Changes in inhibin-A (α-βA dimer) and total α inhibin in the peripheral circulation and ovaries of rats after gonadotrophin-induced follicular development and during the normal oestrous cycle

1995 ◽  
Vol 147 (2) ◽  
pp. 271-283 ◽  
Author(s):  
P A Fahy ◽  
C A Wilson ◽  
A J Beard ◽  
N P Groome ◽  
P G Knight
Keyword(s):  
Plasma Concentrations ◽  
Follicular Development ◽  
Serum Levels ◽  
Peripheral Circulation ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Immature Female ◽  
Adult Rats ◽  
Inhibin A ◽  
Α Subunit

Abstract Recent modifications to a previously reported two-site IRMA have permitted the measurement of serum/plasma concentrations and ovarian contents of inhibin-A (α-βA dimer) in pregnant mare serum gonadotrophin (PMSG)treated immature female rats and adult rats throughout the 4-day oestrous cycle. For comparison, total α inhibin levels were also measured by α subunit-directed inhibin RIA and found to be at least tenfold higher (relative to the same 32 kDa bovine inhibin standard used to calibrate both assays). In immature female rats, serum levels of inhibin-A dimer and total α inhibin increased within 3 h of PMSG injection and rose in parallel over the next 48 h to values four- to fivefold higher than pretreatment levels. Ovariectomy led to a rapid and parallel fall in both inhibin-A dimer and total α inhibin; initial half-lives (±95% confidence intervals) were 22 ± 4 and 20 ± 5 min respectively. In adult rats, marked fluctuations in plasma concentrations and ovarian contents of inhibin-A dimer and total α inhibin occurred during the 4-day oestrous cycle, most notably between the morning of pro-oestrus and the morning of oestrus. Plasma levels of inhibin-A dimer and total α inhibin peaked on the afternoon of pro-oestrus just before the preovulatory gonadotrophin surge. After ovulation, both inhibin-A dimer and total α inhibin fell abruptly (two- to threefold by 0200 h on oestrus; P<0·001), while FSH showed a secondary rise which peaked at 0700 h on oestrus. Although IRMA- and RIA-derived inhibin values generally followed a similar pattern across the 4-day cycle (plasma: r=0·52, P<0·001; ovary: r=0·41, P<0·001), a transient rise in plasma and ovarian inhibin-A dimer was detected at 0700 h on oestrus (P<0·01) which was unaccompanied by a rise in total α inhibin. This rise in plasma inhibin-A dimer was probably responsible for terminating the post-ovulatory FSH surge since FSH levels declined steadily over the next 15 h. Overall, plasma inhibin-A dimer and FSH concentrations across the whole cycle were negatively correlated (r= −0·22, P<0·01) whereas no correlation existed between total α inhibin and FSH (r= −0·11, P=0·12). Journal of Endocrinology (1995) 147, 271–283

scholarly journals Secretion of inhibin A, inhibin B and inhibin pro-alphaC during the oestrous cycle of the golden hamster (Mesocricetus auratus)

1999 ◽  
Vol 162 (3) ◽  
pp. 451-456 ◽  
Author(s):  
K Ohshima ◽  
H Kishi ◽  
M Itoh ◽  
G Watanabe ◽  
K Arai ◽  
...  
Keyword(s):  
Golden Hamster ◽  
Plasma Concentrations ◽  
Follicular Development ◽  
Early Morning ◽  
Oestrous Cycle ◽  
Inhibin B ◽  
Enzyme Linked Immunosorbent Assay ◽  
Inhibin A ◽  
Negative Relationships ◽  
Plasma Oestradiol

Plasma concentrations of inhibin pro-alphaC, inhibin A and inhibin B were determined by enzyme-linked immunosorbent assay at 6 h intervals throughout the 4-day oestrous cycle of the golden hamster. Plasma concentrations of follicle-stimulating hormone (FSH) and oestradiol-17beta were also measured by radioimmunoassay during the oestrous cycle. Plasma concentrations of inhibin A increased from the early morning of day 1 (day 1=day of ovulation) and reached plateau levels at 0500 h on day 2. An abrupt increase in plasma concentrations of inhibin A was found at 1700 h on day 4, when the preovulatory FSH surge was observed. An increase in plasma concentrations of inhibin B occurred on day 1 and reached plateau levels at 1700 h on day 1. The levels remained elevated until 0500 h on day 4 and declined gradually by 2300 h on day 4. Plasma concentrations of inhibin pro-alphaC gradually increased with some fluctuation from day 1 to 1700 h on day 4 and then declined. Significant negative relationships were noted between plasma FSH and both dimeric forms of inhibin from day 1 to day 3. Significant positive relationships were found between plasma oestradiol-17beta and inhibin A or inhibin pro-alphaC throughout the oestrous cycle. In contrast, no significant relationship was found between plasma oestradiol-17beta and inhibin B. These findings suggest that both dimeric forms of inhibin play a role in the regulation of FSH secretion during follicular development. These findings also suggest that inhibin pro-alphaC could be secreted primarily by large follicles, and early atretic follicles could also be responsible for inhibin pro-alphaC secretion. On the other hand, the secretory pattern of dimeric inhibins might shift from inhibin B to inhibin A with follicular development.

FSH AND LH LEVELS IN THE INTACT AND UNILATERALLY OVARIECTOMIZED CYCLING RAT

1972 ◽  
Vol 69 (2) ◽  
pp. 267-280 ◽  
Author(s):  
Richard D. Peppler
Keyword(s):  
Plasma Concentrations ◽  
Follicular Development ◽  
Slight Modification ◽  
Oestrous Cycle ◽  
Successive Cycle ◽  
Unilateral Ovariectomy ◽  
Subsequent Cycle ◽  
Intact Rats

ABSTRACT Intact 5-day cycling rats were killed between 8–10 a. m. on each day of the oestrous cycle; experimental rats were unilaterally ovariectomized (ULO) at 9 a. m. on day 1 (oestrus) and killed between 8 and 10 a. m. on days 2, 3, 4 or 1 of the subsequent cycle. Pituitary and plasma concentrations of FSH and LH were measured in both groups of rats. Pituitary FSH concentration was measured by the Steelman-Pohley method with slight modification; plasma FSH by the Igarashi-McCann assay and pituitary and plasma LH concentration by the OAAD method. In intact rats, pituitary FSH values remained constant for the first three days of the cycle, increased on day 4 and reverted to early cycle values by day 5. Plasma FSH increased between days 2 and 3 and days 5 and 1. Pituitary LH concentration remained the same for days 1 and 2; increased two-fold on days 3 and 4, and increased further by day 5. Plasma LH increased between days 2 and 3; other differences between successive cycle days were not apparent. Following ULO on day 1, pituitary FSH increased steadily, but not significantly, for the remaining cycle. Plasma FSH did not change from day 2 through day 1 of the subsequent cycle. Pituitary LH remained low on day 2, increased sharply by day 3 and decreased (50 %) by day 4. Plasma LH also increased between days 2 and 3. Other differences between successive days following unilateral ovariectomy on day 1 were not apparent. Correlation of gonadotrophin activity with follicular development suggests that the mechanism of compensatory ovulation in the rat may be one of an increase in time of exposure to a constant gonadotrophic level for the duration of the oestrous cycle rather than to increased levels of the gonadotrophin.

Follicular dynamics and secretion of inhibin and oestradiol-17β during the oestrous cycle of the hamster

1995 ◽  
Vol 146 (1) ◽  
pp. 169-176 ◽  
Author(s):  
H Kishi ◽  
K Taya ◽  
G Watanabe ◽  
S Sasamoto
Keyword(s):  
Plasma Levels ◽  
Marked Decrease ◽  
Plasma Concentrations ◽  
Follicular Development ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Oestrous Cycle ◽  
Antral Follicles ◽  
Follicular Maturation ◽  
Follicular Dynamics

Abstract Plasma and ovarian levels of inhibin were determined by a radioimmunoassay (RIA) at 3-h intervals throughout the 4-day oestrous cycle of hamsters. Plasma concentrations of FSH, LH, progesterone, testosterone and oestradiol-17β were also determined by RIAs. In addition, hamsters were injected at various times with human chorionic gonadotrophin (hCG) to determine the follicular development. The changes in plasma concentrations of FSH after injection of antisera to oestradiol-17β (oestradiol-AS) and inhibin (inhibin-AS) on the morning of day 2 (day 1=day of ovulation) were also determined. Plasma concentrations of inhibin showed a marked increase on the afternoon of day 1, remained at plateau levels until the morning of day 4, then increased abruptly on the afternoon of day 4 when preovulatory LH and FSH surges were initiated. A marked decrease in plasma concentrations of inhibin occurred during the process of ovulation after the preovulatory gonadotrophin surges. An inverse relationship between plasma levels of FSH and inhibin was observed when the secondary surge of FSH was in progress during the periovulatory period. Plasma concentrations of oestradiol-17β showed three increase phases and these changes differed from those of inhibin. Changes in plasma concentrations of oestradiol-17β correlated well with the maturation and regression of large antral follicles. Follicles capable of ovulating following hCG administration were first noted at 2300 h on day 1. The number of follicles capable of ovulating reached a maximum on the morning of day 3 (24·8± 0·6), and decreased by 0500 h on day 4 (15·0 ± 1·1), corresponding to the number of normal spontaneous ovulations. Plasma concentrations of FSH were dramatically increased within 6 h after inhibin-AS, though no increase in FSH levels was observed after oestradiol-AS. These findings suggest that changes in the plasma levels of inhibin during the oestrous cycle provide a precise indicator of follicular recruitment, and that the changes in plasma concentrations of oestradiol-17β are associated with follicular maturation. These findings also suggest that inhibin may play a major role in the inhibition of FSH secretion during the oestrous cycle of the hamster. Journal of Endocrinology (1995) 146, 169–176

scholarly journals Effects of hypothyroidism on ovarian hormone secretion and follicular development in immature female rats

1997 ◽  
Vol 73 ◽  
pp. 103
Author(s):  
Minoru Hatsula ◽  
Kazuhiro Tamura ◽  
Gen Watanabe ◽  
Kazuyoshi Taya ◽  
Hiroshi Kogo Kogo
Keyword(s):  
Hormone Secretion ◽  
Follicular Development ◽  
Female Rats ◽  
Ovarian Hormone ◽  
Immature Female

THE SENSITIVITY OF ADRENALECTOMIZED RATS TO GONADOTROPHINS

1954 ◽  
Vol 11 (4) ◽  
pp. 359-376 ◽  
Author(s):  
ANITA M. MANDL
Keyword(s):  
Chorionic Gonadotrophin ◽  
Female Rats ◽  
Corpora Lutea ◽  
Surgical Trauma ◽  
Normal Reaction ◽  
Normal Response ◽  
Immature Female ◽  
Adult Rats ◽  
Immature Rats ◽  
Adrenalectomized Rats

SUMMARY The sensitivity of adrenalectomized, control-operated and unoperated rats to pregnant mare serum (PMS) and chorionic gonadotrophin (CG) has been studied. A total of 638 mature and immature female rats was used. The ovaries of adrenalectomized rats were found to contain fewer large follicles and corpora lutea than those of control-operated litter-mates, and the slight ovarian hypertrophy which occurs after surgical trauma was found to be due to an increase in the number of Graafian follicles and corpora lutea. Further experiment showed that, as judged by the weight of the ovaries, adrenalectomy reduces the ovarian reaction to injected PMS (10 i.u./day) in both adult and immature rats. Replacement therapy with DCA (1 mg/day) failed to re-establish the normal response in adults. Treatment with cortisone (1 mg/day) restored the normal reaction in both adult and immature adrenalectomized rats. Adrenalectomized adult rats responded to injected CG (10 i.u./day) as vigorously as their operated and unoperated litter-mates. On the other hand, immature adrenalectomized animals did not respond fully to CG. Treatment with cortisone again fully restored the normal reaction.

Variations in oxytocin secretion during the 4-day oestrous cycle of the rat

1993 ◽  
Vol 136 (2) ◽  
pp. 305-311 ◽  
Author(s):  
R. J. Windle ◽  
M. L. Forsling
Keyword(s):  
Clearance Rate ◽  
Significant Variation ◽  
Plasma Clearance ◽  
Plasma Concentrations ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Male Rats ◽  
Hormone Release ◽  
Diurnal Pattern ◽  
The Hours

ABSTRACT Oxytocin concentrations in the plasma, pituitary and hypothalamus of female rats were determined in the morning and evening over the 4-day oestrous cycle. Vasopressin concentrations were also determined to allow calculation of the ratios of the two hormones. The results were compared with those from male rats. Plasma oxytocin concentrations were significantly higher in the evening than in the morning on the day of oestrus. Although the evening concentration achieved was similar on each day of the cycle, morning plasma oxytocin concentrations showed a progressive rise from oestrus to pro-oestrus so that no significant diurnal increases were observed on the other days of the cycle. Vasopressin concentrations in the plasma were also seen to increase over the days of oestrus, dioestrus day 1 and dioestrus day 2. On pro-oestrus the plasma concentrations of vasopressin remained unchanged. The ratio of oxytocin:vasopressin fell during the light hours of the cycle. The hypothalamic content of both hormones showed a rise during the hours of daylight parallel to that seen in the plasma, whereas the pituitary content fell over the same period. The diurnal pattern of hormone release observed in male rats was similar to that in females at oestrus. However, the plasma oxytocin concentrations were significantly higher in the male. The plasma clearance rate of vasopressin did not vary significantly during the oestrous cycle. However, the plasma clearance rate for oxytocin did show significant variation, being highest on dioestrus day 1 and lowest on dioestrus day 2. Journal of Endocrinology (1993) 136, 305–311

EFFECTS OF NEONATAL EXPOSURE TO MONOSODIUM GLUTAMATE ON THE ELECTRICAL ACTIVITY OF NEURONES IN THE MEDIOBASAL HYPOTHALAMUS, AND ON THE PLASMA CONCENTRATIONS OF THYROID-STIMULATING HORMONE AND PROLACTIN, FOLLOWING STIMULATION OF THE ROSTRAL HYPOTHALAMUS IN ADULT FEMALE RATS

1981 ◽  
Vol 89 (3) ◽  
pp. 379-387 ◽  
Author(s):  
D. J. SAPHIER ◽  
R. G. DYER
Keyword(s):  
Adult Female ◽  
Median Eminence ◽  
Monosodium Glutamate ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Mediobasal Hypothalamus ◽  
Adult Rats ◽  
Thyrotrophin Releasing Hormone ◽  
Rostral Hypothalamus ◽  
Stimulation Of

Action potentials were recorded from 174 neurones in the mediobasal hypothalamus of ovariectomized adult female rats exposed neonatally to monosodium glutamate (MSG) and from 145 neurones in control rats. All of the animals, which were anaesthetized with urethane, had been ovariectomized for at least 3 weeks and received two injections of oestradiol benzoate (20 μg/100 g body weight, i.m.) 72 h and immediately before the recording experiments. The response of each neurone to electrical stimulation of the median eminence and rostral hypothalamus (preoptic and anterior hypothalamic areas; PO/AH) was analysed. The most striking feature of the results obtained was the significant (P < 0·001) loss of inhibitory responses in those neurones remaining in the adult rats after neonatal treatment with MSG. The loss of inhibitory responses applied to both stimulation sites. In each rat the response of one neurone, which was antidromically identified as projecting to the median eminence, was recorded before and during stimulation of the PO/AH at 50 Hz for 30 s in every min for 15 min. Before and after this stimulation blood was collected from a jugular vein for estimation by radioimmunoassay of concentrations of prolactin and TSH. In the MSG-treated rats significantly (P < 0·05) fewer neurones were inhibited by the 50 Hz stimulation than in control rats. In control rats the plasma concentrations of prolactin nearly quadrupled as an immediate consequence of this treatment, whereas in MSG-treated rats plasma concentrations barely doubled. However, in the MSG-treated rats plasma concentrations of prolactin continued to rise after stimulation ceased, possibly as a consequence of enhanced secretion of thyrotrophin releasing hormone.

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