Virgin Rabbits Research Articles

Effects of Punicalagin and Its Combination with Hcg on Some Productive And Reproductive Traits In Virgin Rabbit Does

Effects of Punicalagin and Its Combination with Hcg on Some Productive And Reproductive Traits In Virgin Rabbit Does

Effect of Punicalagin on maternal live body weight during pregnancy in virgin rabbit does

Effect of Punicalagin on maternal live body weight during pregnancy in virgin rabbit does

Hypothyroidism induces uterine hyperplasia and inflammation related to sex hormone receptors expression in virgin rabbits

AimsIn women, uterine alterations have been associated with sex steroid hormones. Sex hormones regulate the expression of thyroid hormone receptors (TRs) in the uterus, but an inverse link is unknown. We analyzed the impact of hypothyroidism on histological characteristics, vascular endothelial growth factor (VEGF-A), progesterone receptors (PR), estrogen receptors (ER), thyroid hormone receptors (TRs), perilipin (PLIN-A), and lipid content in the uterus of virgin rabbits. Main methodsTwelve Chinchilla-breed adult female rabbits were grouped into control (n = 6) and hypothyroid (n = 6; 0.02% of methimazole for 30 days). The thickness of endometrium and myometrium, number of uterine glands, and infiltration of immune cells were analyzed. The expression of VEGF-A, PR, ERα, and PLIN-A was determined by RT-PCR and western blot. The uterine content of triglycerides (TAG), total cholesterol (TC), and malondialdehyde (MDA) was quantified. Key findingsHypothyroidism promoted uterine hyperplasia and a high infiltration of immune cells into the endometrium, including macrophages CD163+. It also increased the expression of VEGF-A, TRA, and ERα-66 but reduced that of PR and ERα-46. The uterine content of PLIN-A, TAG, and TC was reduced, but that of MDA was augmented in hypothyroid rabbits. SignificanceOur results suggest that uterine hyperplasia and inflammation promoted by hypothyroidism should be related to changes in the VEGF-A, PR, ER, and TRs expression, as well as to modifications in the PLIN-A expression, lipid content, and oxidative status. These results suggest that hypothyroidism should affect the fertility of females.

SAT-561 Protective Effect of Moderated Dose of Iodine in Pancreatic Alterations during Hypothyroidism

Pancreatitis and insulitis are known causes of type 2 diabetes mellitus, and recently it has been shown that hypothyroidism can exacerbate these alterations. Molecular iodine (I2) exerts antioxidant, anti-inflammatory, and anti-dyslipidemia effects in diverse tissues. The objective of this study was to evaluate the effect of the oral supplement of this halogen in the induction of prediabetic status in a model of pharmacological hypothyroidism. Adult virgin rabbits of the Chinchilla breed were divided into control (n = 6) and hypothyroid (methimazole, MMI n = 6, 10 mg/kg in drinking water) groups, supplemented with moderate (MMI + I2 0.2 mg/kg; n= 6) and high dose of I2 (MMI + I2 2 mg/kg, n= 6). The results showed that hypothyroidism (1 month) was accompanied by circulating elevations of total cholesterol, HDL, LDL (enzymatic methods) and sCD163 (Western blot). It also promoted pancreatitis (H & E, Masson's trichrome, and PAS stains, as well as western blot for CD163) and insulitis (PAS and Masson's trichrome stains). In the pancreas, hypothyroidism increased the beta-amyloid around vessels (Congo red stain); triglycerides (Folch method), lipoperoxidation (levels of malondialdehyde MDA, enzymatic method) and expression of insulin and GLUT4. A low cholesterol synthesis (Folch method and western blot for CYP51A1) and a decrease in the expression of PPARγ (immunohistochemistry and western blot) were also observed. High doses of I2 supplement (2 mg/kg) aggravated pancreatic damage, promoting even islet amyloidosis and fibrosis. In contrast, the moderate dose of I2 (0.2 mg / kg) was able to prevent alterations in circulating lipids and in the pancreatic tissue. This prevention was accompanied by a significant decrease in the lipoperoxidation and a great expression of PPARγ. These results describe for first time the anti-inflammatory and anti-dyslipidemia effect of the moderate dose of I2 in the pancreas and suggest the possible participation of PPARγ receptors. More studies are needed to analyze the therapeutic effect of iodine in chronic pancreatic diseases associated with inflammation. This work was partially supported by grants CONACyT 257549 and PAPIIT-UNAM 201516.

Morphological, Histological and Immunohistochemical Study of the Rabbit Uterus during Pseudopregnancy

Ten mature virgin rabbit does (4-5 months old) with mean weight of 2.4 kg were induced to ovulate; by intramuscular injection of HCG (50-70 IU). The day of induction was considered 0 days. Uteri were obtained from 14 h, 3, 7, 18 days post induction. At first stage of pseudopregnancy; the two uteri became hyperemic and slightly swollen. The uterine epithelium and endometrial glands epithelium were of columnar type with oval basal nuclei. The endometrial glands were few in number and small in size. The endometrial glands showed apocrine activity. The uterus had six longitudinal folds and the uterine epithelium form crypts. The endometrium had slight vascularization. At middle stage of pseudopregnancy, the two uteri became hyperemic and more swollen. This stage characterized by; mucosal folding, glandular formation, epithelial proliferation and thickening of the uterine wall. At last stage of pseudopregnancy; the two uteri became flaccid and more swollen. This stage characterized by dramatic changes in the uterine architecture in the form of: increased epithelial proliferation and crypt formation increase the complexity of luminal folding, increase in length, size and abundance of the uterine endometrial glands, increase in the uterine micro vascular development (increased abundance of the large microvessels and development of subepithelial capillary plexuses). Tunica vascularis could be demonstrated between the inner circular and outer longitudinal smooth muscle fibers of the myometrium at the all stages of psedopregnancy. Telocytes with its characteristic morphology could be demonstrated in the myometrium of the rabbit uterus during pseudopregnancy. Cell-specific immuno-localization of progesterone receptors alpha (PRA) in the rabbit uterus during pseudopregnancy revealed that, there were mild, moderate and strong nuclear PRA immunostaining in the endometrial epithelial cells, endometrial glands and in the smooth muscles fibers of the myometrium of the first, middle and last stages of pseudopregnancy respectively. The present study revealed that the morphological, histological and immunohistochemical changes in the rabbit uterus during pseudopregnancy resembled that occurred during early stage of pregnancy. These changes were characterized by dramatic changes in the uterine architecture in the form of: increased epithelial proliferation and crypt formation increase the complexity of luminal folding, increase in length, size and abundance of the uterine endometrial glands, increase in the uterine microvascular development. These uterine changes were accompanied with PRA immunolocalization in the uterine tissues.

Distribution of thyroid hormone and thyrotropin receptors in reproductive tissues of adult female rabbits

ABSTRACTPurpose: Thyroid dysfunctions are related to anovulation, miscarriages, and infertility in women and laboratory animals. Mechanisms associated with these effects are unknown, although indirect or direct actions of thyroid hormones and thyrotropin could be assumed. The present study aimed to identify the distribution of thyroid hormones (TRs) and thyrotropin (TSHR) receptors in reproductive organs of female rabbits. Material and Methods: Ovary of virgin and pregnant rabbits, as well as the oviduct, uterus, and vagina of virgin rabbits were excised, histologically processed, and cut. Slices from these organs were used for immunohistochemical studies for TRα1-2, TRß1, and TSHR. Results: The presence of TRs and TSHR was found in the primordial, primary, secondary, tertiary, and Graafian follicles of virgin rabbits, as well as in the corpora lutea, corpora albicans, and wall of hemorrhagic cysts of pregnant rabbits. Oviductal regions (fimbria-infundibulum, ampulla, isthmus, and utero-tubal junction), uterus (endometrium and myometrium), and vagina (abdominal, pelvic, and perineal portions) of virgin rabbits showed anti-TRs and anti-TSHR immunoreactivity. Additionally, the distal urethra, paravaginal ganglia, levator ani and iliococcygeus muscles, dorsal nerve and body of the clitoris, perigenital skin, and prostate had TRs and TSHR. Conclusions: The wide presence of TRs and TSHR in female reproductive organs suggests varied effects of thyroid hormones and thyrotropin in reproduction.

MP28-09 A NOVEL MODEL OF PELVIC ORGAN ISCHEMIA: PELVIC FLOOR CONTRACTILE FUNCTION IS MORE RESISTANT TO ISCHEMIA AND POST-ISCHEMIA REPERFUSION THAN BLADDER DETRUSOR MUSCLE

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology I1 Apr 2016MP28-09 A NOVEL MODEL OF PELVIC ORGAN ISCHEMIA: PELVIC FLOOR CONTRACTILE FUNCTION IS MORE RESISTANT TO ISCHEMIA AND POST-ISCHEMIA REPERFUSION THAN BLADDER DETRUSOR MUSCLE Amy D. Dobberfuhl, Catherine Schuler, Robert E. Leggett, Elise J.B. De, and Robert M. Levin Amy D. DobberfuhlAmy D. Dobberfuhl More articles by this author , Catherine SchulerCatherine Schuler More articles by this author , Robert E. LeggettRobert E. Leggett More articles by this author , Elise J.B. DeElise J.B. De More articles by this author , and Robert M. LevinRobert M. Levin More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.1059AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Weakness of the pelvic floor musculature (PFM) is well described in stress urinary incontinence and pelvic organ prolapse. Periods of low blood flow, hypoxia and ischemia have been implicated as causes of pelvic floor and bladder dysfunction. We explored the contractile characteristics of PFM and bladder detrusor muscle (BDM) in a novel model of in-vitro ischemia-reperfusion. METHODS Female adult virgin rabbits were selected for their well developed pelvic floor. Five animals were euthanized. BDM, pubococcygeus (PC) and coccygeous (CC) were isolated into 150 mg strips. Tissues were equilibrated with oxygenated Tyrodes containing glucose, stimulated with field stimulation, and then stimulated under ischemic conditions for 1 hour in nitrogenated Tyrodes without glucose. Tissues were then incubated in oxygenated Tyrodes for 2 hours and stimulated. RESULTS PFM required 10 times the stimulus duration to generate contractions under baseline conditions. Both maximal contractile response and rate of tension generation were significantly greater for BDM than either PC or CC. However, PC and CC were both significantly less sensitive to the effects of ischemia than BDM and continued to have stable contractile responses to field stimulation during the entire hour of ischemia (Figure 1). There was progressive decline in BDM contractile strength after 1 hour of ischemia. Following the ischemic period, PFM contractile recovery was significantly superior to BDM (Figure 2) and consistent with markers of oxidative stress. CONCLUSIONS PFM contractions and recovery were significantly slower than BDM, yet not as sensitive to either in-vitro ischemia or the effects of post-ischemia reperfusion. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e374 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Amy D. Dobberfuhl More articles by this author Catherine Schuler More articles by this author Robert E. Leggett More articles by this author Elise J.B. De More articles by this author Robert M. Levin More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Contribution of Suckling Stimulation to the Daily Periodic Display of Nursing Behavior in Non-Lactating Virgin Rabbits

A female rabbit (does) nurse once a day for three min with circadian periodicity. This timing is controlled by the amount of suckling stimulation received as small litters (2-4 kits) disrupt nursing periodicity and increase the duration of nursing bouts. Yet, as suckling induces: a) the secretion of oxytocin and prolactin and b) milk ejection, the relative contribution of those two types of factors to the daily timing of nursing needs to be independently explored. Therefore, the objective of the present work was to determine the relevance of milk output for the circadian display of rabbit nursing behavior. Methods: We used the model of anosmic virgins, as they can be induced to behave maternally (by lesioning the olfactory epithelium), they allow suckling from (foster) kits, but they are unable to produce milk. Does were given five foster kits, aged 1-5 days, placed inside a transparent nest box within the maternal cage, and replaced daily. The does' behavior was recorded continuously for 15 days through a video system allowing us full view of the animals. Results: By day 6 post-lesion 70% of virgins (i.e., 14/20) were entering the nest box, adopting a crouching posture over the litter, allowing suckling, and leaving ca. 3 min. later. 55% (i.e., 11/20) of lesioned virgins displayed nursing behavior with a ca. 24 hr periodicity, as determined by a Rayleigh analysis (3 does) or a linear regression (8 does). Conclusions: a) daily periodicity of nursing behavior can occur regardless of milk output or a preceding pregnancy; b) such factors, however, contribute to the display of a single daily episode of circadian nursing behavior in most does.

Noxious electrical stimulation of the pelvic floor and vagina induces transient voiding dysfunction in a rabbit survival model of pelvic floor dystonia.

PurposeExisting data supports a relationship between pelvic floor dysfunction and lower urinary tract symptoms. We developed a survival model of pelvic floor dysfunction in the rabbit and evaluated cystometric (CMG), electromyographic (EMG) and ambulatory voiding behavior.Materials and MethodsTwelve female adult virgin rabbits were housed in metabolic cages to record voiding and defecation. Anesthetized CMG/EMG was performed before and after treatment animals (n=9) received bilateral tetanizing needle stimulation to the pubococcygeous (PC) muscle and controls (n=3) sham needle placement. After 7 days all animals were subjected to tetanizing transvaginal stimulation and CMG/EMG. After 5 days a final CMG/EMG was performed.ResultsOf rabbits that underwent needle stimulation 7 of 9 (78%) demonstrated dysfunctional CMG micturition contractions versus 6 of 12 (50%) after transvaginal stimulation. Needle stimulation of the PC musculature resulted in significant changes in: basal CMG pressure, precontraction pressure change, contraction pressure, interval between contractions and postvoid residual; with time to 3rd contraction increased from 38 to 53 minutes (p=0.008 vs. prestimulation). Vaginal noxious stimulation resulted in significant changes in: basal CMG pressure and interval between contractions; with time to 3rd contraction increased from 37 to 46 minutes (p=0.008 vs. prestimulation). Changes in cage parameters were primarily seen after direct needle stimulation.ConclusionsIn a majority of animals, tetanizing electrical stimulation of the rabbit pelvic floor resulted in voiding changes suggestive of pelvic floor dysfunction as characterized by a larger bladder capacity, longer interval between contractions and prolonged contraction duration.

Morphometry of paravaginal ganglia from the pelvic plexus: impact of multiparity, primiparity, and pregnancy

Objectives(1) To describe the morphology of paravaginal ganglia and the neurochemical pattern of their neurons in virgin rabbits. (2) To analyze the effects of multiparity, primiparity and late pregnancy on morphometry of ganglia and their neurons. Study designThe morphology and neurochemical pattern of paravaginal ganglia were described in virgin nulliparous Chinchilla breed rabbits. Acetylcholinesterase histochemistry, Masson's trichrome, and immunohistochemistry for cholinergic and adrenergic neurons, and estrogen receptors (ERs) were undertaken. The area covered by ganglia (ganglionic area), the number of neurons, and the neuron soma area were measured in multiparas (4 consecutive and successive deliveries) and age-matched nulliparas. The same variables were measured in primiparous, late-pregnant, and age-matched nulliparous rabbits. ResultsParavaginal ganglia were adjoined to the dorsolateral walls of the pelvic vagina. Their neurons were mostly cholinergic and expressed ERα and ERβ. Multiparity increased the ganglionic area and reduced the number of ganglionic neurons. Late pregnancy transiently reduced the neuron soma area, which was coincident with a low expression of ERs. ConclusionMultiparity but not primiparity affected the morphometry of ganglia. The hormonal state present in late pregnancy alters the neuron soma area and ER expression. Our findings support the notion that reproduction influences the morphometry of the pelvic plexus.

Multiparity Causes Uncoordinated Activity of Pelvic- and Perineal-Striated Muscles and Urodynamic Changes in Rabbits

Temporal and coordinated activation of pelvic- (pubococcygeous) and perineal- (bulbospongiosus and ischiocavernosus) striated muscles occurs during micturition in female rabbits. We have hypothesized that the coordinated activation of pelvic and perineal muscles is modified during the micturition of young multiparous rabbits. Young virgin and multiparous female chinchilla rabbits were used to simultaneously record cystometrograms and electromyograms of the pubococcygeous, ischocavernosus, and bulbospongiosus muscles. Bladder function was assessed using standard urodynamic variables. The temporal coordination of pelvic- and perineal-striated muscle activity was changed in multiparous rabbits. The cystometrogram recordings were different than those obtained from virgin rabbits, as seen in alterations of the threshold volume, the residual volume, the voiding duration, and the maximum pressure. In rabbits, we find that multiparity causes uncoordinated activity of pubococcygeous, ischiocavernosus, and bulbospongiosus muscles and modifies the urodynamics.

Lesion of the main olfactory epithelium facilitates maternal behavior in virgin rabbits

Maternal behavior is induced in virgin female rabbits (normally unresponsive to foster pups) by removing the accessory olfactory bulbs. To determine if the main olfactory system (MOS) plays a similar inhibitory role in the present work we investigated the effect of lesioning the olfactory epithelium with a ZnSO 4 spray on the facilitation of maternal behavior in New Zealand white virgin rabbits. Four days after the chemical lesion 40% of females showed behaviors indistinguishable from those of normal mothers, i.e.: rapid entrance into the nest box containing the pups, adoption of a crouching posture over them, acceptance of suckling, and exit from the nest box after ca. 3 min. The proportion of females showing these behaviors rose to 70% by day 14 post-lesion. Ovariectomized rabbits sprayed with ZnSO 4 or animals sprayed with NaCl did not behave maternally. ZnSO 4 also provoked a transient reduction in olfactory perception: before the lesion animals from all groups directed significantly more sniffs to a flask containing male urine than to one containing water. This difference was abolished in ZnSO 4-sprayed females (intact and ovariectomized) for 3–6 days post-lesion and was re-established by 7–9 days. NaCl did not provoke such transitory hyposmia. ZnSO 4 lesions did not provoke malaise in the animals, as determined by food intake and the frequency of scent-marking and ambulation. Results suggest that olfactory cues from the pups are aversive to virgin rabbits and that a transitory reduction in their perception (accompanied by the action of ovarian secretions) is enough to facilitate maternal responsiveness.

Removal of the accessory olfactory bulbs promotes maternal behavior in virgin rabbits

Virgin rabbits exposed to foster pups for 14 days did not show maternal responsiveness. However, surgical removal of the accessory olfactory bulbs (AOB) activated maternal responsiveness (crouching over the litter inside the nest box for about 3 min, which is the normal duration of a nursing bout) in 37% of virgin rabbits ( P<0.007). This behavior appeared abruptly and was first observed between days 3 and 13 of pup exposure. This variation in the latency to respond maternally was not related with the number of sniffings or entrances into the nest box displayed by a female on the days that preceded crouching over the litter. Maternal responsiveness was not observed in any AOB-lesioned animals that were also ovariectomized ( P<0.02 versus AOB-lesioned with ovaries). These results indicate a tonic inhibitory action of the AOB over the expression of maternal behavior in virgin rabbits and a stimulation of maternal responsiveness by ovarian hormones following AOB lesions.

Histological and ultrastructural regulation in rabbit endometrial explants by estrogen in serum-free culture.

A repertoire of hormonal signals including estrogen regulate the growth, differentiation, and functioning of diverse target tissues, including the ovary, the mammary gland, and skeletal tissue. A serum-free culture system derived from rabbit endometrium explants has been devised and is reported here to explore estrogen action in vitro. The system involves aseptically harvesting the uterus from a virgin rabbit, dissecting the endometrium, explanting it into 1- to 2-mm(3) pieces weighing approximately 1-2 mg each, and incubating these pieces in serum-free Medium-199. The culture is carried out for a period of 4 d in a humidified CO(2) incubator at 37 degrees C with 5% CO(2). The effect of extraneously added estrogen (1 microg/ml) was investigated by histological and ultrastructural procedures. It was observed that estrogen could induce specific changes, such as abundant mitochondria, rough endoplasmic reticulum, golgi complex, and intracellular collagen deposition, in both the epithelial and the fibroblast cell components of the explanted tissue. The study, therefore, indicates that the proposed system is an ideal tool for exploring and demonstrating estrogen responsiveness under in vitro conditions.

Prostanoid-Induced Contraction of the Rabbit Isolated Uterus Is Mediated by FP Receptors

Natural and synthetic prostanoid agonists were used to study the prostanoid receptors involved in contraction of the mature, isolated uterus of virgin rabbits. The prostanoids elicited contractile responses with a rank order of potency of PGF 2α, fluprostenol > PGD 2 > U-46619 > PGE 2 > carbaprostacyclin with mean EC 50 (nM) values of 4, 6, 34, 550, 1318 and >10,000, respectively. Carbachol, a muscarinic agonist given after the prostanoids to elicit a reference contraction, had a mean EC 50 value of 1.1 μM. The results show that the mature rabbit uterus is most sensitive to prostaglandin FP agonists and, thus, can be defined pharmacologically as an FP receptor preparation. These findings may facilitative investigations into the possibility of different prostanoid receptor populations. In the absence of useful competitive FP receptor antagonists, agonist potency data is particularly useful in systems where cross-species comparisons and tissue-related factors are not involved. The potent activities of the FP agonists, PGF 2α and fluprostenol, in the isolated jugular vein and uterus of the rabbit suggest that these tissues may be useful for intra-species comparisons.

Think globally, act locally: the making of a mouse mammary gland.

On a phylogenetic scale of organ development the mammary gland is a recent acquisition. It was introduced 200 million years ago with the appearance of mammals to provide nourishment to the newborn in the form of milk. The mammary gland is characterized by a unique dependence on hormonal signals for terminal differentiation, which is attained only after pregnancy. At the time of birth, the anlage consists of a few rudimentary ducts in the vicinity of the nipple. Pronounced ductal outgrowth and branching commences at puberty, and in pregnancy an expanded lobulo-alveolar compartment develops. Functional differentiation of the secretory epithelium coincides with parturition and large amounts of milk are produced and secreted during lactation. After weaning of the young, the entire alveolar epithelial compartment is remodeled to resemble a virgin-like state. With each pregnancy, a new round of lobulo-alveolar development occurs. During the past 100 years, intensive efforts have been made to understand the endocrine control of mammopoiesis and lactogenesis. Classical research on endocrine ablated animals firmly established that ovarian steroids and pituitary peptide hormones are mandatory and sufficient for breast development and lactation. In 1900, Halban first established that mammary growth is controlled by the ovary (Halban 1900). He demonstrated that ovariectomy caused mammary regression, and that transplanted ovaries prevented the castration atrophy of mammary glands. Twenty-eight years later, Stricker and Grueter induced mammary development and milk secretion artificially in castrated virgin rabbits by injection of pituitary extract (Stricker and Grueter 1928). In 1933, Riddle, Bates, and Dykshorn purified the respective pituitary hormone (Riddle et al. 1933) and named it prolactin(PRL). In the last several years, the ability to delete genes from the mouse genome has allowed us to identify genetic components of mammary gland development. Molecular insight into the underlying genetic framework and signaling networks of the developing tissue has been gained through experimental manipulations of tissues from wild-type and knockout mice. Two distinct, yet braided, developmental concepts have unfolded. First, discrete signaling networks activated by systemic endocrine hormones induce mammopoiesis. Secondly, some of these signals are relayed through reciprocal interactions between the epithelium and the stroma. Table 1 contains those genes whose elimination from the mouse genome results in impaired mammary gland development. Among these genes are some of the ‘‘usual suspects’’ but also some previously unidentified players. Each mutation affects specific and distinct aspects of mammary development. These knockout mice not only confirmed the involvement of hormonal signaling but also provided tools to identify the tissue compartment that receives and executes these signals.

Prolactin Signaling in Mammary Gland Development

Prolactin Signaling in Mammary Gland Development

Oestrogen-dependent expression of the SM2 smooth muscle-type myosin isoform in rabbit myometrium.

Ovarectomized rabbits displayed a decreased SM1 to SM2 ratio of smooth muscle-type myosin heavy chain isoforms compared to unoperated, virgin females which was reversed after 17beta-oestradiol administration to a value similar to that of control animals. When this steroid was given to sexually immature animals or to adult virgin rabbits, SM2 expression was not induced, as also happened with proliferating myometrial smooth muscle cells grown in vitro. In growing rabbit, the 17beta-oestradiol administration induced the formation of the circular and the longitudinal muscle layers, characteristics of sexually competent females. The SM2 isoform was up-regulated during postnatal development and the SM1 to SM2 ratio changed during pregnancy and post-partum period but not with human gonadotropin treatment which increases the level of circulating progesterone. Immunofluorescence staining of adult myometrium with anti-SM2 antibody indicated that this isoform is localized to the longitudinal layer exclusively and, in contrast to the circular layer, its expression was independent of oestrogen level. Difference in oestrogen sensitivity between the two layers was also detected for the expression of the intermediate filament protein vimentin and the thin filament protein calponin. Changes of SM2 expression in the myometrium correlated with variations in the oestrogen receptor density as also confirmed by decreased SM2 content/oestrogen receptor density in the circular layer when ovarectomized females were treated with the oestrogen antagonist ICI 182,780. Our results indicate that: (1) a specific distribution of myosin heavy chain exists within rabbit myometrium, and (2) SM2 myosin expression in this smooth muscle is under oestrogen control.

Effects of pregnancy on urethral and bladder neck function

Pregnancy and menopause induce morphologic as well as functional changes in the female urethra. Symptoms of bladder irritation (frequency, urgency) and incontinence are frequent findings in these conditions and are considered to be due to alterations in the distribution of autonomic receptors induced by the changes in the hormonal milieu. In the present study, the functional responses to field stimulation (FS) and autonomic agonists of the bladder neck and urethra of pregnant, and virgin New Zealand White rabbits were compared using isolated muscle strips. Passive length-tension studies demonstrated a significantly greater compliance of strips (bladder neck and urethra) from pregnant rabbits than from virgin rabbits. FS elicited frequency dependent contractile responses in all strips. Phentolamine was significantly more effective at inhibiting the field stimulated contractile response of urethral strips from pregnant than from virgin rabbits. Atropine was significantly more effective at inhibiting the response to FS of strips isolated from bladder necks of virgin rabbits than in strips isolated from pregnant rabbits. Atropine was significantly less effective at inhibiting the response to FS of strips isolated from urethras of pregnant rabbits than of strips from virgin rabbits. Strips of bladder neck and urethra isolated from virgin rabbits responded with significantly greater contraction to phenylephrine than strips isolated from pregnant rabbits. The magnitude of field stimulated relaxation was significantly greater in urethral strips than in bladder neck strips, and also greater in urethral strips isolated from virgin rabbits than in strips isolated from pregnant rabbits. In conclusion, pregnancy induces profound hormonal changes which, in turn, result in the alteration of the compliance and functional responses of the bladder neck and urethra to various forms of autonomic stimulation and relaxation.

Localized increases in ovarian vascular permeability and leucocyte accumulation after induced ovulation in rabbits.

Colloidal carbon was injected i.v. in mature virgin rabbits at different times after induction of ovulation by human chorionic gonadotrophin (hCG, 100 iu) or mating. Before induction of ovulation, slight carbon leakage was observed in the inner vascular ring of the theca interna of antral follicles, but blood vessels in the other ovarian compartments were unstained. Between 4 and 10.5 h after hCG-treatment or mating, vascular leakage was most marked in the blood vessels of the interstitial gland and in the theca interna of antral follicles. Just before ovulation, carbon particles were observed between granulosa cells and some carbon was seeping into the follicular fluid of preruptured follicles. Vascular leakage was also observed over the follicle dome before rupture as well as at the dorsomedial junction between the mesovarium and the ovary. The blood vessels stained with carbon were 7-70 microns diameter, representing capillaries and postcapillary venules. About 6 h after hCG injection, an increased number of polymorphonuclear leucocytes migrated from the vessels of these ovarian compartments into the surrounding interstitial tissue. The number of leucocytes seen in the follicular wall and ovarian medulla increased markedly towards ovulation. During early corpus luteum formation, the number of leucocytes decreased markedly. The localized vascular changes seen after mating and hCG stimulation were similar to an inflammatory reaction and could form the basis for the formation of peritoneal exudate after ovulation in rabbits and periovulatory ascitic accumulation seen in the peritoneal cavity of women during the menstrual cycle.