Relationship between growth hormone-releasing hormone and somatostatin in the rat: effects of age and sex on content and in-vitro release from hypothalamic explants

1989 ◽  
Vol 123 (1) ◽  
pp. 53-58 ◽  
Author(s):  
F. Ge ◽  
S. Tsagarakis ◽  
L. H. Rees ◽  
G. M. Besser ◽  
A. Grossman
Keyword(s):  
In Vitro Release ◽  
Pulse Amplitude ◽  
Female Rats ◽  
Male Rats ◽  
Male And Female ◽  
Releasing Hormone ◽  
Male And Female Rats ◽  
Age And Sex

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

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

2014 ◽  
Vol 307 (4) ◽  
pp. H504-H514 ◽  
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.

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

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.

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

1963 ◽  
Vol 43 (4) ◽  
pp. 601-608 ◽  
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.

Effect of age on the 3,5,3′-tri-iodothyronine-induced increase in sugar uptake in rat thymocytes

1986 ◽  
Vol 110 (3) ◽  
pp. 511-515 ◽  
Author(s):  
J. Segal ◽  
B. R. Troen
Keyword(s):  
Female Rats ◽  
In Vivo Studies ◽  
Sugar Uptake ◽  
Male And Female Rats ◽  
Old Rats ◽  
Effect Of Age ◽  
Age And Sex ◽  
In Cells

ABSTRACT The effect of age on the responsiveness of rat thymocytes to 3,5,3′-tri-iodothyronine (T3) was studied. It has been demonstrated previously that the plasma membrane-mediated effect of T3 to increase sugar uptake by rat thymocytes is influenced by age and sex. In both sexes, T3 given in vitro stimulated sugar uptake in cells from animals of 15 days of age, had no effect at 21 days and was again effective at 26 days. In the male, thymocytes from animals of 40 days of age and older were refractory to T3. However, in the female, T3, although less effective than in cells from 26-day-old animals, remained stimulatory in cells from 40- and 60-day-old rats. T3 had no effect in cells from animals of 90 days of age and older. In in-vivo studies in which female rats of 26, 60 and 90 days of age were first injected with T3 and 1 h later with [3H]2-deoxyglucose, the responsiveness of thymocytes to T3 also declined progressively with advancing age; T3 was most effective in cells from 26-day-old animals, less stimulatory in 60-day-old and essentially without effect in cells from 90-day-old animals. From these observations we have concluded that in both male and female rats the responsiveness of thymocytes to T3 declines progressively with age, and that this decline occurs at an earlier age in cells obtained from males. J. Endocr. (1986) 110, 511–515

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

Toxicology ◽  
1984 ◽  
Vol 29 (3) ◽  
pp. 221-234 ◽  
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

Inhalation Toxicity and Genotoxicity of Hydrofluorocarbon (HFC)-236fa and HFC-236ea

2000 ◽  
Vol 19 (2) ◽  
pp. 69-83 ◽  
Author(s):  
William J. Brock ◽  
David P. Kelly ◽  
Susan M. Munley ◽  
Karin S. Bentley ◽  
Kathy M. McGown ◽  
...  
Keyword(s):  
Developmental Toxicity ◽  
Human Lymphocytes ◽  
Female Rats ◽  
Male Rats ◽  
Whole Body ◽  
Seminiferous Tubules ◽  
Inhalation Toxicity ◽  
Male And Female ◽  
Male And Female Rats

The acute, subchronic, and developmental and genetic toxicity of hydrofluorocarbon (HFC)-236fa and HFC-236ea were evaluated to assist in establishing proper handling guidance. In acute inhalation studies, rats were exposed whole body for 4 hours to various concentrations of each isomer. Based on the lack of mortality, the approximate lethal concentration for HFC-236ea for male rats was > 85,000 ppm. For HFC-236fa, the LC50 for males and females (combined) was > 457,000 ppm. Narcotic-like effects, e.g., prostration, incoordination, and reduced motor activity, were observed only during exposure to either isomer, but were not evident after termination of exposure. In cardiac sensitization studies, HFC-236ea induced cardiac sensitization at ≥ 35,000 ppm, with fatal responses occurring at 50,000 ppm and greater. For HFC-236fa, a cardiac sensitization response was observed at 150,000 ppm and greater but not at 100,000 ppm. A fatal cardiac sensitization response was observed in one dog exposed to 150,000 ppm HFC-236fa. In 90-day subchronic inhalation studies, male and female rats were exposed whole body to HFC-236ea at concentrations of 0, 5000, 20,000, or 50,000 ppm for 6 hours/day, 5 days/week. Similarly, male and female rats were exposed whole body to HFC-236fa at concentrations of 0, 5000, 20,000, or 50,000 ppm for 6 hours/day, 5 days/week. During exposure, narcotic-like effect (reduced acoustic startle response) was observed at 50,000 ppm with both isomers, although there appeared to be an adaptive response to this effect as the study progressed. With HFC-236ea, dilatation of the seminiferous tubules, without effects on germ or Sertoli cells, was observed only in rats at 50,000 ppm. No other effects on in-life measures or on clinical or anatomic pathology, including histopathology, were observed for either isomer. In rat developmental toxicity studies, no evidence of embryotoxicity or teratogenicity was observed with either isomer exposed up to 50,000 ppm during gestational days 7 to 16. Also, no developmental toxicity was observed in rabbits exposed to HFC-236fa at concentrations of up to 50,000 ppm during gestational days 7 to 19. Neither of the HFC-236 isomers was mutagenic in the Ames reverse mutation assay or clastogenic in the chromosomal aberration assay with human lymphocytes. No increase in chromosomal aberrations was observed in in vivo micronucleus studies with either isomer.

Phosphatidylinositol 4,5-bisphosphate stimulates alveolar epithelial fluid clearance in male and female adult rats

2011 ◽  
Vol 301 (5) ◽  
pp. L804-L811 ◽  
Author(s):  
Edgar E. Kooijman ◽  
Stephanie R. Kuzenko ◽  
Denghuang Gong ◽  
Michael D. Best ◽  
Hans G. Folkesson
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Na Channel ◽  
Alveolar Fluid Clearance ◽  
Membrane Phospholipids ◽  
Adult Rats ◽  
Male And Female ◽  
Alveolar Epithelial ◽  
Male And Female Rats

Cell membrane phospholipids, like phosphatidylinositol 4,5-bisphosphate [PI( 4 , 5 )P2], can regulate epithelial Na channel (ENaC) activity. Gender differences in lung ENaC expression have also been demonstrated. However, the effects in vivo on alveolar fluid clearance are uncertain. Thus PI( 4 , 5 )P2 effects on alveolar fluid clearance were studied in male and female rats. An isosmolar 5% albumin solution was intrapulmonary instilled; alveolar fluid clearance was studied for 1 h. Female rats had a 37 ± 19% higher baseline alveolar fluid clearance than male rats. Bilateral ovariectomy attenuated this gender difference. Compared with controls, PI( 4 , 5 )P2 instillation (300 μM) increased alveolar fluid clearance by ∼93% in both genders. Amiloride or the specific αENaC small-interfering RNA inhibited baseline and PI( 4 , 5 )P2-stimulated alveolar fluid clearance in both genders, indicating a dependence on amiloride-sensitive pathways. The fraction of amiloride inhibition was greater in PI( 4 , 5 )P2-instilled rats (male: 64 ± 10%; female: 70 ± 11%) than in controls (male: 30 ± 6%; female: 44 ± 8%). PI( 4 , 5 )P2 instillation lacked additional alveolar fluid clearance stimulation above that of terbutaline, nor did propranolol inhibit alveolar fluid clearance after PI( 4 , 5 )P2 instillation, indicating that PI( 4 , 5 )P2 stimulation was not secondary to endogenous β-adrenoceptor activation. PI( 4 , 5 )P2 amine instillation resulted in an intermediate alveolar fluid clearance stimulation, suggesting that, to reach maximal alveolar fluid clearance stimulation, PI( 4 , 5 )P2 must reside in cell membranes. In summary, PI( 4 , 5 )P2 instillation upregulated in vivo alveolar fluid clearance similar to short-term β-adrenoceptor upregulation of alveolar fluid clearance. PI( 4 , 5 )P2 stimulation was mediated partly by increased amiloride-sensitive Na transport. There exist important gender-related effects suggesting a female advantage that may have clinical implications for resolution of acute lung injury.

HYPOTHALAMIC LUTEINIZING HORMONE RELEASING FACTOR AND CORTICOTROPHIN RELEASING ACTIVITY IN RELATION TO PITUITARY AND PLASMA HORMONE LEVELS IN MALE AND FEMALE RATS

1977 ◽  
Vol 72 (2) ◽  
pp. 195-210 ◽  
Author(s):  
SHARON A. CHIAPPA ◽  
G. FINK
Keyword(s):  
Plasma Corticosterone ◽  
Female Rats ◽  
Male Rats ◽  
Male And Female ◽  
Male And Female Rats ◽  
Protein Binding Assay ◽  
Female Wistar Rats ◽  
Competitive Protein Binding Assay ◽  
Animal House

SUMMARY Hypothalamic corticotrophin releasing (CR) activity and LH-releasing factor (RF) content, and pituitary and plasma LH, FSH and ACTH were measured in adult male and female Wistar rats maintained under 14 h light per day. Hypothalamic LH-RF and pituitary and plasma hormones were estimated by radioimmunoassay while CR-activity was assessed by the amount of ACTH released from hemipituitaries in vitro. Two experiments were carried out on male animals. In the first, some of the animals were kept in a room, distant from the animal house, in which the lighting was reversed with respect to the external environment. In animals exposed to the reversed lighting régime, hypothalamic LH-RF content and pituitary gonadotrophin concentrations were significantly lower than the values in male rats kept in the animal house where they were in close proximity to female rats. In the second experiment, which was carried out on animals which had all been kept in the animal house, there were no significant differences between the LH-RF contents measured at 3–4 h intervals throughout the day. Pituitary LH and FSH contents, but not concentrations, were significantly increased at 12.00 h. There was little difference between the experiments in CR-activity, plasma ACTH concentrations and profiles of pituitary ACTH content and concentration. As expected there was a diurnal rhythm in plasma corticosterone concentrations (determined by competitive protein-binding assay) with the peak occurring between 15.00 and 18.00 h. The profiles of plasma and pituitary ACTH were similar to that of plasma corticosterone. Corticotrophin releasing activity dropped significantly between 12.00 and 16.00 h, but remained steady at the other times.

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