Effects of Gonadectomy on the in Vitro and in Vivo Gonadotropin Responses to Gonadotropin-Releasing Hormone in Male and Female Rats*

ABSTRACT Secretion of GH in the rat has been shown to be dependent upon age and sex. Using rat hypothalamic explants in vitro, we have studied the release and hypothalamic content of GH-releasing hormone (GHRH) and somatostatin in male and female Wistar rats at four different ages (10, 30 and 75 days, and 14 months). Basal release of GHRH was not significantly different between male and female rats, but at all ages males released more GHRH in response to stimulation by both 28 and 56 mmol potassium/l than female rats (P<0·05). Neither basal nor potassium-stimulated release of GHRH altered with age. In contrast, both basal and potassium-stimulated secretion of somatostatin increased significantly (P<0·01) with age, but was the same in the two sexes. Hypothalamic GHRH content, as assessed by the extractable tissue content following incubation, was significantly (P<0·01) lower in 10-day-old rats compared with older rats, but remained constant after 30 days of age. Somatostatin content, in contrast, increased progressively with age (P<0·01). The hypothalamic content of the two peptides was the same in both sexes. In conclusion, our findings demonstrate that male rats release more GHRH in vitro than female rats, possibly reflecting the increased pulse amplitude of GH seen in males in vivo; the progressive fall in secretion of GH previously reported during ageing appears to parallel the progressive increase in somatostatin release and content seen in our in-vitro system. Journal of Endocrinology (1989) 123, 53–58

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

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00986.2013 ◽

2014 ◽

Vol 307 (4) ◽

pp. H504-H514 ◽

Cited By ~ 11

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.

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Effects of Ghrelin upon Gonadotropin-Releasing Hormone and Gonadotropin Secretion in Adult Female Rats: In vivo and in vitro Studies

Neuroendocrinology ◽

10.1159/000092753 ◽

2005 ◽

Vol 82 (5-6) ◽

pp. 245-255 ◽

Cited By ~ 124

Author(s):

Rafael Fernández-Fernández ◽

Manuel Tena-Sempere ◽

Víctor M. Navarro ◽

María L. Barreiro ◽

Juan M. Castellano ◽

...

Keyword(s):

Adult Female ◽

Gonadotropin Releasing Hormone ◽

In Vitro Studies ◽

Female Rats ◽

Gonadotropin Secretion ◽

Releasing Hormone

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Study on in vivo and in vitro metabolism of dimethylformamide in male and female rats

Toxicology ◽

10.1016/0300-483x(84)90023-4 ◽

1984 ◽

Vol 29 (3) ◽

pp. 221-234 ◽

Cited By ~ 47

Author(s):

V. Scailteur ◽

E. de Hoffmann ◽

J.P. Buchet ◽

R. Lauwerys

Keyword(s):

In Vitro Metabolism ◽

Female Rats ◽

Male And Female ◽

Male And Female Rats

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Different effects of (CIS+TRANS) 1,3-dichloropropene in renal cortical slices derived from male and female rats

Human & Experimental Toxicology ◽

10.1177/096032719901800207 ◽

1999 ◽

Vol 18 (2) ◽

pp. 106-110

Author(s):

Livia Secondin ◽

Stefano Maso ◽

Andrea Trevisan

Keyword(s):

Reduced Glutathione ◽

Organic Anion ◽

Female Rats ◽

Male Rats ◽

Aminooxyacetic Acid ◽

Male And Female ◽

Male And Female Rats ◽

Cortical Slices

1 Nephrotoxic effects of 1,3-dichloropropene (cis and trans isomers mixture) was investigated in vitro by means of renal cortical slice model in male and female rats, including treatment with metabolism modifiers as an inducer of cytochrome P-450 1A class (β-naphtho-flavone), a reduced glutathione depleting (DL-buthio-nine-[S, R]-sulfoximine), an inhibitor of g-glutamyltransferase (AT-125) and inhibitor of cysteine conjugate β-lyase (aminooxiacetic acid).2 Dose-dependent decrease of p-aminohippurate uptake was observed in male renal cortical slices. Only the high doses (3.0 and 4.0×10-4M) caused a significant loss of organic anion uptake in females.3 β-Naphthoflavone and α-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (AT-125) partially, but significantly, reduced organic anion loss in males. In females, DL-buthionine-[S, R]-sulfoximine significantly increased in females but in males loss of organic anion accumulation caused by 1,3-dichloropropene. Aminooxyacetic acid did not ameliorate 1,3 D effects in vivo and in vitro in male rats. It appeared very toxic for female rats (all rats died) after in vivo injection.4 Sensitivity to nephrotoxicity induced by 1,3-dichlor-opropene in vitro was about double in male than female rats. Reduced glutathione conjugation appeared involved in nephrotoxicity induced in males but in females, probably by means of a chloropropylcysteinylglycine-conjugate formation; slight toxicity in females is likely related to oxidative metabolism.

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Hypothalamic cocaine- and amphetamine-regulated transcript neurons project to areas expressing gonadotropin releasing hormone immunoreactivity and to the anteroventral periventricular nucleus in male and female rats

Neuroscience ◽

10.1016/j.neuroscience.2003.12.045 ◽

2004 ◽

Vol 125 (3) ◽

pp. 735-748 ◽

Cited By ~ 66

Author(s):

T.A Rondini ◽

S.P Baddini ◽

L.F Sousa ◽

J.C Bittencourt ◽

C.F Elias

Keyword(s):

Gonadotropin Releasing Hormone ◽

Female Rats ◽

Male And Female ◽

Releasing Hormone ◽

Male And Female Rats ◽

Periventricular Nucleus

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EFFECTS OF TESTOSTERONE ON PITUITARY CORTICOTROPHIN AND ADRENAL STEROID SECRETION IN MALE AND FEMALE RATS

Acta Endocrinologica ◽

10.1530/acta.0.0430601 ◽

1963 ◽

Vol 43 (4) ◽

pp. 601-608 ◽

Cited By ~ 17

Author(s):

Julian I. Kitay

Keyword(s):

Plasma Corticosterone ◽

Female Rats ◽

Male Rats ◽

Intact Male ◽

Male And Female ◽

Adrenal Steroid ◽

Adrenal Steroidogenesis ◽

Male And Female Rats

ABSTRACT Administration of a depot testosterone preparation to male and female rats resulted in no change in body or pituitary weight in either sex. Pituitary corticotrophin content was unaltered in male animals but was reduced in females. Adrenal weights and adrenal RNA and DNA contents were decreased in both sexes. Plasma corticosterone concentrations were unaffected in males but were reduced in female rats after stress or corticotrophin injection. Hepatic reduction of ring A in vitro and biological half-life of corticosterone in vivo were unchanged in male animals but impaired in females. Testosterone administration to intact male rats significantly increased adrenal steroidogenesis measured in vitro. A significant decrease in steroid production was found in intact females but increased steroidogenesis was observed in adrenals from testosterone-treated oophorectomized animals. No effect was obtained following addition of testosterone directly in vitro. The data suggest that testosterone leads both to diminution of corticotrophin secretion and enhancement of adrenal steroid secretory capacity. In intact female rats, these effects are complicated by suppression of oestrogen secretion, the effects of which have been reported previously.

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Toxicity of orally administered food-grade titanium dioxide nanoparticles

10.21203/rs.3.rs-33962/v1 ◽

2020 ◽

Author(s):

Hyoung-Yun Han ◽

Eunsol Seong ◽

Mi-Jin Yang ◽

Cheolho Yoon ◽

Gwang Hee Lee ◽

...

Keyword(s):

Titanium Dioxide ◽

Female Rats ◽

International Agency ◽

In Vitro Test ◽

Ags Cells ◽

Male And Female ◽

Food Grade ◽

Male And Female Rats

Abstract Background The International Agency for Research on Cancer classified as a Group B carcinogen inhaled titanium dioxide (TiO 2 ) nanoparticles, and France banned the application of TiO 2 nanoparticles as a food additive based on the insufficient oral toxicity data. However, there still remains controversial due to the insufficient evidence for its safety. Here, we explored the toxicity of food-grade TiO 2 nanoparticles (hereafter, E171) in vivo and in vitro . Methods We investigated the subchronic toxic responses of E171 (0, 10, 100, and 1,000 mg/kg) under the Good Laboratory Practice (GLP) system and tried to elucidate the possible toxic mechanism using AGS cells, a human stomach epithelial cell line. Results There were no dose-related changes in the Organization for Economic Co-operation and Development test guideline-related endpoints. Meanwhile, E171 deeply penetrated cells lining the stomach tissues of rats administered the maximum dose, and blood IgM (male and female) and GM-CSF (female) levels were significantly lower in the E171-treated rats than in the control rats. Colonic SOD-1 (male and female) and SOD-2 (female) protein levels decreased with increasing Ti accumulation. When exposed to AGS cells for 24 h, E171 (40 μg/mL) located in the perinuclear region. The E171 treatment affected expression of ER stress-related proteins but did not induce cell death up to the used maximum concentration (40 μg/mL). A gene profile analysis also showed that immune response-related microRNAs were most strongly affected by E171 exposure. Conclusion Considering the potential toxicity observed in vivo and in vitro test, we concluded that the NOAEL of E171 for 90-days repeated oral administrations is less than 1,000 mg/kg for both male and female rats. Additionally, E171 may attenuate host's defense function against foreign bodies by decreasing antioxidant capacity, thus we propose that chronic toxicity studies on E171 are required to warrant the safety for use in the food industry.

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