The effect of short-term nutritional supplementation of ewes with lupin grain (Lupinus luteus), during the luteal phase of the estrous cycle on the number of ovarian follicles and the concentrations of hormones and glucose in plasma and follicular fluid

2007 ◽  
Vol 68 (7) ◽  
pp. 1037-1046 ◽  
Author(s):  
A. Somchit ◽  
B.K. Campbell ◽  
M. Khalid ◽  
N.R. Kendall ◽  
R.J. Scaramuzzi
Reproduction ◽  
2011 ◽  
Vol 142 (5) ◽  
pp. 699-710 ◽  
Author(s):  
Shijia Ying ◽  
Ziyu Wang ◽  
Changlong Wang ◽  
Haitao Nie ◽  
Dongyang He ◽  
...  

This study investigated the effects of short-term food restriction or supplementation on folliculogenesis and plasma and intrafollicular metabolite and hormone concentrations. Ewes were randomly assigned to three groups: the control group received a maintenance diet (M) while the supplemented group and restricted group received 1.5×M and 0.5×M respectively on days 6–12 of their estrous cycle. Estrus was synchronized by intravaginal progestogen sponges for 12 days. On days 7–12, blood samples were taken. After slaughter, the ovarian follicles were classified and the follicular fluid was collected. Compared with restriction, supplementation shortened the estrous cycle length, decreased the number of follicles 2.5–3.5 mm and follicular fluid estradiol (E2) concentration, increased the number of follicles >3.5 mm and plasma glucose, insulin and glucagon concentrations, and augmented the volume of follicles >2.5 mm. Restricted ewes had higher intrafollicular insulin concentration, but it was similar to that of supplemented ewes. Compared with follicles ≤2.5 mm, the intrafollicular glucose and E2concentrations were increased and the testosterone, insulin, and glucagon concentrations and lactate dehydrogenase (LDH) activity were decreased in follicles >2.5 mm. Only in restricted ewes were intrafollicular LDH and testosterone concentrations in follicles ≤2.5 mm not different from those in follicles ≤2.5 mm. In conclusion, the mechanism by which short-term dietary restriction inhibits folliculogenesis may involve responses to intrafollicular increased E2, testosterone, and LDH levels in late-stage follicles. This may not be due to the variation of intrafollicular insulin level but rather due to decreased circulating levels of glucose, insulin, and glucagon.


Reproduction ◽  
2013 ◽  
Vol 145 (4) ◽  
pp. 319-333 ◽  
Author(s):  
A Somchit-Assavacheep ◽  
B K Campbell ◽  
M Khalid ◽  
N R Kendall ◽  
R J Scaramuzzi

An experiment was conducted on 48 ewes during follicular and luteal phases of the oestrous cycle to determine the effect of a 5-day lupin grain supplementation (500 g/day) on folliculogenesis, plasma concentrations of glucose, insulin, FSH and oestradiol-17β (E2), follicular fluid concentrations of glucose, E2, androstenedione and progesterone and the levels of P450aromatase and insulin receptor substrate 1 (IRS-1), -2 and -4 in theca and granulosa cells. Average weight did not differ between lupin-fed and control groups. The numbers of follicles were increased (P<0.05; χ2) in the lupin-fed group. The plasma concentrations of glucose (P<0.05; ANOVA) and insulin (P<0.001; ANOVA) were higher in lupin-fed ewes. The plasma concentrations of FSH were not different but those of E2were decreased (P<0.001) in the lupin-fed group. Both the follicular fluid concentration of E2(P<0.05) and the level of P450aromatase in granulosa cells (P<0.05; ANOVA) were decreased in the lupin-fed group, but only during the follicular phase. The level of P450aromatase in granulosa cells was positively correlated with the concentration of E2in follicular fluid (r=0.820;P<0.001; ANOVA). The levels of IRS-1 and -2 in theca and granulosa cell lysates were increased in the lupin-fed group. These data suggest that insulin has a local role in the control of folliculogenesis and is likely to be a mediator of the effects of dietary energy intake on ovulation rate. We suggest that insulin acting through IRS proteins mediates the reproductive actions of insulin in the follicle and that IRS-1 and -2 are nutritionally regulated mediators of the action of insulin in the follicle.


1988 ◽  
Vol 116 (1) ◽  
pp. 123-135 ◽  
Author(s):  
J. M. Wallace ◽  
G. B. Martin ◽  
A. S. McNeilly

ABSTRACT It has previously been shown that treatment of ewes with bovine follicular fluid (bFF) throughout the luteal phase of the oestrous cycle lowers plasma levels of FSH but increases the frequency and amplitude of the pulses of LH. Under these conditions, ovarian follicles grow to a maximum diameter of 2·7 mm and have a reduced capacity to release oestradiol. We have examined the nature of the gonadotrophin signals controlling follicular development in the normally cycling ewe and have investigated the effects of previous exposure to bFF on these signals and the follicular responses to them. Control ewes (n = l) were injected i.v. with 9 ml bovine serum and treated ewes were injected with 9 ml bFF, twice daily from days 1 to 10 of the luteal phase (day 0 = oestrus). The ewes were injected with prostaglandin analogue on day 11 of the cycle to induce luteolysis and the gonadotrophin patterns were studied in blood sampled from these animals every 10 min for up to 72 h during the subsequent follicular phase. Following luteolysis (and the end of bFF treatment), LH pulse frequency increased rapidly in both groups and reached 1 pulse/h within 6 h. Thereafter, pulse frequency increased marginally and reached 1 pulse/50 min by the onset of the LH surge. This pattern was not affected by previous treatment with bFF. In the control ewes, the amplitude of the LH pulses did not change significantly following luteolysis or at any time during the follicular phase, while the levels of FSH declined slowly until the onset of the surge. In the treated ewes, on the other hand, there was an immediate increase in both LH pulse amplitude and the concentration of FSH immediately after the end of bFF treatment at luteolysis, and they remained above control levels for 24 and 16 h respectively. Plasma prolactin levels did not appear to change around the time of luteolysis but showed a marked and significant diurnal rhythm (nadir around noon and peak around midnight) in both groups. The concentrations of prolactin were significantly (P<0·001) lower and the preovulatory peak was delayed and reduced in the bFF-treated ewes relative to controls. The onset of oestrus was also significantly (P<0·01) delayed by bFF treatment, but the ovulation rates did not differ between the groups. Furthermore, comparisons within or between groups revealed no significant relationships between any of the variables of plasma LH secretion during the follicular phase and the subsequent ovulation rate. These observations provide a complete description of gonadotrophin patterns during the follicular phase of the ewe and confirm the suggestion that an increase in LH pulse frequency is the major driving force behind the follicular growth that ultimately leads to ovulation. On the other hand, it appears most unlikely that the pattern of LH secretion during the follicular phase has any influence on ovulation rate. The levels of FSH declined in the period leading up to the preovulatory surge, presumably as a consequence of rising peripheral levels of oestrogen (and/or inhibin). We also expected LH pulse amplitude to decline during the follicular phase because it has been proposed that pulse amplitude is also controlled by oestrogen. The absence of any significant fall in amplitude suggests that hypotheses about the control of LH secretion drawn from studies with ovariectomized ewes require further verification in the intact ewe. The effect of bFF on prolactin levels probably reflects the low rates of secretion of oestradiol by the small ovarian follicles in these ewes. J. Endocr. (1988) 116, 123–135


1988 ◽  
Vol 118 (1) ◽  
pp. 96-104 ◽  
Author(s):  
H. H. D. Meyer ◽  
Th. Mittermeier ◽  
D. Schams

Abstract. The levels of oxytocin receptor (OTR), cytosolic progestin receptor (cPR), cytosolic and nuclear estrogen receptor (cER, nER) were measured in the endometrium of 28 heifers that had been slaughtered on a defined day of the estrous cycle, In an additional, trial endometrial tissue obtained from 78 heifers or cows at the abattoir was analyed for OTR. OTR was absent during the luteal phase (after day 6), but a minor elevation was observed after day 15. OTR increased rapidly after luteolysis on days 17–18 reaching a maximum during estrous on day 21, and decreased again during days 1–6. cER and cPR were different to OTR but followed a similar pattern with maximal levels during days 1–8 of the estrous cycle. At day 12 both receptors were minimal and increased again towards day 21. nER was maximal at day 19–21 coinciding with maximal estradiol levels and estrous. Our data indicate that owing to an increasing sensitivity of the endometrium to progesterone and estradiol after day 12, these steroids may be mainly responsible for the initiation of first PGF2α surges and luteolysis. Oxytocin seems to be of minor importance at this stage owing to low sensitivity of the endometrium for oxytocin.


1995 ◽  
Vol 145 (3) ◽  
pp. 479-490 ◽  
Author(s):  
B K Campbell ◽  
B M Gordon ◽  
C G Tsonis ◽  
R J Scaramuzzi

Abstract Ewes with ovarian autotransplants received either inhibin antiserum (10 ml i.v. raised in sheep against recombinant 32 kDa human inhibin; n=6) or sheep serum (10 ml i.v.; n=5) on day 3 of the luteal phase with additional daily injections (1 ml i.v.) from 48 h after the initial bolus until day 13. Jugular and ovarian venous blood samples were taken 4-hourly over days 2–13 of the luteal phase. Blood samples were also taken at more frequent intervals (every 10–15 min for 2–3 h) to examine pulsatile secretory responses from the ovary to endogenous and gonadotrophin-releasing hormone-induced (150 ng i.m.) LH pulses on days 4, 6, 8, 10 and 12 of the luteal phase. Plasma FSH levels, ovarian steroid secretion and ovarian follicular development were measured. The ovarian follicle population was estimated daily by real time ultrasound scanning. Immunisation against inhibin resulted in a 3- to 4-fold increase (P<0·001) in plasma FSH levels within 8 h with levels remaining elevated over controls for 6–7 days. Within 24 h of immunisation there was an increase in the number of small ovarian follicles (P<0·05) and by 3 days after treatment immunised ewes had 4–6 large ovarian follicles/ewe with this increase in the total number of large follicles being maintained for the rest of the experimental period (P<0·05). Mean ovarian oestradiol secretion during intensive bleeds was not different from controls 24 h after immunisation, but by 3 days after immunisation it was elevated 4- to 5-fold (P<0·001) over controls with this increase being maintained throughout the experiment. Similar responses to immunisation against inhibin in androstenedione secretion were observed although mean androstenedione secretion was not elevated until 7 days after treatment. In vitro antibody titres in immunised ewes remained elevated but declined steadily (P<0·001) over the experimental period. We conclude that the initial stimulation of follicle development and ovarian steroid secretion following passive immunisation against inhibin can be attributed to increased blood FSH. However, the fact that with time FSH declined but increased follicle development was sustained, despite maintenance of high circulating antibody titres, suggests that on a longer term basis inhibin immunisation may stimulate ovarian function by interfering with the modulation of follicle development by inhibin at an ovarian level. Journal of Endocrinology (1995) 145, 479–490


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