Repetitive Treatment With Gonadotrophin Releasing Factor or a Long-Acting Analogue Upon Gonadotrophin Secretion in the Ferret

Gledhill, B.; Donovan, B. T.

doi:10.1677/joe.0.0900275

Cited by 3 publications

(3 citation statements)

References 12 publications

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“…At the dosage used, GnRF is known to cause a surge in LH and FSH secretion in female ferrets, with more gonadotrophin being released from the pitutiary glands of anoestrous females than during oestrus (Donovan & ter Haar 1977;Gledhill & Donovan 1981). The effect of repetitive or long-continued treatment with GnRF was not explored because the pattern of steroidogenesis within the ovaries may change during an experiment and differences between the anoestrous and oestrous states become ob¬ scured.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Acute effects of GnRF-induced gonadotrophin secretion upon ovarian steroid secretion in the ferret

Matson¹,

Donovan²

1986

Acta Endocrinologica

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The effects of an increase in endogenous gonadotrophin secretion on the production of oestradiol, progesterone, androstenedione and testosterone by the ovaries of anaesthetized anoestrous and oestrous ferrets were followed. Gonadotrophin secretion was enhanced by the injection of gonadotrophin releasing factor (GnRF), and serial blood samples were collected over 9 h for hormone assay. Thyrotrophic hormone releasing factor (TRF) or acetic acid were injected for control purposes. The plasma content of oestradiol in oestrous females was significantly higher than during anoestrus, but secretion of this steroid was not increased by any means. The plasma concentration of progesterone in anoestrous females was significantly higher than during oestrus. It was increased by GnRF in anoestrous ferrets and less markedly in oestrous females. The plasma concentration of androstenedione was raised by GnRF to a greater extent during anoestrus than during oestrus. Testosterone was present in higher concentration in the plasma during anoestrus than during oestrus, and the level was increased by GnRF administration. These findings indicate that the ovaries of the anoestrous ferret secrete significant quantities of steroid hormones, and that they respond readily to gonadotrophic hormone. The hormonal changes underlying the seasonal alternation between anoestrus and oestrus in the ferret are not understood. During both physio¬ logical states gonadotrophins are secreted (Dono¬ van & ter Haar 1977) and steroids are produced by the ovaries (Donovan et al. 1983), yet during anoestrus the uterus and vulva remain in a regres¬ sed condition. Donovan et al. (1983) followed the changes in the secretion of oestradiol, oestrone,progesterone, androstenedione, testosterone and cortisol in ferrets brought from anoestrus into oestrus by exposure to long days. There was no change in the plasma concentrations of oestrone and cortisol, a rise in oestradiol occurred asso¬ ciated with the onset of oestrus, and falls in the concentrations of androstenedione, testosterone and progesterone following extension of the length of day were noted. Since the changes in pituitary gland function responsible for these effects upon ovarian steroid secretion are not understood, the effects of an acute increase in endogenous gonadotrophin secretion, induced by GnRF administration, upon ovarian function in anoestrous and in oestrous females was investi¬ gated. GnRF is known to cause the discharge of follicle-stimulating hormone (FSH) and luteiniz¬ ing hormone (LH) from the hypophyses of ferrets (Donovan & ter Haar 1977). Peripheral blood samples were collected before and after treatment and assayed for oestradiol, androstenedione, tes¬ tosterone and progesterone. Materials and MethodsAnimals

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Section: Discussionmentioning

confidence: 99%

“…Yet the sensitivity of the pituitary gland to GnRF differs distinctly between anoestrous and oestrous females (Donovan & ter Haar 1979;Gledhill & Donovan 1981), so that the diagnosis is regarded as valid, particularly as it supported by histological study of the ovaries.…”

Section: Discussionmentioning

confidence: 99%

Acute effects of GnRF-induced gonadotrophin secretion upon ovarian steroid secretion in the ferret

Matson¹,

Donovan²

1986

Acta Endocrinologica

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“…For example, when lesions were placed in the hypothalamus, a sharp increase in FSH secretion with no rise in LH occurred in some animals but the exact converse in others (Donovan & ter Haar, 1981), suggesting that separate releasing factors may be produced. Furthermore, daily treatment of ferrets with an LH-RH agonist (HOE 766) consistently induced an elevation in LH secretion but appeared to depress FSH release (Gledhill & Donovan, 1981), particularly in spayed animals.…”

Section: Introductionmentioning

confidence: 99%

Effect of passive immunization against LH-RH on gonadotrophin secretion in the ferret

Gledhill¹,

Fraser²,

Donovan³

1982

Reproduction

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Administration of ovine antiserum containing antibodies against synthetic LH-RH to spayed female ferrets caused an immediate fall in plasma LH concentration and by 2 h after injection circulating levels had declined by 70--80%. A further decline of 50% was observed on Day 2, but by Day 4 a return to normal levels had begun and control values were regained on Day 6. In contrast, the fall in plasma FSH concentration was delayed, with a significant reduction being first observed on Day 2 and minimal values occurring on Day 4. Control values were regained by Day 7. The results accord with the concept that a single hypothalamic releasing factor controls the tonic secretion of both pituitary hormones. However, the slow change in FSH secretion implies that the mechanism for FSH release may be more autonomous than that for LH.

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The effect of method of administration on ovarian responses of seasonally anestrous ewes administered gonadotrophin releasing hormone

Vincent

Kinser

Kesler

1984

Animal Reproduction Science

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Repetitive Treatment With Gonadotrophin Releasing Factor or a Long-Acting Analogue Upon Gonadotrophin Secretion in the Ferret

Cited by 3 publications

References 12 publications

Acute effects of GnRF-induced gonadotrophin secretion upon ovarian steroid secretion in the ferret

Acute effects of GnRF-induced gonadotrophin secretion upon ovarian steroid secretion in the ferret

Effect of passive immunization against LH-RH on gonadotrophin secretion in the ferret

The effect of method of administration on ovarian responses of seasonally anestrous ewes administered gonadotrophin releasing hormone

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