Microdialysis Measurement of In Vivo Gonadotropin-Releasing Hormone Secretion in the Goat.

Yamaguchi, Miyuki; Manabe, Yasuhiro; Tanaka, Tomomi; Mori, Yuji; Hoshino, Kazuhiro

doi:10.1262/jrd.38.143

Cited by 9 publications

(4 citation statements)

References 22 publications

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“…Similarly, in the ovariectomized goat given estradiol infusion the GnRH surge was found to occur at the time of LH surge [30] using the microdialytic perfusion technique [31]. To de termine the role of the GnRH pulse generator in the induction of the GnRH surge, we used the same experi mental model, namely the ovariectomized goats receiving estradiol infusion, and examined the change in MUA vol leys around the time of the LH surge [12], which showed a recurrence of MUA volleys with slightly decreased pulse frequency around the LH surge.…”

Section: Discussionmentioning

confidence: 99%

Changes in the Gonadotropin- Releasing Hormone Pulse Generator Activity during the Estrous Cycle in the Goat

et al. 1995

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The hypothalamic GnRH pulse generator activity, which was assessed by the characteristic increases in the multiple unit activity (MUA) specifically associated with the pulsatile LH secretion (MUA volleys), was monitored throughout the estrous cyle of the female goat. Blood samples were collected daily for analysis of progesterone, estradiol and LH levels to monitor ovarian cyclicity. The frequency of the MUA volleys showed a reciprocal relationship with the plasma progesterone profile; being low during the luteal phase, whereas increased during the follicular phase until the onset of the subsequent luteal phase. On the other hand, the duration of the MUA volleys changed in parallel with plasma progesterone levels showing considerable prolongation in the luteal phase. More frequent blood sampling was carried out at 2-hour intervals for timing the LH surge during the follicular phase induced by prostaglandin F2α (PGF2α) administration. During the PGF2α-induced follicular phase, the MUA volley frequency was abruptly increased from 4 h after PGF2α injection, and this high frequency was maintained throughout the follicular phase except for the period around the preovulatory LH surge when the MUA volley frequency was lowered temporarily. These results were in accordance with our previous observation that the recurrence of MUA volleys continued with decreased frequency during the estradiol-induced LH surge in ovariectomized goats. The present study revealed that GnRH pulse generator activity changes dramatically during the estrous cycle in the goat, and it is suggested that GnRH pulse generator activity becomes fully potentiated following luteolysis to induce the final follicular development and to stimulate estradiol secretion, which eventually provokes another neural mechanism responsible for the induction of the LH surge.

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Section: Discussionmentioning

confidence: 99%

Changes in the Gonadotropin- Releasing Hormone Pulse Generator Activity during the Estrous Cycle in the Goat

et al. 1995

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“…This scientific study of domestic ruminants. Some aspects of their endocrine and neuroendocrine characteristics governing the reproductive system have been studied [9][10][11][12][13][14]. However, a method for monitoring changes in the ovarian structures of this species without surgery or slaughter has not been established in this species, and, therefore, ovarian dynamics in various reproductive states remains unknown.…”

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confidence: 99%

Ultrasonographic Observation of Follicular and Luteal Dynamics during the Estrous Cycle in Shiba Goats.

Orita

Tanaka

Kamomae

et al. 2000

Journal of Reproduction and Development

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Abstract. Transrectal ovarian ultrasonography was performed to examine follicular and luteal dynamics during the estrous cycle in four adult female Shiba goats. Detectable follicles and the corpora lutea in both ovaries were monitored daily for 44 days using a B-mode scanner with a 7.5 MHz transrectal transducer. Blood samples were collected by jugular venipuncture at the time of ultrasonography and analyzed for estradiol-17β and progesterone by radioimmunoassay to monitor ovarian activity. Three to six follicles, whose diameters ranged from 1 to 7 mm, were observed throughout the estrous cycle; a few follicles grew to more than 5 mm in diameter and most of them atrophied during the luteal phase. Ovulatory follicles appeared from 5 days before ovulation coinciding with the start of the regression of corpora lutea, and then grew rapidly into 5.5 ± l.0 mm (mean ± SD) in diameter in parallel with the increase in the plasma concentration of estradiol-17β. The corpora lutea, 6.1 ± 1.3 mm in major axis, were detected from 3.0 ± 1.6 days after ovulation and stopped growing on 6 to 8 days after ovulation, with a major axis of 8.1 ± 2.2 mm. The mean length of the major axis of fully developed corpora lutea remained constant until 14 days after ovulation and then decreased rapidly to 5.2 ± 1.7 mm on the day of the next ovulation. In the early and functional luteal phase, there was a positive correlation between mean length of the total major axis of corpora lutea and mean plasma concentration of progesterone, whereas in the late luteal phase, the mean length of the total major axis of corpora lutea decreased slower than the progesterone levels. The present study demonstrated the ovarian follicular and luteal dynamics throughout the estrous cycle, indicating that ultrasonography is a reliable means for monitoring ovarian activity in Shiba goats.

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“…1988; Kendrick 1989, 1990; Robinson et al . 1991; Ungerstedt 1991; Yamaguchi et al . 1992; Hashizume et al .…”

Section: Methods For In Vivo Experiments To Study Hypothalamic Actionmentioning

confidence: 99%

“…1991), methionine‐enkephalin (met‐enk) (Kendrick 1990; Hashizume et al . 1994a), GnRH (Yamaguchi et al . 1992) and SS (Hashizume et al .…”

Section: Methods For In Vivo Experiments To Study Hypothalamic Actionmentioning

confidence: 99%

Methodology for the study of the hypothalamic‐pituitary hormone secretion in cattle

Hashizume

Kasuya

2009

Animal Science Journal

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Studies on the neuroregulatory mechanisms on the secretion of anterior pituitary (AP) hormones in domestic animals are important because nearly all complex physiological and metabolic processes are regulated by the AP hormones. To examine them, this article considers in vivo approaches such as the techniques of intrahypothalamic injection, intracerebroventricular injection, push-pull perfusion, and microdialysis, which have been employed in our own research group for the study in cattle. Also, in vitro approaches such as bovine AP cell culture and the AP explants superfusion system are described. This article clarifies the potential of neuroendocrine study techniques in cattle.

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Microdialysis Measurement of In Vivo Gonadotropin-Releasing Hormone Secretion in the Goat.

Cited by 9 publications

References 22 publications

Changes in the Gonadotropin- Releasing Hormone Pulse Generator Activity during the Estrous Cycle in the Goat

Changes in the Gonadotropin- Releasing Hormone Pulse Generator Activity during the Estrous Cycle in the Goat

Ultrasonographic Observation of Follicular and Luteal Dynamics during the Estrous Cycle in Shiba Goats.

Methodology for the study of the hypothalamic‐pituitary hormone secretion in cattle

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