Acute and chronic estrogen supplementation decreases uterine sympathetic innervation in ovariectomized adult virgin rats

Uterine innervation undergoes substantial reorganization associated with changes in reproductive status. Nerves innervating the uterus are decreased in pregnancy and puberty, and even the normal rodent estrous cycle is characterized by fluctuations in numbers of myometrial nerve fibers. During the follicular (proestrus/estrous) phase of the estrous cycle, intact nerves are rapidly depleted and then return over the next 2-3 days in the luteal (metestrus/diestrus) phase. We hypothesize that uterine nerve depletion is initiated by increased circulating estrogen in the follicular phase. However, studies have not shown whether estrogen can reduce uterine innervation and, if so, whether the time course is compatible with the rapid changes observed in the estrous cycle. These questions were addressed in the present study. Mature ovariectomized virgin rats received 17-beta-estradiol as a single injection (10 microg/kg s.c.) or chronically from timed-release pellets (0.1 microg/pellet for 3 weeks sustained release). Total (protein gene-product 9.5-immunoreactive) and sympathetic (dopamine beta-hydroxylase-immunoreactive) uterine innervation was assessed quantitatively. Both total and sympathetic innervation was abundant in uterine longitudinal smooth muscle of ovariectomized rats. However, following acute or chronic estrogen administration, total and sympathetic fiber numbers were markedly decreased. This was not due to altered uterine size, as reductions persisted after correcting for size differences. Our results indicate that sympathetic nerves are lost from uterine smooth muscle after estradiol treatment in a manner similar to that seen in the intact animal during estrus and pregnancy. This suggests that the rise in estradiol prior to estrus is sufficient to deplete uterine sympathetic innervation.     

Differential effects of oestrogen on developing and mature uterine sympathetic nerves

Oestrogen is a key factor in the remodelling of uterine sympathetic nerves during puberty and the oestrous cycle; these nerves are influenced by changes in their target uterine tissue. The magnitude of oestrogen-induced responses might however be influenced by the maturation stage of sympathetic nerve fibres, the age of the neurons and/or the developmental state of the uterus. We have therefore compared the sympathetic innervation of the uterus following chronic oestrogen treatment of infantile/prepubertal and young adult intact and ovariectomised rats. Treatment of infantile/prepubertal rats resulted in the complete loss of intrauterine noradrenaline (NA)-labelled sympathetic nerves and a marked reduction in the total NA content in the uterine horn. Chronic treatment of young adult rats had little effect. To examine whether the age of the neurons or the degree of development of the uterus determined responsiveness of nerves to oestrogen, we assessed the effects of oestrogen on the sympathetic reinnervation of intraocular transplants of young adult uterine myometrium into ovariectomised adult host rats. Early treatment (10 days post-transplantation) resulted in less sympathetic innervation than late treatment (30 days post-transplantation). Measurements of nerve growth factor (NGF) levels in the uterine horn of control rats before and after puberty and following infantile/prepubertal chronic oestrogen treatment and acute oestrogen treatment of young adult rats revealed a coordinated increase between the growth of the uterus and NGF protein levels. Thus, developing and recently regrown sympathetic nerves are more susceptible to oestrogen-induced changes in the uterus than mature nerves, differential susceptibility is not related to the age of the neurons or the developmental state of the uterus and changes in NGF protein do not account for the differential susceptibility of developing and mature uterine sympathetic nerve fibres to oestrogen. Growing sympathetic fibres are more vulnerable to oestrogen than mature fibres and nerve fibres that have been in contact for longer periods with their target become less susceptible to oestrogen.     

Sprouted innervation into uterine transplants contributes to the development of hyperalgesia in a rat model of endometriosis

Endometriosis is an enigmatic painful disorder whose pain symptoms remain difficult to alleviate in large part because the disorder is defined by extrauteral endometrial growths whose contribution to pain is poorly understood. A rat model (ENDO) involves autotransplanting on abdominal arteries uterine segments that grow into vascularized cysts that become innervated with sensory and sympathetic fibers. ENDO rats exhibit vaginal hyperalgesia. We used behavioral, physiological, and immunohistochemical methods to test the hypothesis that cyst innervation contributes to the development of this hyperalgesia after transplant. Rudimentary sensory and sympathetic innervation appeared in the cysts at two weeks, sprouted further and more densely into the cyst wall by four weeks, and matured by six weeks post-transplant. Sensory fibers became abnormally functionally active between two and three weeks post-transplant, remaining active thereafter. Vaginal hyperalgesia became significant between four and five weeks post-transplant, and stabilized after six to eight weeks. Removing cysts before they acquired functional innervation prevented vaginal hyperalgesia from developing, whereas sham cyst removal did not. Thus, abnormally-active innervation of ectopic growths occurs before hyperalgesia develops, supporting the hypothesis. These findings suggest that painful endometriosis can be classified as a mixed inflammatory/neuropathic pain condition, which opens new avenues for pain relief. The findings also have implications beyond endometriosis by suggesting that functionality of any transplanted tissue can be influenced by the innervation it acquires.     

Estrous changes in vaginal nociception in a rat model of endometriosis

A rat model of endometriosis, in which pieces of uterine horn (versus fat in controls) are autotransplanted into the abdomen where they form cysts, reduces fecundity and produces vaginal hyperalgesia. The cysts gradually enlarge over a 2-month period postsurgically and then plateau. Cysts regress with low estrogen levels and reappear when they rise. Based on the hypothesis that the vaginal hyperalgesia depends upon the cysts, this study tested two predictions: that (1) the hyperalgesia would develop postsurgically in parallel with the cysts, and (2) the hyperalgesia would vary with estrous, being greatest when estrogen levels are high (proestrus) and least when low (estrus). In rats trained to escape vaginal distention, percentage escape responses to different distention volumes were measured across the rat's 4-day estrous cycle for 2.5 months before and up to 4 months after autotransplantation of uterus (n=9) or fat (n=6) in abdominal sites. Vaginal pressures were also measured. In rats with uterine but not fat autotransplants, escape percentages increased postsurgically over a 2-month period and then plateaued. The increase was greatest in proestrus and failed to occur in estrus. Vaginal pressures were unchanged in all groups. These results strongly support the hypothesis that the vaginal hyperalgesia depends upon the cysts. Because the cysts were located in sites remote from the vagina, the hyperalgesia involves viscero-visceral interactions and is likely centrally mediated, whereas the estrous modulation could involve hormonal actions either on the cysts or, more likely, on vaginal afferent fibers, and/or on central neurons.     

Plasticity in developing rat uterine sensory nerves: the role of NGF and TrkA

In the present study we investigated the effects of infantile/prepubertal chronic oestrogen treatment, chemical sympathectomy with guanethidine and combined sympathectomy and chronic oestrogen treatment on developing sensory nerves of the rat uterus. Changes in sensory innervation were assessed quantitatively on uterine cryostat tissue sections stained for calcitonin gene-related peptide (CGRP). Uterine levels of NGF protein, using immunohistochemistry and ELISA, and mRNA, using Northern blots and in situ hybridization, were also measured. Finally, levels of TrkA NGF receptor in sensory neurons of T13 and L1 dorsal root ganglia (DRG), which supply the uterus, were assessed using densitometric immunohistochemistry. These studies showed that: (1) chronic oestrogen treatment led to an 83% reduction in the intercept density of CGRP-immunoreactive nerves; (2) sympathectomy had no effect on the density of uterine sensory nerves or on the pattern of oestrogen-induced changes; (3) NGF mRNA and protein increased following sympathectomy or chronic oestrogen treatment; and (4) oestrogen produced increased intensity of labelling (28%) for TrkA receptors in small-diameter sensory neurons, but decreased labelling (13%) in medium-sized neurons, which represent the large majority of the DRG neurons supplying the upper part of the uterine horn. Contrary to expectations, increased levels of NGF after sympathectomy and oestrogen treatment did not lead to increased sensory innervation of the uterus. The possibility that alterations in neuronal levels of TrkA contribute to the lack of response of uterine sensory nerves to the oestrogen-induced increase in NGF levels is discussed.This work was supported by The Wellcome Trust, UK (CRIG Grant 058122/Z/99/Z/JC/KO), and PEDECIBA, Universidad de la República, Montevideo, Uruguay     

Spinal effects of oxytocin on uterine motility in anesthetized rats

The rat uterus receives an innervation from the lumbosacral and thoracolumbar segments of the spinal cord. These segments receive descending oxytocinergic projections from the paraventricular nucleus of the hypothalamus. We tested the hypothesis that oxytocin regulates uterine motility through a spinal site of action. Oxytocin was administered in anesthetized female rats either intrathecally at the lumbosacral or thoracolumbar spinal cord levels or intravenously. Uterine activity was revealed by measuring changes of intrauterine pressure using an indwelling balloon placed in one caudal uterine horn. The uterus displayed a spontaneous activity characterized by intrauterine pressure rises, the frequency, amplitude, and duration of which were dependent on the stage of the estrous cycle. Oxytocin delivered at the lumbosacral level affected the frequency (during proestrus, estrus, and diestrus) and amplitude (during proestrus and estrus) of uterine activity. During estrus, oxytocin delivered at the thoracolumbar level affected the frequency, amplitude, and duration of the intrauterine pressure rises. Intravenous oxytocin not only affected intrauterine pressure rises (namely amplitude during proestrus and estrus and frequency and duration during estrus) but also increased the basal tone during estrus. The effects of lumbosacral oxytocin were partly mimicked by the oxytocin agonist [Thr(4),Gly(7)]-oxytocin blocked by the oxytocin receptor antagonist atosiban and by hexamethonium. Arginine vasopressin delivered at the lumbosacral level had no effect. These results support our hypothesis that oxytocin released by descending paraventriculo-spinal pathways and acting on spinal oxytocin receptors modulates the activity of the uterus. This regulation is cycle dependent.     

Role of the sympathetic innervation on uterine electromyographic activity in nonpregnant ovariectomized sheep under estrogen supplementation.

The aims of the present study were to characterize the sympathetic innervation of the nonpregnant sheep uterus, to determine the catecholamine content in myometrium (MYO) and endometrium, and to study the effects of chemical sympathectomy (CHSPX) on uterine catecholamine content and on uterine electromyographic (EMG) activity recorded from the MYO and mesometrium (MESO) in the nonpregnant ovariectomized sheep. After synchronization of estrus, 9 nonpregnant sheep were anesthetized with halothane, ovariectomized, and fitted with vascular catheters and EMG electrodes. Estradiol-17 beta was administered intravascularly at a rate of 50 micrograms/24 h for 10 days. CHSPX was induced with 6-hydroxy dopamine (20 mg/kg). Uterine tissues were obtained for determination of catecholamine content by HPLC and for immunocytochemical staining using an antibody against tyrosine hydroxylase (TH). In nonpregnant ovariectomized sheep, TH immunostaining was present in nerve fibers located in endometrium and MYO. In all layers of the uterus, catecholamine fibers were found in the proximity of blood vessels as well as in defined regions of the parenchyma. Throughout the uterus, norepinephrine content and TH immunostaining were dramatically decreased after CHSPX. CHSPX decreased uterine short EMG event activity in both MYO and MESO. Contracture-type activity was not affected in MYO and was increased in MESO. We conclude that sympathetic innervation modulates the MYO and MESO EMG activity in nonpregnant ovariectomized sheep under estradiol supplementation, and that the removal of the sympathetic innervation induces a decrease in the spontaneous activity.     

酪氨酸对大鼠子宫胞浆雌,孕激素受体的影响

采用放射受体分析法,测定了动情周期不同阶段及去卵巢大鼠子宫胞浆雌二醇和孕酮受体含量,并观察了子宫腔内注射酪、丝、苏三种氨基酸对子宫胞浆雌。醇、孕酮受体含量的影响。结果表明：（１）Ｌ－酪氨酸对动情前期、动情期、间情期大鼠子宫胞浆雌二醇和孕酮受体都具有明显的降低作用。（２）Ｌ－酪氨酸也降低去卵巢大鼠子宫胞浆雌二醇和孕酮含量,即这一作用不是通过影响卵巢激素分泌实现的。（３）Ｌ－苏氨酸仅可降低动情期和间情期大鼠子宫胞浆孕酮受体含量,而对相应周期雌二醇受体没有明显作用。（４）Ｌ－丝氨酸和Ｌ－苏氨酸对去卵巢大鼠子宫胞浆雌二醇和孕酮受体均无影响。     

Neuritogenic effects of T cell-derived IL-3 on mouse splenic sympathetic neurons in vivo

To determine the role played by lymphocytes and cytokines in the growth of sympathetic neurons in vivo, the innervation and cytokine levels were examined in the spleens of SCID mice that lack T and B cells. Splenic noradrenaline, nerve growth factor (NGF), and IL-1beta levels were elevated in SCID mice. Immunohistochemical examination revealed that the density of tyrosine hydroxylase-positive (TH(+)) fibers of splenic central arteries in SCID mice was increased compared with wild-type C.B-17 mice, while SCID mice had significantly fewer TH(+) fibers in their periarteriolar lymphatic sheaths (PALS). Two weeks after SCID mice were injected with C.B-17 splenic T cells, their TH(+) fiber staining increased in the PALS. IL-3 levels increased significantly in SCID mice following T cell reconstitution, and the administration of anti-IL-3 Ab blocked the above T cell-induced increase in innervation in the PALS. Anti-IL-3 treatment also inhibited the regeneration of splenic sympathetic neurons in C.B-17 mice after they were chemically sympathetomized with 6-hydroxydopamine. Depletion of NK cells by anti-asialo GM1 promoted the splenic innervation in SCID mice, while there were no significant changes in the innervation between CD8(+) T cell-deficient beta(2)-microglobulin knockout mice and their wild type. Our results suggest that T cells (probably CD4(+) Th cells but not CD8(+) CTLs) play a role in regulating the sympathetic innervation of the spleen; this effect appeared to be mediated, at least in part, by IL-3. On the contrary, NK cells may exert an inhibitory effect on the sympathetic innervation.     

Effects of infantile/prepubertal chronic estrogen treatment and chemical sympathectomy with guanethidine on developing cholinergic nerves of the rat uterus.

The innervation of the uterus is remarkable in that it exhibits physiological changes in response to altered levels in the circulating levels of sex hormones. Previous studies by our group showed that chronic administration of estrogen to rats during the infantile/prepubertal period provoked, at 28 days of age, an almost complete loss of norepinephrine-labeled sympathetic nerves, similar to that observed in late pregnancy. It is not known, however, whether early exposure to estrogen affects uterine cholinergic nerves. Similarly, it is not known to what extent development and estrogen-induced responses in the uterine cholinergic innervation are affected by the absence of sympathetic nerves. To address this question, in this study we analyzed the effects of infantile/prepubertal chronic estrogen treatment, chronic chemical sympathectomy with guanethidine, and combined sympathectomy and chronic estrogen treatment on developing cholinergic nerves of the rat uterus. Cholinergic nerves were visualized using a combination of acetylcholinesterase histochemistry and the immunohistochemical demonstration of the vesicular acetylcholine transporter (VAChT). After chronic estrogen treatment, a well-developed plexus of cholinergic nerves was observed in the uterus. Quantitative studies showed that chronic exposure to estrogen induced contrasting responses in uterine cholinergic nerves, increasing the density of large and medium-sized nerve bundles and reducing the intercept density of fine fibers providing myometrial and perivascular innervation. Estrogen-induced changes in the uterine cholinergic innervation did not appear to result from the absence/impairment of sympathetic nerves, because sympathectomy did not mimic the effects produced by estrogen. Estrogen-induced responses in parasympathetic nerves are discussed, considering the direct effects of estrogen on neurons and on changes in neuron-target interactions.     

The influence of ovarian hormones on the rat oviductal and uterine concentration of noradrenaline and 5-hydroxytryptamine

This paper describes the effects of estradiol and progesterone on the concenirations of noradrenaline and 5-hydroxytryptamine in the Wistar rat oviduct and uterus. The levels of noradrenaline and 5-hydroxytryptamine are higher in the oviduct than in the uterus whereas p-tyrosine and tryptophan are similar in both tissues. Estradiol treatment reduced the oviductal concentration of noradrenaline but not 5-hydroxytryptamine in oviduct, while the concentrations of both noradrenaline and 5-hydroxytryptamine were reduced in uterine horn. The levels of noradrenaline in the oviduct and uterus in rats in estrus were lower than those of diestrous rats. Bilateral ovariectomy produced an increase in uterine noradrenaline and 5-hydroxytryptamine levels. These changes were reversed in the presence of ovarian hormones as indicated by experiments where unilateral ovariectomy was performed. Reserpine administration reduced noradrenaline concentration in both the oviduct and the uterus but did not change oviductal or uterine 5-hydroxytryptamine.These results indicate the existence of noradrenaline within postganglionic sympathetic nerve terminals and suggest that estrogens increase the utilization and the synthesis of noradrenaline in both the oviducts and the uterine horns. With respect to 5-hydroxytryptamine the data support the concept that it is mainly associated with mast cells.     

Interleukin-1, interleukin-6, and tumor necrosis factor alpha are produced in the mouse uterus during the estrous cycle and are induced by estrogen and progesterone.

The ovarian steroids, estrogen and progesterone, regulate cellular and molecular changes which occur in the uterus during the estrous cycle. Cycles of protein synthesis, cell proliferation and differentiation, and cell death are the direct results of changes in hormone concentration. To explore the possibility that cytokines, which stimulate proliferation and differentiation of numerous types of cells, might be associated with those cyclic changes, the production of IL-1, IL-6, and TNF alpha was examined in the mouse uterus. Cytokine mRNA expression, bioactivity, and immunoreactivity were quantitated during the estrous cycle, following ovariectomy and exposure of ovariectomized mice to estrogen and progesterone. IL-1, IL-6, and TNF alpha mRNA was detected, and mRNA levels for each of the cytokines varied with the stage of the cycle. Cytokine bioactivity was expressed throughout the cycle, but levels of each cytokine were highest during proestrus and/or estrus. Immunoreactivity paralleled bioactivity. Uterus from ovariectomized mice contained little or no cytokine activity, and systemic administration of estrogen or progesterone resulted in the induction of IL-1 alpha and IL-1 beta mRNA expression. Significant amounts of IL-6 and TNF alpha mRNA appeared only following the exposure of ovariectomized mice to estrogen plus progesterone. Cytokine bioactivity and immunoreactivity also appeared following the administration of estrogen and/or progesterone. The highest activity levels for each cytokine were observed following the injection of estrogen plus progesterone. Cyclic expression of IL-1, IL-6, and TNF alpha in the uterus and their apparent regulation by estrogen and progesterone raise the possibility that cytokines and factors which are induced by cytokines are part of the regulatory process which is induced by ovarian hormones in the uterus of reproductive age females.     

Vagal afferents from the uterus and cervix provide direct connections to the brainstem

Previous anatomical studies demonstrated vagal innervation to the ovary and distal colon and suggested the vagus nerve has uterine inputs. Recent behavioral and physiological evidence indicated that the vagus nerves conduct sensory information from the uterus to the brainstem. The present study was undertaken to identify vagal sensory connections to the uterus. Retrograde tracers, Fluorogold and pseudorabies virus were injected into the uterus and cervix. DiI, an anterograde tracer, was injected into the nodose ganglia. Neurectomies involving the pelvic, hypogastric, ovarian and abdominal vagus nerves were performed, and then uterine whole-mounts examined for sensory nerves containing calcitonin gene-related peptide. Nodose ganglia and caudal brainstem sections were examined for the presence of estrogen receptor-containing neurons in ”vagal locales." Labeling of uterine-related neurons in the nodose ganglia (Fluorogold and pseudorabies virus) and in the brainstem nuclei (pseudorabies virus) was obtained. DiI-labeled nerve fibers occurred near uterine horn and uterine cervical blood vessels, in the myometrium, and in paracervical ganglia. Rats with vagal, pelvic, hypogastric and ovarian neurectomies exhibited a marked decrease in calcitonin gene-related peptide-immunoreactive nerves in the uterus relative to rats with pelvic, hypogastric, and ovarian neurectomies with intact vagus nerves. Neurons in the nodose ganglia and nucleus tractus solitarius were immunoreactive for estrogen receptors. These results demonstrated: (1) the vagus nerves serve as connections between the uterus and CNS, (2) the nodose ganglia contain uterine-related vagal afferent neuron cell bodies, and (3) neurons in vagal locales contain estrogen receptors.     

基质金属蛋白酶-2、-9及其组织抑制因子(TIMPs)在动情周期大鼠子宫中的表达(英文)

基质金属蛋白酶（ＭＭＰｓ）家族的作用是降解所有细胞外基质,其活性受其特异性组织抑制因子（ＴＩＭＰｓ）的抑制。细胞外基质成分的降解与重组在动物生殖生长过程中起重要作用,其变化可以通过ＭＭＰｓ和ＴＩＭＰｓ两者表达水平的变化进行监测。大鼠虽然没有月经形成,但是在其子宫内膜也出现类似灵长类的生殖生物学变化。本文从ＭＭＰｓ和ＴＩＭＰｓ两者的表达水平,对大鼠子宫内膜的这些变化进行了研究。于大鼠动情周期的不同时期,将其处死、取子宫制备酶粗提液和组织切片,采用酶谱法（ｚｙｍｏｙｒａｎｈｎ）和原位杂交方法研究动情周期大鼠子宫中ＭＭＰ－２和－９的活性变化以及ＭＭＰ－２、－９和ＴＩＭＰ－１、－２、－３ｍＲＮＡ的表达。并通过光密度扫描方法对酶谱结果进行半定量分析。所用杂交探针见Ｔａｂｌｅ１。酶谱结果显示：在动情周期大鼠子宫中只检测到６７ｋＤａ的ＭＭＰ－２活性,而没有检测到ＭＭＰ－９的活性（Ｆｉｇ．１）。ＭＭＰ－２的活性在动情前期最高,动情期和动情后期次之,间情期最低（Ｆｉｇ．２）。原位杂交结果显示：ＭＭＰ－２、－９、ＴＩＭＰ－１、－２、－３ｍＲＮＡ主要在子宫内膜基底部的基质细胞中表达。ＭＭＰ－２和－９ｍＲＮＡ在动情前期、动情期和动     

Uterus sympathetic nervous apparatus in sexual cycle dynamics in rats

Uterus sympathetic nervous apparatus in various phases of sexual cycle in rats was studied with the microspectral fluorescent method. The main part of nervous fibers in the form of perivascular plexus and terminals deviating from them are localized in myometrium. We suppose presence of reserve ("silent") nervous fibers in uterus which explains the inconstancy of their revealing in the organ. Catecholamines and serotonin are identified in varicose enlargements and intervaricose parts of nervous fibers by the way of microspectrofluorometry. Their concentration in probing places is characterized by high degree of linear correlation at all stages of sexual cycle. Maximal concentration of bioamines in most structural elements of uterus sympathetic nervous apparatus in detected in late diestrus. Stages of early and late estrus and proestrus are characterized by low levels of monoamines in adrenergic fibers. A number of reliable differences between bioamines saturation and spatial distribution density of nervous fibers in the neck and body of the womb are revealed.     

Relationship of length of uterus in prepubertal pigs and number of corpora lutea and fetuses at 30 days of gestation

Relationships of the length of the uterus at one reproductive stage to the length at other stages and the effect on potential litter size were determined. In Experiment 1, the length of the uterus was measured in situ at 20, 60, or 100 days of age at laparotomy with 20 gilts in each of the three age groups. Forty days after the initial measurement, the uterus was again measured in situ, gilts were ovariectomized and hysterectomized, and associations among uterine measurements at the two different stages were determined. Correlations between uterine length in situ and between uterine length and weight 40 days later were all greater than 0.75 (P < 0.001). The length of one uterine horn increased from 13.9 cm at 20 days of age to 36.7 cm at 140 days of age (P < 0.01). In Experiment 2, 66 gilts were unilaterally hysterectomized and ovariectomized (UHOX) at 150 days of age and the ovary was weighed. Length of the one horn was measured in 36 gilts. At 10 days after first estrus, the length of the remaining uterine horn was measured at laparotomy and corpora lutea were counted in 53 gilts. In 15 of the 53 gilts the remaining uterine horn was removed to obtain uterine weights. At the second or third estrus, 38 gilts were mated and at Day 30 of gestation, 31 gilts were pregnant. The gilts were killed, and the length of the uterus measured and corpora lutea (CL) and fetuses were counted. The length of one uterine horn at 150 days of age was 70 cm with a range of 47–110 cm. At 10 days after first estrus, length had increased to a mean of 141 cm with a range of 86–194 cm and at 30 days of gestation the mean was 244 cm with a range of 186–311 cm. There were 12.2 CL at first estrus, which was not different from 12.4 CL at the second or third estrus. The mean number of fetuses in one horn at 30 days of gestation was 9.5 with 77% prenatal survival. Length of uterine horn at 150 days of age was correlated with uterine horn length (r = 0.56, P < 0.001) at 10 days after first estrus and number of live fetuses (r=0.39, P<0.05) at 30 days of gestation. At Day 10 after first estrus, uterine length was not correlated with the number of CL, whereas at Day 30 of gestation, the number of CL and uterine length were correlated with the number of live fetuses in those gilts with below the mean number of live fetuses, but not in those gilts with above the mean of live fetuses. The number of live fetuses (r=0.66, P < 0.001) and fetal survival (r=0.63; P < 0.001) were correlated with uterine horn length in pregnant UHOX gilts. Length of the prepubertal uterus gives an indication of postpubertal length and the potential litter size in pigs.     

Principal features of the nerve supply to the ovary, oviduct and tubal third of the uterus in the golden hamster

The autonomic outflow and sensory structures in the ovary and accessory reproductive organs of the hamster are described by means of specific fluorescence and enzyme histochemical techniques for the demonstration of catecholamine and acetylcholinesterase (AChE), respectively. Sympathetic nerves accompany branches of the major blood vessels in the mesentery of the ovary, oviduct and tubal uterine horn and invest the vascular bed in each of these organs. Vasomotor fibers predominate in the ovary and oviduct, though occasional adrenergic axons supply thecal and interstitial tissues in the ovary and the longitudinal smooth muscle of the oviduct. Fluorescent myomotor axons run in the suspensory ligament and outer myometrial layer of the uterus, but most of the numerous sympathetic and AChE-fibers in the tubal third of the horn supply the intramural and submucosal vascular plexuses. A limited electron microscopic study of the central spiral (preplacental) arteries of the endometrium indicates that the surrounding terminal AChE-fibers are identical to the fluorescent and granular vesicle-bearing adrenergic axons which form neuromuscular junctions with these vessels. Based on the discovery of specialized sensory endings in the walls of the large collecting veins which drain the hamster uterus, a mechanism is proposed to account for the regulation of blood flow through maternal placental vessels which are devoid of an arteriolar neuromuscular apparatus.     

Immunohistochemical detection of estrogen receptors in the canine uterus and their relation to sex steroid hormone levels

Cyclic changes in estrogen receptor expression in the uterine tissue of 60 female dogs were evaluated, using an immunohistochemical technique on formalin-fixed paraffin-embedded sections. The expression of estrogen receptors in the uterine horns, body and cervix was quantified by means of an immunohistochemical score. A negative correlation was found between staining scores in the uterine horns and serum progesterone levels. Generally, staining scores in the uterine horns were highest during proestrus, declined during estrus and were lowest during early metestrus. During anestrus high staining scores for estrogen receptors were observed, indicating sensitivity for estrogens in a sexual quiescence stage. Compared with the uterine horns, high staining scores were found in the uterine body and cervix during estrus and metestrus. No positive staining for estrogen receptors was detected in 1 pregnant uterus. Fluctuations in estrogen receptors were more pronounced in endometrial stroma cells than in epithelial cells of the uterine horns. The importance of stromal cells in the sexual cyclicity of the canine uterus should not be underestimated when studying uterine endocrinology and pathology.     

Early postnatal exposure of mice to side-steam tobacco smoke increases neuropeptide Y in lung

Our recent study showed that prenatal and early postnatal exposure of mice to side-steam tobacco smoke (SS), a surrogate to environmental tobacco smoke (ETS), leads to increased airway responsiveness and sensory innervation later in life. However, the underlying mechanism initiated in early life that affects airway responses later in life remains undefined. The concomitant increase in nerve growth factor (NGF) after exposures suggests that NGF may be involved the regulation of airway innervation. Since NGF regulates sympathetic nerve responses, as well as sensory nerves, we extended previous studies by examining neuropeptide Y (NPY), a neuropeptide associated with sympathetic nerves. Different age groups of mice, postnatal day (PD) 2 and PD21, were exposed to either SS or filtered air (FA) for 10 consecutive days. The level of NPY protein in lung and the density of NPY nerve fibers in tracheal smooth muscle were significantly increased in the PD2-11SS exposure group compared with PD2-11FA exposure. At the same time, the level of NGF in lung tissue was significantly elevated in the PD2-11SS exposure groups. However, neither NPY (protein or nerves) nor NGF levels were significantly altered in PD21-30SS exposure group compared with the PD21-30FA exposure group. Furthermore, pretreatment with NGF antibody or K252a, which inhibits a key enzyme (tyrosine kinase) in the transduction pathway for NGF receptor binding, significantly diminished SS-enhanced NPY tracheal smooth muscle innervation and the increase in methacholine-induced airway resistance. These findings show that SS exposure in early life increases NPY tracheal innervation and alters pulmonary function and that these changes are mediated through the NGF.     

Targeted mutation of the gene encoding the low affinity NGF receptor p75 leads to deficits in the peripheral sensory nervous system.

We have generated mice carrying a mutation of the gene encoding the low affinity NGF receptor p75NGFR by targeted mutation in embryonic stem cells. Mice homozygous for the mutation were viable and fertile. Immunohistochemical analyses of the footpad skin of mutant mice revealed markedly decreased sensory innervation by calcitonin gene-related peptide- and substance P-immunoreactive fibers. The defective innervation was correlated with loss of heat sensitivity and associated with the development of ulcers in the distal extremities. Complicated by secondary bacterial infection, the ulcers progressed to toenail and hair loss. Crossing a human transgene encoding p75NGFR into the mutant animals rescued the absent heat sensitivity and the occurrence of skin ulcers and increased the density of neuropeptide-immunoreactive sensory innervation of footpad skin. The mutation in the gene encoding p75NGFR did not decrease the size of sympathetic ganglia or the density of sympathetic innervation of the iris or salivary gland. Our results suggest that p75NGFR has an important role in the development and function of sensory neurons.