OSTEOPOROSIS AFTER OOPHORECTOMY IN THE MATURE FEMALE RAT AND THE EFFECT OF OESTROGEN AND/OR PROGESTOGEN REPLACEMENT THERAPY IN ITS PREVENTION

1972 ◽  
Vol 55 (1) ◽  
pp. 79-87 ◽  
Author(s):  
J. M. AITKEN ◽  
E. ARMSTRONG ◽  
J. B. ANDERSON
Keyword(s):  
Replacement Therapy ◽  
Mineral Content ◽  
Unit Length ◽  
Hormone Replacement ◽  
Mature Female ◽  
Relative Increase ◽  
Female Rats ◽  
Female Rat ◽  
New Bone Formation ◽  
Femoral Morphology

SUMMARY Fifty-two mature female rats on a controlled diet were studied to compare the effects of oophorectomy, and hormone replacement therapy after oophorectomy, on femoral morphology and mineral content. Oophorectomy was followed by the development of osteoporosis after 11 months of observation. This was characterized by a reduction in ash per unit length of bone and a diminution of mid-shaft femoral cortical width. The administration of a progestogen (9 μg ethynodiol diacetate/rat/day) for 10 months after oophorectomy prevented the reduction in ash per unit length from occurring, whereas an oestrogen (0·9 μg mestranol/rat/day) had no significant effect on either parameter of osteoporosis. The progestogen appeared to produce this effect by a relative increase in periosteal new bone formation at the expense of increased loss of bone from the endosteal surface.

scholarly journals Effects of Combined Estrogen and Progesterone on Brain Infarction in Reproductively Senescent Female Rats

2004 ◽  
Vol 24 (10) ◽  
pp. 1160-1166 ◽  
Author(s):  
Thomas J. Toung ◽  
Tsung-Ying Chen ◽  
Marguerite T. Littleton-Kearney ◽  
Patricia D. Hurn ◽  
Stephanie J. Murphy
Keyword(s):  
Hormone Replacement Therapy ◽  
Replacement Therapy ◽  
Postmenopausal Women ◽  
Brain Infarction ◽  
Combined Therapy ◽  
Hormone Replacement ◽  
Treated Group ◽  
Female Rats ◽  
Female Rat ◽  
Triphenyltetrazolium Chloride

Recent data from the Women's Health Initiative have highlighted many fundamental issues about the utility and safety of long-term estrogen use in women. Current hormone replacement therapy for postmenopausal women incorporates progestin with estrogen, but it is uncertain if combined therapy provides major cerebrovascular risks or benefits to these women. No experimental animal stroke studies have examined combined hormone administration. The authors tested the hypothesis that combined hormone treatment reduces ischemic injury in middle-aged female rat brain. Reproductively senescent female rats underwent 2-hour middle cerebral artery occlusion (MCAO) followed by 22 hours reperfusion. Estrogen implants were placed subcutaneously at least 7 days before MCAO, and progesterone intraperitoneal injections were given 30 minutes before MCAO, at initiation, and at 6 hours of reperfusion. Rats received no hormone, a 25-μg estrogen implant, a 25-μg estrogen implant plus 5 mg/kg intraperitoneal progesterone, or 5 mg/kg intraperitoneal progesterone. Cortical, caudoputamen, and total infarct volumes were assessed by 2,3,5-triphenyltetrazolium chloride staining and digital image analysis at 22 hours reperfusion. Cortical and total infarct volumes, except in the acute progesterone-treated group, were significantly attenuated in all estrogen-alone and combined hormone-treated groups. There were no significant differences in caudoputamen infarct volumes in all hormone-treated groups as compared with untreated rats. These data have potential clinical implications relative to stroke for postmenopausal women taking combined hormone replacement therapy.

scholarly journals The role of bilateral ovariectomy in the impairments of prooxidant-antioxidant balance and renal concentrating capacity in rats in the period of late manifestations of the traumatic disease and the efficacy of hormone replacement therapy

2021 ◽  
Vol 11 (2) ◽  
pp. 277-289
Author(s):  
I. Lutsiv ◽  
A. Hudyma ◽  
S. Halnykina ◽  
O. Denefil
Keyword(s):  
Hormone Replacement Therapy ◽  
Replacement Therapy ◽  
Renal Cortex ◽  
Hormone Replacement ◽  
Female Rats ◽  
Control Groups ◽  
Renal Tubular ◽  
Trauma Model ◽  
Renal Concentrating Capacity

Introduction. Traumatic events are currently considered to be one of the topical issues. The progression of renal failure plays an important role in the pathogenesis of traumatic disease. It is essential to evaluate the ability of renal tubular epithelium to the urine osmotic concentration in order to indicate the direct renal tubular damage. A sodium-free water clearance (S-CH2O) is a sensitive indicator reflecting the kidneys ability to concentrate the urine. It is established that the renal functional state, the resistance of the kidneys to the development of various disorders depends on the estrogen concentration. The key mechanism of the indirect effect of estrogens on the kidneys is via their direct antioxidant action. However, the role of estrogens in the pathogenesis of oxidative and functional impairments of the kidneys in the presence of cranioskeletal trauma is insufficiently studied. There is no data available on the efficacy of hormone replacement therapy under those circumstances.The objective of research: to determine the pro-oxidant-antioxidant balance and renal concentrating capacity following the cranioskeletal trauma model in rats with bilateral ovariectomy in the period of late manifestations of the traumatic disease and evaluate the efficacy of hormone replacement therapy.Material and methods: The experimental studies were conducted on 64 white non-linear female rats weighing 200-220g. The experimental model of hypoestrogenism was performed through the surgical removal of gonads. The rats were subjected to the cranioskeletal model one month after removal of the gonads. Hormone replacement therapy (HRT) was used as a corrective treatment in the separate subgroup of gonadectomized rats subjected to the cranioskeletal trauma. The control groups consisted of intact animals and rats 1 month after removal of the gonads that were not injured. The renal functional state was determined via a water loading test in the control groups of animals and after 1 and 2 months of postrraumatic period. The sodium concentration, as well as the S-CH2O value was measured in serum and urine. The content of thiobarbituric acid reactive substances (TBARs) and catalase activity were determined in renal cortex and medulla. The prooxidant/antioxidant ratio (ProAntidex) was calculated based on the above data.The results and discussion. The conducted studies indicated the considerable decrease in ProAntidex value in renal cortex and medulla in the group of gonadectomized rats compared to the animals without gonadectomy after 1 month of the posttraumatic period, confirming the protective antioxidant role of estrogens in adequate renal function. The cranioskeletal trauma model led to the declined parameter value in renal cortex and medulla in both experimental groups after 1 month of the posttraumatic period. The prooxidant/antioxidant ratio was significantly decreased in the first month following the trauma in the gonadectomized rats as compared to the rats without the gonadectomy, and remained at the same level up to the 2nd month of the posttraumatic period. The identified abnormal value of ProAntidex in the posttraumatic period clearly affected the dynamics of S-CH2O. This parameter was reported as decreased in both experimental groups compared to the control. However, the parameter was substantially decreased 1 and 2 months after trauma under conditions of the gonadectomy.                   The administration of hexestrol and progesterone to the gonadectomized rats with trauma model resulted in the considerable increase in value of ProAntidex in renal cortex and medulla starting from the 1st day of the posttraumatic period compared to the animals without corrective medication. Moreover, it was accompanied by a statistically significant increase in S-CH2O rate, indicating the enhancement in the functional capacity of the renal tubules.Conclusions. The value of ProAntidex decreases in renal cortex and medulla in the group of gonadectomized female rats after 1 month of the posttraumatic period, and is significantly lower compared to the animals without removal of the gonads. The cranioskeletal trauma model leads to the substantially declined prooxidant/antioxidant ratio value in renal cortex and medulla, which is reported as considerably greater in the group of gonadectomized animals after 1 month of the posttraumatic period, showing no tendency to enhance after 2 months of the experiment. The administration of hormone replacement therapy to the gonadectomized rats is accompanied by the increase in ProAntidex value and S-CH2O rate compared to the animals without corrective medication.

Core temperature in the female rat: effect of pinealectomy or altered lighting

1976 ◽  
Vol 231 (2) ◽  
pp. 355-360 ◽  
Author(s):  
F Spencer ◽  
HW Shirer ◽  
JM Yochim
Keyword(s):  
Core Temperature ◽  
Continuous Light ◽  
Mature Female ◽  
Female Rats ◽  
Female Rat ◽  
Light Phase ◽  
Continuous Darkness ◽  
Temperature Rhythm ◽  
Two Component ◽  
Lighting Regimen

Radiotelemetry of core temperature in unrestrained, mature female rats revealed the existence of a 24-h rhythm that was bimodal. The principal peak occurred during the night under control conditions of 14 h light and 10 h darkness, and a less pronounced, secondary peak occurred 3-4 h after the onset of the light phase. Shifts in the phase of the photoperiod or alteration of the proportion of light per day revealed that the temperature rhythm was entrained by light, but that the two component peaks were governed by different aspects of the lighting regimen. Exposure of rats to continuous darkness, continuous light, or to a 20-h photoperiod revealed that the primary rhythm was endogenous, entrained by circadian photoperiods only, whereas the secondary rhythm was exogenous, requiring a circadian light/dark rhythm. A relationship between mean core temperature and ttion pressure, end-systolic L was constant, despite variations in filling and therefore independent of initial L and delta L; moreover, the L to which the ventricle shortened was determined by the course of the systolic force L-relation. Thus, irrespective of loading, delta L occurs within the confines of the contractile state-depdendent isovolumic force-L relation and where the latter is equivalent to the end-systolic force-length relation.

Stimulation of food intake and weight gain in mature female rats by bovine prolactin and bovine growth hormone

1993 ◽  
Vol 264 (6) ◽  
pp. E986-E992 ◽  
Author(s):  
J. C. Byatt ◽  
N. R. Staten ◽  
W. J. Salsgiver ◽  
J. G. Kostelc ◽  
R. J. Collier
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Weight Gain ◽  
Food Intake ◽  
Body Weight Gain ◽  
Mature Female ◽  
Female Rats ◽  
Bovine Growth Hormone ◽  
Female Rat ◽  
Moisture Percentage

Recombinant bovine prolactin (rbPRL) or bovine growth hormone (rbGH) was administered to mature female rats (10/treatment group) by daily subcutaneous injection for 10 days. Doses ranged from 7 to 5,000 micrograms/day (0.03-24 mg/kg body wt). Both rbPRL and rbGH increased body weight gain and food intake, but these parameters were increased at lower doses of rbPRL (7-63 micrograms/day) than rbGH (> 190 micrograms/day). Weight gain and food intake were maximally stimulated by 190 micrograms/day rbPRL, whereas maximal increased weight gain was obtained with the highest dose of rbGH (5,000 micrograms/day). Total carcass protein was increased by both hormones; however, protein as a percentage of body weight was unchanged. Similarly, neither rbPRL nor rbGH changed the percentage of carcass moisture. Percentage of body fat was increased by rbPRL but was decreased by rbGH. Weight of the gastrointestinal tract and kidneys was increased by both hormones, but increases were in proportion to body weight gain. These data confirm that ungulate prolactin is a hyperphagic agent in the female rat. In addition, they suggest that, while prolactin stimulates growth in mature female rats, this growth is probably not via a somatogenic mechanism.

Change from beta- to alpha-adrenergic glycogenolysis induced by corticosteroids in female rat liver

1997 ◽  
Vol 273 (1) ◽  
pp. R153-R160
Author(s):  
M. Moriyama ◽  
Y. Nakanishi ◽  
S. Tsuyama ◽  
Y. Kannan ◽  
M. Ohta ◽  
...  
Keyword(s):  
Glucose Production ◽  
Plasma Corticosterone ◽  
Mature Female ◽  
Female Rats ◽  
Male Rats ◽  
Female Rat ◽  
Circadian Variations ◽  
Male And Female ◽  
Male And Female Rats ◽  
The Difference

The conversion of beta- to alpha-adrenergic glycogenolysis by corticosteroids was studied in perfused livers of mature female rats. Isoproterenol stimulated glucose production more effectively in female rats than in male rats, but the difference in its stimulatory effect disappeared in adrenalectomized (ADX) rats, whereas it remained in adrenodemedulated rats. When ADX female rats were treated with dexamethasone sulfate, alpha-responses increased and beta-responses decreased, depending on the concentration of dexamethasone sulfate. The treatment of female rats with 1.5 mg/kg dexamethasone sulfate changed the levels of the alpha- and beta-responses to those observed in male rats, and the changes were associated with changes in the number of receptors. Although periodicity of changes in plasma corticosterone levels was observed in both male and female rats, the extent of circadian variations was significantly lower in female rats during the estrous cycle than in male rats. The variations in plasma corticosterone levels and in both alpha- and beta-responses after ovariectomy approached those in male rats. The results suggest that the level of plasma corticosterone might play an important role in the regulation of the relative levels of alpha- and beta-adrenergic responses in female rats.

Induction of prolactin receptors in the liver is more closely related to the growth-promoting than to the lactogenic potency of peptides

1987 ◽  
Vol 114 (3) ◽  
pp. 350-356 ◽  
Author(s):  
G. Norstedt ◽  
B. Husman ◽  
A. Mode ◽  
P. Eneroth ◽  
U.J. Lewis ◽  
...  
Keyword(s):  
Time Course ◽  
Mature Female ◽  
Female Rats ◽  
Male Rats ◽  
Female Rat ◽  
Hypophysectomized Rats ◽  
Liver Membranes ◽  
Growth Promoting ◽  
Rat Livers

Abstract. The sex differentiated binding 125I-human prolactin (PRL) to rat liver membranes was studied and the present results extend our previous studies on induction of hepatic PRL receptors by growth hormone (GH). In prepubertal female rats, PRL receptor levels are low compared with those in mature female rat livers. Infusion of hGH during one week to 17-day-old female rats resulted in a receptor level typical of adult female rats. The time course of receptor disappearance in male rats treated with hGH was also studied. When the receptor-inducing hormone was removed, receptor levels in hGH-treated male rats returned to the normal level characteristic of male rats after approximately 96 h. The specificity of various GH-like and PRL-like hormones in PRL receptor induction was studied in hypophysectomized rats. The PRL-like hormones were identified by measuring their potency to displace 125I-hPRL from a receptor preparation obtained from female rat livers, and the GH-like hormones were identified by their potency to increase body weight in hypophysectomized rats. Using similar doses of hormones it was found that in vivo administration of growth-promoting peptides (rGH, hGH, bGH) induced PRL receptors, whereas lactogenic hormones (rPRL, hPL) had a very small or no effect on PRL receptor induction. This suggests that binding to a type of GH receptor is the first step in PRL receptor induction.

Hindlimb unloading has a greater effect on cortical compared with cancellous bone in mature female rats

2003 ◽  
Vol 94 (2) ◽  
pp. 642-650 ◽  
Author(s):  
Matthew R. Allen ◽  
Susan A. Bloomfield
Keyword(s):  
Cortical Bone ◽  
Bone Mineral ◽  
Cancellous Bone ◽  
Proximal Tibia ◽  
Mature Female ◽  
Hindlimb Unloading ◽  
Female Rats ◽  
Female Rat ◽  
Mineral Density ◽  
Tibia Bone

This study was designed to determine the effects of 28 days of hindlimb unloading (HU) on the mature female rat skeleton. In vivo proximal tibia bone mineral density and geometry of HU and cage control (CC) rats were measured with peripheral quantitative computed tomography (pQCT) on days 0and 28. Postmortem pQCT, histomorphometry, and mechanical testing were performed on tibiae and femora. After 28 days, HU animals had significantly higher daily food consumption (+39%) and lower serum estradiol levels (−49%, P = 0.079) compared with CC. Proximal tibia bone mineral content and cortical bone area significantly declined over 28 days in HU animals (−4.0 and 4.8%, respectively), whereas total and cancellous bone mineral densities were unchanged. HU animals had lower cortical bone formation rates and mineralizing surface at tibial midshaft, whereas differences in similar properties were not detected in cancellous bone of the distal femur. These results suggest that cortical bone, rather than cancellous bone, is more prominently affected by unloading in skeletally mature retired breeder female rats.

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