Influence of gonadotrophins on early follicle cell development and early oocyte growth in the immature rat

Wolff-Exalto, E. Arendsen de

doi:10.1530/jrf.0.0660537

Cited by 29 publications

(9 citation statements)

References 11 publications

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“…The number of follicles that start to grow per day in 16-day-old rats is reportedly higher than that in older rats [25]. Thus, previous reports indicate that the elevation of FSH during this time appears to be essential for normal follicular development in the neonatal rat and mouse [6][7][8]. The present data are in agreement with those of previous studies that reported elevated plasma FSH levels during the second to third week of postnatal life in the female rat.…”

Section: Discussionsupporting

confidence: 92%

“…The primary follicles can be seen in the female rat ovary as early as PND 5, and they develop into preantral follicles by PND 12 [6]. The early rise in plasma FSH levels coincides with the appearance of these preantral follicles, with a few layers of granulosa cells; thus, the elevated plasma FSH level during this time frame has been implicated as being essential for normal follicular growth [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Regulation of Follicle-Stimulating Hormone Secretion by Estradiol and Dimeric Inhibins in the Infantile Female Rat1

Herath¹,

Yamashita²,

Watanabe³

et al. 2001

Biology of Reproduction

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Plasma and ovarian levels of the dimeric forms of inhibin and plasma estradiol-17beta were investigated and compared with changes in plasma gonadotropins from Postnatal Day (PND) 5 to PND 30 in the female rat. The inhibin subunit proteins were localized in follicular granulosa cells of the ovary. Plasma immunoreactive inhibin levels were low until PND 15 and increased thereafter. Plasma levels of inhibin B (alpha and beta(B) subunits) remained very low until PND 15 and then increased by approximately 24-fold. In contrast, plasma levels of inhibin A (alpha and beta(A) subunits) were relatively low and steady until PND 20, then increased by approximately 3-fold at PND 25. Changes in ovarian inhibin A and B levels closely resembled those in plasma levels. Plasma FSH levels were low at PND 10 but started to peak from PND 15 and remained high until PND 20, followed by a remarkable reduction at PNDs 25 and 30. This dramatic fall in FSH coincided with the rise of inhibin A. A significant inverse correlation was observed between plasma FSH and plasma inhibin A (r = -0.67, P < 0.0002), ovarian inhibin A (r = -0.48, P < 0.01), plasma inhibin B (r = -0.48, P < 0.05), and ovarian inhibin B (r = -0.54, P < 0.01). Plasma estradiol-17beta levels were elevated from PND 5 through PND 15, then fell sharply through PND 30. Plasma estradiol-17beta was significantly and positively (r = 0.75, P < 0.0002) correlated with plasma FSH. Plasma LH rose to higher levels at PND 15 and tended to be lower thereafter. The inhibin alpha, beta(A), and beta(B) subunits were localized to primary, secondary, and antral and large antral follicles, but the types of these immunopositive follicles varied with age. It appeared that, at PND 25 and afterward, all three subunits were mainly confined to large antral follicles in the ovary. We conclude that estradiol-17beta likely is the major candidate in stimulation of FSH secretion in the infantile female rat. We also conclude that inhibin regulation of pituitary FSH secretion through its negative feedback in the infantile female rat begins to operate after PND 20. We suggest that this negative feedback is achieved by increases in plasma levels of the two dimeric forms, and that inhibin A appears to be the major physiological regulator of FSH secretion at the initiation of this mechanism. We also conclude that large antral follicles in the ovary are the primary source of these bioactive inhibins that are secreted in large amounts into the circulation after PND 20.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Regulation of Follicle-Stimulating Hormone Secretion by Estradiol and Dimeric Inhibins in the Infantile Female Rat1

Herath¹,

Yamashita²,

Watanabe³

et al. 2001

Biology of Reproduction

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“…Hypothetical local factors from atretic [4,13] or growing follicles [2] have been proposed to affect the onset of follicular growth. Some investigators have maintained that gonadotropins regulate the onset of follicular growth [14,15]; others disagree [4,16]. It is useful in this context to distinguish between true "feedback regulation" (in which perturbation of the system is followed by a return to homeostasis) and mere "impact" (in which perturbation of the system alters the status quo but does not result in return to homeostasis).…”

Section: Discussionmentioning

confidence: 99%

Relationship between the Supply of Primordial Follicles and the Onset of Follicular Growth in Rats1

Hirshfield

1994

Biology of Reproduction

105

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Primordial follicles enter a state of suspended animation when they are formed and constitute a "stockpile" from which all growing follicles are derived. The factors that release individual follicles from their quiescent state are unknown. Many investigators believe that the number of follicles in the primordial stockpile is a major factor in determining the rate at which follicles begin to grow. However, the relationship between the size of the stockpile of primordial follicles and the rate at which follicles move into the growing pool is unclear. The purpose of the present study was to attempt to clarify this relationship. The initial size of the stockpile of primordial follicles was experimentally reduced by exposing rats to various doses of busulphan (BUS) in utero. Ovaries were collected at various ages postpartum and prepared for histological analysis. A computer-controlled image analyzer was used to perform size/frequency analysis of oocytes in control and treated ovaries; onset of follicular growth was recognized by enlargement of the oocyte. There was an inverse correlation between the number of primordial follicles in the ovary at birth and the rate at which they moved into the growing pool. In rats most severely affected by the BUS, all of the remaining follicles began to grow very early in life. By the time these severely affected rats reached adulthood, the stockpile of primordial follicles had been nearly exhausted. Nevertheless, the number of large antral follicles remained at normal levels until the follicular reserve was completely depleted.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…But the present histological study revealed the presence of more atretic follicles in the ovary upon treatment with the above mentioned doses. Since gonadotropins were the regulator of follicular development (Nimrod et al, 1976;de Wolff-Exalto, 1982;Albertini and Wassarman, 1994) and steroid production in rats (Albertini and Wassarman, 1994), it was quite possible that subnormal levels of gonadotropins might have affected oocyte development and maturation, ovulation, and corpora lutea formation in rat (Terranova, 1981).…”

Section: Discussionmentioning

confidence: 99%

Seed extracts of a Bangladeshi medicinal plant Abrus precatorius L. show antifertility activity in female rats

Hannan¹,

Hossain²,

Islam³

2010

Oriental Pharmacy and Experimental Medicine

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SUMMARYThe seed powder of Abrus precatorius L. has traditionally been used as oral contraceptive agent by the women in some rural areas in Bangladesh. The present study aimed to examine the antifertility activity of A. precatorius seed extracts in experimental female rats. Finely ground seeds were extracted with aqueous acetone followed by successive partitioning with n-hexane, ethyl acetate (EtOAc), methanol (MeOH) and water. Water suspended crude seed powder, organic fractions of acetone extract and a standard contraceptive drug (Nordette ® 28) were separately administered orally to the female rats for 30 days. n-Hexane, EtOAc and MeOH solubles at the doses of 2, 4 and 6 mg/rat/day, respectively and crude seed powder at 100 mg/rat/day exhibited 100% antifertility activity with lowest levels of serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and 17β-estradiol. Histological study of ovary and uterus of these rats exhibited reduced number of developing follicles and increased number of atretic follicles in the ovary, and fewer uterine glands with shrunken morphology, reduced endometrial height, poor vascularity and compact stroma in uterus. However, the activities of serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase and the body weight of the rats remained almost unaffected in all the seed extract treated rats compared to control. These results suggest that A. precatorius seed extracts reduced the levels of serum FSH, LH and 17β-estradiol probably by affecting hypothalamicpituitary-gonadal axis. The reduced levels of these hormones might have affected the oestrous cycle, follicular development, and subsequently the establishment of pregnancy in treated rats.

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Influence of gonadotrophins on early follicle cell development and early oocyte growth in the immature rat

Cited by 29 publications

References 11 publications

Regulation of Follicle-Stimulating Hormone Secretion by Estradiol and Dimeric Inhibins in the Infantile Female Rat1

Regulation of Follicle-Stimulating Hormone Secretion by Estradiol and Dimeric Inhibins in the Infantile Female Rat1

Relationship between the Supply of Primordial Follicles and the Onset of Follicular Growth in Rats1

Seed extracts of a Bangladeshi medicinal plant Abrus precatorius L. show antifertility activity in female rats

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