Prostaglandin F2  Prostaglandin E2, Progesterone, 20 -dihydroprogesterone and Ovarian 20  Hydroxysteroid Dehydrogenase Activity in Preparturient Pelvic Neurectomized Rats

Louis, Thomas M.; Lawrence, Irvin E.; Becker, Robert J.; Burden, Hubert W.

doi:10.3181/00379727-158-40262

Cited by 13 publications

(8 citation statements)

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“…The decline in progesterone in circulation before birth was common to all groups in the study but was postponed, and, as previously found, births were delayed by pelvic neurectomy [11,25,26]. A neurectomyinduced delay in the fall in systemic progesterone contrasts with reports that earlier in pregnancy, transection of the pelvic nerve, as well as the vagus nerve, was associated with reduced serum progesterone [13,48], the significance of which is uncertain because preterm birth did not occur.…”

Section: Discussioncontrasting

confidence: 34%

“…By contrast, it has been known for a long time that input from the pelvic nerve is involved in the process of parturition at term. In rats, transection of the sensory branch of the pelvic nerve was found to result in interference with birth [11,[22][23][24][25][26][27][28], delayed timing and labor, and, commonly, dystocia. Moreover, pelvic neurectomy has been reported to acutely decrease [13] or increase [25,26] serum progesterone in pregnant rats, depending on whether neurectomy was performed early or late in pregnancy, respectively.…”

Section: Introductionmentioning

confidence: 98%

“…In rats, transection of the sensory branch of the pelvic nerve was found to result in interference with birth [11,[22][23][24][25][26][27][28], delayed timing and labor, and, commonly, dystocia. Moreover, pelvic neurectomy has been reported to acutely decrease [13] or increase [25,26] serum progesterone in pregnant rats, depending on whether neurectomy was performed early or late in pregnancy, respectively. Although little is known about the birth process in women with damage to innervation of the cervix or major spinal cord damage, complete transection extending to as high as the sixth cervical vertebra does not block the perception of labor pains [29]; these patients often deliver by cesarean section.…”

Section: Introductionmentioning

confidence: 98%

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Transection of the Pelvic or Vagus Nerve Forestalls Ripening of the Cervix and Delays Birth in Rats1

Clyde

Lechuga

Ebner

et al. 2011

Biology of Reproduction

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Innervation of the cervix is important for normal timing of birth because transection of the pelvic nerve forestalls birth and causes dystocia. To discover whether transection of the parasympathetic innervation of the cervix affects cervical ripening in the process of parturition was the objective of the present study. Rats on Day 16 of pregnancy had the pelvic nerve (PnX) or the vagus nerve (VnX) or both pathways (PnX+VnX) transected, sham-operated (Sham) or nonpregnant rats served as controls. Sections of fixed peripartum cervix were stained for collagen or processed by immunohistochemistry to identify macrophages and nerve fibers. All Sham controls delivered by the morning of Day 22 postbreeding, while births were delayed in more than 75% of neurectomized rats by more than 12 h. Dystocia was evident in more than 25% of the PnX and PnX+VnX rats. Moreover, on prepartum Day 21, serum progesterone was increased severalfold in neurectomized versus Sham rats. Assessments of cell nuclei counts indicated that the cervix of neurectomized rats and Sham controls had become equally hypertrophied compared to the unripe cervix in nonpregnant rats. Collagen content and structure were reduced in the cervix of all pregnant rats, whether neurectomized or Shams, versus that in nonpregnant rats. Stereological analysis of cervix sections found reduced numbers of resident macrophages in prepartum PnX and PnX+VnX rats on Day 21 postbreeding, as well as in VnX rats on Day 22 postbreeding compared to that in Sham controls. Finally, nerve transections blocked the prepartum increase in innervation that occurred in Sham rats on Day 21 postbreeding. These findings indicate that parasympathetic innervation of the cervix mediates local inflammatory processes, withdrawal of progesterone in circulation, and the normal timing of birth. Therefore, pelvic and vagal nerves regulate macrophage immigration and nerve fiber density but may not be involved in final remodeling of the extracellular matrix in the prepartum cervix. These findings support the contention that immigration of immune cells and enhanced innervation are involved in processes that remodel the cervix and time parturition.

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Section: Discussioncontrasting

confidence: 34%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Transection of the Pelvic or Vagus Nerve Forestalls Ripening of the Cervix and Delays Birth in Rats1

Clyde

Lechuga

Ebner

et al. 2011

Biology of Reproduction

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show abstract

“…Bilateral pelvic neurectomy prolongs or blocks delivery in rats (Carlson and Defeo 1965;Spies et al 1971 ;Louis et al 1978;Higuchi et al 1986Higuchi et al , 1987. The pelvic nerve consists of muscular and viscerocutaneous branches (Pacheo et al 1989).…”

Section: Discussionmentioning

confidence: 99%

Effects of peripheral nerve lesions during pregnancy on parturition in rats

et al. 1990

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Bilateral section of either the sensory or motor branch of the pelvic nerve or pudendal nerve was performed in rats on days 8-10 of pregnancy, and the effects on delivery were observed. Bilateral resection of the sensory branch of the pelvic nerve reduced the number of live pups per litter, and increased the number of stillbirths and the number of fetuses retained in utero per litter at day 24. Sectioning motor components of the pelvic nerve, or both motor and sensory components of the pudendal nerve, had no effects on delivery in rats. We conclude that of the peripheral nerves evaluated in this study, only the sensory branch of the pelvic nerve is required for normal vaginal delivery in this species.

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“…In the absence of pregnancy or pseudopregnancy induction, corpora lutea secrete proges¬ terone for only 2 days and then regress rapidly (Hashimoto et al, 1968;Smith et al, 1975 Gunnet and Freeman 1983). The complex of events that occurs before delivery includes a precipitous drop in circulating progesterone (Wiest et al, 1968;Louis et al, 1978;Renegar et al, 1992), a major controlling event in the delivery process in rats (Csapo and Wiest, 1969 (Brambell, 1956), the number of corpora lutea postpartum reflects the number of ova ovulated. Most embryo wastage occurs before implantation (Nalbandov, 1964 (Rebar et al, 1969;Mori et al, 1974), although some rats show rises in circulating gonadotrophin concentrations as early as 2 h postpartum (Rebar et al, 1969 The pituitary content of LH in rats is low postpartum relative to concentrations at day 20 of gestation (Greenwald, 1966).…”

Section: Discussionmentioning

confidence: 99%