OXYGEN UPTAKE OF RAT MAMMARY TISSUE SLICES

1950 ◽  
Vol 28e (5) ◽  
pp. 217-221 ◽  
Author(s):  
Jules Tuba ◽  
Herbert E. Rawlinson ◽  
Lorna Glen Shaw
Keyword(s):  
Mammary Gland ◽  
Oxygen Uptake ◽  
In Vitro Study ◽  
Female Rats ◽  
Male Rats ◽  
Mammary Tissue ◽  
Oxygen Utilization ◽  
Tissue Slices ◽  
Mammary Gland Tissue

An in vitro study has been made of the oxygen uptake of mammary gland tissue of female rats in various experimental states. Because of the very high proportion of fat in mammary tissue the values of [Formula: see text] are determined on a fat-free as well as a water-free basis, thus providing a more accurate measure of the oxygen consumption of this tissue. The oxygen utilization by mammary gland of pregnant animals is increased approximately three times over the activity in the normal, or resting, gland. This increase is maintained during lactation and a return toward normal levels occurs during postlactational involution. The response to p-phenylenediamine indicated that during lactation the increased energy requirements decreased the reserves of the cytochrome system in mammary tissue. There is a well developed mammary gland in adult male rats; but the average fat content and response to p-phenylenediamine of the tissue are almost identical with values for adult female rats. The use of p-phenylenediamine as a histological stain for the cytochrome system in mammary tissue is described.

Effects of in vivo gonadal hormone environment on in vitro hGRF-40-stimulated GH release

1985 ◽  
Vol 249 (3) ◽  
pp. E276-E280 ◽  
Author(s):  
W. S. Evans ◽  
R. J. Krieg ◽  
E. R. Limber ◽  
D. L. Kaiser ◽  
M. O. Thorner
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Gonadal Hormone ◽  
Base Line ◽  
Pituitary Cells ◽  
Intact Male ◽  
Castrate Male ◽  
Basal Release

The effects of gender and the gonadal hormone environment on basal and stimulated growth hormone (GH) release by dispersed and continuously perifused rat anterior pituitary cells were examined. Cells from intact male and diestrus day 2 female rats and from castrate male rats either untreated or treated with testosterone (T) or 17 beta-estradiol (E2) were used. Basal GH release (ng/min per 10(7) cells; mean +/- SE) by cells from diestrus day 2 female rats was less than by cells from castrate rats treated with T (4.3 +/- 0.6 vs. 11.4 +/- 2.7, respectively; P less than 0.025). No other differences in basal release were detected. Concentration-response relationships were documented between human GH-releasing factor 40 (hGRF-40; 0.03-100 nM given as 2.5-min pulses every 27.5 min) and GH release. Mean (+/- SE) overall GH release (ng/min per 10(7) cells) above base line was greater by cells from intact male rats (496 +/- 92) than by cells from castrate (203 +/- 37.3; P less than 0.0001), castrate and T-treated (348 +/- 52.8; P = 0.008), or castrate and E2-treated (58.1 +/- 6.8; P less than 0.001) male rats or by diestrus day 2 rats (68.6 +/- 9.5; P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

IN VITRO STUDIES ON CARBOHYDRATE METABOLISM IN THE VITAMIN-B6-DEPRIVED RAT

1955 ◽  
Vol 33 (1) ◽  
pp. 562-567
Author(s):  
John R. Beaton
Keyword(s):  
Carbohydrate Metabolism ◽  
Vitamin B6 ◽  
Glucose Utilization ◽  
Female Rats ◽  
Male Rats ◽  
Vitamin B ◽  
Significant Difference ◽  
Aldolase Activity ◽  
Food Consumed

Following earlier studies on carbohydrate metabolism in the vitamin-B6-deprived rat, in vitro investigations have been carried out. In all cases, comparisons were made between tissues from vitamin-B6-deprived and pair-fed control animals so that differences in the amount of food consumed would not affect the interpretation of experimental results. No significant difference was found in glucose utilization by muscle nor in liver cytochrome oxidase activity. Liver aldolase activity was significantly decreased and the activity of plasma alkaline phosphatase was significantly increased in the vitamin-B6-deprived rats. In vitamin-B6-deprived female rats, but not male rats, liver catalase activity was significantly increased. These results are discussed in the light of earlier observations indicating disturbances in carbohydrate metabolism in the vitamin-B6-deprived rat.

STUDIES ON FACTORS INFLUENCING THE ACUTE TOXICITY OF MALATHION AND MALAOXON IN RATS

1967 ◽  
Vol 45 (4) ◽  
pp. 621-631 ◽  
Author(s):  
Jules Brodeur ◽  
K. P. DuBois
Keyword(s):  
Enzymatic Activity ◽  
Young Male ◽  
Female Rats ◽  
Male Rats ◽  
Age Difference ◽  
Adult Males ◽  
Organophosphate Insecticide ◽  
In Vitro Measurements ◽  
Immature Rats

A study was undertaken to investigate the mechanisms responsible for the higher susceptibility of immature rats to the organophosphate insecticide malathion. In vitro measurements of the activity of malathionase in the tissues of rats, at various time intervals after birth, indicated that the livers of immature rats detoxify the insecticide at a much slower rate than do the livers of adult animals. Evidence was obtained which showed that prolonged administration of testosterone causes a significant increase of the enzymatic activity in the livers of castrated young male rats and adult female rats. On the other hand, castration interferes with the maintenance of normal levels of malathionase in adult males and partially prevents the development of the activity in weanlings. Estradiol decreases the enzymatic activity in adult males. It appears, therefore, that the age difference in the susceptibility of rats to malathion might be due, to a large extent, to a slower rate of inactivation of the insecticide by the livers of immature animals. The results obtained also indicate that the sex hormones play an important role in the development and maintenance of normal levels of the enzyme system involved in the degradation of malathion in the livers of rats.

THE ROLE OF THE ADRENAL GLAND IN THE CONTROL OF AMINO ACID INCORPORATION INTO PROTEIN OF ISOLATED RAT LIVER MICROSOMES

1960 ◽  
Vol 21 (2) ◽  
pp. 177-189 ◽  
Author(s):  
A. KORNER
Keyword(s):  
Amino Acid ◽  
Rat Liver ◽  
Liver Microsomes ◽  
Female Rats ◽  
Male Rats ◽  
Rat Liver Microsomes ◽  
Hypophysectomized Rats ◽  
Normal Rat ◽  
Secondary Result

SUMMARY 1. Microsomes, isolated from rat liver a day after adrenalectomy, incorporate more radioactive amino acid into their protein in vitro than microsomes from normal rat liver. This enhanced rate of incorporation progressively declines with time after adrenalectomy until it reaches a plateau level which is below the normal rate of incorporation. 2. Following adrenalectomy microsomes isolated from liver of male rats show a greater rise in incorporating ability than those from liver of female rats, and maintain it longer. 3. Most of the increased incorporation observed in the in vitro system soon after adrenalectomy of the rat, and most of the decreased incorporation observed in rats adrenalectomized for some time, results from alterations in the microsomes which change their ability to incorporate activated amino acids into proteins. 4. Treatment of rats with cortisol acetate results in an increase in the ability of liver microsomes to incorporate amino acid into protein. This heightened incorporating ability is probably a secondary result of the breakdown of extrahepatic tissue protein which is stimulated by cortisol. 5. Somewhat similar responses to acute adrenalectomy and to treatment with cortisol were found in hypophysectomized rats. 6. The protein anabolic response of adrenalectomized rats to treatment with insulin, and of adrenalectomized-hypophysectomized rats to treatment with insulin or growth hormone, is greater than that shown by rats which possess adrenal glands.

Uteroplacental insufficiency alters the mammary gland response to lactogenic hormones in vitro

2008 ◽  
Vol 20 (4) ◽  
pp. 460 ◽  
Author(s):  
Rachael O'Dowd ◽  
Mary E. Wlodek ◽  
Kevin R. Nicholas
Keyword(s):  
Gene Expression ◽  
Mammary Gland ◽  
Postnatal Growth ◽  
Mammary Development ◽  
Mammary Tissue ◽  
Sham Surgery ◽  
Uterine Vessel ◽  
Lactogenic Hormones ◽  
Vessel Ligation

Adequate mammary development and coordinated actions of lactogenic hormones are essential for the initiation of lactation. Pregnancies compromised by uteroplacental insufficiency impair mammary development and lactation, further slowing postnatal growth. It is not known whether the initiation of lactation or galactopoesis is compromised. Uteroplacental insufficiency induced in rats by bilateral uterine vessel ligation (Restricted) or sham surgery (Control) on Day 18 of gestation preceded collection of mammary tissue on Day 20 of pregnancy. Mammary explants were cultured with combinations of insulin, cortisol and prolactin and analysed for α-lactalbumin and β-casein gene expression. Mammary tissue from late pregnant Restricted rats had elevated α-lactalbumin, but not β-casein, mRNA, which is consistent with premature lactogenesis resulting from an early decline in peripheral maternal progesterone. Explants from Restricted rats were more responsive to hormone stimulation after 3 days in culture, indicating that compromised galactopoesis, not lactogenesis, most likely leads to the reduced growth of suckled pups.

Involvement of cGMP in LHRH-stimulated gonadotropin release.

1978 ◽  
Vol 235 (6) ◽  
pp. E586 ◽  
Author(s):  
Z Naor ◽  
C P Fawcett ◽  
S M McCann
Keyword(s):  
Mechanism Of Action ◽  
Female Rats ◽  
Male Rats ◽  
Camp Content ◽  
Luteinizing Hormone Releasing Hormone ◽  
Gonadotropin Release ◽  
Male And Female Rats ◽  
The Relationship ◽  
Stimulation Of

Anterior pituitary content of cyclic AMP (cAMP) and cyclic GMP (cGMP) has been measured during stimulation of gonadotropin release by luteinizing-hormone-releasing hormone (LHRH) in vitro to gain more information concerning the relationship between the mechanism of action of LHRH and cyclic nucleotides. During the increased gonadotropin release obtained by incubation by hemipituitaries with LHRH (0.25--25 X 10(-9) M) for 180 min, the glands taken from both male and female rats exhibited increased cGMP content, whereas cAMP content rose only in those taken from male rats. The increase in cGMP content was observed after only 2 min in the presence of LHRH (5 X 10(-9) M) and prior to augmented gonadotropin release. The increase in cAMP content in the male glands was detectable only after 60 min of incubation. These results suggest that cGMP might be involved in the mechanism of action of LHRH.

Vasopressin responses and receptors in the mesenteric vasculature of estrogen-treated rats

1986 ◽  
Vol 251 (5) ◽  
pp. H885-H889 ◽  
Author(s):  
J. St-Louis ◽  
A. Parent ◽  
R. Lariviere ◽  
E. L. Schiffrin
Keyword(s):  
Binding Sites ◽  
Pressor Response ◽  
Female Rats ◽  
Maximum Response ◽  
Male Rats ◽  
Ovariectomized Rats ◽  
Binding Characteristics ◽  
Vascular Bed ◽  
Mesenteric Vascular Bed

The effect of treatment with estrogens on the biological activity of arginine8 vasopressin (AVP) in the in vitro perfused mesenteric vascular bed and on the binding characteristics of [3H]AVP on membranes prepared from the same vascular bed was studied. Female rats treated with estradiol (400 micrograms/24 h sc), compared with ovariectomized rats, had an increase in the maximum response to AVP (from 128 +/- 3 to 153 +/- 3 mmHg) in the perfused preparation and an increase in the density of AVP binding sites (from 402 to 732 fmol/mg protein) in the membrane preparation. In male rats, the injection of estradiol increased the maximum response to AVP (from 109 +/- 4 to 137 +/- 3 mmHg) and the density of AVP binding sites (from 289 to 519 fmol/mg protein). The effective concentration producing 50% of maximum response of AVP in the perfused preparation was higher in male than in female rats, while the Kd in the binding experiments was similar in the four experimental groups. Our results show that estrogens upregulate the number of AVP binding sites, leading to an increase in the pressor response to AVP in the rat mesenteric vascular bed.

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