Initiation of ovarian follicular maturation without a surge of FSH in cyclic rats treated with antiserum to LH-releasing hormone

Abstract

The relationship between a surge of FSH and the initiation of follicular maturation was examined using rats with a 4-day oestrous cycle. When antiserum against LH-releasing hormone (LHRH-AS) was given at 13.00 h on the day of pro-oestrus (day 0), surges of FSH and LH were blocked. Plasma FSH and LH were maintained at low basal levels without a surge release until the next spontaneous surge occurred on the afternoon of day 4, the predicted day of pro-oestrus. Follicular responsiveness to an injection of human chorionic gonadotrophin (hCG) indicated that preovulatory follicles, present at the time of treatment with LHRH-AS, were capable of ovulating on day 1 but had regressed by day 2. Subsequently, as shown by the ovulatory response to hCG, a new set of follicles had begun to mature by the morning of day 3 without a preceding surge of FSH. Changes in oestradiol-17 beta levels in the plasma throughout the oestrous cycle were the same in rats injected with LHRH-AS or non-immune control serum. The mature follicles in the rats treated with LHRH-AS thus retained the capacity to ovulate after losing their ability to secrete oestrogen. These results suggest that an FSH surge is not essential for initiation of follicular maturation and that basal levels of FSH may be enough to initiate follicular maturation in the absence of newly formed corpora lutea.

Roles of the Basal Level of LH and FSH in the Regulation of Follicular Development during Pseudopregnancy in the Rat.

“…A specific surge of FSH is not essential for the recruitment and development of a new set of follicles in cyclic rats [6]. On the other hand, there is a previous study that shows the importance of basal levels of FSH in plasma to cause a normal follicular development and maturation in cyclic rats [7].…”

“…43: [279][280][281][282][283][284][285][286][287] 1997) ntral follicles usually exist in the ovary during pseudopregnancy of the rat, although plasma reported previously [4,5]. A specific surge of FSH is not essential for the recruitment and development of a new set of follicles in cyclic rats [6]. On the other hand, there is a previous study that shows the importance of basal levels of FSH in plasma to cause a normal follicular development and maturation in cyclic rats [7].…”

A New Alternative Method for Superovulation Using Passive Immunization Against Inhibin in Adult Rats1

“…This conjugate was kindly provided by Dr. N Ling (Neuroendocrine Biosciences, Inc., San Diego, CA). The titer of the antiserum was determined as in our previous reports [36]. The serum used in the present experiment had a titer of 1:1 000 000 as defined by final dilution of the antiserum required to bind 50% of added 125 I-labeled bovine 32-kDa inhibin.…”

Expression of Nerve Growth Factor (NGF), and Its Receptors trkA and p75 in Ovaries of the Cyclic Golden Hamster (<i>Mesocricetus auratus</i>) and the Regulation of Their Production by Luteinizing Hormone

“…The antiserum against LHRH (LHRH-AS) used in the present study was the antiserum previously described [20]. Golden hamsters were given a single i.v.…”