Effect of adrenalectomy on the regulation of ovarian function during lactation in the rat

1983 ◽  
Vol 98 (2) ◽  
pp. 233-240 ◽  
Author(s):  
W. J. de Greef ◽  
P. van der Schoot
Keyword(s):  
Adrenal Glands ◽  
Ovarian Function ◽  
Post Partum ◽  
Acute Effect ◽  
Prolactin Secretion ◽  
Daily Treatment ◽  
Corpora Lutea ◽  
Plasma Prolactin ◽  
Adrenal Hormones ◽  
Adrenalectomized Rats

Corpora lutea formed after post-partum ovulation in the rat become functionally active under the influence of prolactin released as a result of suckling. During this period of luteal activity (lactational pseudopregnancy) ovulations do not occur. Despite continued suckling plasma prolactin declines gradually during lactation but this gradual decrease was not observed when adrenalectomy was performed on day 2 of lactation. The prolongation of lactational pseudopregnancy after adrenalectomy is probably associated with this observation. Daily treatment of adrenalectomized lactating rats with 5 mg corticosterone acetate, but not with 1·5 mg, reduced the duration of lactational pseudopregnancy to that of controls. Removal of litters of five pups on day 13 of lactation was followed by resumption of ovulation 3 days later in control animals. However, in adrenalectomized rats the interval between removal of the five-pup litter and the next ovulation was prolonged to 10 or more days because of the persistence of luteal activity. This prolonged interval in adrenalectomized rats was not caused by an acute effect of the absence of adrenal hormones since it was not observed in rats which had been adrenalectomized 3 days before removal of the litter. Furthermore, the increase in the interval between removal of the five-pup litter and resumption of ovulation was also not due to the absence of the main glucocorticoid in the rat, since daily treatment with corticosterone from the day of adrenalectomy failed to prevent the occurrence of the long delay. Adrenal transplants could, however, prevent the effect induced by adrenalectomy. Since the medulla of these transplants had become necrotic, it seems that factors of adrenocortical, but not of adrenal medullary origin, are important in preventing the occurrence of the prolonged interval. It is concluded that the adrenal glands affect the regulation of prolactin secretion during lactation and, as a consequence, are important in establishing the duration of the anovulatory state during lactation.

Seasonal differences in ovarian activity in cows

1984 ◽  
Vol 102 (2) ◽  
pp. 189-198 ◽  
Author(s):  
K. P. McNatty ◽  
N. Hudson ◽  
M. Gibb ◽  
K. M. Henderson ◽  
S. Lun ◽  
...  
Keyword(s):  
Granulosa Cells ◽  
Ovarian Function ◽  
Plasma Concentrations ◽  
Peak Frequency ◽  
Ovarian Activity ◽  
Corpora Lutea ◽  
Aromatase Activity ◽  
Plasma Prolactin ◽  
Seasonal Differences ◽  
Time Of Year

ABSTRACT The plasma concentrations of LH and prolactin and various parameters of ovarian function were examined in cows on known days of the oestrous cycle during May and June (autumn and winter) and during October (spring). Luteinizing hormone peak frequency and plasma prolactin concentrations were significantly higher in October than during the May–June period (LH, P<0·05; prolactin, P<0·01). The mean diameters of large healthy follicles (≥8 mm diameter) and the dominant oestrogen-secreting follicles were significantly larger (P<0·01 for both follicle types) and each follicle contained more granulosa cells (both P<0·01) in May–June than in October. The LH responsiveness of theca interna with respect to androstenedione production and the levels of aromatase activity in granulosa cells did not differ with time of year. The corpora lutea were heavier (P<0·05) and secreted more progesterone (P<0·01) in May–June than in October. It is concluded that seasonal differences in ovarian activity exist in cows and that these differences are probably the consequence of seasonal differences in gonadotrophin secretion. J. Endocr. (1984) 102, 189–198

Physiological Adaptations to Milk Production that Affect the Fertility of High Yielding Dairy Cows

2004 ◽  
Vol 29 ◽  
pp. 37-71 ◽  
Author(s):  
V. J. Taylor ◽  
D. E. Beever ◽  
D. C. Wathes
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Ovarian Function ◽  
Post Partum ◽  
Reproductive Function ◽  
Influential Factors ◽  
Corpora Lutea ◽  
Expected Time ◽  
Physiological Adaptations ◽  
Igf I

SummaryThe high yielding dairy cow is expected to produce a substantial milk output every year and at the same time to conceive and maintain a pregnancy to term. To fulfil lifetime production potential a balance between yield, fertility and other influential factors has to be achieved. Any inability on the part of the management system to identify and rectify problems or on the part of the cow to cope with metabolic demands invariably results in economic or welfare issues. Our studies of high yielding dairy cows have revealed that some animals are capable of normal reproductive function whilst others are classic repeat breeders (requiring 3+ services per conception) or simply fail to rebreed. It is well established that the somatotrophic axis (growth hormone and insulin-like growth factors) drives lactation in ruminants but it is also intimately involved in reproductive processes. An awareness of metabolic adaptations to lactation that impact on reproduction in dairy cows is needed for appropriate management.The objective of our studies was to explore the metabolic profiles of high yielding dairy cows to identify factors influencing their ovarian function and fertility, hence to characterise the physiological adaptations involved. Our studies revealed different relationships between progesterone profile categories and metabolic status post partum. Delayed ovulation (DOV) or persistent corpora lutea (PCL) may be an appropriate response to a nutritional state or physiological situation and it may therefore be inaccurate to refer to these as ‘abnormal’. Whilst associated with high milk yields, not all profile categories detrimentally affected fertility parameters. Delayed ovulation postcalving (DOV1) was identified as the most prevalent abnormal profile encountered in first lactation high yielding cows. This may have occurred because the cows were not yet physically mature and unable to sustain both milk production and growth. The condition lasted long enough (71 ± 8.3 days from calving) to have a detrimental impact on their overall fertility parameters and was associated with significant physiological changes, representative of tissue mobilisation. Although the incidence of persistent luteal phases (PCL1 and PCL2) in dairy cows is increasing, this condition was not found to have any substantial detrimental effects on fertility or production parameters of the primiparous or multiparous cows in these studies. The main reproductive problems in our high yielding primiparous and multiparous cows appeared to be a failure to ovulate and conceive at the expected time or to maintain a pregnancy. These situations were associated predominantly with high milk yields and low concentrations of plasma IGF-I. A failure to ovulate appears to occur when body reserves are mobilised to maintain milk yield at the expense of reproduction and seems most likely to occur in primiparous high yielding cows or those experiencing GH-resistance (low IGF-I) due to excessive body condition loss, reduced feed intakes and factors such as stress and disease. More detailed investigations of dietary means of increasing IGF-I and optimising insulin concentrations, targeted at important reproductive times, are required in high yielding dairy cows, to aid in their management.

Effect of adrenalectomy on the regulation of the secretion of gonadotrophins and prolactin in the lactating rat

1983 ◽  
Vol 98 (2) ◽  
pp. 227-232 ◽  
Author(s):  
P. van der Schoot ◽  
W. J. de Greef
Keyword(s):  
Plasma Levels ◽  
Inhibitory Action ◽  
Adrenal Glands ◽  
Marked Effect ◽  
Plasma Concentrations ◽  
Inhibitory Effect ◽  
Blood Levels ◽  
Adrenal Hormones ◽  
Adrenocortical Hormones ◽  
Adrenalectomized Rats

The suckling stimulus exerts an inhibitory action on the release of gonadotrophins during lactation. The possible involvement of the adrenal glands in this process was examined by studying the plasma levels of gonadotrophins in lactating rats ovariectomized on the day after parturition. It appeared that the suppression, throughout suckling, of the rise in levels of gonadotrophins in blood after ovariectomy occurred to the same extent in adrenalectomized and in sham-operated animals. It thus seems unlikely that adrenocortical hormones, albeit secreted in larger quantities during lactation, exert an inhibitory effect on the release of gonadotrophins. Adrenalectomy had a marked effect on the plasma concentrations of prolactin during the second half of lactation. Whereas plasma concentrations of prolactin in the first half of lactation were similar in adrenalectomized and sham-operated rats, the concentrations in adrenalectomized rats did not undergo the reduction found in sham-operated rats. Adrenal hormones may thus be involved in the reduction of blood levels of prolactin observed in rats and in other mammals as lactation progresses.

PATTERNS OF PLASMA PROLACTIN IN POST-PARTUM SUCKLED COWS

1981 ◽  
Vol 90 (3) ◽  
pp. 391-396 ◽  
Author(s):  
R. WEBB ◽  
G. E. LAMMING
Keyword(s):  
Post Partum ◽  
Significant Negative Correlation ◽  
Prolactin Secretion ◽  
The Other ◽  
Plasma Prolactin ◽  
Blood Samples ◽  
Biphasic Pattern ◽  
Stage Of Lactation ◽  
Low Concentrations ◽  
High Concentrations

Blood samples taken on alternate days through indwelling jugular venous catheters from 12 suckled cows between days 14 and 48 post partum contained significantly less prolactin than samples collected on intermediate days by jugular venepuncture. Samples taken through the catheter every 2 h for 72 h periods revealed a repetitive daily biphasic pattern of prolactin secretion with low concentrations at 09.00 and 19.00 h and high concentrations at 13.00 and 23.00 h. In two groups of cows, one group calving at the beginning of March (increasing photoperiod) and the other calving during June (decreasing photoperiod), there was a significant negative correlation between stage of lactation and plasma prolactin concentrations in samples taken by venepuncture.

Involvement of the adrenal gland in the suckling-induced decrease in LH and FSH secretion and the concomitant increase in prolactin secretion in the rat

1990 ◽  
Vol 125 (2) ◽  
pp. 279-285 ◽  
Author(s):  
K. Taya ◽  
S. Sasamoto
Keyword(s):  
Adrenal Gland ◽  
Ovarian Function ◽  
Plasma Concentrations ◽  
Prolactin Secretion ◽  
Plasma Prolactin ◽  
Luteal Function ◽  
Follicular Maturation ◽  
High Concentrations ◽  
Ovulatory Follicles

ABSTRACT The role of the adrenal gland in the regulation of gonadotrophin and prolactin secretion in the lactating rat was investigated. Changes in secretion of LH, FSH, prolactin, ACTH, β-lipotrophin (β-LPH), inhibin, corticosterone and progesterone after adrenalectomy were examined during the second half of lactation. Follicular maturation was determined by the ability of the follicles to ovulate in response to 10IU human chorionic gonadotrophin (hCG). Adrenalectomy on day 10 of lactation prevented an increase in plasma concentrations of LH and FSH in response to ovariectomy performed at the same time as adrenalectomy, and markedly stimulated secretion of ACTH, β-LPH and prolactin. Adrenalectomy reduced the number of follicles capable of ovulating in response to hCG. Concentrations of inhibin and progesterone in the plasma significantly decreased after adrenalectomy, indicating that development of ovulatory follicles and luteal function had been suppressed. Abolishing the increase in plasma concentrations of LH and inducing a decrease in FSH in the plasma by adrenalectomy therefore prevented maturation of a new set of follicles usually seen during the second half of lactation in rats. The decrease in plasma concentrations of LH also inhibited the ability of the corpus luteum to secrete progesterone, although high concentrations of plasma prolactin were maintained in adrenalectomized lactating rats. These results indicate that the pituitary-adrenal system is capable of influencing the maintenance of a normal secretion of gonadotrophin and prolactin as well as the maintenance of ovarian function during lactation in the rat. Journal of Endocrinology (1990) 125, 279—285

The effects of food intake during lactation and post weaning on the reproductive performance and hormone and metabolite concentrations of primiparous sows

1996 ◽  
Vol 63 (2) ◽  
pp. 297-306 ◽  
Author(s):  
C. M. Carroll ◽  
P. B. Lynch ◽  
M. P. Boland ◽  
L. J. Spicer ◽  
F. H. Austin ◽  
...  
Keyword(s):  
Food Intake ◽  
Reproductive Performance ◽  
Ovarian Function ◽  
Serum Insulin ◽  
Post Partum ◽  
Corpora Lutea ◽  
Serum Growth Hormone ◽  
Ad Libitum ◽  
Group D ◽  
Voluntary Food Intake

AbstractThe objective of this study was to investigate the effect of low food intake on post-weaning fertility and hormone concentrations in primiparous sows. One hundred and forty primiparous sows (Landrace × Large White) were randomly assigned to one of four treatment groups: (A) restricted to 3 kg food per day during lactation and 2 kg food per day post weaning (no. = 36); (B) restricted to 3 kg food per day during lactation and ad libitum feeding post weaning (no. = 33); (C) ad libitum feeding throughout with a mean voluntary food intake of 3·7 kg/day during lactation (no. = 36); and (D) ad libitum feeding throughout with a mean voluntary food intake of 4·9 kg/ day during lactation (no. = 35). Litters were standardized at eight to 10 pigs at 2 days post partum and were weaned at 27·2 (s.e. 0·5) days post partum. After weaning, sows were observed twice daily for signs of oestrus and were mated on the day(s) of standing oestrus. Six sows from each group were fitted with indwelling jugular cannulae 2 days before weaning. Blood samples were collected 1 day before weaning (W−l), 1 day after weaning (W+l) and 4 days after weaning (W+4), and these sows were slaughtered on W+4. Ovaries were recovered, follicles and corpora lutea were counted, and folUcular fluid collected. Sows given food at a restricted level (groups A and B) lost more backfat during lactation than sows given food ad libitum (groups C and D) (P < 0·01). Piglet weaning weights, weaning to conception intervals and the proportion of sows ovulating by W+4 were not significantly different among groups. In sows that did not ovulate, numbers of large follicles were not significantly different among groups but the low food intake (groups A, B and C) sows had more medium-sized follicles than high food intake (group D) sows (P < 0·01). FolUcular fluid concentrations of oestradiol, progesterone and insulin-like growth factor-1 (IGF-1) did not differ among groups (P > 0·05). Plasma non-esterified fatty acids concentrations were greater in groups C and D than in groups A and B on W−l, W+l and W+4. Serum insulin and plasma glucose concentrations were lower in groups C and D than in groups A and B on W−l and W+l, but were similar among groups on W+4. Serum growth hormone concentrations were lower in group D than group A and B on W−l and W+l but not W+4. Concentrations of IGF-1 in serum were greater in groups C and D than groups A and B on W−l and W+l but not W+4. It is concluded that low food intakes during lactation and post weaning affected body condition, serum hormones and metabolites and ovarian function of primiparous sows without dramatically affecting ovarian hormones or reproductive performance.

INFLUENCE OF SUCKLING AND OF SUCKLING FOLLOWED BY TRH OR LH-RH ON PLASMA PROLACTIN, TSH, GH AND FSH

1976 ◽  
Vol 82 (1) ◽  
pp. 246-253 ◽  
Author(s):  
S. Jeppsson ◽  
K. O. Nilsson ◽  
G. Rannevik ◽  
L. Wide
Keyword(s):  
Limit Of Detection ◽  
Post Partum ◽  
Prolactin Secretion ◽  
Plasma Prolactin ◽  
Additional Increase ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Before And After ◽  
Plasma Gh ◽  
Lh Rh

ABSTRACT Ten women were studied during the first post-partum week. Suckling for 20 min induced a marked increase in plasma prolactin, reaching a maximum within 0–25 min after the end of suckling and then returning to pre-suckling levels after 120 min. Suckling induced no changes in plasma thyrotrophin (TSH), growth hormone (GH) or follicle stimulating hormone (FSH). The iv injection of 200 μg of thyrotrophin releasing hormone (TRH) immediately after suckling resulted in an additional increase in plasma prolactin and a rise in TSH. When given 120 min after suckling TRH was followed by increased plasma levels of prolactin and TSH, which for both hormones were of a magnitude comparable to the TRH induced increment seen immediately after suckling. Thus, suckling did not inhibit the effect of TRH on the release of TSH. These studies indicate that TRH is probably not involved in the suckling induced increase in prolactin secretion. The mean plasma FSH level was below the limit of detection before and after suckling. Neither plasma FSH nor prolactin showed any appearant changes following the iv injection of 25 μg of luteinizing hormone releasing hormone (LH-RH), when given immediately after and 120 min after suckling. When given after suckling as indicated above, TRH induced no changes in plasma GH or FSH and similarly LH-RH was without influence on plasma GH and TSH.

Bromocriptine treatment of periparturient goats: long-term suppression of prolactin and lack of effect on lactation

1993 ◽  
Vol 60 (3) ◽  
pp. 307-317 ◽  
Author(s):  
Isabel A. Forsyth ◽  
Philip D. Lee
Keyword(s):  
Milk Yield ◽  
Post Partum ◽  
Milk Composition ◽  
Prolactin Secretion ◽  
Plasma Prolactin ◽  
Dairy Goats ◽  
Plasma Growth Hormone ◽  
Short Term ◽  
And Control

SummaryBritish Saanen dairy goats (n = 10) were treated with bromocriptine or vehicle from day 147 of pregnancy to day 4 post partum, a treatment duration of 8·8±1·7 d (mean ± SEM). The periparturient prolactin surge was abolished by this treatment, but there were no significant effects on plasma growth hormone or insulin concentrations. Lactogenesis was delayed in the bromocriptine-treated goats, milk yields being significantly depressed (P < 0·01) for the first week of lactation. Yields had recovered to control values by day 10 when prolactin concentrations were still significantly depressed. Mammary gland biopsies were taken on day 4 post partum from five animals in each group. Using this tissue, no significant differences could be shown in mammary morphology or DNA synthesis, but the RNA:DNA ratio was significantly reduced (P < 0·05). After week 1, there were no significant differences between bromocriptine-treated and control goats in milk yield, milk composition, udder volume, time of peak yield or persistence. The goats given short-term bromocriptine treatment at parturition showed prolonged effects on prolactin secretion, their seasonal prolactin rise being severely blunted (P < 0·001). A normal lactation is therefore not prevented in goats by a delay in lactogenesis, suppression of prolactin at parturition or the resulting prolonged depression of circulating prolactin. Goats in established lactation given bromocriptine for 8 d showed, by contrast, a rapid recovery of plasma prolactin concentrations within 5 d post treatment. Milk yield declined significantly (P < 0·03) compared with pretreatment values during and for 1 week after bromocriptine but then began to recover, with no significant change in vehicle-treated goats.

HEMMUNG VON TESTOSTERONABHÄNGIGEN DIFFERENZIERUNGSVORGÄNGEN DER MÄNNLICHEN RATTE NACH DER GEBURT

1967 ◽  
Vol 54 (2) ◽  
pp. 227-240 ◽  
Author(s):  
F. Neumann ◽  
J. D. Hahn ◽  
M. Kramer
Keyword(s):  
Sexual Behaviour ◽  
Cyproterone Acetate ◽  
Post Partum ◽  
Sexual Attitude ◽  
Normal Male ◽  
Corpora Lutea ◽  
List Type ◽  
Newborn Rats ◽  
Neonatal Treatment ◽  
Triangular Shape

ABSTRACT Male newborn rats were injected with 2 mg of an antiandrogen (1,2α-methylene-6-chloro-pregna-4,6-dien-17α-ol-3,20-dione-17α-acetate = cyproterone acetate) daily from their 1st to their 14th day of life. The following effects of this treatment were observed in these animals after onset of sexual maturity: 84% of the animals are unable to reproduce. Penis: the frenulum is broadened to a lamina of triangular shape, which almost completely prevents the preputium from being pushed back. These males show a rather insufficient male sexual behaviour towards females in oestrus. After castration and ovar implantation, some of the treated animals show true corpora lutea and at attempts of cohabitation partially female sexual behaviour towards normal male animals. From these results it can be concluded, that differentiation of the penis is not completed at the time of birth. The infertility of the animals may be caused by the penile changes (difficulties with intromission) as well as by the aimless sexual behaviour. This aimless sexual behaviour, the ability to produce true corpora lutea and finally their partially female sexual attitude under the influence of the hormones from the implanted ovaries led to the conclusion, that the above described neonatal treatment apparently inhibited testosterone-depending post partum developments of sexual differentiation in hypothalamic centers.

PITUITARY AND BLOOD CORTICOTROPHIN CHANGES IN ADRENALECTOMIZED RATS MAINTAINED ON PHYSIOLOGICAL DOSES OF CORTICOSTEROIDS

1962 ◽  
Vol 39 (1) ◽  
pp. 79-86 ◽  
Author(s):  
J. R. Hodges ◽  
Joan Vernikos-Danellis
Keyword(s):  
Ascorbic Acid ◽  
Pituitary Gland ◽  
Replacement Therapy ◽  
Daily Treatment ◽  
Mild Stress ◽  
Acid Control ◽  
Small Doses ◽  
Response To Stress ◽  
Adrenalectomized Rats

ABSTRACT Pituitary and blood corticotrophin (ACTH) concentrations were estimated in adrenalectomized rats maintained on cortisol or crude adrenocortical extract (ACE) with and without ascorbic acid. Blood ACTH levels were also determined in similarly treated animals after subjection to mild stress. Thirty days after adrenalectomy there were marked rises in pituitary and blood corticotrophin concentration which were prevented by daily treatment with small doses of cortisol or ACE. In contrast to intact animals, adrenalectomized rats exhibited markedly increased adrenocorticotrophic responses to mild stress. This pituitary hyperexcitability was not diminished by replacement therapy with corticoids alone but was considerably reduced by ascorbic acid given in conjunction with ACE. It is suggested that corticoids control the rate at which ACTH is synthesised in the pituitary gland and that other factors, including ascorbic acid, control the excitability of the pituitary gland in its adrenocorticotrophic response to stress.

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