Shift from Pro- to Anti-Inflammatory Phase in Pelvic Floor Muscles at Postpartum Matches Histological Signs of Regeneration in Multiparous Rabbits.

Background and Objectives: Pelvic floor muscles (PFM) play a core role in defecation and micturition. Weakening of PFM underlies urogynecological disorders such as pelvic organ prolapse and stress urinary incontinence. Vaginal delivery damages PFM. Muscle trauma implies an inflammatory response mediated by myeloid cells, essential for subsequent recovery. Molecular signaling characterizing the pro-inflammatory phase shifts M1 macrophages to M2 macrophages, which modulate muscle repair. The present study aimed to evaluate histological characteristics and the presence of M1 and M2 macrophages in bulbospongiosus (Bsm) and pubococcygeus muscles (Pcm). Materials and Methods: Muscles from young nulliparous (N) and multiparous rabbits on postpartum days three (M3) and twenty (M20) were excised and histologically processed to measure the myofiber cross-sectional area (CSA) and count the centralized myonuclei in hematoxylin-eosinstained sections. Using immunohistochemistry, M1 and M2 macrophages were estimated in muscle sections. Kruskal-Wallis or one-way ANOVA testing, followed by post hoc tests, were conducted to identify significant differences (p < 0.05). Results: The myofiber CSA of both the Bsm and Pcm of the M3 group were more extensive than those of the N and M20 groups. Centralized myonuclei estimated in sections from both muscles of M20 rabbits were higher than those of N rabbits. Such histological outcomes matched significant increases in HLA-DR immunostaining in M3 rabbits with the CD206 immunostaining in muscle sections from M20 rabbits. Conclusions: A shift from the pro- to anti-inflammatory phase in the bulbospongiosus and pubococcygeus muscles of multiparous rabbits matches with centralized myonuclei, suggesting the ongoing regeneration of muscles.

G protein-coupled estrogen receptor (GPER/GPR30) levels in pelvic floor muscles and its association with estrogen status in female rabbits.

Objective: To assess the relative expression of the G-protein coupled estrogen receptor (GPER) in the bulbospongiosus (Bsm) and pubococcygeus (Pcm) muscles in control, ovariectomized (OVX), and OVX with estradiol benzoate supplementation (OVX + EB) rabbits.Methods: We used tissues from C, 1-month OVX, and OVX plus 15-day EB implanted (OVX + EB) groups. The GPER expression was evaluated by Western blot and immunohistochemistry for both Bsm and Pcm. Results: Both muscles showed a GPER immunoreactivity in blood vessels, inside myofibers next to myonuclei, and in polymorphonuclear cells. Four-week ovariectomy did not modify the GPER expression in the Bsm and Pcm, but two-week estradiol benzoate increased it in the latter muscle alone.Conclusions: We demonstrated that the Bsm and Pcm of female rabbits express GPER. High serum estradiol levels elevate GPER relative expression in the Pcm alone. The present study supports the remarkable estrogen sensitivity of the Pcm.

Disordered Glucose Levels Are Associated with Xanthine Oxidase Activity in Overweight Type 2 Diabetic Women.

Oxidative stress plays an important role in vascular complications observed in patients with obesity and Type 2 Diabetes (T2D). Xanthine oxidase (XO) breaks down purine nucleotides into uric acid and contributes to the production of reactive oxygen species (ROS). However, the relationship between XO activity and glucose homeostasis in T2D subjects with obesity is unclear. We hypothesized that disordered glucose levels are associated with serum XO activity in overweight women and men with T2D and without hyperuricemia. We studied serum XO activity in women and men with and without T2D. Our results show that serum XO activity was greater in T2D patients with body mass index (BMI) ≥ 25 kg/m2 than in those with BMI < 25 kg/m2 (p < 0.0001). Sex-based comparative analyses of overweight T2D patients showed that serum XO activity correlated with homeostasis model assessment of ß-cell function (HOMA-ß), fasting plasma glucose (FPG), and hemoglobin A1C in overweight T2D women but not in overweight T2D men. In addition, as compared to overweight T2D men, women had higher high-sensitivity C-reactive protein (hs-CRP) levels. However, overweight T2D men had higher XO activity and uric acid levels than women. Our results suggest that XO activity is higher in overweight T2D patients, especially in men, but is more sensitive to disordered glucose levels in overweight women with T2D.

Colourful traits in female birds relate to individual condition, reproductive performance and male-mate preferences: a meta-analytic approach.

Colourful traits in females are suggested to have evolved and be maintained by sexual selection. Although several studies have evaluated this idea, support is still equivocal. Evidence has been compiled in reviews, and a handful of quantitative syntheses has explored cumulative support for the link between condition and specific colour traits in males and females. However, understanding the potential function of females' colourful traits in sexual communication has not been the primary focus of any of those previous studies. Here, using a meta-analytic approach, we find that evidence from empirical studies in birds supports the idea that colourful female ornaments are positively associated with residual mass and immune response, clutch size and male-mate preferences. Hence, colourful traits in female birds likely evolved and are maintained by sexual selection as condition-dependent signals.

Differential estrogen-related responses in myofiber cross-sectional area of pelvic floor muscles in female rats.

OBJECTIVE: To determine the role of estrogens in myofiber cross-sectional area (CSA) of the pubococcyegeus (Pcm) and iliococcygeus muscles (Icm). METHODS: In Experiment 1, we excised the Pcm and Icm during the metestrus and proestrus stages of the estrous cycle to measure the myofiber CSA. In Experiment 2, we allocated other rats into the following groups: sham (Sh), ovariectomized (OVX), OVX plus 1,4,6-androstatriene-3,17-dione (ATD; OVX + ATD), an aromatase inhibitor, and OVX plus estradiol benzoate (OVX + EB). We carried out appropriate statistical tests to determine significant differences (p ≤ 0.05) in variables measured for both Experiments. RESULTS: The Pcm myofiber CSA at proestrus was higher than at metestrus, while the Icm myofiber CSA did not change. Ovariectomy increased the Pcm myofiber CSA, which was exacerbated with the ATD administration. The EB supplementation successfully reversed the ovariectomy-induced enlargement of the CSA. No significant changes were detected for the Icm myofiber CSA. CONCLUSIONS: Fluctuating ovarian steroid levels at the estrus cycle significantly influence the CSA myofiber of the Pcm but not that of the Icm. Estrogen actions, having a gonadal or extragonadal origin, influence importantly the CSA of the Pcm.

Lumbosacral ventral root avulsion alters reflex activation of bladder, urethra, and perineal muscles during micturition in female rabbits.

AIM: To determine the effect of the lumbosacral ventral root avulsion (VRA) on the reflex activation of bladder, urethra, and activation of perineal muscles during micturition in female rabbits. METHODS: We allocated 14 virgin female rabbits to evaluate, first, the gross anatomy of lumbosacral spinal cord root (n = 5) and, second, to determine the effect of VRA on perineal muscles during micturition (n = 9). We recorded cystometrograms, urethral pressure, and electromyograms of the bulbospongiosus (Bsm) and ischiocavernosus (Ism) muscles before and after the L6-S2 VRA. Standard variables were measured from each recording and analyzed to identify significant differences (P < .05). RESULTS: We found that the L6-S2 VRA affected directly the bladder and urethral function and reduced the duration and the frequency of the bursting of Ism and Bsm muscles during voiding. The Ism and Bsm showed a phasic activation, of different frequencies, during the voiding phase and the L6-S2 VRA inhibited the co-contraction of the Ism and Bsm-bladder-urethra. CONCLUSIONS: The Ism and Bsm are activated at different frequencies to trigger the voiding phase. The L6-S2 VRA affected the activity pattern of both perineal muscles. These modifications affected the bladder and urethra function. It is possible that the restoration of the activation frequency of perineal muscles contributed for an efficient bladder contraction.

Bladder and urethral dysfunction in multiparous and mature rabbits correlates with abnormal activity of pubococcygeus and bulbospongiosus muscles.

AIMS: To evaluate the combined effect of age and multiparity on the micturition reflex, including pelvic floor muscle activation. METHODS: Young and mature nulliparous rabbits were compared to young and mature multiparas (n = 6 per group). Cystometrograms and urethral pressure (UP) were performed while simultaneously recording the electromyogram (EMG) activity of the pubococcygeus and bulbospongiosus muscles to establish their functional correlation to urological function. RESULTS: Multiparity and age significantly influence the bladder and UP affecting the voiding efficiency and intercontraction interval. Such interaction also reduced the UP threshold, timing, and duration. Other bladder and urethral variables were predominantly affected only by age. Urodynamic alterations correlated with abnormal patterns or absent EMG activity of the pubococcygeus and bulbospongiosus muscles. CONCLUSIONS: The present findings strongly suggest that multiparity and age affects specific pelvic floor muscle reflex activation during micturition, and may contribute to alterations in bladder and urethral function. This data broadens our understanding of the critical role of the appropriate activity of the individual pelvic floor muscles in micturition.

Signs of damage in pelvic floor muscles at the end of pregnancy in rabbits.

INTRODUCTION AND HYPOTHESIS: Temporary effects to pelvic floor muscles are linked to impairments in micturition, particularly stress urinary incontinence (SUI), during pregnancy. We hypothesize that bulbospongiosus (Bsm) and pubococcygeus (Pcm) are differently damaged in primigravid and primiparous rabbits. METHODS: Twenty-four rabbits allocated evenly (n = 6) into nulliparous, pregnant, and primiparous groups on postpartum days 3 (P3) and 20 (P20) were used to evaluate the myofiber cross-sectional area (CSA), ß-glucuronidase activity, and anti-3-nitrotyrosine (anti-3-NTyr) immunoreactivity in Bsm and Pcm muscles. Appropriate statistical tests were done to determine significant differences among groups (P ≤ 0.05). RESULTS: The average CSA of Bsm was not significantly different, albeit a high percentage of myofibers was enlarged in late-pregnant and primiparous rabbits on P3; ß-glucuronidase activity and indirect parameter of muscle damage was also higher. These variables did not change in the Pcm muscle during the different reproductive stages. In contrast, the 3-NTyr immunoreactivity, an indicator of oxidative damage, was increased on P3 for Pcm myofibers and P20 for myofibers of both muscles. CONCLUSIONS: Our findings demonstrate reliable signs of damage to Bsm and Pcm muscles in young female rabbits passing different reproductive stages. Damage to the Bsm muscles as detected at the end of pregnancy persisted after delivery. This was not the case for Pcm muscles, in which damage seems to appear after delivery.

Multiparity modifies contractile properties of pelvic muscles affecting the genesis of vaginal pressure in rabbits.

AIMS: To characterize the contractile properties of the bulbospongiosus (Bsm), isquiocavernosus (Ism), and pubococcygeus muscles (Pcm), and their involvement in the genesis of vaginal pressure in nulliparous and multiparous rabbits. METHODS: Age-matched nulliparous and multiparous rabbits were used to record the isometric contractile responses of each muscle as well as the intravaginal pressure evoked by single square electrical pulses and stimulation trains of ascending frequency. To establish significant differences between groups, two-tail unpaired Student t tests were carried out. The linear correlation between intravaginal pressure and muscle contractile force was analyzed with Pearson correlation tests. For all cases, a P ≤ 0.05 was set as statistically significant. RESULTS: Multiparity decreased the contractile force of Bsm and Ism generated by high-frequency stimulation trains. The normalized force of the Pcm increased when evoked at 1, 4, and 10 Hz while this decreased at higher frequencies (20, 50, and 100 Hz). The contraction of both Bsm and Ism raised particularly the pressure on the perineal vagina while that of the Pcm increased the pressure in the pelvic vagina. Such a functional segregation is still present in multiparous rabbits albeit it was modified. CONCLUSIONS: Multiparity induces changes in the contractile responses of Bsm, Ism, and Pcm, which alterates the vaginal pressure.

Hypothyroidism impairs somatovisceral reflexes involved in micturition of female rabbits.

AIMS: To determine the impact of hypothyroidism on the bladder and urethral functions as well as in the activation of the pubococcygeous (Pcm) and bulbospongiosus (Bsm) during micturition. METHODS: Age-matched control and methimazole-induced hypothyroid female rabbits were used to simultaneously record cystometrograms, urethral pressure, and the reflex activation of Pcm and Bsm during the induced micturition. Urodynamic and urethral variables were measured. Activation or no activation of the Pcm and Bsm during the storage and voiding phases of micturition were categorized as 1 or 0. Significant differences (P ≤ 0.05) between control and hypothyroid groups were determined with unpaired Student-t or Mann-Whitney tests. RESULTS: One-month induced hypothyroidism increased the residual volume and threshold pressure while the opposite was true for the voided volume, maximal pressure, and voiding efficiency. Urethral pressure was also affected as supported by a notorious augmentation of the urethral resistance, among other changes in the rest of measured variables. Hypothyroidism also affected the reflex activation of the Pcm in the voiding phase of micturition. CONCLUSIONS: Our findings demonstrate hypothyroidism impairs the bladder and, urethral functions, and reflex activation of Pcm and Bsm affecting the micturition in female rabbits.

Individual differences in early body mass affect thermogenic performance and sibling interactions in litter huddles of the house mouse.

We asked whether within-litter differences in early body mass are associated with differences in house mouse pups' thermogenic performance and whether such variation predicts individual differences in competitive interactions for thermally more advantageous positions in the huddle. We explored pups' thermogenic performance in isolation by measuring changes in (maximal) peripheral body temperatures during a 5-min thermal challenge using infrared thermography. Changes in peripheral body temperature were significantly explained by individual differences in body mass within a litter; relatively lighter individuals showed an overall quicker temperature decrease leading to lower body temperatures toward the end of the thermal challenge compared to heavier littermates. Within the litter huddle, relatively lighter pups with a lower thermogenic performance showed consistently more rooting and climbing behavior, apparently to reach the thermally advantageous center of the huddle. This suggests that within-litter variation in starting body mass affects the pups' thermal and behavioral responses to environmental challenges.

Interactive effects of chronic stress and a high-sucrose diet on nonalcoholic fatty liver in young adult male rats.

Glucocorticoids have been implicated in nonalcoholic fatty liver diseases (NAFLD). The influence of a palatable diet on the response to stress is controversial. This study explored whether a high-sucrose diet could protect from hepatic steatosis induced by chronic restraint stress in young adult rats. Male Wistar rats aged 21 days were allocated into four groups (n = 6-8 per group): control, chronic restraint stress, 30% sucrose diet, and 30% sucrose diet plus chronic restraint stress. After being exposed to either tap water or sucrose solution during eight weeks, half of the rats belonging to each group were subject or not to repeated restraint stress (1 h per day, 5 days per week) during four weeks. Triacylglycerol (TAG), oxidative stress, activity of 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD-1), infiltration of immune cells, and glycogen amount in the liver were quantified. Serum concentrations of corticosterone and testosterone were also measured. The stressed group showed normal serum concentrations of corticosterone and did not have hepatic steatosis. However, this group showed increased glycogen, inflammation, mild fibrosis, oxidative stress, and a high activity of 11ß-HSD-1 in the liver. The group exposed to the high-sucrose diet had lower concentrations of corticosterone, hepatic steatosis and moderate fibrosis. The group subject to high-sucrose diet plus chronic restraint stress showed low concentrations of corticosterone, hepatic steatosis, oxidative stress, and high concentrations of testosterone. Thus, restraint stress and a high-sucrose diet each generate different components of nonalcoholic fatty liver in young adult rats. The combination of both the factors could promote a faster development of NAFLD.

The role of the pubococcygeus muscle in the urethrogenital reflex of male rats.

AIM: To determine the response of the pubococcygeus muscle (Pcm) during the urethrogenital reflex (UGR). METHODS: Urethane-anesthetized male rats (n = 20) were used to describe the gross anatomy of the Pcm (n = 3), the effect of the electrical stimulation of the Pcm on the urethral pressure (n = 3), and the reflex activity of the Pcm due to the mechanical stimulation of the urethra (n = 3) and during penile and urethrogenital reflexes (n = 11). The urethral pressure (UP) was recorded as a response to penile stimulation (brushing, extension, and occlusion) and during the UGR; the electromyographic activity of the Pcm was simultaneously evaluated. The role of the Pcm was assessed by measuring urethral pressure variables before and after denervation of this muscle. RESULTS: The Pcm is innervated by the caudal branch of the somatomotor branch of the pelvic nerve. The electrically induced contraction of the Pcm increased the UP. The mechanical stimulation of the urethra during the induced micturition caused the reflex activity of the Pcm. The different penile stimuli caused bursts of activity of the Pcm. During the UGR, the Pcm exhibited a tonic activity. The transection of the caudal branch of the Smb reduced the maximal UP during the penile stimulation. The same was true regarding the duration of the UGR, the pressure that triggers the UGR, and the highest pressure observed during the UGR. CONCLUSION: Our results suggest that the activation of the Pcm is relevant for the UGR in male rats. Neurourol. Urodynam. 36:80-85, 2017. © 2015 Wiley Periodicals, Inc.

Anatomical organization and somatic axonal components of the lumbosacral nerves in female rabbits.

AIM: To determine the anatomical organization and somatic axonal components of the lumbosacral nerves in female rabbits. METHODS: Chinchilla adult anesthetized female rabbits were used. Anatomical, electrophysiological, and histological studies were performed. RESULTS: L7, S1, and some fibers from S2 and S3 form the lumbosacral trunk, which gives origin to the sciatic nerve and innervation to the gluteal region. From S2 to S3 originates the pudendal nerve, whose branches innervates the striated anal and urethra sphincters, as well as the bulbospongiosus, ischiocavernosus, and constrictor vulvae muscles. The sensory field of the pudendal nerve is ∼1800 mm2 and is localized in the clitoral sheath and perineal and perigenital skin. The organization of the pudendal nerve varies between individuals, three patterns were identified, and one of them was present in 50% of the animals. From S3 emerge the pelvic nerve, which anastomoses to form a plexus localized between the vagina and the rectum. The innervation of the pelvic floor originates from S3 to S4 fibers. CONCLUSIONS: Most of the sacral spinal nerves of rabbit are mixed, carrying sensory, and motor information. Sacral nerves innervate the hind limbs, pelvic viscera, clitoris, perineal muscles, inguinal and anal glands and perineal, perigenital, and rump skin. The detailed description of the sacral nerves organization, topography, and axonal components further the knowledge of the innervation in pelvic and perinal structures of the female rabbit. This information will be useful in future studies about the physiology and physiopathology of urinary, fecal, reproductive, and sexual functions.

Fiber type composition of pubococcygeus and bulbospongiosus striated muscles is modified by multiparity in the rabbit.

AIMS: We analyzed the effect of multiparity on the fiber type composition of two skeletal muscles involved in the maintenance of the micturition process, the pelvic pubococcygeus (Pc) and perineal bulbospongiosus (Bs) muscles in nulliparous and multiparous rabbits (Oryctolagus cuniculus). METHODS: We used the basic ATPase and NADH-TR techniques to identify and characterize slow, intermediate, and fast fiber types and glycolitic and oxidative fibers in muscles, respectively. RESULTS: Pc muscles of multiparous rabbits present relatively high percentages of slow and intermediate fibers but a low percentage of fast fibers (P < 0.05) as compared to Pc muscles from nulliparous rabbits, while percentages of glycolytic and oxidative fibers were similar (P > 0.05). Bs muscles of multiparous rabbits had a higher proportion of intermediate and glycolytic fibers (P < 0.05) than muscles of nulliparous. Both, Pc and Bs muscles of nulliparous and multiparous rabbits contain slow fibers with similar large cross sectional area, but fast fibers in multiparous muscles showed small cross sectional area than in nulliparous. CONCLUSIONS: Multiparity modified the fiber type composition of Pc and Bs muscles in female rabbits. We propose that the contractile force and the physiological role of both muscles during micturition are affected because of the observed changes in the relative composition of muscle fiber types.

Moderate-to-high normal levels of thyrotropin is a risk factor for urinary incontinence and an unsuitable quality of life in women over 65 years.

The present study aimed to investigate the relationship between normal serum concentrations of thyrotropin (TSH) and urinary incontinence (IU), urinary infections, and quality of life in old women. Euthyroid post-menopausal women without sarcopenia, estrogen replacement, emotional illness, and/or cancer were enrolled as participants. Anthropometric indicators, serum glucose and estradiol, and thyroid profile were measured. Sociodemographic, clinical, physical activity, and quality of life (SF-36) surveys were applied. One-hour pad test and International Consultation on Incontinence Questionnaire Short Form (ICIQ-SF) were used to determine UI. Urinalysis was also done. In agreement with results from the pad test (cut-off point ≥1.4 g), the ICIQ-SF reveled approximately 50% of incontinent women. A high percentage of women had moderate-high bacteriuria and urinary infections. Logistic regression analysis showed that age is a risk factor for both UI and urinary infection. Diabetes, number of pregnancies or childbirths, urinary infections, and bacteriuria did not influence the presence of UI. To allocate women into four groups according to their age (<65 or ≥65 years old) and TSH concentrations (0.3-1.9 or 2-10 µUI/mL), we found that moderate-to-high normal levels of TSH is a risk factor for UI and a worse quality of life in the oldest women. Our results highlight the profit of measuring TSH concentrations in post-menopausal women.

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

PURPOSE: 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.

Mealtime habits and risk of developing the metabolic syndrome or insulin resistance among Mexican adults.

Meals are an important source of food intake, contributing to body weight and health status. Previous studies have examined the relationship between isolated mealtime behaviours and the metabolic syndrome (MetS). The aim of this study was to examine the influence over time of ten interrelated mealtime habits on the risk of developing the MetS and insulin resistance (IR) among Mexican adults. We conducted a prospective cohort study with a sample of 956 health workers. The Mealtime Habits Quality (MHQ) scale is based on four mealtime situations (availability of time to eat, distractions while eating, environmental and social context of eating, and familiar or cultural eating habits), which were used to assess the participants' MHQ at the baseline (2004-2006) and follow-up (2010-2012) evaluations. The MetS was assessed using criteria from the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) and the International Diabetes Federation (IDF). IR was defined using the homoeostasis model assessment. Crude and adjusted relative risks were calculated to estimate the relationship between MHQ and the risk of developing the MetS or IR. Participants classified in the lower MHQ category had an 8·8 (95 % CI 3·1, 25) and 11·1 (95 % CI 3·4, 36·1) times greater risk of developing the MetS (using the NCEP-ATP III and IDF criteria, respectively), and an 11·2 times (95 % CI 3·9, 31·5) greater likelihood of developing IR, compared with those in the higher MHQ group. This prospective study reveals that individuals who engaged in more undesirable than recommended mealtime behaviours had a >10-fold risk of developing the MetS or IR.

Hypothyroidism modifies morphometry and thyroid-hormone receptor expression in periurethral muscles of female rabbits.

AIM: To evaluate the morphometry and thyroid-hormone receptor (TR) expression in pelvic (pubococcygeus, Pcm) and perineal (bulbospongiosus, Bsm) muscles of control and hypothyroid female rabbits. METHODS: Hypothyroidism was induced administering 0.02% methimazole in the drinking water for one month. Hematoxylin-eosin stained muscle sections were used to evaluate the fiber cross-sectional area (CSA) and the number of peripheral myonuclei per fiber. Immunohistochemistry was used to calculate the proportion of TR immunoreactive nuclei per fiber. Significant differences were considered at a P ≤ 0.05. RESULTS: As compared to control rabbits, hypothyroidism increased the averaged fiber CSA and the myonuclei per fiber in the Bsm. Although the myonuclei number per fiber was also increased in the Pcm, the effect concerning the fiber CSA was only observed in a fraction of the Pcm fibers. Both TRα and TRß were similarly expressed in the Pcm and Bsm. Hypothyroidism increased the expression of the TRα in the Bsm. Meanwhile, the expression of TR isoforms in the Pcm was not altered. CONCLUSION: Our findings support that the TR signaling is directly involved in morphometrical changes induced by hypothyroidism in the Pcm and Bsm. The effect of hypothyroidism on the Pcm and Bsm could be related to the different type of fiber and metabolism that these muscles have. Neurourol. Urodynam. 35:895-901, 2016. © 2015 Wiley Periodicals, Inc.

Differential damage and repair responses of pubococcygeus and bulbospongiosus muscles in multiparous rabbits.

AIM: To determine the extent of damage and regeneration associated with multiparity on the pubococcygeus and bulbospongiosus muscles. METHODS: Age-matched virgin nulliparous and multiparous rabbits that were killed at days 3 and 20 after the fourth delivery were used to harvest pubococcygeus and bulbospongiosus muscles. The activity of the lysosomal enzyme ß-glucuronidase was used as a muscle damage indicator. The number of immunoreactive myofiber-associated nuclei anti-Pax7, -MyoD, and -myogenin, as well as the anti-desmin immunoreactive area were measured in muscle sections to estimate some regenerative stages. Significant differences were considered at a P ≤ 0.05. RESULTS: The ß-glucuronidase activity was increased at postpartum day 20 in the pubococcygeus muscle. This variable was unaltered in the bulbospongiosus muscles of multiparas regardless of the postpartum day on which this was measured. The number of immunoreactive nuclei anti-Pax7 in the pubococcygeus muscle was similar between nulliparas and multiparas, whilst those of anti-MyoD and anti-myogenin were increased at postpartum days 3 and 20. The same was true for these latter three markers evaluated in the bulbospongiosus muscles, supporting an ongoing regeneration. The desmin-positive percentage of muscle area per field was increased at postpartum day 20 in the pubococcygeus muscle, whilst such an increment was seen at postpartum days 3 and 20 in the bulbospongiosus muscles. CONCLUSIONS: Damage and regeneration of the pubococcygeus and bulbospongiosus muscles are differently influenced by multiparity in rabbits. This could rely on the anatomical location, metabolism, myofiber composition, and muscle exertion during pregnancy and/or the delivery of each muscle.