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The effects of superior ovarian nerve sectioning on ovulation in the guinea pig.

Luna F, Cortés M, Flores M, Hernández B, Trujillo A, Domínguez R - Reprod. Biol. Endocrinol. (2003)

Bottom Line: Sectioning the right, left, or both SONs on day 5 (early luteal phase) resulted in a significant increase in the number of fresh corpora lutea.When surgery was performed on days 1 or 8, neither sectioning the right SON (R-SON) nor sectioning the SON bilaterally had an apparent effect on ovulation rates.Unilateral or bilateral sectioning of the SON performed during the early luteal phase (day 5) was associated with a significant decrease in uterine weight.

View Article: PubMed Central - HTML - PubMed

Affiliation: Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, México. flunam@yahoo.com.mx

ABSTRACT
The effects on spontaneous ovulation associated with the unilateral or bilateral sectioning of the superior ovarian nerves (SON) were analyzed in guinea pigs at different time intervals of the estrous cycle. Day 1 of the estrous cycle was defined as the day when the animal presents complete loss of the vaginal membrane (open vagina). Subsequent phases of the cycle were determined by counting the days after Day 1. All animals were autopsied on the fifth day of the estrous cycle after surgery. Sectioning the right, left, or both SONs on day 5 (early luteal phase) resulted in a significant increase in the number of fresh corpora lutea. Ovulation increased significantly when the left SON (L-SON) was sectioned during late follicular phase (day 1) and medium luteal phase (day 8). When surgery was performed on days 1 or 8, neither sectioning the right SON (R-SON) nor sectioning the SON bilaterally had an apparent effect on ovulation rates. Similarly, ovulation rates were not affected when unilateral (right or left) or bilateral sectioning of the SON was performed during late luteal phase two (day 12). Unilateral or bilateral sectioning of the SON performed during the early luteal phase (day 5) was associated with a significant decrease in uterine weight. A comparable effect was observed when the L-SON was sectioned during late follicular phase (day 1), or medium luteal phase (day 8). No effects on uterine weight were observed when unilateral or bilateral sectioning of the SON was performed during late luteal phase. Our results suggest that in the guinea pig the SON modulates ovulation, and that the degree of modulation varies along the estrous cycle. The strongest influence of the SONs on ovulation occurs during early luteal phase, and decrease thereafter, being absent by late luteal phase. In addition, sectioning the left or the right SON caused different responses by the ovaries of adult guinea pigs. This paper discusses the mechanisms by which ovulation increased when the SON was surgically cut.

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Number of corpora lutea (Mean ± SEM) in both ovaries of untouched control guinea pigs, L-SON, R-SON, or bilateral SON sectioning performed on day 1 of the estrous cycle (late follicular phase), on day 5 of the estrous cycle (early luteal phase), on day 8 of the estrous cycle (medium luteal phase) and day 12 of the estrous cycle (late luteal phase). *p < 0.05 in comparison with untouched control group (Kruskal-Walis followed by Mann-Whitney U-test)
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Figure 2: Number of corpora lutea (Mean ± SEM) in both ovaries of untouched control guinea pigs, L-SON, R-SON, or bilateral SON sectioning performed on day 1 of the estrous cycle (late follicular phase), on day 5 of the estrous cycle (early luteal phase), on day 8 of the estrous cycle (medium luteal phase) and day 12 of the estrous cycle (late luteal phase). *p < 0.05 in comparison with untouched control group (Kruskal-Walis followed by Mann-Whitney U-test)

Mentions: Compared to the control group, sham operation procedures did not cause any apparent change in the parameters measured. When the right SON was sectioned during the late follicular phase, the length of the estrous cycle was prolonged (20.2 ± 1.4 vs. 16.4 ± 0.4 days, p < 0.05). An increase in the number of fresh corpora lutea was observed when sectioning the L-SON was performed during the late follicular phase or during early and medium luteal phase. Similar results were observed when the L-SON or both SONs were sectioned during early luteal phase. No changes in ovulation were observed when surgery was performed during the late luteal phase (Figure 2).


The effects of superior ovarian nerve sectioning on ovulation in the guinea pig.

Luna F, Cortés M, Flores M, Hernández B, Trujillo A, Domínguez R - Reprod. Biol. Endocrinol. (2003)

Number of corpora lutea (Mean ± SEM) in both ovaries of untouched control guinea pigs, L-SON, R-SON, or bilateral SON sectioning performed on day 1 of the estrous cycle (late follicular phase), on day 5 of the estrous cycle (early luteal phase), on day 8 of the estrous cycle (medium luteal phase) and day 12 of the estrous cycle (late luteal phase). *p < 0.05 in comparison with untouched control group (Kruskal-Walis followed by Mann-Whitney U-test)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC222920&req=5

Figure 2: Number of corpora lutea (Mean ± SEM) in both ovaries of untouched control guinea pigs, L-SON, R-SON, or bilateral SON sectioning performed on day 1 of the estrous cycle (late follicular phase), on day 5 of the estrous cycle (early luteal phase), on day 8 of the estrous cycle (medium luteal phase) and day 12 of the estrous cycle (late luteal phase). *p < 0.05 in comparison with untouched control group (Kruskal-Walis followed by Mann-Whitney U-test)
Mentions: Compared to the control group, sham operation procedures did not cause any apparent change in the parameters measured. When the right SON was sectioned during the late follicular phase, the length of the estrous cycle was prolonged (20.2 ± 1.4 vs. 16.4 ± 0.4 days, p < 0.05). An increase in the number of fresh corpora lutea was observed when sectioning the L-SON was performed during the late follicular phase or during early and medium luteal phase. Similar results were observed when the L-SON or both SONs were sectioned during early luteal phase. No changes in ovulation were observed when surgery was performed during the late luteal phase (Figure 2).

Bottom Line: Sectioning the right, left, or both SONs on day 5 (early luteal phase) resulted in a significant increase in the number of fresh corpora lutea.When surgery was performed on days 1 or 8, neither sectioning the right SON (R-SON) nor sectioning the SON bilaterally had an apparent effect on ovulation rates.Unilateral or bilateral sectioning of the SON performed during the early luteal phase (day 5) was associated with a significant decrease in uterine weight.

View Article: PubMed Central - HTML - PubMed

Affiliation: Facultad de Ciencias Químicas, Universidad Autónoma de Puebla, México. flunam@yahoo.com.mx

ABSTRACT
The effects on spontaneous ovulation associated with the unilateral or bilateral sectioning of the superior ovarian nerves (SON) were analyzed in guinea pigs at different time intervals of the estrous cycle. Day 1 of the estrous cycle was defined as the day when the animal presents complete loss of the vaginal membrane (open vagina). Subsequent phases of the cycle were determined by counting the days after Day 1. All animals were autopsied on the fifth day of the estrous cycle after surgery. Sectioning the right, left, or both SONs on day 5 (early luteal phase) resulted in a significant increase in the number of fresh corpora lutea. Ovulation increased significantly when the left SON (L-SON) was sectioned during late follicular phase (day 1) and medium luteal phase (day 8). When surgery was performed on days 1 or 8, neither sectioning the right SON (R-SON) nor sectioning the SON bilaterally had an apparent effect on ovulation rates. Similarly, ovulation rates were not affected when unilateral (right or left) or bilateral sectioning of the SON was performed during late luteal phase two (day 12). Unilateral or bilateral sectioning of the SON performed during the early luteal phase (day 5) was associated with a significant decrease in uterine weight. A comparable effect was observed when the L-SON was sectioned during late follicular phase (day 1), or medium luteal phase (day 8). No effects on uterine weight were observed when unilateral or bilateral sectioning of the SON was performed during late luteal phase. Our results suggest that in the guinea pig the SON modulates ovulation, and that the degree of modulation varies along the estrous cycle. The strongest influence of the SONs on ovulation occurs during early luteal phase, and decrease thereafter, being absent by late luteal phase. In addition, sectioning the left or the right SON caused different responses by the ovaries of adult guinea pigs. This paper discusses the mechanisms by which ovulation increased when the SON was surgically cut.

Show MeSH
Related in: MedlinePlus