LACTOSE CONTENT OF MAMMARY GLANDS OF PREGNANT RATS NEAR TERM: EFFECT OF REMOVAL OF OVARY, PLACENTA AND FOETUS

1965 ◽  
Vol 31 (2) ◽  
pp. 105-114 ◽  
Author(s):  
Y. SHINDE ◽  
K. ÔTA ◽  
A. YOKOYAMA
Keyword(s):  
Mammary Gland ◽  
Mammary Glands ◽  
Term Effect ◽  
Ovariectomized Rats ◽  
Milk Secretion ◽  
Abrupt Increase ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Unilateral Ovariectomy ◽  
Near Term

SUMMARY The time of initiation of copious milk secretion in the mammary glands of pregnant rats and the effects of removal of ovaries and/or placentae with foetuses on lactogenesis were investigated by measuring the lactose content of the mammary glands. In the normal pregnant rat, lactose was detected in the mammary gland on the 20th day of pregnancy, but not on the 15th. An abrupt increase in lactose content occurred on the 21st day of pregnancy. Bilateral or unilateral ovariectomy, and Caesarean section, with or without ovariectomy, performed on the 18th or 19th day of pregnancy all resulted in a marked increase in the lactose content on the 2nd day after operation. Bilateral ovariectomy caused early delivery of the young and lactose content in the gland increased further after delivery. Foetuses in the unilaterally ovariectomized rats were retained normally to term. Possible participation of placentae and foetuses in the mechanism of lactogenesis in pregnant animals by controlling the activity of the ovary is discussed.

scholarly journals Hormonal regulation of retinoic acid-binding proteins in the mammary gland

1981 ◽  
Vol 200 (3) ◽  
pp. 591-595 ◽  
Author(s):  
R G Mehta ◽  
R C Moon
Keyword(s):  
Retinoic Acid ◽  
Mammary Gland ◽  
Protein Content ◽  
Hormonal Regulation ◽  
Protein Concentration ◽  
Mammary Glands ◽  
Pregnant Rats ◽  
Rab Protein ◽  
Low Concentrations ◽  
Retinoic Acid Binding Proteins

A cytosolic retinoic acid-binding (RAB) protein that sediments specifically as a 2S component on sucrose density gradients was detected in the mammary glands of virgin, pregnant and lactating rats. Mammary cytosol from pregnant rats contained significantly higher concentrations of cytosolic RAB protein than did cytosol from either virgin or lactating rats. The glands of pregnant animals exhibited increased concentration of cytosolic RAB protein during the first 5 days of pregnancy, and a steady decline was observed thereafter. The concentration of cytosolic RAB protein dropped to the value observed during lactation on the day 20 of pregnancy. Moreover, throughout lactation, low concentrations of cytosolic RAB protein were maintained. Daily treatment of virgin and lactating animals with 5 micrograms of oestradiol-17 beta for 1 week increased cytosolic RAB protein to concentrations comparable with those seen in pregnant rats. Progesterone, however, did not affect the mammary cytosolic RAB protein content of virgin rats. These results suggest hormonal involvement in the regulation of cytosolic RAB protein concentration of mammary gland during differentiation.

EFFECTS OF PROGESTERONE, MEDROXYPROGESTERONE ACETATE (PROVERA) AND OESTRONE ON SHEDDING AND DISSOLUTION OF THE ZONA PELLUCIDA IN THE RAT

1972 ◽  
Vol 54 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Z. DICKMANN
Keyword(s):  
Zona Pellucida ◽  
Medroxyprogesterone Acetate ◽  
Delay Period ◽  
Synergistic Action ◽  
Ovariectomized Rats ◽  
Pregnant Rats ◽  
Pregnant Rat

SUMMARY The effects of progesterone, medroxyprogesterone acetate (MPA), and oestrone on shedding and dissolution of the zona pellucida were studied in intact pregnant rats, ovariectomized pregnant, and ovariectomized pseudopregnant rats into whose uteri blastocysts had been transferred. Treatment with progesterone, MPA and oestrone delayed shedding of the zona. The highest percentage of blastocysts delaying, and with the longest delay period, occurred in ovariectomized, progesterone-treated rats. Ovariectomy of pregnant rats, and treatment of ovariectomized rats with progesterone, MPA or oestrone, delayed dissolution of the zona. Oestrone together with progesterone caused both shedding and dissolution of the zona within 24 h. It is deduced that in the intact pregnant rat, the synergistic action of oestrogen superimposed on progesterone synchronizes shedding and dissolution of the zona so that they occur together at a specified time.

scholarly journals A Case of Pseudopregnancy in a Bitch

2021 ◽  
pp. 1-5
Author(s):  
C. S. Ukwueze ◽  
K. A. Raheem
Keyword(s):  
Mammary Gland ◽  
Epithelial Cells ◽  
Associated Factors ◽  
Clinical Signs ◽  
Mammary Glands ◽  
Milk Secretion ◽  
Normal Range ◽  
Abdominal Palpation ◽  
Nesting Behaviour ◽  
Vaginal Cytology

A case of pseudopregnacy was presented to Veterinary Teaching Hospital, Michael Okpara University of Agriculture Umudike, Nigeria. Eighteen (18) months old bitch weighing 15kg was presentedclinical signs suspected to be pseudopregnacy, which was observed four weeks after the bitch came on heat (estrus). The clinical signs observed were restlessness, anorexia, aggression, nesting behaviour and licking of mammary gland. On clinical examination it was observed that bitch had enlarged mammary glands and milk secretion. The physiological parameters were found to be within the normal range.  Abdominal palpation, ultrasonography and vagina cytology were carried out to confirm pregnancy. Due to absence of foetuses on abdominal palpation and ultrasonography and presence of scanty epithelial cells in vaginal cytology, it was confirmed and concluded to be a case of pseudopregnancy. Causes, treatment and other associated factors with pseudopregnancy were further discussed.

EFFECT OF SUCKLING AND OF EXTEROCEPTIVE STIMULATION UPON PROLACTIN RELEASE IN THE RAT DURING LATE LACTATION

1972 ◽  
Vol 52 (1) ◽  
pp. 11-22 ◽  
Author(s):  
F. MENA ◽  
C. E. GROSVENOR
Keyword(s):  
Mammary Gland ◽  
Post Partum ◽  
Mammary Glands ◽  
The Other ◽  
Male Rats ◽  
Milk Secretion ◽  
Suckling Period ◽  
Prolactin Release ◽  
Other Hand ◽  
Rat Pituitary

SUMMARY The results of experiments in which the prolactin in the primiparous rat pituitary was bioassayed suggested that the failure of suckling to release prolactin after 8 h of non-suckling on day 21 post-partum was due to the fact that prolactin had been discharged from the pituitary during the 8-h non-suckling period, presumably by exteroceptive signals emanating from the general environment of the animal room. This was substantiated in other experiments in which prolactin release was assessed indirectly through its stimulatory effects upon milk secretion. In these experiments, the mammary glands of rats maintained continuously in the animal room filled faster on day 21 after complete emptying of the glands by exogenous oxytocin, than did either rats on day 14 post-partum maintained continuously in the animal room or rats isolated in a room without other rats on day 21 post-partum. The glands of the latter two groups of rats could be stimulated to fill faster provided prolactin was injected 4 h before the initial emptying of the glands. The exteroceptive stimuli in the animal room environment that stimulated the release of prolactin in the 21-day post-partum rat apparently emanated at least in part from other lactating rats and/or their litters, since faster mammary gland refilling occurred in isolated 21 day post-partum rats when they were exposed to the presence of lactating rats with their litters for 30 min halfway through the 8-h non-suckling period which preceded the initial emptying of the gland. Exposure to male rats, on the other hand, was totally ineffective. A release of prolactin occurred in response to animal room environmental stimuli in the day 14 primiparous rat provided 13–14 day old foster pups were inserted in place of the mother's own pups on day 7. Thus, the rapidly changing characteristics of the pups from 14 to 21 days of age in some manner is involved in the increasing responsiveness of the exteroceptive mechanism for prolactin release which occurs from day 14 to day 21 post-partum.

THE EFFECT OF A PLACENTAL MAMMOTROPHIN AND CORTISOL ON THE ULTRASTRUCTURE OF RAT MAMMARY GLAND IN ORGAN CULTURE

1977 ◽  
Vol 86 (3) ◽  
pp. 539-551
Author(s):  
K. D. Njio ◽  
J. M. Peters
Keyword(s):  
Mammary Gland ◽  
Secretory Activity ◽  
Lower State ◽  
Rat Serum ◽  
Pregnant Rats ◽  
Initial Development ◽  
Pregnant Rat ◽  
Rat Mammary Gland ◽  
Secretory Products

ABSTRACT Mammary gland explants obtained from 13 days pregnant rats were cultured for 3, 6 and 9 days in the presence of serum of either virgin rats or 13 days pregnant rats. Insulin was added alone or in combination with cortisol. The way these different forms of treatment affected the ultrastructure was studied. With virgin rat serum plus insulin alone the mammary gland regressed to a lower state of development comparable to that of the virgin rat in vivo. When virgin rat serum was replaced by 13 days pregnant rat serum - which contains rat chorionic mammotrophin - the initial development was maintained, but synthesis of secretory products ceased. When cortisol was added to the virgin rat serum plus insulin, cortisol maintained the differentiated state originally present. Even some secretory activity was induced, but at a minimal level. With cortisol added to the pregnant rat serum plus insulin, the explants were stimulated to synthetize and extrude secretion products.

Salt saving in the pregnant rat

1961 ◽  
Vol 201 (5) ◽  
pp. 765-768 ◽  
Author(s):  
I. J. Lichton
Keyword(s):  
Saline Solution ◽  
Isotonic Saline ◽  
Extracellular Fluid ◽  
Sodium Content ◽  
Sodium Balance ◽  
Sodium Retention ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Near Term ◽  
Total Sodium

Pregnant rats of two strains showed average net accumulation of approximately 83 mEq of sodium/kg of weight gain throughout gestation. Of the total sodium retention, 15, 23, and 62% occurred in each successive third of gestation. Analysis of postpartum sodium balance and of fetal sodium content at term indicated that there was no net accumulation of sodium in the tissues of the dams. Near term, rats given isotonic saline solution showed diminished ability to excrete the administered water in the urine, but showed no impairment in sodium excretion. Serum sodium concentrations were slightly decreased and serum osmolalities were significantly decreased in comparison to values for nonpregnant rats. At term the pregnant rats had greater extracellular fluid volumes than did nonpregnant controls.

Effects of chlorpromazine on mammary glands of rats

1960 ◽  
Vol 199 (6) ◽  
pp. 1073-1076 ◽  
Author(s):  
P. K. Talwalker ◽  
J. Meites ◽  
C. S. Nicoll ◽  
T. F. Hopkins
Keyword(s):  
Body Weight ◽  
Mammary Gland ◽  
Anterior Pituitary ◽  
Post Partum ◽  
Mammary Glands ◽  
Adrenal Weight ◽  
Milk Secretion ◽  
Estradiol Treatment ◽  
Litter Removal ◽  
Thymus Weight

The effects of chlorpromazine were determined on mammary growth and initiation of milk secretion in virgin rats, and on maintenance of mammary structure and secretion in postpartum rats after litter removal. When chlorpromazine was administered in doses of 5 or 15 mg/kg body weight for 5 days, only the higher dose was effective in inducing lobulo-alveolar growth and initiating milk secretion in rats initially primed with 10 µg estradiol daily for 10 days. The higher dose of chlorpromazine also maintained mammary lobulo-alveolar structure and secretion in post-partum rats for 10 days after litter removal. Chlorpromazine produced a significant increase in adrenal weight and decrease in thymus weight, indicating adrenal stimulation. In estrogen-primed rats neither prolactin nor ACTH alone could initiate mammary secretion; however they were effective when given in combination. The present data indicate that chlorpromazine promotes the secretion of both prolactin and ACTH. Hypophysectomy following estradiol treatment prevented chlorpromazine from initiating mammary secretion, showing that its effects are mediated through the anterior pituitary and not directly on the mammary gland.

THE DISTRIBUTION OF [1,2-3H]TESTOSTERONE IN THE TISSUES OF FEMALE RATS

1966 ◽  
Vol 34 (4) ◽  
pp. 491-496 ◽  
Author(s):  
D. Y. WANG ◽  
STRETTON YOUNG ◽  
R. D. BULBROOK
Keyword(s):  
Mammary Gland ◽  
Post Partum ◽  
Virgin Female ◽  
Mammary Glands ◽  
Female Rats ◽  
Pregnant Rat ◽  
Tumour Bearing ◽  
Mesenteric Fat

SUMMARY (1) The incorporation of [1,2-3H]testosterone in vivo into various tissues of virgin, pregnant, post-partum and tumour-bearing female rats was studied. (2) In virgin female rats the clearance of radioactivity from mesenteric fat, mammary gland, uterus, spleen, lung and blood was similar. This similarity in the rates of clearance of radioactivity for all the tissues examined was also found for the tissues of pregnant, post-partum, and tumour-bearing rats. (3) After the administration of [1,2-3H]testosterone different amounts of radioactivity were found in each of the tissues examined. In virgin rats the levels of incorporation were fat > uterus ≥ mammary gland > lung > blood ≥ spleen. This pattern was also obtained in post-partum and tumour-bearing animals; the tumours in the latter behaved in a similar way to normal mammary glands. In the pregnant rat, the foetus incorporated the least amount of radioactivity.

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