IMO, indicating an ERα (ESR1)-, but not ERβ (ESR2)-, mediated mechanism. In the locus coeruleus (LC), the rise in dopamine-β-hydroxylase (Dbh) mRNA with both stress paradigms was abrogated in EB- or PPT-injected animals. However, WAY-200070 blocked the response of DBH mRNA to single IMO but not to repeated IMO. In the nucleus of the solitary tract (NTS), the rise in tyrosine hydroxylase and DBH mRNAs with both IMOs was absent, or greatly attenuated, in EB- or PPT-treated rats. In most cases, WAY-200070 inhibited the response to single IMO but not to repeated IMO. The results demonstrate that pretreatment with estradiol, or ER-selective agonists, modulates the stress-triggered induction of gene expression of norepinephrine biosynthetic enzymes in LC and NTS, with ER selectivity depending on duration of the stress.

scholarly journals Bone effects of hexarelin, a GH-releasing peptide, in female rats: influence of estrogen milieu

2002 ◽  
pp. 855-862 ◽  
Author(s):  
V Sibilia ◽  
D Cocchi ◽  
I Villa ◽  
N Lattuada ◽  
A Soglian ◽  
...  
Keyword(s):  
Lumbar Vertebrae ◽  
Physiological Saline ◽  
Secretory Response ◽  
Female Rats ◽  
Bone Area ◽  
Mineral Density ◽  
Ovx Rats ◽  
Igf I ◽  
Turnover Markers ◽  
Intact Rats

OBJECTIVE: The present study was performed to evaluate the potential influence of the estrogen milieu in modulating the effects of GH/IGF stimulation by a GH-releasing peptide, hexarelin (HEXA), on bone metabolism and mineral density in middle-aged female rats. METHODS: HEXA was administered for 60 days (50 microg/kg s.c. twice a day) to intact and ovariectomized (OVX) 11-month-old female rats and changes in bone parameters were evaluated with respect to those of the same rats under baseline conditions and with those of control rats (intact and OVX) administered isovolumetric amounts of physiological saline. Serum total alkaline phosphatase (ALP) and urinary deoxypyridinoline (Dpd) were measured before and at various times during HEXA treatment. Bone mineral content (BMC) and density of lumbar vertebrae and femoral mid-diaphyses were measured by dual energy X-ray absorptiometry before and after treatment. In all groups, serum IGF-I levels were determined before and during treatment and the GH secretory response to HEXA was assessed at the end of the experiment. RESULTS: In intact rats, HEXA did not modify Dpd urinary excretion, induced a trend toward an increase of serum ALP activity and significantly increased BMC (+6.5%) and bone area (+4.1%) only at lumbar vertebrae. In OVX rats, HEXA did not modify the OVX-induced increase in bone turnover markers (Dpd and ALP) and did not affect the OVX-induced vertebral bone loss, but significantly increased BMC (+7.2%) and bone area (+5.3%) at femoral mid-diaphyses. HEXA significantly increased serum IGF-I levels at day 14, but not at day 60, in both intact and OVX rats, whereas the GH secretory response to HEXA was higher in the former than in the latter. CONCLUSIONS: Overall, the present data demonstrate that chronic HEXA treatment increases BMC and bone area at lumbar vertebrae in intact rats and at femoral diaphyses in OVX rats. The different sensitivity to HEXA of the skeletal districts examined is related to the estrogen milieu and may reflect a complex interplay between estrogens and GH/IGF function.

The role of palatable food and hunger as trigger factors in an animal model of stress induced binge eating

2003 ◽  
Vol 34 (2) ◽  
pp. 183-197 ◽  
Author(s):  
Mary M. Hagan ◽  
Paula C. Chandler ◽  
Pamela K. Wauford ◽  
Rachel J. Rybak ◽  
Kimberly D. Oswald
Keyword(s):  
Animal Model ◽  
Binge Eating ◽  
Palatable Food ◽  
Trigger Factors

Release and synthesis of FSH by pituitary glands of female rats in vitro

1982 ◽  
Vol 100 (4) ◽  
pp. 499-503 ◽  
Author(s):  
A. A. J. Jenner ◽  
J. de Koning ◽  
G. P. van Rees
Keyword(s):  
Protein Synthesis ◽  
Slow Rate ◽  
Female Rats ◽  
Intact Female ◽  
Ovx Rats ◽  
Basal Release ◽  
Pituitary Glands ◽  
Independent Synthesis ◽  
Intact Rats

Abstract. Anterior hemi-pituitary glands from intact female and ovariectomized (OVX) rats were incubated with or without a maximally effective dose of LRH. During an 8 h incubation, LRH-stimulated release of FSH by pituitary glands from intact rats was biphasic: an initial slow rate of release and, from 2 to 8 h, an enhanced rate of release. Basal release was low up to 4 h, after which a marked increase of the rate of release was measured: from 6 to 8 h there was no difference between the rates of basal and LRH-stimulated release. Basal and LRH-stimulated release of FSH by pituitary glands from OVX rats were high and approximately constant during an 8 h incubation. Both basal and LRH-stimulated release by glands from intact as well as OVX rats were protein synthesis dependent. During the incubations an LRH-independent synthesis of FSH was measured. The results suggest that this synthesis is involved, either directly or indirectly, in increasing the rate of basal release of FSH after 4 h. A comparison of release and synthesis of FSH with those of LH reveals characteristic differences.

scholarly journals Gonadal steroid regulation of renal injury in renal wrap hypertension

2005 ◽  
Vol 288 (3) ◽  
pp. F513-F520 ◽  
Author(s):  
Hong Ji ◽  
Stefano Menini ◽  
Koby Mok ◽  
Wei Zheng ◽  
Carlo Pesce ◽  
...  
Keyword(s):  
Renal Disease ◽  
Renal Injury ◽  
Gonadal Steroids ◽  
Female Rats ◽  
Tubular Damage ◽  
Gonadal Steroid ◽  
Ovx Rats ◽  
17Β Estradiol ◽  
Progressive Renal Disease

Renal injury is greater in male compared with female rats after renal wrap (RW) hypertension. We investigated the role of gonadal steroids in the sex differences in RW disease severity in male (M) and female (F), castrated (Cast), and ovariectomized (OVX) rats and after dihydrotestosterone (DHT) and 17β-estradiol (E2) treatment. Male castration attenuated the severity of RW-induced glomerulosclerosis (GS) [GS index (GSI): RW-M, 2.1 ± 0.2; RW-Cast, 1.3 ± 0.2; RW-Cast+DHT, 2.4 ± 0.4], mean glomerular volume (MGV; μm3 × 106: RW-M, 1.9 ± 0.1; RW-Cast, 1.45 ± 0.15; RW-Cast+DHT, 1.91 ± 0.15), tubular damage, and proteinuria (mg/day: RW-M, 130 ± 8; RW-Cast, 105 ± 5; RW-Cast+DHT, 142 ± 9), whereas DHT treatment abrogated these effects. Ovariectomy increased the GSI (RW-F, 0.69 ± 0.05; RW-OVX, 1.2 ± 0.1; RW-OVX+E2, 0.65 ± 0.05), tubular damage, and MGV (μm3 × 106: RW-F, 1.0 ± 0.06; RW-OVX, 1.5 ± 0.05; RW-OVX+E2, 0.96 ± 0.06), whereas E2 treatment prevented these effects. Furthermore, DHT treatment of RW-OVX animals exacerbated the GSI (1.9 ± 0.19), MGV (1.7 ± 0.2 × 106 μm3), and proteinuria (171 ± 21 mg/day) even further. Our data show that the lack of E2 and presence of androgens contribute to progressive renal disease induced by RW hypertension, suggesting that gonadal steroid status is an independent factor in the greater susceptibility men exhibit toward hypertension-associated renal disease compared with women.

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