Pelvic Neurectomy Research Articles

Parasympathetic innervation contributes to the increase of survival rate and anti-inflammatory effect of electroacupuncture at "Ciliao"(BL32) in rats with lethal endotoxemia

To observe the effect of electroacupuncture (EA) at "Ciliao" (BL32) on the survival rate and serum inflammatory cytokine levels in rats with lethal endotoxemia, and to explore its parasympathetic mechanism in suppressing severe systemic inflammation. A total of 82 male SD rats were used in the present study. In the first part of this study, 40 rats were randomized into model and EA-BL32 groups (n=20/group). The endotoxemia model was established by intraperitoneal injection of lethal amount of lipopolysaccharide (LPS, 10 mg/kg). EA (30 Hz, 6 mA) was applied to bilateral BL32 for 30 min before and after LPS injection. The survival rate in 7 days was then recorded. In the second part of this study, 42 rats were randomized into normal control, model, EA-BL32, EA-BL32+cervical vagotomy, EA-BL32+truncal (subdiagrammatical) vagotomy and EA-BL32+pelvic neurectomy groups (n=7/group). The endotoxemia model was established by intraperitoneal injection of LPS (6 mg/kg) 30 min after the neurectomy. Rats of the control group received intraperitoneal injection of 6 mg/kg saline. EA with the same parameters mentioned above was applied to bilateral BL32 for 30 min before and after LPS injection. Blood sample was collected from the abdominal aorta 3 h after LPS injection for detecting the levels of TNF-α, IL-1β and IL-6 by ELISA. ① The EA survival rate was 25% in the model group and 60% in the EA -BL32group, being significantly improved after EA (P<0.05). ② The contents of serum TNF-α, IL-1β and IL-6 were significantly higher in the model group than those in the control group (P<0.000 1). After EA intervention, and compared with the model group, the levels of TNF-α, IL-1β and IL-6 were significantly decreased in the EA-BL32, EA-BL32+cervical vagotomy, EA-BL32+truncal vagotomy and EA-BL32+pelvic neurectomy groups (P<0.000 1，P<0.01). After neurectomy and compared to the EA-BL32 group, the contents of TNF-α and IL-6 in the EA+cervical vagotomy and EA+pelvic neurectomy groups, IL-1β in the EA+pelvic neurotomy group were significantly higher (P<0.0000 1, P<0.05), suggesting an elimination of EA effects after neurectomy. No significant differences were found among the 3 neurectomy groups in the levels of TNF-α, IL-1β and IL-6 (P>0.05). EA of BL32 can improve the survival rate and attenuate the level of inflammatory cytokines in rats with lethal endotoxemia, which is closely related to the intact of parasympathetic pathway including the vagus nerve and pelvic nerve.

The effect of bilateral pelvic neurectomy on uterine and abdominal electrical and pressure activity, as measured by telemetry in conscious, unrestrained pregnant rats

Bilateral pelvic neurectomy (BPN) interferes with delivery in rats. This work measures the effect of BPN on uterine and abdominal electromyography (EMG) and pressure during gestation and delivery. Uterine EMG and intra-uterine pressure (IUP), as well as abdominal muscle EMG and intra-abdominal pressure (IAP), were recorded on days 19-24 in rats. Mean values were determined for the peak frequency of the power density spectrum (PDS) of the uterine and abdominal EMG "bursts," the integral of the abdominal EMG power spectrum (IPS), and the area under the IUP and IAP curves (AUIUP and AUIAP). Uterine EMG power density spectrum peak frequency and AUIUP were low during days 19-21 in all rats, and on days 22-23 increased sharply and significantly in both groups. Before delivery, sham rat recordings showed sudden sharp increases in AUIAP, AUIUP and IPS as "pushing" was observed. Pushing was not observed or recorded in laboring BPN rats and they did not deliver normally. A functional pelvic nerve is required for normal labor and delivery in rats. BPN inhibits abdominal EMG and contractions necessary to expel the fetus.

Contractile properties of the denervated external anal sphincter

The purpose of this study was to evaluate the effect of denervation on contractile properties of the external anal sphincter (EAS) of the female rat. Sham operation, pudendal nerve transection, pelvic neurectomy, or combined pudendal nerve transection/pelvic neurectomy was performed in young female rats. Contractile function of the EAS was determined after 2 weeks. Maximal force-generating capacity of the EAS was not impaired by bilateral pudendal denervation or pelvic neurectomy. Twitch tension, however, was decreased, and fatigability increased after pelvic neurectomy. Combined bilateral pudendal nerve-transection plus pelvic neurectomy resulted in compromised force-generating capacity, decreased twitch tension, and increased fatigability of the anal sphincter. Subtle changes in EAS function are detectable after pelvic neurectomy, but not pudendal denervation. In contrast, combination pudendal and pelvic neurectomy resulted in severe compromise of EAS function. These data suggest that EAS function is relatively preserved unless injury occurs to > 1 source of innervation.

The effect of bilateral pelvic neurectomy on cervical ripening in pregnant rats

To determine the effect of bilateral pelvic neurectomy (BPN) on cervical ripening in pregnant rats by measuring cervical extensibility and changes in collagen cross-linkages. Timed-pregnant rats were randomly laparotomized on days 9 or 10 of gestation and the pelvic nerves were exposed and either bilaterally transected, or left intact in sham control animals. The rats were sacrificed on day 18 and the uterine cervices obtained. Cervical ripening was assessed by cervical resistance-to-stretch, light-induced autofluorescence (LIF) of cross-linked collagen, and collagen changes analyzed by picrosirius polarization microscopy. Measurements of extensibility and collagen cross-linkages indicated that after BPN the cervix was significantly more ripened than the cervix from sham control animals. BPN stimulates cervical ripening instead of inhibiting this event as previously proposed. Further studies in this area could be critical for developing treatments for dystocia, preterm labor, and cervical insufficiency.

Pelvic Nerve Input Mediates Descending Modulation of Homovisceral Processing in the Thoracolumbar Spinal Cord of the Rat

Colonic afferents project to the lumbosacral and thoracolumbar spinal cord via the pelvic and hypogastric/lumbar colonic nerves, respectively. Both spinal regions process inflammatory colonic stimuli. The role of thoracolumbar segments in processing acute colorectal pain is questionable, however, because the lumbosacral spinal cord appears sufficient to process reflex responses to acute pain. Here, we show that activity in pelvic nerve colonic afferents actively modulates thoracolumbar dorsal horn neuron processing of the same colonic stimulus through a supraspinal loop: homovisceral descending modulation. Dorsal horn neurons were recorded in the rat thoracolumbar spinal cord after acute or chronic pelvic neurectomy and cervical cold block. Acute pelvic neurectomy or lidocaine inhibition of lumbosacral dorsal roots facilitated the excitatory response of thoracolumbar dorsal horn neurons to colorectal distention (CRD) and decreased the percentage of neurons inhibited by CRD, suggesting colonic input over the pelvic nerve inhibits thoracolumbar processing of the same stimulus. Ectopic activity developed in the proximal pelvic nerve after chronic neurectomy reactivating the inhibitory circuit, inhibiting thoracolumbar neurons. Cervical cold block alleviated the inhibition in intact or chronic neurectomized rats. However, the facilitated response after acute pelvic neurectomy was inhibited by cervical cold block, exposing an underlying descending facilitation. Inhibiting pelvic nerve input after cervical cold block had minimal effect. These data demonstrate that input over the pelvic nerve modulates the response of thoracolumbar spinal neurons to CRD by a supraspinal loop and that increasing thoracolumbar processing increases visceral hyperalgesia.

Effects of pelvic, pudendal, or hypogastric nerve cuts on Fos induction in the rat brain following vaginocervical stimulation

In the female rat, genitosensory input is conveyed to the central nervous system predominantly through the pelvic, pudendal, and hypogastric nerves. The present study examined the relative contribution of those three nerves in the expression of Fos immunoreactivity within brain regions previously shown to be activated by vaginocervical stimulation (VCS). Bilateral transection of those nerves, or sham neurectomy, was conducted in separate groups of ovariectomized, sexually-experienced females. After recovery, females were primed with estrogen and progesterone and given either 50 manual VCSs with a lubricated glass rod over the course of 1 h. VCS increased the number of neurons expressing Fos immunoreactivity in the medial preoptic area, lateral septum, bed nucleus of the stria terminalis, ventromedial hypothalamus, and medial amygdala of sham neurectomized females. Transection of the pelvic nerve reduced Fos immunoreactivity in the medial preoptic area, bed nucleus of the stria terminalis, ventromedial hypothalamus, and medial amygdala, whereas transection of the pudendal nerve had no effect. In contrast, transection of the hypogastric nerve increased Fos immunoreactivity in the medial preoptic area and lateral septum, whereas transaction of the pelvic nerve increased Fos immunoreactivity in the lateral septum, following VCS. All females given VCS, except those with pelvic neurectomy, displayed a characteristic immobility during each application. These data confirm that the pelvic nerve is largely responsible for the neural and behavioral effects of VCS, and support a separate function for the hypogastric nerve.

Characterization of Vascular Endothelial Growth Factor (VEGF) in the Uterine Cervix over Pregnancy: Effects of Denervation and Implications for Cervical Ripening

Bilateral neurectomy of the pelvic nerve (BLPN) that carries uterine cervix-related sensory nerves induces dystocia, and administration of its vasoactive neuropeptides induces changes in the cervical microvasculature, resembling those that occur in the ripening cervix. This study was designed to test the hypothesis that (a) the cervix of pregnant rats expresses vascular endothelial growth factor (VEGF) and components of the angiogenic signaling pathway [VEGF receptors (Flt-1, KDR), activity of protein kinase B, Akt (phosphorylated Akt), and endothelial nitric oxide synthase (eNOS)] and von Willebrand Factor (vWF) and that these molecules undergo changes with pregnancy, and (b) bilateral pelvic neurectomy (BLPN) alters levels of VEGF concentration in the cervix. Using RT-PCR and sequencing, two VEGF isoforms, 120 and 164, were identified in the rat cervix. VEGF, VEGF receptor-1 (Flt-1), eNOS, and vWF immunoreactivities (ir) were localized in the microvasculature of cervical stroma. Their protein levels increased during pregnancy but decreased to control levels by 2 days postpartum. VEGF receptor-2 (KDR)-ir was confined to the epithelium of the endocervix. BLPN downregulated levels of VEGF by a third. Therefore, the components of the angiogenic signaling pathway are expressed in the cervix and change over pregnancy. Furthermore, angiogenic and sensory neuronal factors may be important in regulating the dynamic microvasculature in the ripening cervix and may subsequently play a role in cervical ripening and the birth process.

Reinnervation of the rectum with a somatic nerve: a canine study.

The purpose of this communication was to evaluate the possibility of rectal stimulation through nerve autografting. Eleven mongrel dogs were studied. The abdomen was opened under anesthesia. The obturator nerve was cut at its entrance into the obturator foramen and was embedded in a tunnel within the musculature of the rectal wall. Six months later, the abdomen was re-opened and bilateral pelvic ganglionectomy was done to denervate the rectum. As the urinary bladder was also denervated subsequent to the pelvic ganglionectomy, cystostomy was performed. Two bipolar electrodes were applied to the obturator nerve. The effects of electrostimulation were evaluated under basic conditions after urecholine and atropine administration and after xylocaine topical application to the obturator nerve. After bilateral pelvic neurectomy, the basic rectal pressure dropped (P < 0.05) and there was no response to urecholine or to atropine injection. Obturator nerve electrostimulation induced evoked potentials within the nerve as well as rectal pressure rise (P < 0.001); the former was abolished with xylocaine topical application to the nerve and the latter with atropine administration. Microscopic examination revealed that the Schwann cells and axons grew in the connective tissue between the rectal muscle bundles. In conclusion, reinnervation of the denervated rectum using a somatic nerve implant is possible. To our knowledge this study is the first to show "smooth' muscle excitability by stimulation of a somatic nerve implant.

Neural mechanisms accounting for the increase in blood pressure and heart rate during vagino-cervical stimulation

The rise in blood pressure and heart rate produced by the mechanical stimulation of the uterine cervix (VS) was examined after adrenalectomy, after pelvic or hypogastric neurectomies or after spinal cord transection in anesthetized rats. Neither adrenalectomy, nor hypogastric neurectomy prevented the rise in heart rate and blood pressure produced by VS. After the spinal cord transection at T6 level, VS was still able to produce the rise in blood pressure. However, the rise in blood pressure was significantly lower than that produced in the same animals before the transection. No changes in heart rate were produced by VS after spinal cord transection. This result can be explained because this level of transection prevents the reach of the afferent inflow to the superior cervical ganglia. Pelvic neurectomy abolished completely the effects of VS on blood pressure and heart rate. Low intensity (1–2 times the threshold) electrical stimulation of the pelvic nerve produced a rise in blood pressure. Even though heart rate increased during electrical stimulation, the change in heart rate was not statistically different from the pre-stimulation value. These results suggest that the changes in blood pressure and heart rate produced by VS represent a neuronal reflex response mediated by the pelvic nerve. The fact that the effects of VS on blood pressure persist in spinal cord-transected animals suggests that the reflex is integrated at the spinal level. However, the cardiovascular responses to VS were significantly lower than before transection, suggesting that supraspinal centers are also involved in the reflex.

Pelvic neurectomy blocks oxytocin-facilitated sexual receptivity in rats

The effect of bilateral pelvic, hypogastric, or pudendal neurectomy on oxytocin-induced facilitation of lordosis behavior was examined in ovariectomized, estrogen, and progesterone primed female rats. Oxytocin-induced facilitation of lordosis behavior was significantly decreased following bilateral pelvic, or combined bilateral pelvic and hypogastric neurectomy. Hypogastric only or pudendal only neurectomy had no effect on the facilitation of lordosis behavior after systemic administration of oxytocin. These results suggest that the integrity of the pelvic nerve is necessary and sufficient to mediate the stimulatory effects of systemically administered oxytocin on receptivity.

Endocrine parameters associated with disruption of parturition after bilateral pelvic neurectomy.

Bilateral lesions of the pelvic nerve (BLPN) result in dystocia, but the processes which control this effect are not fully understood. Plasma progesterone, relaxin, and luteinizing hormone (LH) concentrations were measured in blood samples taken in the morning (AM) and evening (PM) of Days 20-23 of gestation from rats with BLPN or sham neurectomy. Ten of 11 sham-operated control animals delivered their entire litters by Day 23 of gestation, but animals with BLPN did not complete parturition by Day 23 when they were sacrificed. Progesterone concentrations were greater in rats with BLPN than in sham-operated rats on Day 20 PM and Day 21 AM, but hormone concentrations declined to minimal values by Day 22 in both groups. Relaxin concentrations were greater in rats with BLPN than in sham-operated rats on Day 21 PM. Thereafter, relaxin concentrations decreased to reach minimum values on Day 23 in both groups. LH concentrations were low throughout the period of study in rats with BLPN; however, a postpartum LH surge was detected in all sham-operated animals. Data from this study indicate that the pelvic nerve does not control parturition by modulating serum relaxin and progesterone concentrations; however, these data suggest that impulses carried by the pelvic nerve influence ovarian secretion of these hormones. In addition, these data indicate that the pelvic nerve transmits stimuli from the cervix to the hypothalamus to facilitate the postpartum LH surge.

The effects of hypogastric and pelvic neurectomy on oxytocin-induced facilitation of receptivity.

Annals of the New York Academy of SciencesVolume 652, Issue 1 p. 443-444 The Effects of Hypogastric and Pelvic Neurectomy on Oxytocin-Induced Facilitation of Receptivity K. M. MOODY, Corresponding Author K. M. MOODY Institute of Neuroscience, University of Pennsylvania Philadelphia, Pennsylvania 19104Address for correspondence: Kathleen M. Moody, Department of Biology, Stockton State College, Pomona, NJ 08240.Search for more papers by this authorJ. L. STEINMAN, J. L. STEINMAN Institute of Animal Behavior Rutgers University Newark, New Jersey 07101Search for more papers by this authorB. R. KOMISARUK, B. R. KOMISARUK Institute of Animal Behavior Rutgers University Newark, New Jersey 07101Search for more papers by this authorN. T. ADLER, N. T. ADLER Department of Psychology University of Pennsylvania Philadelphia, Pennsylvania 19104Search for more papers by this author K. M. MOODY, Corresponding Author K. M. MOODY Institute of Neuroscience, University of Pennsylvania Philadelphia, Pennsylvania 19104Address for correspondence: Kathleen M. Moody, Department of Biology, Stockton State College, Pomona, NJ 08240.Search for more papers by this authorJ. L. STEINMAN, J. L. STEINMAN Institute of Animal Behavior Rutgers University Newark, New Jersey 07101Search for more papers by this authorB. R. KOMISARUK, B. R. KOMISARUK Institute of Animal Behavior Rutgers University Newark, New Jersey 07101Search for more papers by this authorN. T. ADLER, N. T. ADLER Department of Psychology University of Pennsylvania Philadelphia, Pennsylvania 19104Search for more papers by this author First published: June 1992 https://doi.org/10.1111/j.1749-6632.1992.tb34378.xCitations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume652, Issue1Oxytocin in Maternal, Sexual, and Social BehaviorsJune 1992Pages 443-444 RelatedInformation

The segmental distribution of afferent fibers from the vaginal cervix and hypogastric nerve in rats

Injections of horseradish peroxidase-wheat germ agglutinin (HRP-WGA) into the walls of the vagina and cervix (vaginocervical injections) of rats resulted in labeling of dorsal root ganglia (DRG) cells located at T 11-L 4 and L 6-S 2. In a second group of animals, exposure of the hypogastric nerve to HRP-WGA resulted in a similar bimodal distribution of labeled cells as compared to vaginocervical injections. In a third group, unilateral hypogastric nerve transection prior to injection of HRP-WGA into the vaginocervical walls resulted in a significant reduction in DRG cells labeled at T 13, L 1, L 2, L 6 and S 1. Bilateral transection of the hypogastric nerves prior to vaginocervical injections eliminated labeled DRG cells at thoracolumbar levels but not at L 6 and S 1. Bilateral pelvic neurectomy reduced, but did not eliminate labeled DRG cells at L 6 and S 1 following vaginocervical injections. These results indicate that the hypogastric nerve constitutes a major sensory pathway from the vaginocervical walls to thoracic, lumbar and sacral levels of the spinal cord. The hypogastric nerve may subserve the transmission of noxious input from the vaginocervical walls as well as the activation of ascending spinal pathways involved in neuroendocrine reflexes during parturition.

The influence of pelvic nerve transection on the neuromuscular system of the canine urinary bladder

We previously reported that bladder overdistension led to denervation and subsequent supersensitivity of the detrusor muscle to acetylcholine. Therefore, to exclude the influence of bladder overdistension, we produced a low-pressure bladder in female mongrel dogs using an indwelling urethral catheter, and performed pelvic neurectomy (decentralization). We examined the effects of decentralization on the neuromuscular system of the bladder. The contraction response levels of bladder strips in dogs 1 and 2 weeks after neurectomy was low, and significantly different from that of bladder strips in the control group. The dose-response curves of dogs 4 and 8 weeks after neurectomy showed a shift to the left when compared to those of the control group, indicating a significant increase in sensitivity of the bladder strips. Many cholinergic terminal and varicosity profiles had a normal ultrastructure in all of the groups subjected to neurectomy, while some had degenerating profiles representing clear axoplasm without any recognizable organelles. Microphotographs of bladder obtained from dogs with spontaneous catheter loss showed degenerating axons, which were observed more frequently than in bladders kept empty with indwelling urethral catheters. Micturition in the dogs with spontaneous catheter loss was achieved by overflow incontinence without catheterization. These findings suggest that post-synaptic nerve degeneration may be augmented by impairment of micturition, followed by decentralization. Our observations also suggest that post-synaptic nerve degeneration (denervation) plays an important role in the increased sensitivity of the detrusor muscle to acetylcholine in the parasympathetically decentralized urinary bladder, whether denervation is due to trans-synaptic degeneration or impairment of micturition.

Analgesia is produced by uterocervical mechanostimulation in rats: roles of afferent nerves and implications for analgesia of pregnancy and parturition

Afferent activity from the reproductive tract activates intrinsic pain attenuating processes. For example, analgesia results from vaginocervical mechano-stimulation in nonpregnant rats and occurs during pregnancy and parturition. In the present study, the effect of uterocervical mechanostimulation on pain thresholds was investigated in order to determine whether direct stimulation of the uterine cervix could play a role in the analgesia of pregnancy. Uterocervical mechanostimulation was applied to nonpregnant rats via a silastic disc implanted in the uterus. The disc abutted against the cervix and was attached to a thread externalized through the vaginal orifice. Application of a force of 150 g, but not 100 g, produced a significant increase in tail flick latency (110.4 ± 40.6%, P < 0.03). This effect was abolished by pelvic neurectomy, but was not altered by hypogastric neurectomy. Stimulation of the uterine cervix in combined pelvic and hypogastric neurectomy rats produced a decrease in tail flick latency. These results indicate that the analgesia that occurs during pregnancy and/or parturition may result, at least in part, from the uterocervical mechanostimulation that occurs during this condition.

Intrinsic neuromuscular defects in the neurogenic bladder: X. Value and limitations of neurohistochemistry

AbstractHistochemical changes in bladder innervation have been described in various types of clinical and experimental neurogenic voiding dysfunction. Recent studies in the cat have shown that both decentralization and postganglionic “denervation” lead to ultrastructural changes in muscular innervation of the bladder base. The present study was conducted to find out whether these changes can be detected histochemically. Decentralization of the bladder by unilateral sacral ventral rhizotomy, bilateral sacral ventral rhizotomy, or unilateral pelvic neurectomy was performed in 25, and postganglionic “denervation” by unilateral pelvic plexus neurectomy in 9, adult male cats. Specimens of the bladder body and bladder base were collected 2–4 and 8–10 weeks after decentralization, and 2–4 weeks and 10 weeks after “denervation.” The specimens were processed by histochemical methods to demonstrate cholinergic and adrenergic nerves. No recognizable differences from the norm were observed in cholinergic muscular innervation of either the body or base specimens of the decentralized bladder. While adrenergic muscular innervation of both regions was similar to normal in short‐term samples of the same specimens, there was an obvious adrenergic hyperinnervation of both in the long‐term samples. By contrast, there was an obvious, early‐developing, and persistent hypoinnervation by both cholinergic and adrenergic nerves in both the body and base regions after postganglionic “denervation.” It is concluded that histochemistry (1) has no value in detecting either short‐ or long‐term changes in cholinergic muscular innervation of the decentralized bladder and (2) is useful for revealing both short‐ and long‐term cholinergic and adrenergic hypoinnervation of the “denervated,” as well as long‐term adrenergic hyperinnervation of the decentralized vesical muscularis.

Intrinsic neuromuscular defects in the neurogenic bladder: VIII. Effects of unilateral pelvic and pelvic plexus neurectomy on ultrastructure of the feline bladder base

AbstractIt has been shown previously that unilateral parasympathetic decentralization of the feline bladder by sacral ventral rhizotomy results in early degenerative and eventual regenerative ultrastructural neuromuscular changes in the bladder base. The present study was conducted to define the effects of unilateral parasympathetic decentralization by pelvic neurectomy and postganglionic “denervation” by pelvic plexus neurectomy on the neuromuscular ultrastructure of the feline bladder base. Eighteen sexually mature male cats were used. Three cats provided the control material; six cats underwent unilateral pelvic and nine unilateral pelvic plexus neurectomy. Bladders were collected for study 2, 3, and 10 weeks following the former and 1–4 days, 3 weeks, and 7–12 weeks following the latter procedure. Samples from both the neurectomized and the intact sides of each bladder were obtained for electron microscopic study. The ultrastructural neuromuscular changes observed after pelvic neurectomy were identical to those previously described following unilateral sacral ventral rhizotomy, except for early developing and persistent, widespread degeneration of myelinated axons in the former model. As in the rhizotomy model, there was cholinergic axonal regeneration, adrenergic hyperinnervation, and a prominent population of probable copeptidergic axons in long‐term samples of the bladder base following pelvic neurectomy. In contrast, pelvic plexus neurectomy (a postganglionic “denervation” procedure) resulted in early developing and persistent degeneration of all axons in the bladder base: i.e., myelinated, cholinergic and adrenergic, with long‐term hypoinnervation by both cholinergic and adrenergic neural elements. Our observations indicate that two forms of the experimentally induced lower‐motor neurogenic bladder can be distinguished ultrastructurally.

Mating induces pupillary dilatation in female rats: Role of pelvic nerve

In the present study, we demonstrate that natural or artificial vaginal stimulation exerts a powerful effect on autonomic activity, as measured by pupillary diameter. Pupillary diameter was recorded approximately 3–5 sec after copulatory mounts, intromissions, ejaculations or experimenter delivered stimulation. The pupil was magnified 43× and its diameter was measured directly from a calibrated video screen. Mating tests were performed on 13 female rats which received at least one complete ejaculatory series. Compared to the premount (baseline) value (1.01 mm), mean pupillary diameters were significantly greater during (a) mounts without intromissions (1.20 mm; 20% increase), (b) mounts with intromissions (1.34 mm; 33% increase), or (c) ejaculation (1.49 mm; 48% increase. Mean pupillary diameter during the post-ejaculatory interval (0.95 mm; 6% decrease) did not differ significantly from the premount baseline. Since the mean pupillary diameter at the last intromission before ejaculation was significantly larger (by 18%) than the diameter at the first intromission, repeated intromissions may generate a gradually increasing net sympathetic response reaching a peak at ejaculation. In order to identify the adequate stimuli for increasing pupillary diameter, we applied external genital stimulation (flank-perineal palpation), internal genital stimulation (probing the vaginal cervix with a glass rod), or both combined. Vaginal stimulation alone produced near-maximal pupillary dilatation; external genital stimulation was less effective, and combined internal and external genital stimulation was more effective. Thus, vaginal afferent activity is an adequate stimulus to produce pupillary dilatation. Furthermore, bilateral pelvic neurectomy markedly attenuated the effect of vaginal stimulation on dilating the pupil. Since pupillary diameter is at least partly a function of autonomic tone, this “bioassay” indicates that genital stimulation may produce a net sympathetic activating effect.

The effects of pelvic neurectomy on collagen in the cervix of the pseudopregnant rat.

Bilateral section of the pelvic parasympathetic nerves (pelvic-neurectomy) on day 5 of pseudopregnancy had no effect on the wet weight of ovaries, uteri, and/or cervices, but at day 9 serum progesterone was reduced to approximately half that of sham-operated animals. Collagen in the cervix was visualized with picrosirius red staining under polarization microscopy. Pelvic neurectomy decreased the birefringence of Type 1 collagen in the cervix to less than half that of sham operated animals. The decreased birefringence, an index of the organization of collagen fibers, is believed to be attributable to reduced progesterone levels. Alternatively, the pelvic nerve may directly influence mucopolysaccharides or collagenolytic enzymes in the cervix.

Gap junctions in the myometrium of pelvic-neurectomized rats with blocked parturition.

AbstractPregnant Sprague‐Dawley rats were laparotomized on days 8–10 and sham‐operated (S) or subjected to bilateral section of the pelvic parasympathetic nerves (pelvic neurectomy (PN)). Both S and PN animals were allowed to go to term and the time of delivery was recorded. Eight of ten S animals delivered on the afternoon of day 22 and two delivered on the morning of day 23. Pelvic neurectomy blocked parturition in five rats autopsied on day 24, and five rats autopsied on day 26. On these days the PN animals had full‐term fetuses; live on day 24, but dead on day 26. In a second study, the fine structure of the myometrium of S and PN pregnant rats was examined during the parturient period for the presence of gap junctions. Gap junctions were present between myometrial smooth muscle cells of the S group during delivery and in the PN group on days 23, 24, and 25, in the absence of delivery. There was a significant increase (p &lt; 0.05) in the number of gap junctions on day 23 in the PN animals. There was no difference in the length of gap junctions in the different groups. These observations indicate that the parturition block characteristic of PN animals is not attributable to the failure of gap junction formation between smooth muscle cells. Apparently, the nervi erigentes participate in the orchestration of events terminating in parturition, but their specific role remains an enigma.