Search Results
Results 251 - 300 of 860
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Cheuk B L - - 2000
Bradykinin and a number of peptide hormones such as angiotensin, endothelin, and vasopressin stimulate anion secretion in rat epididymis via local formation of PGE(2). These effects are mediated by cyclooxygenase (COX)-1 isozyme. The present study was undertaken to assess the androgen control of COX expression in the epididymis. Adult male ...
Nishi N - - 2000
The rat prostate is dependent on androgen for normal growth and differentiation. In addition, the organ undergoes rapid cell death upon withdrawal of androgen on castration, and the atrophied tissue is capable of regrowth after androgen replacement in adult animals. In our search for novel factor(s) that participate in this ...
Ventura S - - 2000
This study investigated the presence and effects of calcitonin gene-related peptide (CGRP) within the rat and guinea-pig prostate glands. Immunohistochemical studies demonstrated that CGRP immunoreactive nerve fibres are sparsely distributed throughout the prostatic fibromuscular stroma in both species. These CGRP immunopositive nerve fibres shared a similar distribution profile but were ...
Boileau T W - - 2000
Diets rich in lycopene from tomato products as well as greater concentrations of blood lycopene have been associated with a decreased risk for prostate cancer in epidemiologic studies. However, little is known about factors modulating lycopene absorption, metabolism and tissue distribution in humans and animal models of prostate cancer. A ...
Ichihara G - - 2000
1-Bromopropane has been newly introduced as an alternative to ozone-depleting solvents. We aimed to clarify its dose-dependent reproductive toxicity in male rats. Thirty-six Wistar male rats were randomly divided into 4 groups of 9. The groups were exposed to 200, 400, or 800 ppm 1-bromopropane or only fresh air, 8 ...
Tørring N - - 2000
Epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) are strong inducers of proliferation to prostate cells cultured in serum-free medium. Accordingly we wanted to study the growth of the prostate gland in castrated rats after treatment with EGF, IGF-I and testosterone. Castrated Wistar rats were treated with growth ...
Van Coppenolle F - - 2000
BACKGROUND: The growth of the prostate gland is mainly dependent on androgens. Other hormones, like prolactin (PRL), also influence prostate development. Our purpose was to analyze and compare the effects of two drugs (5alpha-reductase inhibitor) used in the therapy of benign prostatic hyperplasia: lipidosterolic extract of Serenoa repens (LSESR), and ...
Sabry I - - 2000
OBJECTIVE: To investigate the effect of castration, bromocriptine and cyproterone acetate treatment on lysosomal hydrolytic enzymes and ultrastructure of the rat Harderian gland. METHODS: Groups of rats were subjected to the treatment by bromocriptine, cyproterone acetate and castration. Harderian glands were dissected from each experimental animal cut into small pieces ...
Leung P S - - 2000
Evidence for the existence of an intrinsic angiotensin system based on locally formed angiotensinogen as a precursor for angiotensin production has been demonstrated in the rat epididymis. The data strongly support the presence of an epididymal renin-angiotensin system (RAS) which may be important for epididymal and sperm functions. In the ...
Frye C A - - 2000
Testosterone (T), dihydrotestosterone (DHT), 3alpha-diol (5alpha-androstane-3alpha,17beta-diol), or vehicle was administered daily to gonadectomized, adrenalectomized male Long-Evans rats. Four days after adrenalectomy (ADX), animals were tested for inhibitory avoidance. Vehicle-treated rats had shorter latencies than 3alpha-diol-treated rats and non-corticosterone-depleted rats. All three androgens significantly reduced the number of pyknotic cells in ...
Stuart G R - - 2000
Male lacl transgenic rats were fed a diet containing 200 ppm of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a heterocyclic amine present in cooked meats. PhIP was found to be a powerful prostate mutagen. After 61 days of treatment, the lacl mutant frequency was 71 x 10(-5), >20-fold higher than the spontaneous mutant frequency ...
Pavlov V - - 2000
Effects of testosterone (10 micrograms/100g body weight) on polyamine-oxidizing enzyme activities in female rat uterus, liver and kidney were demonstrated. Testosterone-treated rats exhibited 2.07 fold (p < 0.002) higher uterine polyamine oxidase (PAO) activity and 1.93 fold (p < 0.02) higher diamine oxidase (DAO) activity, as compared to the controls. ...
Jotova I - - 2000
Ornithine decarboxylase (ODC) and diamine oxidase (DAO) are important enzymes involved in the metabolism of polyamines (putrescine, spermidine and spermine). The influence of testosterone (T) and 17, beta-estradiol (E2) on the activity of ODC and DAO was examined in cultivated normal rat kidney (NRK) epithelial cells. The results showed an ...
Shioya N N Department of Laboratory Animal Science, School of Veterinary Medicine, Azabu University, Kanagawa, - - 2000
The influence of castration on the development of the thymus in neonatal rats was studied to elucidate when after birth the thymus comes under inhibitory regulation by the testis in rats. The relative and absolute weights of the thymus were measured five days after castration these cases. No excessive changes ...
Harley C W - - 2000
Estrogen has been reported to enhance CA1 functional plasticity in adult rats, as measured by the induction of long-term potentiation (LTP). In the present study, the effects of androgens on CA1 LTP were assessed in adult male Sprague-Dawley rats in vivo following peripubertal castration. Castrated rats with cholesterol implants showed ...
Lin H - - 1999
Evodiamine, a bioactive component isolated from the Chinese medicine Wu-chu-yu, exhibits vasodilative and antianoxic action. Although evodiamine indeed has many biological effects, its effects on the endocrine system are not clear. The present study explored the effects of evodiamine on testosterone secretion in vitro. Rat collagenase-dispersed testicular interstitial cells (TICs) ...
Seo S I - - 1999
AIM: To investigate the effects of androgen on penile erection through the reflex arc and penile corpus cavernosum, and study the respective roles of testosterone (T) and dihydrotestosterone (DHT) in penile erection in rats. METHODS: Male Sprague-Dawley rats were castrated and implanted with silastic brand silicone tube containing T or ...
Zhang X H - - 1999
AIM: To investigate the effect of androgen on the structure of corpus cavernosum. METHODS: Thirty mature rats were randomized into 3 groups, i.e., simple castration, castration with testosterone (T) supplementation and sham-operated controls. One week after operation, the animals were sacrificed and corpora cavenosa harvested. Apoptosis was detected with the ...
Slater M - - 1999
Avidin binds to damaged DNA with high specificity. Avidin conjugated to horseradish peroxidase may therefore be used to label apoptotic DNA damage, using standard immunohistochemical protocols. However, the resulting label may be too weak to visualise. We used tyramide signal amplification to enhance the avidin-peroxidase signal in a rat model ...
Hayek O R - - 1999
PURPOSE: Previous studies demonstrating a rapid and drastic reduction of blood flow to the rat prostate gland resulting from castration caused us to consider the influence of castration on the state of vascular constriction and on the activity of the vascular tone-regulating factors (nitric oxide synthase and cyclic GMP) in ...
Takechi S - - 1999
The pathogenesis of nonbacterial prostatitis (NBP) is not understood mainly due to the lack of appropriate experimental models. We developed a new experimental model of NBP by inducing a partial obstruction of the urethra (PUO) in the rat. Male Wistar rats aged 12 weeks were used. PUO was produced by ...
Marin R - - 1999
Androgens are known to influence penile erection and nitric oxide synthase (NOS) activity in cavernosal tissue homogenates. The present study was an assessment of the effects of castration and androgen replacement on the in vivo release of nitric oxide (NO), and of the simultaneously recorded intracavernosal pressure (ICP) changes elicited ...
Silva M A - - 1999
In the present study, we investigated the alpha1-adrenoceptor subtypes mediating adrenaline-induced contractions of the rat seminal vesicle by using functional studies. The reverse transcription combined with polymerase chain reaction (RT-PCR) was also used to identify of alpha1-adrenoceptor mRNA subtypes. The rank order of potency of alpha1-adrenoceptor antagonists in blocking the ...
Tilakaratne A - - 1999
BACKGROUND: Androgens, particularly 5alpha-dihydrotestosterone (DHT), have anabolic effects on connective tissues and bone with implications on periodontal healing. This can be enhanced by estradiol-17beta (E-17beta), in synergy with androgen action. The effects of progesterone (P) contribute to plaque-induced inflammatory changes. The aim of this investigation was to study the modulation ...
Windmill K F - - 1999
In previous studies, we have shown that castration of Sprague-Dawley rats enhances thymic weight through puberty whilst sex steroids reduce the castration-induced hypertrophy. In the current study, we have confirmed that castration enhances thymic growth compared to age-matched intact controls. In addition, immunoassays were used to measure thymosin alpha1 and ...
de la Taille A - - 1999
BACKGROUND: Fas antigen/CD 95 is a 45-kDa transmembrane protein that can initiate intracellular signaling pathways, leading to apoptosis when it is clustered on the cell surface. A recent report claiming that the ventral prostate glands of lpr -/- mutant mice (lacking functional fas antigen) do not regress following castration prompted ...
Angelsen A - - 1999
BACKGROUND: Androgens are implicated in the pathogenesis of prostatic carcinoma. We have elucidated the role of pre- and postnatal testosterone administration in the occurrence of proliferative lesions as well as neuroendocrine (NE) cells in the rat prostatic complex. METHODS: Female rats were given a single dose of 9 mg testosterone ...
Huang W J - - 1999
The goal of this study was to characterize the mechanism by which hyperprolactinemia alters testosterone production in rat testicular interstitial cells (TICs). Hyperprolactinemia was induced by grafting 2 anterior pituitary (AP) glands under the subcapsular space of the kidney in experimental rats. Control rats were grafted with brain cortex (CX). ...
Wang S W - - 1999
Both in vivo and in vitro experiments were conducted to determined the effects of digitoxin on the secretion of testosterone, and its underlying mechanisms including testicular adenosine 3':5'-cyclic monophosphate (cAMP), and the activities of steroidogenic enzymes. Male rats were injected with digitoxin, human chorionic gonadotropin (hCG), or hCG plus digitoxin ...
Chiao Y C - - 1999
The effects of a thyroidectomy and thyroxine (T4) replacement on the spontaneous and human chorionic gonadotropin (hCG)-stimulated secretion of testosterone and the production of adenosine 3',5'-cyclic monophosphate (cAMP) in rat testes were studied. Thyroidectomy decreased the basal levels of plasma luteinizing hormone (LH) and testosterone, which delayed the maximal response ...
Wimalawansa S M - - 1999
Microgravity causes rapid decrement in musculoskeletal mass is associated with a marked decrease in circulatory testosterone levels, as we reported in hindlimb-suspended (HLS) rats. In this model which simulates microgravity, we hypothesized that testosterone supplementation should prevent these losses, and we tested this in two studies. Muscle volumes and bone ...
Shabsigh A - - 1999
BACKGROUND: There is growing interest as to the potential role of the prostatic vascular system in mediating the effects of androgenic steroids on growth control of the prostate. Here we describe the use of a vascular corrosion casting technique that enables the visual characterization of the vascular system of the ...
Poletti A - - 1999
In the rat brain, several steroids can be converted by specific enzymes to either more potent compounds or to derivatives showing new biological effects. One of the most studied enzyme is the 5alpha-reductase (5alpha-R), which acts on 3keto-delta4 steroids. In males, testosterone is the main substrate and gives rise to ...
Campos M G - - 1999
Norethisterone (NET) and its metabolite 5alpha-norethisterone (5alpha-NET) are competitors for the androgen receptor. The sensitivity of the rat vas deferens to the contractile action of methoxamine and serotonin is regulated by hormonal and anatomical factors. The aim of this study was to evaluate the ability of NET and 5alpha-NET to ...
Foster B A - - 1999
The studies presented herein quantitated ductal branching morphogenesis in the anterior prostate (AP) of the newborn rat. Four parameters were measured: epithelial area, epithelial perimeter, node number, and form factor. Nine natural and synthetic androgens were tested for their effectiveness in inducing postnatal prostatic development using 808 newborn rat APs ...
Xue Y - - 1999
Tenascin (tenascin-C), a mesenchymal glycoprotein, is expressed in many tissue remodeling processes. We evaluated tenascin expression during androgen-deprivation-related involution of the rat prostate. At set intervals following castration and subsequent testosterone repletion, prostates were removed in 30 adult rats. Each prostate was immunostained with a polyclonal antiserum against rat tenascin ...
Veräjänkorva E - - 1999
The presence of sperm antibodies correlates with nearly every pathological condition of the male reproductive tract. In the seasonal breeder, mink, a decrease in gonadotrophin secretion and testicular regression also induces sperm antibodies. Because the Sertoli cells and the principal cells of the epididymis (i.e. the cells mainly responsible for ...
Lin H - - 1998
1. In vivo and in vitro experiments were performed to examine inhibitory effects of digoxin on testosterone secretion and to determine possible underlying mechanisms. 2. A single intravenous injection of digoxin (1 microg kg(-1)) decreased the basal and human chorionic gonadotropin (hCG)-stimulated plasma testosterone concentrations in adult male rats. 3. ...
Banerjee P P - - 1998
We showed previously that exogenously administered testosterone caused age- and lobe-specific overgrowth of the prostate in Brown Norway rats. A common feature observed in testosterone-treated animals was cell hypertrophy in each of the ventral, dorsal, and lateral lobes of both young (6 mo old) and old (24 mo old) rats. ...
Maruyama K - - 1998
1. The present study was designed to assess the displacement potencies of tamsulosin to 3H-prazosin bindings in two alpha1-adrenoceptor (AR) subtypes (alpha1H and alpha1L) in bovine prostate, rat heart and brain compared with those of amosulalol, labetalol, ketanserin, clonidine and propranolol. 2. The pKi values of tamsulosin to alpha1H and ...
Park M S - - 1998
OBJECTIVE: To evaluate the long-term effects of infarction, which usually induces organ atrophy, on the prostate by examining the changes occurring in rat ventral prostate after infarction. MATERIALS AND METHODS: The unilateral arteriolar branches to the ventral prostate were electrocauterized under an operative microscope in 10 adult rats. The gross ...
Shabsigh R - - 1998
OBJECTIVES: The androgen sensitivity of the mammalian penis has long been appreciated. However, the precise biochemical and structural sequelae of alterations in testosterone, and the mechanisms thereof, remain to be elucidated. Recently, the androgen dependence of rat penile erectile tissue was further clarified at our institution, where the induction of ...
Nnane I P - - 1998
The effects of some novel steroidal compounds were evaluated against both human C17,20-lyase and 5alpha-reductase in vitro and also against androgen synthesis in normal male rats. L-2, L-36, L-37, and I-41 showed potent inhibition of human testicular C17,20-lyase, with IC50s of 43, 39, 42, and 58 nM, respectively. In contrast, ...
Watson M A - - 1998
We examined the influence of androgens on fetal medial basal hypothalamic and preoptic area (MBH-POA) calbindin-D28K levels (via Western analysis) by treating pregnant rats with testosterone or flutamide, (an androgen receptor blocker). MBH-POA calbindin-D28K levels were significantly decreased in flutamide-treated male fetuses, whereas, MBH-POA calbindin-D28K levels were significantly increased in ...
Shabsigh A - - 1998
BACKGROUND: Androgenic steroids regulate the development and size of the mammalian prostate gland. The mechanism(s) for this growth control might involve a direct effect on prostate cell proliferation and survival as well as more complex effects on the tissue environment supporting nourishment and oxygenation. In this study, we evaluated an ...
Veeramachaneni D N - - 1998
BACKGROUND: A previous study revealed that exposure of rats to microgravity for 14 d on Cosmos 2044 reduced production of testosterone by > 80%, although spermatogenesis remained essentially normal. METHODS: To ascertain if testicular function was altered in hypergravity, 60-d-old rats were randomly assigned to 2 groups (10 per group) ...
Lephart E D - - 1998
We investigated medial basal hypothalamic-preoptic area (MBH-POA) 5alpha-reductase and aromatase enzyme activities in gonadally intact and castrated adult Long-Evans (L-E) male rats treated with testosterone (T), progesterone (P), and a combination of T+P. MBH-POA 5alpha-reductase and aromatase activities did not differ significantly among the groups. The lack of a difference ...
Liu Y J - - 1998
To investigate the effects of thyroid hormone and testosterone on 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), we measured changes in hepatic 11beta-dehydrogenase activity and its mRNA levels in pubertal methimazole (MMI)-induced hypothyroid male rats following treatment with thyroxine ([T4] 50 microg/kg/d) or testosterone (250 microg/d) for 14 days. Hypothyroidism in male ...
Tørring N - - 1998
BACKGROUND: Epidermal growth factor (EGF) induces proliferation in prostate epithelial and stromal cells in primary culture. This investigation was set up to characterize the time and spatial expression of EGF in the rat prostate. METHODS: The expression of EGF was characterized in the distinct lobes of the rat prostate by ...
Diserio G P - - 1998
PROBLEM: In rats, immunization with male accessory gland (MAG) extract promotes experimental autoimmune vesicle prostatitis. A specific mononuclear cell-mediated immune response and prostate androgen metabolism impairment in MAG-immunized rats were observed. The possibility that lymphocytic soluble factors (SoFs) can regulate the local steroid metabolism in these rats directly was studied. ...
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