Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study investigated the influence of chronic hyperthyroidism on mammary function in lactating rats and the effects on their pups. Thyroxine-treated (10 microg per 100 g body weight per day; hyperthyroid (HT)) or vehicle-treated rats were mated 2 weeks after the start of treatment and killed with their litters on days 7, 14 and 21 of lactation. Serum concentrations of triiodothyronine (T(3)) and tetraiodothyronine (T(4)) increased in thyroxine-treated rats. In HT mothers, serum prolactin decreased on day 7 and day 14 of lactation, whereas insulin-like growth factor I (IGF-I) and progesterone concentrations decreased, and corticosterone increased on day 7 of lactation. In HT pups, T(4) concentration increased on day 7 and day 14 of lactation, whereas T(3) increased only on day 14 of lactation, and growth hormone increased on day 7 of lactation. Mammary prolactin binding sites did not vary, but there was an increase in the binding sites in the liver on day 14 of lactation in thyroxine-treated rats. In an acute suckling experiment, thyroxine-treated rats released less oxytocin, growth hormone and prolactin and excreted less milk than did control rats. Mammary casein, lactose and total lipid concentrations in thyroxine-treated rats were similar to those of control rats on day 14 of lactation. Histological studies of the mammary glands showed an increased proportion of alveoli showing reduced or no lumina and cells with condensed nuclei on day 14 and day 21 of lactation; the TdT-mediated dUTP nick-end labelling (TUNEL) test revealed an increase in apoptosis in alveolar cells on day 21 of lactation in thyroxine-treated rats. Expression of SGP-2, a gene expressed during mammary involution, increased in thyroxine-treated rats on day 14 and day 21 of lactation, whereas expression of insulin-like growth factor binding protein 5, a proapoptotic signal, was unchanged. Bcl-2, which promotes survival of mammary gland epithelial cells was unchanged, whereas expression of IGF-I, which also promotes survival of mammary gland epithelial cells, increased on day 21 of lactation in thyroxine-treated rats. These results indicate that thyroxine treatment produces some milk stasis as a result of impairments in suckling induced release of oxytocin that may initiate the first stage of mammary involution, increasing apoptosis in a gland that is otherwise actively producing and secreting milk.
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PMID:Hyperthyroidism and production of precocious involution in the mammary glands of lactating rats. 1241 8

There is a close relationship between mammary blood flow (MBF) and milk production, but whether MBF is limiting milk yield has not been determined. Five lactating goats received close arterial (external pudic) infusion of PBS or the nitric oxide donor diethylamine NONOate (0.5 mg/h; NONate) for 6 h, according to a crossover design. Goats were hand milked (with oxytocin) every 2 h starting 2 h before and ending 6 h after the end of the infusion. In one goat, a transit time flow probe was implanted around the infused and noninfused artery, whilst in another goat a flow probe was implanted around the infused artery only. Infusion of PBS did not affect MBF or milk production. As with previous results (Lacasse et al., 1996), NONate induced a rapid increase (up to 250% of preinfusion level) in MBF in the infused gland only. Mammary blood flow was still above the preinfusion level at the end of the infusion period. Despite this increase in MBF, NONate did not affect milk production. Milk yield ratio (infused/noninfused gland) averaged 1.20, 1.12, and 1.17 for the preinfusion, infusion and post infusion periods, respectively. Similarly, protein, fat and lactose yields were not affected by PBS or NONate infusion. These results provide no support to the contention that increasing MBF can enhance milk production.
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PMID:Mammary blood flow does not limit milk yield in lactating goats. 1283 45

Previous studies have suggested that upstream stimulatory factors (USFs) regulate genes involved with cell cycle progression. Because of the relationship of USFs to an important oncogene in breast cancer, c-myc, we chose to determine the importance of USF to normal mammary gland development in the mouse. Expression of USF in the mammary gland throughout development demonstrated only modest changes. Mutation of the Usf2 gene was associated with reduced fertility in females, but had no effect on prepartum mammary gland development. However, lactation performance in Usf2-/- females was only half of that observed in Usf2+/+ females, and both lactose and nitrogen were decreased in milk from Usf2-/- dams. This decrease was associated with diminished mammary tissue wet weight and luminal area by d 9 of lactation and with a decreased protein-DNA ratio. This decrease was associated with reduced abundance of the eukaryotic initiation factors eIF4E and eIF4G. Blood oxytocin concentrations on d 9 postpartum were also lower in Usf2-/- mice than Usf2+/+ mice. In contrast, the mutation had no effect on blood prolactin concentrations, mammary cell proliferation or apoptosis, mammary tissue oxytocin receptors, or milk protein gene expression. The mutation had only modest effects on maternal behavior. These data support the idea that USF is important to physiological processes necessary for the establishment and maintenance of normal lactation and suggest that USF-2 may impact lactation through both systemic and mammary cell-specific mechanisms.
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PMID:Diminished milk synthesis in upstream stimulatory factor 2 null mice is associated with decreased circulating oxytocin and decreased mammary gland expression of eukaryotic initiation factors 4E and 4G. 1290 52

Thyroid dysfunctions can produce reproductive problems. Untreated maternal hypothyroidism has serious consequences on development of offspring, resulting in stunted growth and mental retardation. The effects of propylthiouracyl-induced hypothyroidism (0.1 g l(-1) in drinking water starting 8 days before mating, or given to virgin rats for 30 or 50 days) on the serum profiles of hormones related to reproduction and mammary function (prolactin, growth hormone (GH), progesterone, corticosterone, oestradiol, insulin-like growth factor I (IGF-I), thyroid-stimulating hormone (TSH), triiodothyronine and tetraiodothyronine), and on mammary function in virgin, pregnant and lactating rats, were investigated. Propylthiouracyl treatment severely decreased circulating triiodothyronine and tetraiodothyronine concentrations, and increased serum TSH concentrations. Virgin rats showed prolonged periods of vaginal dioestrus, increased circulating progesterone concentrations and afternoon peaks of prolactin concentration, which are indicative of prolactin-induced pseudopregnancy. Propylthiouracyl-treated virgin rats had mammary development comparable to that of midpregnancy, and half of these rats had increased mammary casein and lactose concentrations. Serum prolactin concentrations were decreased on the afternoon of day 5 of pregnancy, increased during late pregnancy (days 15-21) and were normal during lactation. Circulating GH concentrations decreased on days 15-21 of pregnancy, whereas progesterone concentrations increased during late pregnancy and early lactation. Circulating oestradiol (measured in late pregnancy and in virgin rats), IGF-I and corticosterone concentrations were decreased. Although assessment of mammary histology showed no differences in extent of development, casein content was increased in propylthiouracyl-treated rats on day 21 of pregnancy; litter growth was severely reduced and at day 20 of age the pups were hypothyroid, with decreased GH serum concentrations. An acute suckling experiment was performed on days 10-12 of lactation to determine whether some impairment in mammary function or the suckling reflex might account for these differences. After an 8 h separation of mothers from their litters and 30 min of suckling, circulating prolactin values were not affected by propylthiouracyl treatment, but serum oxytocin concentration and milk excretion were reduced. In conclusion, hypothyroidism induces various alterations in the hormone profiles of virgin and pregnant rats, and induces pseudopregnancies and mammary development in virgin rats. These alterations do not appear to have an overt impact on the outcome of pregnancy and on mammary function during lactation, with the exception of the milk ejection reflex, which may account at least partially for the reduced litter growth.
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PMID:Effect of hypothyroidism on hormone profiles in virgin, pregnant and lactating rats, and on lactation. 1296 45

Researchers have turned their attention to the effects of alcohol consumption on breastfeeding, with significant negative findings concerning both the mother and the newborn. This study is a meta-analysis of the principle research performed in the last decade that was concerned with lactation and alcohol. Results from experimental and human subject research has shown that effects of alcohol include: behavioural changes, reduced milk and luteinising hormone production, with increased fat content, reduced lactose content. Increased lipogenesis and increased activity of lipoprotein and hormone-sensitive lipase, structural alterations in the epithelial cells of the breast and abnormal casein production, reduced oxytocin and prolactin production with subsequent reduced milk ejection, and reduced weight and protein content of the breast. Reduction in food consumption, body weight, growth and development and hepatic glycogen, serum glucose, amino-acids, insulin, glycerol, fatty acids and urea, and an increase in serum acetoacetic acid is seen in newborn children that were breastfed by animals with a high intake of alcohol during pregnancy or the puerperal period. Alcohol consumption during lactation caused a reduction in liver weight and triglyceride, protein, DNA and lipid content, in the newborns. Serum changes included a reduction in protein, triglyceride, cholesterol, fatty acid and glycerol level with an increase in beta-hydroxybutirate levels. Changes also included alterations in the motor system and behaviour. Further studies are needed to determine, with confidence, the minimum level of alcohol consumption that can provoke pathological effects in both the mother and the child.
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PMID:[Lactation and alcohol: clinical and nutritional effects]. 1533 53

Exogenous hormone treatments designed to induce nonpregnant ewes to lactate at levels sufficient to rear orphan lambs were investigated in three breeds (Blackface, Dorset and Greyface) and in a total of 14 groups. The hormone treatments consisted of an induction phase lasting 1-6 weeks during which most ewes received daily subcutaneous injections of 75 mg of progesterone and 100 microg of oestradiol-17beta, and a trigger phase lasting 1 or 2 weeks during which 5 mg of oestradiol-17beta and/or 10 mg of dexamethasone were given daily and the daily dose of progesterone was reduced to zero. From the end of the trigger phase for at least 2 weeks, milk production was determined three times daily by hand milking after prior intravenous injections of 5 IU of oxytocin. The linear dimensions of the udder were measured in each ewe at 5-6 day intervals throughout the induction and trigger phases. Udder sizes increased in response to hormone treatment in all cases, and the rate of increase was usually 1.75-11.3 times greater during the trigger phase than during the induction phase. Accumulation of milk in the udder during the trigger phase resulted in mean milk yields of 212-763 ml on the first day of milking, which were higher than the mean yields of 130-354 ml on the second day. Thereafter the mean daily milk yields increased progressively to reach 579-1301 ml after 14 days of milking. Group comparisons revealed the following: an induction phase of at least 4 weeks duration was required to ensure that all hormone-treated ewes produced 800 ml or more of milk/day by 14 days of milking; during the trigger phase, oestradiol-17beta alone was a more effective lactogenic agent than dexamethasone alone, and dexamethasone apparently hindered the lactogenic actions of oestradiol-17beta when both hormones were given together; extending the duration of the trigger phase from 1 to 2 weeks did not improve subsequent milk yields; and there were no significant breed differences in milk yield responses to similar hormone treatments. It is concluded that a 4-6 week induction phase followed by a 1-week trigger phase using the progesterone and oestradiol-17beta doses noted above but excluding dexamethasone would induce in most nonpregnant ewes lactation at levels sufficient to rear orphan lambs. Compared to the compositions of normal colostrum and milk, the milk from some of the present ewes had lower dry matter contents, fat concentrations and immunoglobulin-G concentrations and generally similar lactose concentrations. These differences were not considered to be sufficient to jeopardize the survival of lambs reared by such ewes.
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PMID:Hormonal induction of lactation in non-pregnant ewes. 1603 26

The capability of goats to maintain milk production during water deprivation is remarkable and not yet fully understood. The aim of the present study was to investigate whether intravenous infusions of hypertonic NaCl cause release of both vasopressin and oxytocin and whether the peptides, in combination with the hyperosmolality, affect milk flow and milk composition. Six Swedish domestic landrace goats in their first to third lactation were milked every 30 min during experiments. Hypertonic NaCl (HNaCl) or isotonic NaCl (IsoNaCl) were infused for 90 min. Goats were not allowed to drink during infusions. Plasma vasopressin concentration increased during HNaCl infusions, and did not change in response to IsoNaCl infusions. Plasma oxytocin concentration did not change during either infusion. Milk flow was maintained during the infusions. Milk fat concentration decreased in the three samples taken before onset of the infusions, but then increased gradually during HNaCl infusions, while it continued to fall during the IsoNaCl infusions. Milk osmolality followed the rise in plasma osmolality during the HNaCl infusions and did not change in IsoNaCl experiments. Milk lactose concentration increased throughout both series of experiments, the concentration being higher during HNaCl infusions. Milk protein concentration did not change during HNaCl infusions, but fell in the IsoNaCl experiments. It is concluded that the hyperosmolality in combination with elevated plasma vasopressin levels did not disturb the secretory activity of the mammary cells, but rather facilitated emptying of the alveolar milk. Such a mechanism may help to explain the sustained milk production in water deprived goats.
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PMID:Hypertonic NaCl infusions affect milk composition in goats. 1656 80

The aim of this work was to evaluate the effects of milking interval (4, 8, 12, 16, 20, and 24 h) on cisternal size and milk partitioning (cisternal and alveolar) in the udders of dairy ewes. Twenty-four dairy ewes (Manchega, n = 12; Lacaune, n = 12) were used in a 2-wk experiment during mid-lactation. Cisternal and alveolar milk yields were measured and milk samples from each udder fraction were collected for analysis. Cisternal milk was obtained after i.v. injection of an oxytocin receptor antagonist, and alveolar milk was obtained after i.v. injection of oxytocin. Enlargement of the cisternal compartment due to milking intervals was measured by ultrasonography for each half udder. Volumes of cisternal and alveolar milk differed according to breed, being greater in Lacaune (888 +/- 43 and 338 +/- 25 mL, respectively) than in Manchega ewes (316 +/- 43 and 218 +/- 25 mL, respectively). Alveolar milk increased linearly to 16 h in Manchega and 20 h in Lacaune and remained constant thereafter. Cisternal milk accumulated linearly to 24-h milking intervals in both breeds. Cisternal area (values per udder half) increased as milking interval increased, reaching a plateau at 20 h in Manchega (21 +/- 1 cm(2)) and 16 h in Lacaune (37 +/- 1 cm(2)). Correlation between cisternal area and cisternal milk was the greatest at 8 h (Manchega: r = 0.70 and Lacaune: r = 0.56). Cisternal area correlated with total milk (r = 0.80). Milk fat content varied markedly with milking intervals, increasing in alveolar milk (until 12 h in Manchega, 8.90 +/- 0.18%; and 20 h in Lacaune, 8.67 +/- 0.19%) and decreasing until 24 h in cisternal milk (5.74 +/- 0.29% and 4.85 +/- 0.29%, respectively). Milk protein content increased in alveolar milk until 24 h (Manchega, 6.46 +/- 0.11%; Lacaune, 5.95 +/- 0.11%), but did not vary in cisternal milk. Milk lactose content only decreased at the 24-h milking interval in the cisternal milk of Manchega ewes (4.60 +/- 0.04%). In conclusion, our results suggest that cisterns play an important role in accommodating secreted milk during extended milking intervals. Thus, long milking intervals could be a recommended strategy for large-cisterned dairy sheep. Evidence indicates that ultrasonography provides accurate estimations of udder cistern size and could be used as an indicator for selecting large-cisterned dairy ewes.
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PMID:Changes in alveolar and cisternal compartments induced by milking interval in the udder of dairy ewes. 1876 99

Effects of 4 different milking intervals (8, 12, 16, and 24 h) on milk yield and milk composition were studied in Tunisian Maghrebi dairy dromedaries (n = 6) at late lactation [240 +/- 14 days in milk (DIM), 5.84 +/- 1.62 L/d]. Camel-cows suckled their calves for 2 mo, were hand milked while suckling until mo 4 of lactation (calf weaning) and machine milked thereafter. Intravenous injection of oxytocin was administered before machine milking at each experimental milking to induce complete milk ejection and to avoid carryover effects of milking intervals. Cisternal and alveolar milk were measured at 380 +/- 16 DIM for a 24-h milking interval. Milk accumulated logarithmically (R(2) = 0.95) in the udder from 8- to 24-h milking interval without reaching a plateau. Consequently, milk secretion rate decreased exponentially (R(2) = 0.93) according to milking interval. Compared with 12-h milking interval (6.1 L/d), estimated daily milk yield was 113, 87, and 70% for 8-, 16-, and 24-h intervals, respectively. Total milk solids, milk fat content, and milk pH decreased with increasing milking interval, showing the greatest value at 8-h intervals (14.1 +/- 0.4%, 4.6 +/- 0.5%, and 6.66 +/- 0.05, respectively) and the lowest at 24-h intervals (12.3 +/- 0.9%, 2.9 +/- 0.6%, and 6.54 +/- 0.02, respectively). Milk protein (3.9 +/- 0.1%), lactose (4.5 +/- 0.2%), ash (0.84 +/- 0.01%) and density (1.028 +/- 0.01) remained constant for all milking intervals. Milk K, Ca, and Mg contents increased as milking interval increased, but Na content did not change (0.06 +/- 0.01%, on average). Milk Na:K ratio tended to decrease from 0.35 (1:2.9) to 0.22 (1:4.5) for the extreme milking intervals. Plasma lactose concentration steadied from 8- to 16-h (67 +/- 32 micromol) but increased dramatically at 24-h intervals (338 +/- 118 micromol), indicating that mammary tight junctions became permeable after 24 h of milk accumulation. Camel udders showed small cisterns (19.3% of total milk in the udder at 24 h) when compared with other dairy animals; we recommend the use of prestimulation for machine milking and selection for larger udder cisterns. Alveolar milk contained more fat (5.16 vs. 1.75%; SEM, 0.39%) and protein (3.23 vs. 2.73%; SEM, 0.15%) than cisternal milk. Despite the increase of plasma lactose during tight junction leakiness, the tendency for the Na:K ratio to decrease may be indicative of a camel's specific regulatory mechanism for controlling Na and K concentrations in milk and delaying the inhibitory effect of milk stasis on milk secretion rate. In conclusion, this short-term study proved the low storage capacity of the Tunisian Maghrebi camel udder but also showed their moderate ability to adapt to extended milking intervals at late lactation.
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PMID:Effects of milking interval and cisternal udder evaluation in Tunisian Maghrebi dairy dromedaries (Camelus dromedarius L.). 1930 26

The potential impacts of injecting oxytocin (OXY) to sows in the early postpartum period on the quality of mammary tight junctions, milk composition, and immune status of sows and piglets were studied. Postparturient sows received i.m. injections of either saline (control [CTL]; = 10) or 75 IU of OXY ( = 10). Injections were given twice daily (0800 and 1630 h) starting on d 2 of lactation (i.e., between 12 and 20 h after birth of the last piglet), totaling 4 injections. Milk samples were obtained before the first injection (d 2 morning [AM]), before the second injection (d 2 afternoon [PM]), and on d 4 PM and d 5 PM. Blood samples were obtained from sows before milking on d 2 AM, d 2 PM, and d 5 PM. On d 5 of lactation, a blood sample was obtained from 3 piglets per litter. Circulating concentrations of prolactin, IGF-I, lactose, and IgA in sows did not differ between treatments at any time ( > 0.10), but OXY sows had less IgG than CTL sows ( < 0.01) on d 2 PM before the second OXY injection. There were differences in milk composition on d 2 PM, with OXY sows having more IGF-I ( < 0.01), solids ( < 0.05), protein ( < 0.01), energy ( < 0.05), and IgA ( < 0.01) and a greater Na:K ratio ( < 0.01) than CTL sows. These differences were not seen in the next 2 milk samples, except for protein and IgA that still tended ( < 0.10) to be greater in OXY vs. CTL sows on d 4 PM (for protein) and on d 5 PM (for IgA) after the last injection. Milk lactose content was lower in OXY vs. CTL sows on d 5 PM ( < 0.01). Values for immunoglobulin immunocrit, IgG, IgA, and IGF-I in piglet blood did not differ between treatments ( > 0.10). Injecting OXY to sows in the early postpartum period increased leakiness of the mammary tight junctions, improved composition of early milk, and may potentially affect immune status of neonatal piglets.
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PMID:Oxytocin injections in the postpartal period affect mammary tight junctions in sows. 2880 89


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