SUPPRESSION OF PROGESTERONE SECRETION IN LACTATING RATS BY ADMINISTRATION OF ERGOCORNINE AND THE EFFECT OF PROLACTIN REPLACEMENT

1975 ◽  
Vol 65 (2) ◽  
pp. 155-161 ◽  
Author(s):  
H. TOMOGANE ◽  
K. ÔTA ◽  
A. YOKOYAMA
Keyword(s):  
Milk Production ◽  
Venous Blood ◽  
Experimental Period ◽  
Prolactin Secretion ◽  
Corpora Lutea ◽  
Undetectable Level ◽  
Stage Of Lactation ◽  
Progesterone Secretion ◽  
Treatment Administration ◽  
Very High

SUMMARY In order to assess the stimulatory effect of prolactin on the secretion of progesterone from corpora lutea in lactating rats, ergocornine maleate (ECO; 1 mg/day), an inhibitor of prolactin secretion, was administered subcutaneously on days 6 and 7 of lactation in primiparous rats. By day 8 of lactation, the concentration of progesterone in ovarian venous blood fell to an undetectable level in the ECO-treated animals, while the concentration in the control animals was very high at this stage of lactation. The level of 20α-hydroxypregn-4-en3-one was significantly higher on day 8 of lactation in ECO-treated than in control rats. Lactational dioestrus was interrupted by treatment with ECO and vaginal oestrus appeared 3–4 days after the start of treatment. Administration of ECO caused deleterious depression of milk production and of food intake of mother rats. In the pair-fed control animals, lactation continued almost normally throughout the experimental period. Prolactin (1 mg/day) administered simultaneously with ECO increased progesterone to levels even higher than those in control rats and restored 20α-hydroxypregn-4-en-3-one levels to those of the controls. The effect of the drug on milk production was alleviated. The results strongly suggest that prolactin is the most important factor in maintaining the function of corpora lutea in the lactating rat.

Pineal denervation by cervical sympathetic ganglionectomy suppresses the role of photoperiod on pregnancy or pseudopregnancy, body weight and moulting periods in the mink (Mustela vison)

1985 ◽  
Vol 107 (1) ◽  
pp. 31-39 ◽  
Author(s):  
L. Martinet ◽  
D. Allain ◽  
Y. Chabi
Keyword(s):  
Body Weight ◽  
Environmental Factors ◽  
Prolactin Secretion ◽  
Corpora Lutea ◽  
Progesterone Secretion ◽  
Cervical Ganglion ◽  
Cervical Sympathetic ◽  
Implantation Period ◽  
Short Days

ABSTRACT In mink, termination of the delayed implantation period, following reactivation of the corpora lutea, and onset of the spring moult are associated with a rise in prolactin secretion triggered by increasing daylength, while decreasing daylength induces the autumn moult. To establish whether suppression of the function of the pineal rendered the mink unresponsive to daylength changes, the superior cervical ganglion was removed bilaterally 2–4 weeks before mating. Intact and operated females were then left outdoors or were put under a lighting regime of either 15 h light: 9 h darkness (15L: 9D) or 8L: 16D. In July, at the end of the spring moult, the 15L: 9D lighting regime was changed to one of 8L: 16D. Under artificial photoperiods ganglionectomy suppressed the stimulatory role of long days and the inhibitory role of short days on prolactin secretion, and consequently on progesterone secretion and spring moult. Neither was the autumn moult, induced early in intact females by the change to a short photoperiod, advanced in ganglionectomized females, showing that the latter were unresponsive to the artificial modification of the photoperiod. However, in animals kept outdoors, prolactin and progesterone secretion and spring moult were not changed by ganglionectomy. Increase in body weight and autumn moult were only slightly delayed by the operation suggesting that other environmental factors had replaced the synchronizing effect of the daylength changes. Alternatively the desynchronization between intact females responsive to photoperiodism and those rendered unresponsive may be too slow to be observed soon after ganglionectomy. J. Endocr. (1985) 107, 31–39

scholarly journals Metabolic Attributes, Milk Production and Ovarian Activity of Ewes Supplemented with a Soluble Sugar or a Protected-Fat as Different Energy Sources During Postpartum Period

2017 ◽  
Vol 17 (1) ◽  
pp. 229-240 ◽  
Author(s):  
Nesrein M. Hashem ◽  
Samir Z. El-Zarkouny
Keyword(s):  
Milk Production ◽  
Postpartum Period ◽  
Serum Insulin ◽  
Soluble Sugar ◽  
Body Weight Loss ◽  
Experimental Period ◽  
Energy Sources ◽  
Ovarian Activity ◽  
Corpora Lutea ◽  
Serum Triglycerides

Abstract The effects of two dietary supplemental energy sources on metabolic attributes, milk production and ovarian activity of ewes during early to mid-postpartum period were studied using thirty multiparous lactating ewes (Rahmani × Barki) weighing 43.10±1.22 kg and 3-6 years old. The ewes were assigned to three groups (n=10 per group). All ewes received the same diet supplemented with isocaloric and isonitrogenous protected-palm oil (50 g/ewe/d, F-group) or a sugar cane molasses (140 g/ewe/d, M-group) or without supplementation (control, C-group), for 60 days starting 2 weeks postpartum. Results showed that, during the experimental period, both energy sources reduced (P<0.05) body weight loss of ewes compared with the control (2.57 kg in F-group, 0.911 kg in M-group and 4.71 kg in C-group). The metabolic profiles of ewes were affected by the sources of energy, the highest (P<0.05) concentration of serum triglycerides was in the F-group, whereas the highest (P<0.05) concentration of serum insulin was in the M-group. The lowest serum glucose concentration was (P<0.05) in the F-group (73.20 mg/dL) and the highest in the C-group (76.85 mg/dL), whereas it was intermediate in the M-group (74.69 mg/dL). Ewes in the F-group had (P<0.05) the highest milk yield and energy-corrected milk (531.72 g/d and 554.40 g/d, respectively) compared with those in the M-group (491.76 g/d and 525.12 g/d, respectively) and C-group (429.96 g/d and 462.00 g/d, respectively). The highest (P<0.05) number of corpora lutea (CL; ovulation activity) was in the F-group (0.45), whereas it was not different between the M-group (0.25) and the C-group (0.15). In conclusion, during early to mid-postpartum period, protected-fat supplementation increased serum triglycerides concentration which was effectively used as an energyyielding nutrient for improving milk production. It could also be suggested that specific fatty acid in protected-fat improved quality of the ovulatory follicle and thus occurrence of ovulation.

SIMULTANEOUS INFUSION OF PROSTAGLANDIN E2 ANTAGONIZES THE LUTEOLYTIC ACTION OF PROSTAGLANDIN F2α IN VIVO

1977 ◽  
Vol 72 (3) ◽  
pp. 379-383 ◽  
Author(s):  
K. M. HENDERSON ◽  
R. J. SCARAMUZZI ◽  
D. T. BAIRD
Keyword(s):  
Prostaglandin E2 ◽  
Venous Blood ◽  
Prostaglandin F2α ◽  
Corpora Lutea ◽  
Progesterone Secretion ◽  
Prostaglandin F ◽  
Infusion Period

SUMMARY Corpora lutea of ewes bearing ovarian autotransplants were infused for 4 h with prostaglandin F2α (PGF2α) (10 μg/h), PGF2α + PGE2 (10 μg/h of each), PGE2 (10 μg/h) or saline on day 10 of the cycle. Ovarian venous blood obtained before, during, and up to 12 h after the infusion period, was assayed for progesterone. Prostaglandin F2α produced an immediate, rapid and sustained decline in progesterone secretion, but infusion of PGE2 together with PGF2α prevented the decline until after the infusion. Progesterone secretion was unaffected by infusion of PGE2 alone. Oestrous behaviour was observed in four out of seven animals infused with PGF2α but in only one out of six infused with PGF2α + PGE2. None of the animals infused with PGE2 alone or saline only came into heat.

SERUM LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, PROLACTIN AND PROGESTERONE CONCENTRATIONS AND FOLLICULAR DEVELOPMENT IN THE PSEUDOPREGNANT RAT AFTER UNILATERAL OVARIECTOMY

1975 ◽  
Vol 66 (2) ◽  
pp. 249-256 ◽  
Author(s):  
W. J. DE GREEF ◽  
J. DULLAART ◽  
G. H. ZEILMAKER
Keyword(s):  
Follicular Development ◽  
Prolactin Secretion ◽  
Corpora Lutea ◽  
Follicular Growth ◽  
Unilateral Ovariectomy ◽  
Progesterone Secretion ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Follicular Size ◽  
Limited Degree

SUMMARY Serum LH, FSH, prolactin and progesterone concentrations and follicular size were measured in rats during pseudopregnancy after unilateral ovariectomy (ULO) on day 1. This operation did not affect the duration of pseudopregnancy. Following pseudopregnancy compensatory ovulation occurred. After ULO progesterone concentrations remained low as compared with control values but the progesterone secretion per ovary was increased slightly. After ULO, LH concentrations were significantly increased on days 3 and 4 of pseudopregnancy. FSH concentrations were increased 5 h after the operation and again on days 4–7 of pseudopregnancy when compared with sham-operated control animals. During pseudopregnancy prolactin secretion increased each night. Increased prolactin levels were observed 18 and 36 h after ULO. The number of medium-sized follicles had increased 24 h after ULO. From the present study it is concluded that progesterone secretion by the corpora lutea can be increased to a limited degree by the increased release of gonadotrophins. Furthermore, it is concluded that a rapid increase in FSH concentrations after ULO is responsible for the initiation of the compensatory follicular growth.

Feed conversion efficiency and marginal milk production responses of pasture-fed dairy cows offered supplementary grain during an extended lactation

2011 ◽  
Vol 51 (3) ◽  
pp. 204 ◽  
Author(s):  
M. J. Auldist ◽  
C. Grainger ◽  
K. L. Macmillan ◽  
L. C. Marett ◽  
M. Hannah ◽  
...  
Keyword(s):  
Milk Production ◽  
Conversion Efficiency ◽  
Milk Fat ◽  
Experimental Period ◽  
Energy Concentration ◽  
Feed Conversion ◽  
Feed Conversion Efficiency ◽  
Stage Of Lactation ◽  
Milk Solids ◽  
Extended Lactation

A study was conducted to quantify the feed conversion efficiency (FCE) and marginal milk responses of pasture-fed cows offered supplementary grain during an extended lactation of 670 days. The experiment used three groups of 10 Holstein cows in four experimental periods of 4 weeks, beginning when cows were ~60, 240, 420 and 530 days in milk (DIM). In each experimental period, cows were individually fed diets of either freshly cut perennial ryegrass pasture supplemented with triticale (60 and 420 DIM), or pasture silage and lucerne hay supplemented with wheat (240 and 530 DIM). On each occasion, one of the three groups was offered additional grain at 0.0, 2.5 or 5.0 kg DM/cow.day. Milk production was measured daily and concentrations of milk fat and protein weekly. These data were used to calculate FCE and marginal responses of milk, energy-corrected milk and milk solids (fat + protein). Results showed FCE was highest at 60 DIM and lowest at 530 DIM. Increased DM intake because of increased grain intake led to increased FCE at 240 and 530 DIM when the energy concentration of forage was lowest. Marginal milk responses were not different at any stage of lactation. For milk solids and energy-corrected milk, responses at 240 DIM were the same as at 530 DIM, but greater than at 60 DIM and 420 DIM. This study provides the first Australian data about FCE and marginal milk production responses to grain supplementation of pasture-fed cows undergoing an extended lactation. The results should provide farmers with confidence that good responses to grain can be achieved even in the latter part of a 22-month lactation.

Effects of feeding peas to high-producing dairy cows

1995 ◽  
Vol 75 (4) ◽  
pp. 625-629 ◽  
Author(s):  
R. R. Corbett ◽  
L. A. Goonewardene ◽  
E. K. Okine
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Milk Yield ◽  
Milk Fat ◽  
Dairy Herd ◽  
Protein Source ◽  
Canola Meal ◽  
Stage Of Lactation ◽  
Nutrient Analyses ◽  
Protein Milk

The effect of substituting peas for soybean and canola meals as a protein source in a high-producing dairy herd was studied in 66 Holstein cows, divided into two groups based on stage of lactation, parity, level of milk production and days in milk. Two 18.5% crude protein grain concentrate diets were formulated based on the nutrient analyses of the forages available. The control grain mix contained standard protein sources, principally soybean and canola meal (SBM\CM) while the test grain mix was formulated to contain approximately 25% field peas as the major source of protein. Both grain rations were formulated to the same nutrient specifications and balanced for undegradable protein. The duration of the trial was 6 mo during which grain feeding levels were adjusted monthly based on milk yield. For cows in early lactation, 4% fat-corrected milk yield was higher (P < 0.05) for cows fed pea based concentrates (31.3 kg d−1) than for cows fed SBM\CM supplement (29.7 kg d−1). Fat-corrected milk yield was not affected by source of protein in mid- and late-lactation cows. Fat-corrected milk production was not different (P > 0.05) for cows fed SBM\CM compared with cows fed the pea supplement when cows across all stages of lactation were included in the analyses. Milk fat percent was significantly higher (P < 0.05) for early- and mid-lactation cows fed the pea supplement. The results suggest that peas can be substituted for SBM\CM as a protein source for high-producing dairy cows. Key words: Dairy cow, pea, soybean and canola meal supplement, undegradable protein, milk production

Indomethacin treatment prevents prolactin-induced luteolysis in the rat

1987 ◽  
Vol 112 (2) ◽  
pp. 317-322 ◽  
Author(s):  
J. E. Sánchez-Criado ◽  
K. Ochiai ◽  
I. Rothchild
Keyword(s):  
Corpus Luteum ◽  
Left Kidney ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Silicone Elastomer ◽  
Serum Prolactin ◽  
Corpora Lutea ◽  
Synthesis Inhibitor ◽  
Significant Difference ◽  
Indomethacin Treatment

ABSTRACT Adult female rats were hypophysectomized and their pituitary glands autotransplanted beneath the left kidney capsule on day 2 (day 1 was the day of ovulation). In such rats the pituitary secretes prolactin fairly constantly and the corpora lutea secrete progesterone for several months. To induce the luteolytic effect of prolactin the rats were first injected s.c. with 2-bromo-α-ergocryptine (CB-154) on cycle days 12, 13 and 14 (i.e. 10, 11 and 12 days after operation) to depress prolactin secretion, and then with CB-154 vehicle (70% ethanol) daily until cycle day 21, to allow prolactin secretion to resume. One ovary was removed from each rat on day 15 and the remaining one on day 22. The mean (± s.e.m.) weight of the corpora lutea on day 15 was 1·46±0·06 mg and 0·98±0·07 mg on day 22 (n = 17). In contrast, rats in which the CB-154 treatment was maintained to day 21 had corpora lutea which weighed 1·31 ±0·09 on day 15 and 1·47 ±0·08 mg on day 22 (n = 15). To investigate whether indomethacin, a prostaglandin synthesis inhibitor, affected the luteolytic action of prolactin, the experiment was repeated, but on day 15 (after the removal of one ovary) the groups in which CB-154 treatment was stopped, as well as the group in which CB-154 treatment was maintained, were each divided into two groups. In one, indomethacin-containing silicone elastomer wafers and, in the other, blank silicone elastomer wafers, were placed within the bursa of the remaining ovary. There were no differences in corpus luteum weight on day 15 among any of these groups and the two groups of the first experiment. There was no significant difference in corpus luteum weight between day 15 and day 22 in any of the six groups except for the two groups treated with the CB-154 vehicle and not with indomethacin. Thus, treatment with indomethacin prevented the fall in corpus luteum weight associated with the discontinuation of CB-154 treatment. Serum prolactin levels fell until day 15 in all rats and remained low in those in which the CB-154 treatment was maintained to day 21, but returned to control values in those treated with vehicle after day 14. Serum progesterone levels fell and remained low in all groups. Indomethacin treatment had no effect on the levels of either serum prolactin or progesterone. We conclude that some of the pharmacological effects of indomethacin are to prevent prolactin-induced luteolysis, and we suggest that prolactin induces rapid regression of the corpus luteum by stimulating intraluteal prostaglandin production or by being necessary for the effect of luteolytic prostaglandins. J. Endocr. (1987) 112, 317–322

scholarly journals Synthesis of [1,2-3H2]cholecalciferol and metabolism of [4-14C,1,2-3H2]- and [4-14C,1-3H]-cholecalciferol in rachitic rats and chicks

1971 ◽  
Vol 121 (4) ◽  
pp. 673-682 ◽  
Author(s):  
D. E. M. Lawson ◽  
B. Pelc ◽  
P. A. Bell ◽  
P. W. Wilson ◽  
E. Kodicek
Keyword(s):  
Vitamin D ◽  
Substance P ◽  
Rat Kidney ◽  
Intracellular Localization ◽  
Specific Radioactivity ◽  
Experimental Period ◽  
Time Interval ◽  
High Concentration ◽  
Very High ◽  
25 Hydroxycholecalciferol

[1,2-3H2]Cholecalciferol has been synthesized with a specific radioactivity of 508mCi/mmol by using tristriphenylphosphinerhodium chloride, the homogeneous hydrogen catalyst. With doses of 125ng (5i.u.) of [4-14C,1-3H2]cholecalciferol the tissue distribution in rachitic rats of cholecalciferol and its metabolites (25-hydroxycholecalciferol and peak P material) was similar to that found in chicken with 500ng doses of the double-labelled vitamin. The only exceptions were rat kidney, with a very high concentration of vitamin D, and rat blood, with a higher proportion of peak P material, containing a substance formed from vitamin D with the loss of hydrogen from C-1. Substance P formed from [4-14C,1,2-3H2]cholecalciferol retained 36% of 3H, the amount expected from its distribution between C-1 and C-2, the 3H at C-1 being lost. 25-Hydroxycholecalciferol does not seem to have any specific intracellular localization within the intestine of rachitic chicks. The 3H-deficient substance P was present in the intestine and bone 1h after a dose of vitamin D and 30min after 25-hydroxycholecalciferol. There was very little 25-hydroxycholecalciferol in intestine at any time-interval, but bone and blood continued to take it up over the 8h experimental period. It is suggested that the intestinal 3H-deficient substance P originates from outside this tissue. The polar metabolite found in blood and which has retained its 3H at C-1 is not a precursor of the intestinal 3H-deficient substance P.

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