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PubMed1980

Estrogen metabolism in neural tissues of six-day-old rats.

In vitro incubation of pituitary, hypothalamus and cerebral cortex from 6-day-old rats with [6,7-3H]estradiol revealed that estradiol is actively metabolized in these tissues. Pituitary was found to be more active than hypothalamus and cerebral cortex in metabolizing estradiol in these animals. Covalent binding of estradiol to acid-precipitable proteins was observed in all these tissues from both sexes. While there was no significant sex difference in protein binding of estradiol in any of the tissues tested, treatment with progesterone or estradiol valerate increased protein binding. 2- and 16-hydroxylation and 17 beta-oxidation were demonstrated in all the tissues tested. While there were no significant sex differences observed in 2,16-hydroxylation, 17 beta-oxidation appeared to be more in males. Progesterone treatment of males increased 2-hydroxylation of estradiol 4-fold in pituitary and doubled the levels in hypothalamus. 16-Hydroxylation and 17-oxidation were also elevated significantly in pituitary and hypothalamus by progesterone treatment. Estradiol valerate treatment, however, decreased 2-hydroxylation and 16-hydroxylation in pituitary and hypothalamus; 17-oxidation was increased in pituitary. These results suggest that the estradiol metabolism, and especially 2-hydroxyestradiol formation, can be increased by progesterone and thereby mediate antagonistic effect of progesterone on estrogen-mediated brain sexual differentiation.

Animals↗
PubMed1985

Effect of single or repeated estrogen administration on tuberoinfundibular GABA neurons and anterior pituitary GABA receptors: biochemical and functional studies.

The effect of single or protracted administration of estradiol valerate on the hypothalamo-pituitary gamma-aminobutyric acid (GABA)ergic system and on plasma prolactin levels has been evaluated in female rats 2 months after the last (chronic treatment) or the single dose of the steroid. In the group of animals receiving one dose of estrogen, no modifications were detected in the activity of the tuberoinfundibular GABAergic neurons as implied by unchanged GABA accumulation either in the median eminence or the anterior pituitary after blockade of GABA catabolism with ethanolamine-O-sulphate. However, a complete disappearance of the low affinity population of GABA receptors in the anterior pituitary was observed. In this experimental condition, where baseline prolactin levels were 3-fold higher than in control rats, muscimol, a potent GABA agonist, was effective in significantly lowering plasma prolactin concentrations. Chronic estradiol valerate administration reduced GABA accumulation in the median eminence and the anterior pituitary at 4, but not at 2 h, after intracerebroventricular injection of ethanolamine-O-sulphate. Moreover, in this instance, a complete disappearance of the high affinity population of GABA receptors in the anterior pituitary was detected. Long-term estrogen administration induced also a 55-fold increase of plasma prolactin titers and muscimol was ineffective in reducing prolactin concentrations in plasma. The ability of muscimol to inhibit prolactin release only in single-estrogen-treated animals strongly suggests that the high affinity population of anterior pituitary GABA receptors is that involved in the mechanisms whereby GABA inhibits prolactin release from anterior pituitary.

Animals↗
PubMed1987

Estrogen-induced synaptic remodelling in adult rat brain is accompanied by the reorganization of neuronal membranes.

Adult cycling female rats were injected with estradiol valerate (2 mg/100 g body wt.), a treatment which has previously been shown to result in synaptic remodelling in the arcuate nucleus and constant vaginal estrus. During the 32 weeks following estrogen treatment, arcuate nucleus neuronal plasma membranes were quantitatively assessed for intramembrane particle (IMP) number and size using freeze-fracture techniques. Neuronal membranes from untreated cycling females, females injected with oil and untreated males were also studied. Untreated rats had dimorphic sexual phenotypes in membrane organization; female rats had more IMP than males, mainly due to greater numbers of small (less than 10 nm) particles. These sex differences were observed in perikarya and dendritic shafts, but not in dendritic spines. Following estrogen treatment the density of IMP in membranes from females decreased. The IMP changes were found only in neuronal perikarya and dendritic shafts, not in dendritic spines, and were mainly due to a massive decrease in the number of small (less than 10 nm) IMP which was only partially offset by an increase in the number of large (greater than or equal to 10 nm) IMP. Thus, by 32 weeks after estradiol valerate treatment, the number and size of IMP in neuronal membranes from females were not different from those seen in normal males. These results strengthen the idea that estradiol may affect the turnover of certain neuronal membrane components in sex-steroid sensitive areas of the brain.

Animals↗
PubMed1988

Estrogen treatment increases the density of D1 dopamine receptors in the rat striatum.

Adult, male rats were treated with 17 beta-estradiol valerate by s.c. injection of 125 micrograms/rat. Six days later the density and affinity of striatal D1 dopamine (DA) receptors were determined. Estrogen treatment significantly increased the density of D1 DA receptors without altering their affinity. In vitro co-incubation with 17 beta-estradiol 17 beta-estradiol valerate at concentrations up to 1.0 microM did not alter binding to D1 DA receptors.

Animals↗
PubMed1989

Interaction of N-alkylanthracyclines with lipid bilayers: correlations between partition coefficients, lipid phase distributions and thermotropic behavior.

The thermotropic behavior of multilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC), or of DPPC in admixture with cardiolipin or cholesterol, in the presence of various N-alkyl derivatives of both adriamycin and adriamycin-14-valerate has been investigated by high sensitivity differential scanning calorimetry. The analogues, particularly the 14-valerate derivatives, which were most lipophilic as judged by their lipid/buffer, and to a lesser extent by their octanol/buffer, partition coefficients, were the most effective in depressing the tm of the investigated lipids; correlations, however, were not absolute. Other factors, such as the distribution of the drugs between the solid and liquid-crystalline phases of the bilayer, were also important to the observed membrane perturbations. With all anthracyclines, however, no major changes in the transition enthalpy were observed. In the case of vesicles prepared from pure DPPC, curve fitting analysis based on ideal solution theory (J.M. Sturtevant (1984) Proc. Natl. Acad. Sci. USA 81, 1398-1400) applied at relatively low drug concentrations where single peak transitions were produced, adequately described the differential scanning calorimetric results. At high drug concentrations, however, the presence of multi-peak transitions were indicative of non-ideality.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1978

The variability of metabolite excretion in propionicacidaemia.

Random urine samples from eight patients with propionicacidaemia were analyzed by gas chromatography and mass spectrometry in order to see if a consistent metabolite pattern with a high diagnostic value could be found. However, wide variations were observed. The presence of 3-hydroxypropionate and/or methylcitrate were considered to be diagnostic of propionyl-CoA carboxylase deficiency. In addition, samples from ketotic periods frequently contained 3-hydroxy-n-valerate and 3-oxo-n-valerate.

Amino Acid Metabolism, Inborn Errors↗
PubMed1994

Metabolic effects of once-a-month combined injectable contraceptives. The World Health Organization Task Force on Long-Acting Systemic Agents for Fertility Regulation, Geneva, Switzerland.

The results of metabolic studies on once-a-month combined injectable contraceptives are summarized, focusing on four preparations: dihydroxyprogesterone acetophenide 150 mg/estradiol enanthate 10 mg; depot-medroxyprogesterone acetate 25 mg/estradiol cypionate 5 mg; norethisterone enanthate 50 mg/estradiol valerate 5 mg; and 17 beta-hydroxyprogesterone caproate 250 mg/estradiol valerate 5 mg. Their effects on carbohydrate metabolism, lipid metabolism, hemostasis, serum prolactin, cortisol, binding globulins and liver functions are reviewed. Areas requiring further research are identified.

17 alpha-Hydroxyprogesterone Caproate↗
PubMed1983

Effect of oestrogen replacement therapy on blood coagulation factors in postmenopausal women.

Natural oestrogens "Premarin", (Ayerst, conjugated equine oestrogens) "Harmogen", (Abbott, piperazine oestrone sulphate) and "Progynova" (Schering, oestradiol valerate) alone and in combination with proestational agents such as "Primolut N", (Schering, norethisterone) "Neogest", (Schering, norgestrel), "Norgeston", (Schering, levonorgestrel), "Duphaston" (Duphar, dydrogesterone) did not have adverse effects on clotting factors. One patient developed deep vein thrombosis following treatment using "Progynova" (oestradiol valerate) alone and a second patient suffered from mild myocardial infarction following the use of "Premarin" (conjugated equine oestrogens) alone.

Blood Coagulation↗
PubMed1984

Clinical evaluation of intramuscular injection of microencapsulated compound megestrol acetate.

A comparative clinical study was undertaken by the Sichuan Cooperative Research Group for Microencapsulated Contraceptives to assess the efficacy of intramuscular microencapsulated megestrol compound as a long-acting contraceptive and to find the optimal dosage as regards efficacy, side effects and menstrual irregularities. Eight hundred twenty eight women were divided into four groups and injected monthly with four different dosage combinations that consisted of megestrol acetate and estradiol valerate. In all, 5298 dosage cycles were observed. The investigation indicated that microencapsulation effectively prolonged contraceptive effect of the short-acting agents, reduced the required dosage and lowered the incidence of side effects. A combination of 15 mg megestrol acetate and 5 mg estradiol valerate, as compared to the other three regimens, was found to be clinically most acceptable because of the lower incidence of menstrual irregularities.

Adult↗
PubMed1976

Production and characterisation of antisera to diphenylhydantoin suitable for radioimmunoassay.

The effect of carrier protein, nature of hapten-carrier bridge, and density of hapten substitution on the immunogenicity of diphenylhydantoin (DPH) derivatives in rabbits is described. DPH-3-valerate-bovine serum albumin (BSA) with a hapten: protein ratio of 27: 1 yields antisera of high titre and specificity for DPH. An antiserum to DPH-valerate-BSA was employed to develop a rapid, sensitive, one stage double antibody radioimmunoassay suitable for clinical application to serum, saliva, and urine samples. The assay, using 14C-DPH as tracer, is accurate and precise over the range 0.5--50 mug DPH per ml. Results by radioimmunoassay correlate closely with those obtained by gas-liquid chromatography (r = 0.97).

Animals↗
PubMed1987

Baclofen induces catatonia in rats.

Baclofen (10 and 20 mg/kg, i.p.) induced catatonia in rats within 10 min of its administration and the effect lasted for 3 hr. Muscimol (100 ng i.c.v. or 1 mg/kg, i.p.) as well as GABA (5 micrograms i.c.v.) potentiated the effect without producing any effect per se. Bicuculline, bromocriptine and scopolamine failed to modify the catatonia induced by baclofen, thereby ruling out the involvement of GABAA receptors, dopaminergic and cholinergic mechanisms. However, GABAB receptor antagonists, such as homotaurine and delta-amino-n-valeric acid, reversed the catatonia induced by baclofen in rats. Since baclofen is known to bind to a subpopulation of GABA receptors (bicuculline-insensitive) and baclofen-induced catatonia was susceptible to reversal by homotaurine and delta-amino-n-valeric acid, it is suggested that this effect could be mediated through GABAB receptors.

Animals↗
PubMed1985

Neurotoxic esterase in rooster testis.

Neurotoxic esterase (NTE) is the putative target protein in the nervous system for the initiation of organophosphorus-induced delayed neuropathy. Here it is reported that NTE activity is present in rooster testis. Complete titration of rooster testis phenyl valerate esterases with paraoxon shows that about 15% of the enzymic activity is resistant to paraoxon. NTE activity after complete mipafox titration accounts for 30% of paraoxon-resistant phenyl valerate esterases and corresponds to 7.93 +/- 0.39 nmol/min/mg of protein (mean +/- SD, n = 7). Testis NTE is inhibited in vitro similarly to brain NTE by several organophosphorus compounds. Subcellular fractionation studies of the testis indicate that most NTE activity is particle bound. Testis NTE is also inhibited in vivo by several organophosphorus esters but to a lesser extent than brain NTE. Birds doses with organophosphorus compounds, causing delayed neuropathy, became grossly ataxic, but no testicular pathology was noted by light microscopy in roosters killed 15 days after administration. Serum testosterone levels also measured 15 days after dosing were not different from those of a control group. Recovery of NTE activity was faster in testis than in brain (4 days vs 6 days to recover to 50% of initial activity) in animals that received a high dose of an organophosphorus ester which cause delayed neuropathy.

Animals↗
PubMed1992

Control of FSH, follicular development and estrus synchronization in the mare with steroid-free follicular fluid.

Twenty-two pony mares were used in a project designed to determine the effectiveness of different treatments in controlling FSH, follicular development and synchronization of estrus and ovulation. Mares in Group 1 (n=8) received daily oral altrenogest (0.044 mg/kg); those in Group 2 (n=7) received daily altrenogest (0.044 g/kg) and, during the last 4 days of treatment they received steroid-free follicular fluid, (15 cc) intravenously (I.V.) two times a day; Mares in Group 3 (n=7) received daily intramuscular (I.M.) injections of progesterone (80 mg) and estradiol valerate (7 mg). All treatments lasted for 10 days, at the end of which prostaglandin (PgF(2)alpha, 10 mg) was administered. Sexual behavior, follicular development and FSH concentrations were monitor daily. Concentrations of FSH in Group 2 mares, were not significantly different (P>0.05) from those of Group 1 until the mares in Group 2 were treated with follicular fluid (P<0.05). Concentrations of FSH in Group 3 mares, were significantly lower than those of Groups 1 and 2 (P<0.05) until the mares in Group 2 were treated with steroid-free follicular fluid. At this point there was no significant difference between groups 2 and 3 (P>0.05). Steroid-free follicular fluid appears to induce atresia in larger follicles (>11 mm), and the initiation of new follicular wave. The combination of progesterone and estradiol valerate appears to delay follicular growth and not to induce atresia, since larger follicles (>11 mm) continued to grow after treatment. Both treatments (groups 2 and 3) resulted in ovulations within 5 days period. The treatment in Group 1 did not have any effect on FSH or follicular development and ovulations were dispersed through a 9-day period. We concluded that steroid-free follicular fluid offers a new possibility to synchronize ovulation in the mare by controlling FSH and follicular development.

Journal Article↗
PubMedDate not supplied

Estrogen induction of glial heat shock proteins: implications for hypothalamic aging.

In the aging mammalian hypothalamus, a unique subpopulation of glial cells accumulates peroxidase-positive cytoplasmic inclusions distinct from lipofuscin. In adult rodents, this senescence-dependent glial granulation is accelerated by administration of estradiol valerate. In the present study, brain sections derived from male rats given 3 monthly intramuscular injections of estradiol valerate (0.2 mg or 2.0 mg) were immunostained for heat shock proteins and glial fibrillary acidic protein to determine whether a glial stress response is implicated in estrogen-induced granulation. Our findings indicate that estrogen elicits a heat shock response and subsequent granulation in astrocytes residing in estradiol receptor-rich brain regions including the arcuate nucleus and the wall surrounding the third ventricle but not in estradiol receptor-deficient regions such as the striatum and corpus callosum. The heat shock proteins induced by estrogen, namely, the 27, 72, and 90 kDa stress proteins, are upregulated in astrocytes in response to oxidative challenge supporting our hypothesis that estrogen mediates senescent changes in the rodent hypothalamus through oxidative mechanisms.

Aging↗
PubMed1975

Androgen-dependent accumulation of carnitine by rat epididymis after injection of [3H]butyrobetaine in vivo.

After i.m. injection of [3H]butyrobetaine into rats, the accumulation of carnitine into the epididymis, prostate gland, seminal vesicles, testis and heart was studied. The concentration of radiolabeled carnitine into the cauda epididymis increased linearly with time up to 72 h after the injection of the precursor, while its level in the prostate and seminal vesicles decreased rapidly. Very low levels of carnitine were found in the testis. Castration reduced the carnitine accumulation by cauda epididymis to 6% of the control levels while treatment of castrated animals with testosterone propionate (500 mug/day) partly restored the carnitine uptake. Similar treatment with 17beta-oestradiol valerate or 17alpha-hydroxyprogesterone had no effect. Surprisingly, cyproterone acetate (5 mg/day) also significantly stimulated carnitine accumulation by the epididymis to a level above that of the castrated controls. Simultaneous injection of both cyproterone acetate and testosterone propionate to castrated animals caused an additive effect of these steroids. This indicated that cyproterone acetate in this system is working as a weak androgen. Treatment of rats with 17beta-oestradiol valerate also reduced carnitine accumulation by the cauda epididymis. This is due to suppression of pituiatry gonadotrophin secretion, since concommitant treatment with testosterone propionate (500 mug/day) caused a normalization of the carnitine uptake. Treatment of intact rats with cyproterone acetate significantly reduced the epididymal weight, but not the carnitine accumulation. 17alpha-Hydroxyprogesterone treatment had no effect either on the epididymal weight or the accumulation of the carnitine. Unilateral orchiectomy reduced the carnitine accumulation by the cauda epididymis to about 40% of that occurring in the non-operated control side. This indicates that the luminal contact between the testis and epididymis or the luminal content of the epididymis itself is of importance for the androgen-dependent metabolic process occurring in the cauda epididymis. Castration or hormone treatment did not change the conversion of butyrobetaine to carnitine, or the carnitine uptake by heart. Carnitine uptake by the testis after [3H]butyrobetaine injection was rather low and this would exclude the possibility of synthesis of carnitine in the testis as a source of epididymal carnitine. Carnitine only accumulated in the cauda epididymis in vivo 4 to 96 h after injection of [3H]butyrobetaine. The presence of radioactively labeled butyrobetaine or methylcholine was not detected.

Animals↗
PubMed1992

Detecting changes in neuronal activities induced by N-methyl-D-aspartate receptor blockade using non-linear dynamics techniques.

The dynamics of N-methyl-D-aspartate receptor blockade-induced transitions between two types of intracellularly recorded spontaneous membrane potential oscillation from cat thalamic neurons have been studied using non-linear dynamics techniques. We report that, as previously predicted by theoretical studies, the number of degrees of freedom of these oscillations (the minimal number of independent variables governing the activity) is small, i.e. they are low dimensional. The N-methyl-D-aspartate receptor antagonists DL-2-amino-5-phosphono-valeric acid and ketamine, which transformed one type of oscillation into another, decreased the calculated dimension. DL-2-Amino-5-phosphono-valeric acid had no effect on the dimension when Mg2+ was present in the perfusion medium. The decrease in dimension was gradual and its time-course had a sigmoidal shape. It is suggested that the application of the machinery of dynamical systems theory might help to detect and monitor drug-induced membrane potential state transitions and to identify the factors underlying membrane potential oscillations.

2-Amino-5-phosphonovalerate↗
PubMed1994

An investigation of activities and paraoxon sensitivities of hepatic aliesterases in beta-naphthoflavone-treated rats.

Aliesterases (carboxylesterases, EC 3.1.1.1) are serine esterases which may protect acetylcholinesterase during organophosphorus insecticide intoxication by providing alternative phosphorylation sites. Levels of hepatic aliesterase activity were investigated after the intraperitoneal administration of beta-naphthoflavone (BNF) to female rats using nine 4-nitrophenyl esters as substrates (including straight and branched chain aliphatic and aromatic esters) and 1-naphthyl acetate. In addition, the in vitro sensitivities of aliesterases to inhibition by paraoxon, the active metabolite of the common insecticide parathion, were studied. Hepatic aliesterases from BNF-treated rats displayed lower activities than those from the controls with all substrates except 4-nitrophenyl phenylbutyrate and isovalerate. The aliesterases from BNF-treated rats were more sensitive to paraoxon inhibition with 4-nitrophenyl phenylbutyrate, valerate, and butyrate. Esterases hydrolyzing 4-nitrophenyl butyrate, valerate, and branched chain esters were most sensitive to paraoxon inhibition while those hydrolyzing 4-nitrophenyl hexanoate and aromatic esters were least sensitive. The results suggested that BNF-induced changes in hepatic aliesterases could alter responses to organophosphates.

Animals↗
PubMed1984

Skinfold thickness and long-term post-menopausal hormone therapy.

Skinfold thickness was measured in 130 post-menopausal women treated with long-term hormone therapy. One group of 50 women took oestradiol valerate 2 mg/day for 3 wk out of 7, a second group comprising 19 women received oestriol succinate 2 mg/day and the remaining group of 61 women used oestradiol valerate 2 mg/day combined sequentially with norgestrel 0.5 mg/day. The duration of treatment in these groups was 6.3 +/- 0.4, 6.4 +/- 0.4 and 3.3 +/- 0.3 yr, respectively. The control group was made up of a further 89 post-menopausal women. The skinfold thickness in all the treated groups was significantly greater than that in the controls.

Estradiol↗