Activity In Female Rats Research Articles

Skeletal Growth and IGF Levels in Rats after HT042 Treatment

HT042, a new herbal prescription consisting of Astragalus membranaceus, Phlomis umbrosa and Eleutherococcus senticosus, is used in traditional Korean medicine to stimulate growth in children. This study was conducted to investigate the effects of HT042 on skeletal growth, insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) levels, and oestrogenic activity in female rats. Female Sprague-Dawley rats were divided into control, recombinant human growth hormone (rhGH; 20 µg/kg/day), and HT042 (100 mg/kg/day) groups and treated for 3 weeks. Axial skeletal growth, femur length, and growth plate length were measured every 3 weeks. The serum IGF-1 and IGFBP-3 levels were analysed. Moreover, the oestrogenic activity of the herbal extracts in the immature and ovariectomized rats was tested. The nose-anus, nose-tail, femur and growth-plate lengths were increased significantly in the HT042 group. Both IGF-1 and IGFBP-3 were highly expressed in the hypertrophic zone of the growth plate. The serum IGF-1 levels were increased. Moreover, HT042 had no uterotrophic effects in the rats. Consequently, HT042 promoted longitudinal bone growth by stimulating cell proliferation in the epiphyseal plate and inducing the expression of IGF-1 without an oestrogenic response. HT042 may be helpful in stimulating growth in children with short stature.

Oral Hypoglycemic Activity of Culinary-Medicinal Mushrooms Pleurotus ostreatus and P. cystidiosus (Higher Basidiomycetes) in Normal and Alloxan-Induced Diabetic Wistar Rats

This study investigates the oral hypoglycemic activity of Pleurotus ostreatus (P.o.) and P. cystidiosus (P.c.) mushrooms on normal and alloxan-induced diabetic Wistar rats. Different doses (250, 500, 750, 1000, and 1250 mg/kg/body weight) of suspensions of freeze-dried and powdered (SFDP) P.o. and P.c. were administered to normal rats, and postprandial serum glucose levels were measured. Optimal time of activity was investigated using the dose 500 mg/kg. Hypoglycemic effect of a single dose of SFDP P.o. and P.c. (500 mg/kg) were investigated using diabetic male and female rats at different stages of estrous cycle and compared with metformin and glibenclamide. Chronic hypoglycemic activity of SFDP P.o. and P.c. (500 mg/kg) was studied using serum glucose levels and glycosylated hemoglobin levels. Maximally effective dose of SFDP P.o. and P.c. was 500 mg/kg. The highest reduction in the serum glucose level was observed 120 minutes after administration of mushrooms. A single dose of P.o. and P.c. significantly (P < 0.05) reduced the serum glucose levels of male diabetic rats. The hypoglycemic activity in female rats was highest in proestrous stage. The hypoglycemic effect of P.o. and P.c. is comparable with metformin and glibenclamide. Daily single administrations of P.o. and P.c. to diabetic rats exert apparent control on the homeostasis of blood glucose. SFDP P.o. and P.c. possessed marked and significant oral hypoglycemic activity. This study suggests the consumption of P.o. and P.c. mushrooms might bring health benefits to mankind as it shows hypoglycemic activity in rats.

The effect of adrenalectomy on hepatic mixed function oxidase activity in female rats.

The effect of adrenalectomy on hepatic mixed function oxidase activity in female rats.

Combination of Testosterone and Vardenafil Increases Female Sexual Functioning in Sub‐Primed Rats

Hypoactive sexual desire disorder (HSDD) is a common problem in women and may have a negative impact on quality of life. A recent clinical study shows an increase in sexual drive of HSDD women after cotreatment of testosterone and vardenafil (phosphodiesterase type 5 inhibitor). In this study, we investigated the effect of testosterone and vardenafil on sexual activity in female rats. Proceptive (darts and hops), receptive (lordosis), and paced-mating (percentages after exits and contact-return latencies) behaviors were quantified. Ovariectomized female rats, sub-primed with only estradiol and fully primed with estradiol and progesterone, were tested in a paced-mating sex test and sexual behaviors were quantified. The sub-primed rats are thought to model HSDD. The effect of testosterone (100 and 300 µg, subcutaneous [SC]) and vardenafil (10 mg/kg, per os [PO]) alone and testosterone (300 µg, SC) in combination with vardenafil (3 and 10 mg/kg, PO) were tested. We also studied the effects of testosterone (300 µg, SC) + intracerebroventricular (ICV) injections of vardenafil (25 and 50 µg) on sexual activity. No effect of testosterone and vardenafil alone was found, but cotreatment of testosterone and vardenafil (PO) caused a significant increase in proceptive and receptive behavior in the sub-primed female rats. Testosterone and vardenafil did not affect fully primed females. ICV administration of vardenafil combined with systemic testosterone, on the other hand, had no effect on sexual activity in both sub-primed and fully primed female rats. We conclude that cotreatment of subcutaneous testosterone and oral vardenafil increase sexual activity in sub-primed female rats. Our data supports the human finding that combination treatment of testosterone and vardenafil could be used as a new treatment for women with HSDD.

Toxicological screening of Mikania glomerata Spreng., Asteraceae, extract in male Wistar rats reproductive system, sperm production and testosterone level after chronic treatment

Some compounds present in therapeutic plants may be responsible for the occurrence of adverse side effects. Coumarin and flavonoids are substances found in many plant species that showed antifertility activity in female rats and dogs, respectively. Mikania glomerata Spreng., Asteraceae, known as guaco in Brazil, is a plant largely used in folk medicine and its leaves are reported to have coumarin and flavonoids. This work analyzes the effect of chronic administration of M. glomerata on the reproductive system of male rats. Thirty-day-old Wistar rats were treated with M. glomerata hydroalcoholic extract at a dose of 3.3 g/kg of body weight for ninety days. Body and organ weights, gamete concentration on the epididymis cauda, serum testosterone level and food consumption were evaluated. No significant alteration was observed in any of the variables analyzed, suggesting the absence of toxic action or antifertility activity of the M. glomerata hydroalcoholic extract.

Impact of the estrus cycle and reduction in estrogen levels with aromatase inhibition, on renal function and nitric oxide activity in female rats

Estradiol increases mRNA and/or protein expression of the nitric oxide synthase (NOS) isoforms in a variety of tissues including kidney. In this study we determined the relationship between cyclical variations in estradiol levels and renal function and total NO production in the virgin female rat. In addition, we used an aromatase inhibitor (Anastrozole), to inhibit synthesis of estradiol from testosterone. Estradiol levels were higher in proestrus vs. diestrus, and were markedly suppressed by 7 days treatment with aromatase inhibitor. There was no difference in total NO production (from urinary and plasma nitrate + nitrite = NO X) between proestrus and diestrus but aromatase inhibition resulted in increases in total NO production. The renal cortical NOS activity and protein abundance also increased in aromatase-inhibited female rats. There were no differences in blood pressure (BP) in any group but the renal vascular resistance (RVR) was low in proestrus, increased in diestrus and did not change further after aromatase inhibition. In summary, the cyclical changes in renal function correlate with estradiol but not NO levels. Pharmacologic castration with aromatase inhibition leads to a marked increase in total and renal NOS. This contrasts to earlier work where surgical castration causes decreased NOS.

Serotonin Transporter Null Mutation and Sexual Behavior in Female Rats: 5-HT1A Receptor Desensitization

Serotonin plays a key role in sexual behavior. In serotonin transporter (SERT) knockout rats (-/-), basal extracellular 5-HT levels are considerably increased, indicating a serotonergic disturbance. Heterozygous SERT(+/-) rats express 50% of SERT in comparison to wild-type rats and may therefore model the s/s phenotype of the human SERT promoter (5-HTTLPR) polymorphism. In the present study, we used both homozygote and heterozygote SERT knockout and wild-type rats (+/+) to study the putative role of the SERT in female sexual behavior. Female rats were brought into estrous by hormonal injections before a paced mating sex test. The effects of the 5-HT(1A)/5-HT(7) receptor agonist (+/-)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (+/-8-OH-DPAT) (0.03-1 mg/kg s.c.) and the 5-HT(1A) receptor antagonist WAY-100635 (0.1-1-mg/kg i.p.) on sexual behaviors of the females were tested separately and in a selected combination of both in all three genotypes. Proceptive (darting and hopping) and receptive (lordosis) behaviors were quantified. Basal proceptive and receptive sexual activities were not different between SERT+/+, +/- and -/- female rats. The dose-effect curve after +/-8-OH-DPAT for these activities was clearly shifted to the right in SERT-/- animals compared to other genotypes. WAY-100635 alone had no effect on sexual behavior in any genotype, but was able to antagonize the +/-8-OH-DPAT-induced decrease in sexual activities indicating the involvement of the 5-HT(1A) receptor. The absence (-/-) or reduced (+/-) expression of SERT does not affect basal sexual activity in female rats in a paced mating situation. The data indicate a desensitized 5-HT1A receptor in the SERT-/-, but not in the SERT+/- females. Under normal basal conditions, desensitized 5-HT1A receptors apparently do not play a role in female sexual behavior of the SERT-/-. However, upon activation of the 5-HT1A receptor in "normal" females (SERT+/+ and SERT+/-), a hyposexual behavior is induced.

Seed extracts of a Bangladeshi medicinal plant Abrus precatorius L. show antifertility activity in female rats

The seed powder of Abrus precatorius L. has traditionally been used as oral contraceptive agent by the women in some rural areas in Bangladesh. The present study aimed to examine the antifertility activity of A. precatorius seed extracts in experimental female rats. Finely ground seeds were extracted with aqueous acetone followed by successive partitioning with n-hexane, ethyl acetate (EtOAc), methanol (MeOH) and water. Water suspended crude seed powder, organic fractions of acetone extract and a standard contraceptive drug (<TEX>$Nordette^{(R)}28$</TEX>) were separately administered orally to the female rats for 30 days. n-Hexane, EtOAc and MeOH solubles at the doses of 2, 4 and 6 mg/rat/day, respectively and crude seed powder at 100 mg/rat/day exhibited 100% antifertility activity with lowest levels of serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and <TEX>$17{\beta}$</TEX>-estradiol. Histological study of ovary and uterus of these rats exhibited reduced number of developing follicles and increased number of atretic follicles in the ovary, and fewer uterine glands with shrunken morphology, reduced endometrial height, poor vascularity and compact stroma in uterus. However, the activities of serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase and the body weight of the rats remained almost unaffected in all the seed extract treated rats compared to control. These results suggest that A. precatorius seed extracts reduced the levels of serum FSH, LH and <TEX>$17{\beta}$</TEX>-estradiol probably by affecting hypothalamic-pituitary-gonadal axis. The reduced levels of these hormones might have affected the oestrous cycle, follicular development, and subsequently the establishment of pregnancy in treated rats.

Erythrocyte antioxidants enzymes imbalance following subcutaneous pyrethroid treatments in rats of different sex

Permethrin and deltamethrin are insecticides used all over the world in agriculture to control pests. The aim of this work is to investigate the effects of subcutaneous permethrin and/or deltamethrin treatments on erythrocyte antioxidant enzymes activity in rats of different sex. The results obtained show that permethrin decreases SOD and GPx activity in female rats, while it increases SOD activity in male rats. Deltamethrin treatment reduces GPx activity in male rats, while permethrin has a similar effect but only for short time treatments. A catalase activity decrease was observed in both sexes following pyrethroid treatment but when both the pyrethroids were administrated in male rats, the enzyme activity has increased. In conclusion, this study points out for the first time the importance of rat gender on erythrocyte antioxidant enzymes, which are influenced not only by the length and the type of insecticide treatment but importantly by sex.

Puerarin exhibits weak estrogenic activity in female rats

A weak estrogenicity of puerarin on reproductive organs was addressed in female rats. In short-term treatment, immature ovariectomized rats were injected with 0.7 mg/kg BW/day of puerarin, for 14 days. Puerarin did not increase uterus weights, endometrium and myometrium areas, and the percent of cornified cells (%Co), but it increased the number of uterine glands. In long-term treatment, mature rats were injected with 7.0 mg/kg BW/day of puerarin for 140 days. Puerarin did not increase uterus weights, endometrium and myometrium areas, and the number of uterine glands, but a significant increase in the %Co was observed from day 98 onwards.

Longitudinal assessment of the effects of oestrogen on blood pressure and cardiovascular autonomic activity in female rats

1. Published data concerning the effects of ovarian hormones on haemodynamic variability are contradictory. For the first time, the present study used radiotelemetric haemodynamic monitoring to investigate the long-term effects of chronic oestrogen depletion and repletion on cardiovascular autonomic control and arterial baroreflex sensitivity (BRS) in female rats. 2. Blood pressure (BP), heart rate (HR) and +dP/dt(max) of arterial pressure (an estimate of myocardial contractility) were monitored in sham-operated (SO), ovariectomized (OVX) and oestrogen-replaced OVX rats (OVXE2) for 16 weeks. Cardiovascular autonomic control and baroreflexes were assessed by frequency domain analysis of interbeat intervals (IBI) and systolic BP (SBP). 3. Compared with SO rats, OVX rats exhibited no changes in BP, short-lived decreases in HR and sustained reductions in +dP/dt(max) of arterial pressure. The high- (HF; 0.75-3 Hz) and low-frequency (LF; 0.25-0.75 Hz) components of spectral power of IBI were significantly decreased and increased, respectively, by ovariectomy. An increase in the IBI(LF/HF) ratio in OVX rats suggests a shift in the cardiac sympathovagal balance towards sympathetic dominance. Index alpha, the spectral index of spontaneous BRS, was reduced by OVX. 4. Oestrogen replacement caused significant reductions in BP and HR and reversed OVX-induced changes in +dP/dt(max) of arterial pressure and cardiac autonomic activity. The LF oscillations of SBP were reduced in OVXE2 rats, suggesting a reduction in vascular sympathetic tone by oestrogen. 5. These findings highlight the importance of long-term oestrogen therapy in rectifying the detrimental effects of depletion of ovarian hormones on the cardiovascular system and baroreflex.

Antiandrogenic effects of oestradiol on enzyme activities of hepatic steroid metabolism.

Intact female rats and gonadectomized rats of both sexes were administered 0.5 mg 5 alpha-dihydrotestosterone s.c. daily for 15 days. On the 16th day the activities of hepatic microsomal 3 alpha- and 3 beta-hydroxysteroid dehydrogenase and 5 alpha-reductase were determined. Androgen treatment increased the activity of both hydroxysteroid dehydrogenases and decreased the activity of the 5 alpha-reductase in all animal models. Simultaneous administration of a steroidal antiandrogen, cyproterone (5 mg/day; 15 days s.c.) did not prevent this androgenic effect, whereas oestradiol (5 micrograms/day; 15 days s.c.) completely reversed the action of 5 alpha-dihydrotestosterone. The nonsteroidal antiandrogen, flutamide, also exhibited a potent antiandrogenic influence on these enzyme activities in female rats, whereas its antagonizing action in males was limited. The effects of cyproterone, oestradiol and flutamide on enzyme activities of hepatic steroid metabolism do not reflect the biological activity of these compounds on the weights of target organs (uterus, seminal vesicle, levator ani).

Effect of Carum carvi and Curcuma longa on hormonal and reproductive parameter of female rats.

Rhizome of Curcuma longa and seeds of Carum Carvi a folk medicinal plant used as have antifertility potentials. Present investigation study the effect of both the plant on hormone and reproductive parameter of female rat. The aqueous and ethanolic extract of rhizome of Curcuma longa and seeds of Carum Carvi used for testing antifertility activity in female rat. Aqueous and ethanolic extract of plants were administered orally to female rat for 30 consecutive days. Estrous cycle, reproductive hormones (LH, FSH and estrogen) and weight of reproductive organ were studied in both control and extract-administered groups by using standard methods . The female albino rats after oral administration of different doses of aqueous and ethanolic extracts of Carum carvi and Curcuma longa, showed a significant antifertility activity. FSH and LH level was significantly decreased in both drugs while amount of estrogen in ethanolic extract of both the drugs treated animals was found to be increased.The blockage of estrus phase induced by treatment of aqueous and ethanolic extract of both drug. They also increase the weight of ovary, uterus and body weights while uterine weight in immature rats increased in extract treated group. The present study which was undertaken to find endocrinological and physiological changes in the reproductive system of female albino rats after oral administration of different doses of aqueous and ethanolic extracts of Carum carvi and Curcuma longa, showed a significant antifertility activity. Keywords: Antifertility; Estrogenic, Reproductive, Curcuma longa and Carum carvi

Subacute exposure to N-ethyl perfluorooctanesulfonamidoethanol results in the formation of perfluorooctanesulfonate and alters superoxide dismutase activity in female rats

Perfluorooctanesulfonamides, such as N-ethyl perfluorooctanesulfonamidoethanol (N-EtFOSE), are large scale industrial chemicals but their disposition and toxicity are poorly understood despite significant human exposure. The hypothesis that subacute exposure to N-EtFOSE, a weak peroxisome proliferator, causes a redox imbalance in vivo was tested using the known peroxisome proliferator, ciprofibrate, as a positive control. Female Sprague-Dawley rats were treated orally with N-EtFOSE, ciprofibrate or corn oil (vehicle) for 21 days, and levels of N-EtFOSE and its metabolites as well as markers of peroxisome proliferation and oxidative stress were assessed in serum, liver and/or uterus. The N-EtFOSE metabolite profile in liver and serum was in good agreement with reported in vitro biotransformation pathways in rats and the metabolite levels decreasing in the order perfluorooctanesulfonate >> perfluorooctanesulfonamide ~ N-ethyl perfluorooctanesulfonamidoacetate >> perfluorooctanesulfonamidoethanol approximately N-EtFOSE. Although N-EtFOSE treatment significantly decreased the growth rate, increased relative liver weight and activity of superoxide dismutases (SOD) in liver and uterus (total SOD, CuZnSOD and MnSOD), a metabolic study revealed no differences in the metabolome in serum from N-EtFOSE-treated and control animals. Ciprofibrate treatment increased liver weight and peroxisomal acyl Co-A oxidase activity in the liver and altered antioxidant enzyme activities in the uterus and liver. According to NMR metabolomic studies, ciprofibrate treated animals had altered serum lipid profiles compared to N-EtFOSE-treated and control animals, whereas putative markers of peroxisome proliferation in serum were not affected. Overall, this study demonstrates the biotransformation of N-EtFOSE to PFOS in rats that is accompanied by N-EtFOSE-induced alterations in antioxidant enzyme activity.

Ovarian‐Steroid Modulation of Locus Coeruleus Activity in Female Rats: Involvement in Luteinising Hormone Regulation

The noradrenergic nucleus locus coeruleus (LC) has been reported to regulate luteinising hormone (LH) secretion in female rats. Both oestrogen and progestin receptors have been demonstrated in LC neurones, suggesting that these cells are possibly responsive to variations in circulating levels of ovarian steroids. We therefore evaluated changes in the activity of LC neurones during the oestrous cycle and after ovarian-steroid treatment in ovariectomised (OVX) rats, as determined by immunoreactivity to Fos-related antigens (FRA), which comprises all of the known members of the Fos family. Effects of ovarian steroids on the firing rate of LC neurones were also determined in a slice preparation. The number of FRA/tyrosine hydroxylase (TH)-immunoreactive (ir) neurones in the LC increased from 14.00-16.00 h on pro-oestrus, coinciding with the onset of the LH surge and rise in plasma progesterone. FRA immunoreactivity was unaltered during dioestrus. Oestradiol-treated OVX rats (OVX+E) displayed marked reduction in FRA/TH-ir neurones in LC compared to oil-treated OVX rats. Accordingly, oestradiol superfusion significantly reduced the spontaneous firing rate of LC neurones in slices from OVX rats. Compared to OVX+E, oestradiol-treated rats injected with progesterone at 08.00 h (OVX+EP) exhibited higher number of FRA/TH-ir neurones in the LC at 10.00 h and 16.00 h, and great amplification of the LH surge. Bath application of progesterone significantly increased the spontaneous firing rate of OVX+E LC neurones. Our data suggest that ovarian steroids may physiologically modulate the activity of LC neurones in females, with possible implications for LH secretion. Moreover, oestradiol and progesterone appear to exert opposite and complementary effects (i.e. whereas oestradiol inhibits, progesterone, after oestradiol priming, stimulates LC activity).

Pubertal exposure to thiodiazole copper inhibits thyroid function in juvenile female rats

Thiodiazole copper, as a thiadiazole fungicide, is widely used in China. The structure of thiodiazole copper shows a close relationship with N,N-methylene-bis (2-amino-1,3,4-thiadiazole) (Bis-A-TDA), which is a teratogen. A few studies have shown that some of the thiadiazole fungicides act as endocrine disruptors via disturbance in thyroid hormone homeostasis. Little is known about the effect of pubertal exposure to thiodiazole copper on the thyroid in pubertal female rats. Based on the protocol of the 20-day Pubertal Female Assay, we attempt to estimate the possible effects of exposure to thiodiazole copper on thyroid hormone and hepatic enzyme activity in female rats. Postnatal days (PND) 22-old Sprague–Dawley rats were administered with thiodiazole copper daily by oral gavage at doses 0, 4, 10, 20 or 30 mg/kg/day for 20 days. After treatments, the rats were sacrificed for blood collection; the reproductive organs, liver, pituitary, adrenal and thyroid gland were harvested. The results indicated that changes in thyroid endpoints following thiodiazole copper administration decreased serum triiodothyronine (T 3) and thyroxine (T 4) concentrations, increased thyroid stimulating hormone (TSH) concentrations and the weight of thyroid gland, induced hepatic uridine diphosphate glucuronyl transferase (UDPGT) activities in the highest dose group and produced thyroid gland hyperplasia. No histological changes were observed in uterus and ovaries moreover, age and weight at vaginal opening (VO) were unaffected by thiodiazole copper in all treatment groups. The absolute weights of liver and kidney were found to have decreased significantly in female rats. These data and changes demonstrate that thiodiazole copper is likely a thyroid disrupter in female rat following exposure during development, but doesnot have effect on the development of pubertal female rats. Further studies using environmentally relevant doses are needed for hazard identification.

Pubertal exposure to saisentong: Effects on thyroid and hepatic enzyme activity in juvenile female rats

Saisentong, as a thiadiazole fungicide, is widely used in China. The structure of saisentong shows a closer relationship to N, N-methylene-bis (2-amino-1, 3, 4-thiadiazole) (Bis-A-TDA), which is a teratogen. A few studies have shown that some of the thiadiazole fungicides act as endocrine disruptors via disturbance in thyroid hormone homeostasis. Little is known about the effect of pubertal exposure to saisentong on the development in pubertal female rats. Based on the protocol of the 20-Day Pubertal Female Assay, we attempt to estimate the possible effect of exposure to saisentong on thyroid hormone and hepatic enzyme activity in female rats. Postnatal days (PND) 22 old SD rats were administered with saisentong daily by oral gavage at doses of 0, 5, 10 or 15 mg/kg/day for 20 days. After treatment, the rats were sacrificed for blood collection; the reproductive organs, liver, pituitary, adrenal and thyroid gland were harvested. The results indicated that saisentong administration increased thyroid weight and thyroid stimulating hormone (TSH) concentrations, and induced hepatic uridine diphosphate glucuronyl transferase (UDPGT) activities in the highest-dose group, although not statistically significant. The high dose caused a decrease in weight at vaginal opening (VO), but the age at VO was unaffected by saisentong in all treatment groups. No histological changes were observed in uterus and ovaries. These data and changes demonstrate that saisentong is a potential thyroid disrupter in female rat following exposure during development, but does not affect the development of pubertal female rats.

Effects of sex hormones on metabolic rate, ventilation and respiratory‐related upper airway muscle activities in female rats

We tested the hypothesis that changes in sex hormones in female rats resulting from ovarian failure induced by exposure to 4‐vinylcyclohexene diepoxide (VCD) alter metabolism, ventilation and respiratory‐related upper airway muscle activities.Two groups of Fischer‐344 female rats were used, one group injected daily with VCD, 80 mg/kg i.p. for 25 days (N=5), the other an age‐matched control group (N=5) injected daily with sesame oil. We obtained in‐vivo measures of VCO2/VO2, tidal volume (VT ) and breathing frequency (FR) using a sealed whole‐body plethysmography chamber. In the same animals, we recorded EMG activities of hyoglossus (HG) and genioglossus (GG) muscles and esophageal pressure (Pes) under urethane anesthesia in hyperoxia (FICO2=0) and hyperoxic hypercapnia (FICO2=0.03, 0.06, 0.09, 0.12 balance O2).Preliminary data reveal increased basal VO2, VCO2 and the ratio of VCO2/VO2 for VCD treated rats relative to age‐matched controls. Measures of ventilation and whole muscle EMG were comparable for the two groups in hyperoxia whereas VCD treated rats exhibited a trend toward higher VT and FR and greater average GG and HG EMG activities in hyperoxic hypercapnia relative to the age‐matched controls.These studies provide preliminary insights into metabolic rate, ventilation and respiratory‐related upper airway activities as a function of ovarian failure in age‐matched controls.

Androgenic activity of the Thai traditional male potency herb, Butea superba Roxb., in female rats

Aim of the study Butea superba Roxb. (Leguminosae) is a well-known Thai male potency herb with androgenic and anti-estrogenic activities. We evaluated whether oral administration of Butea superba has an androgenic or anti-estrogenic activity in female rats. Materials and methods Normal and ovariectomized adult female rats were each subdivided into five groups, DW, BS-10, BS-50, BS-250 and TP, and gavaged with 0, 10, 50 and 250 mg/kg BW/day of the crude of Butea superba and subcutaneously injected with 6 mg/kg BW/day of testosterone propionate (TP), respectively, during the treatment period. Results In intact rats, only BS-250 increased the uterine thickness and the number of uterine glands, and could induce a prolonged diestrous phase. In ovariectomized rats, treatment with BS-50 as well as BS-250 increased the uterine thickness and the number of uterine glands. However, serum luteinizing hormone (LH) levels were also increased. TP reduced serum follicle stimulating hormone and LH levels with the appearance of anestrous cycle, and could significantly increase the relative uterine weight and thickness and the number of uterine glands in both intact and ovariectomized rats. Conclusions Orally administered Butea superba tubers have an androgenic effect on the reproductive organs of intact and ovariectomized rats, and exhibit anti-estrogenic activity on LH secretion in ovariectomized rats.

Estrus cycle stage modifies the presentation of stress-induced startle suppression in female Sprague–Dawley rats

Tailshock stress causes transient reductions in startle reactivity, associative learning and open field activity in female rats in an ovarian hormone dependent manner. Others have shown estrogen modulation of associative learning by testing across the estrus cycle and pharmacological manipulations. Here we tested whether stress-induced suppression of startle reactivity can be attributed to circulating ovarian hormones. Female rats were tracked across the estrus cycle and subjected to the stressor (2 h periodic tailshock) the morning of diestrus, proestrus, estrus, or metestrus. Startle reactivity was tested 2 h following the cessation of the tailshock. Using a multi-stimulus protocol, we determined there were differences in startle sensitivity and responsivity. Following stressor exposure, estrus females exhibited reduced startle responsivity. In contrast, diestrus females exhibited increased sensitivity to the lowest acoustic stimulus. The results are discussed with respect to ovarian hormone regulation of the immune system and sensory reactivity during and following trauma that may lead to different abnormal behaviors in females in the wake of traumatic stress.