The untranslated first exon ''exon 0S'' of the rat estrogen receptor (ER) gene

Occasionally, ipsilateral ischemia develops following the groin insertion of an intra-aortic balloon catheter. Various treatment options have evolved, and include replacing the catheter in the opposite groin, removing it completely, or performing a femorofemoral bypass to deliver blood flow below the catheter. Outlined in this paper is a simple method to restore blood flow to a threatened limb, during femoral artery exploration, in the presence of an intra-aortic balloon. This method is also appropriate for optimal positioning of the balloon catheter prior to femorofemoral bypass.     

Chronic morphine administration increases beta-adrenergic receptor kinase (beta ARK) levels in the rat locus coeruleus

Based on the established role of beta-adrenergic receptor kinase (beta ARK) and beta-arrestin in the desensitization of several G protein-coupled receptors, we investigated the effect of chronic morphine administration on beta ARK and beta-arrestin levels in selected brain areas. Levels of beta ARK were measured by blot immunolabeling analysis using antibodies specific for two known forms of beta ARK, i.e., beta ARK1 and beta ARK2. It was found that chronic morphine treatment produced an approximately 35% increase in levels of beta ARK1 immunoreactivity in the locus coeruleus, but not in several other brain regions studied. In contrast, chronic morphine treatment failed to alter levels of beta ARK2 immunoreactivity in any of the brain regions studied. Levels of beta-arrestin immunoreactivity, measured using an antiserum that recognizes two major forms of this protein in brain, were also found to increase (by approximately 20%) in the locus coeruleus. It is proposed that chronic morphine regulation of beta ARK1 and beta-arrestin levels may contribute to opioid-receptor tolerance that is known to occur in this brain region.     

Intracerebroventricular administration of angiotensin type 1 (AT1) receptor antisense oligonucleotides attenuate thirst in the rat

Chinese hamster ovary cells were pulse-labeled with 125I-iododeoxyuridine during early S phase, and cell samples were harvested 30 min or 5 h after labeling. The samples were frozen (with or without 25 mM cysteamine) and stored at -196 degrees C for accumulation of 125I decays. X-ray control experiments were performed at 37 degrees C and -196 degrees C. Aliquots of cells were plated for evaluating micronucleus formation and cell survival. The results demonstrated a striking shift in micronucleus formation and cell death with time after labeling. Cells frozen 30 min after labeling exhibited effects typical of low-LET radiation, but cells frozen 5 h after labeling showed a response characteristic of high-LET radiation. Cysteamine provided protection against the effects of 125I during the initial phase of effects characteristic of low-LET radiation, but no protection was seen during the phase characteristic of high-LET radiation. When cell survival was evaluated as a function of micronucleus frequency rather than dose in decays/cell, the survival curves for all treatment groups became superimposed. Previous work using the same experimental system had failed to show a direct link between 125I-induced DNA double-strand breaks and cell death. These findings are consistent with the hypothesis that DNA damage may not be the sole mechanism for cell killing and that damage to higher-order structures in the cell nucleus may contribute to (or modify) radiation-induced cell death.     

Excretion of 35S-Tobias acid (2-naphthylamino, 1-sulphonic acid) by the rat after oral and intravenous administration

The lipid-lowering effects of 3 g of the nicotinic acid derivative pentaerythritoltetranicotinate (niceritrol) given either 1 g X 3 or 1.5 g X 2 have been evaluated in 18 subjects with hyperlipoproteinaemia. When 1 g niceritrol was given three times daily, the serum TG concentration fell from 3.14 +/- 0.48 to 1.86 +/- 0.18 mmol/1 (41% reduction) and the serum cholesterol concentration from 282 +/- 9 to 227 +/- 11 mg/100 ml (20% reduction). The same daily dose, given 1.5 g twice, did not significantly lower the serum TG concentration, and serum cholesterol was lowered by only 12%. Niceritrol tablets prepared with a dissolution time of 60 or 90 min had identical lipid-lowering properties. Although patients may find it practical to take niceritrol only twice daily, such a dose regimen has considerably less effect on elevated serum lipids than a thrice-daily regimen.     

Accumulation of (-)-epicatechin metabolites in rat plasma after oral administration and distribution of conjugation enzymes in rat tissues

Absorption of orally administered (-)-epicatechin (EC) in rats was studied to obtain plasma pharmacokinetic profiles of EC metabolites. Rats were administered 172 micromol/kg body weight of EC, and blood was collected from the tail for 8 h after administration. Seven groups of compounds possessing the basic structure of EC were identified by using a combination of enzymatic hydrolysis, HPLC and electron impact mass spectrometry. Metabolites were quantified with a new, simple and sensitive method using HPLC with electrochemical detection. Ingested EC was absorbed from the alimentary tract and was present in the rat common blood circulation in the form of glucuronide and/or sulfate conjugates. The activity of conjugative enzymes in rat tissues was studied. The highest activity of glucuronosyltransferase was found in the intestinal mucosa of both of the small and large intestine; the highest activity of phenolsulfotransferase occurred in the liver, and that of catechol-O-methyl transferase was found in the liver and kidney. It has been proposed that the first detoxification step of dietary EC, namely, glucuronidation, occurs at the level of the intestinal mucosa in rats, and EC enters the common blood circulation exclusively in the glucuronized form. The compound is then sulfated in the liver and methylated in the liver and kidney. Because ingested EC undergoes extensive conjugation, its biological activities previously demonstrated in vitro may not be occurring in in vivo systems.     

Expression of GABA(A) receptor subunits in the hippocampus of the rat after kainic acid-induced seizures

The GABA(A) receptor is a ligand gated chloride channel consisting of five membrane spanning proteins for which 13 different genes have been identified in the mammalian brain. The present review summarizes recent work from our laboratory on the characterization of the immunocytochemical distribution of these GABA(A) receptor subunits in the rat brain and changes in immunoreactivity and mRNA expression after kainic acid-induced status epilepticus. A heterogeneous distribution of immunoreactive GABA(A) receptor subunits was observed. The most abundant ones were: alpha1, alpha2, alpha4, alpha5, beta2, beta3, gamma2, and delta. Alpha1, beta2, and gamma2 were about equally distributed in all subfields of the hippocampus; alpha4- and delta-subunits were preferentially found in the dentate molecular layer and in CA1; alpha2 was localized to the dentate molecular layer and CA3; alpha5 was found in the dendritic areas of CA1 to CA3; and beta1 was preferentially seen in CA2. Alpha1, beta2, gamma2 and delta were highly concentrated in interneurons. Kainic acid-induced seizures caused acute and chronic changes in the expression of mRNAs and immunoreactive proteins. Acute changes included decreases in alpha2, alpha5, beta1, beta3, gamma2 and delta mRNA levels (by about 25-50%), accompanied by increases (by about 50%) in alpha1, alpha4, and beta2 messages in granule cells (after 6-12 h). Chronic changes, characterized by losses in mRNA and immunoreactive proteins in CA1 and CA3, are undoubtedly due to seizure-related cell damage. However, compensatory expression of alpha2 and beta3 subunits, especially in CA3b/c, was observed. Furthermore, increases in mRNAs and immunoreactive proteins were seen for alpha1, alpha2 alpha4, beta1, beta2, beta3 and gamma2 in granule cells and in the molecular layer of the dentate gyrus at 7-30 days after kainic acid injection. The changes in the expression of GABA(A) receptor subunits, observed in practically all hippocampal subfields, may reflect altered GABA-ergic transmission during development of the epileptic syndrome. Increased expression of GABA(A) receptor subunits in the dendritic field of granule cells and CA3 suggest that GABA-ergic inhibition may be augmented at these levels. However, the lasting preservation of alpha1-, beta2-, and gamma2-subunits in interneurons could provide a basis for augmented inhibition of GABA-ergic interneurons, leading to net disinhibition.     

Ontogeny of estrogen receptor messenger ribonucleic acid expression in the postnatal rat uterus

During the first 2 wk of postnatal life, the rodent uterus undergoes a period of marked growth and differentiation. To further examine the role of the estrogen receptor (ER) in the mediation of uterine development, we analyzed the ontogeny of ER mRNA expression in the postnatal rat uterus using in situ hybridization. ER mRNA was present in the uterine stroma on the day of birth and progressively increased in abundance during the first 2 wk of postnatal life. In contrast, ER mRNA was not detectable in the luminal epithelium at birth and did not become abundant in this region until postnatal day (P) 7. ER mRNA abundance increased in the luminal epithelium and in the invaginating and fully formed glandular epithelium during the second week of life. At P21 ER mRNA was more abundant in the glandular epithelium than in any other uterine cell type. These results are consistent with, and extend the findings of, previous studies using uterine homogenate binding assays and immunohistochemistry to define ER ontogeny in rodents. Delineation of the temporal and cell-type specific pattern of ER mRNA ontogeny in the postnatal rat uterus furthers our understanding of the molecular basis of both endogenous and exogenous estrogen effects on uterine growth and development.     

The role of gonadal steroid receptor activation in the restoration of sociosexual behavior in adult male rats

This work tested the hypothesis that gonadal steroid receptor activation was necessary for the restoration of several sociosexual behaviors (such as copulatory behavior, partner preference, 50-kHz vocalizations, and scent marking) in testosterone-treated gonadectomized male rats. Gonadal steroid receptors were blocked by systemic administration of the antiandrogen hydroxyflutamide, the antiestrogen RU 58668, or both antagonists simultaneously in a restoration paradigm. Inhibiting androgen receptors with hydroxyflutamide blocked the restoration of male copulatory behavior, partner preference (time spent with a sexually receptive female over a nonreceptive female), 50-kHz ultrasonic vocalizations, and scent marking. On the other hand, we did not find that blocking estrogen receptors with RU 58668 inhibited the restoration of copulatory behavior or partner preference in testosterone-treated gonadectomized male rats, even though the level of brain nuclear estrogen receptor occupation was significantly reduced to the level found in gonadectomized males. However, the restoration of scent marking and 50-kHz vocalizations were impaired by RU 58668. Blocking both nuclear androgen and estrogen receptors with the two antagonists simultaneously did not have a greater inhibitory effect than treatment with each antagonist alone. Therefore, the activation of nuclear estrogen receptors is necessary for the restoration of some, but not all, sociosexual behaviors, which are also androgen receptor-dependent. Besides nuclear estrogen receptors, there are additional, but unknown, targets of estradiol that play a role in mediating copulatory behavior in adult male rats. Moreover, the signals from multiple gonadal steroid signaling pathways converge in the regulation of some sociosexual behaviors in adult male rats.     

Effects of fluoxetine administration on mu-opoid receptor immunostaining in the rat forebrain

Fluoxetine is a selective serotonin reuptake inhibitor. Analysis of mu-opioid receptor immunostaining after chronic fluoxetine administration in rats revealed an increase in the density of cells expressing mu-opioid receptors in the caudatus-putamen, the dentate gyrus, the lateral septum and the frontal, parietal and piriform cortices. These data suggest that mu-opioid receptor expression in the rat forebrain is altered by in vivo chronic fluoxetine treatment.     

Aging decreases the abundance of retinoic acid (RAR) and triiodothyronine (TR) nuclear receptor mRNA in rat brain: effect of the administration of retinoids

Aging is accompanied by troubles resulting from changes in hormonal and nutritional status. Therefore, the abundance of mRNA coding for triiodothyronine (TR) and retinoic acid (RA) nuclear receptors was studied in the brain of young, adult and aged (2.5, 6 and 24 months, respectively) rats. In the brain of aged rats, there was a lower abundance of TR and RAR mRNA and a lower activity of tissue transglutaminase (tTG), an enzyme the gene of which is a target for retinoids. Administration of RA in these rats restored TR and RAR mRNA and the activity of tTG in the brain. The importance of these observations to the function of the aged brain is discussed.     

Testosterone and progesterone level alterations in the adult rat after retinoid (retinol or retinoic acid) treatment (imprinting) in neonatal or adolescent age

Newborn rats were treated with a single dose of vitamin A (retinol), or with three doses of retinoic acid (in the 1st, 3rd and 5th days). Serum testosterone and progesterone level was measured in the four months old male and female rats, respectively. Retinol significantly decreased both hormone levels, however retinoic acid decreased the progesterone level only. In the second part of the experiments adolescent rats (in the 6th and 7th week after birth) were treated and measured similar to the newborns. In this case retinol significantly diminished testosterone level, without influencing the progesterone level. Retinoic acid decreased testosterone level and elevated progesterone level. The results demonstrate the long lasting effects of retinoid treatments at a neonatal or adolescent age, pointing also to the differences in the direction of the effects. Considering that previously the receptorial and sexual-behavioral effects of perinatal vitamin A treatments were observed, the experiments call attention to such harmful influences of perinatal vitamin A treatments, which are not manifested in morphological alterations.     

Regulation of immunoreactive androgen receptor in the adrenal gland of the adult rat

The androgen receptor (AR) was measured by an immunoblot assay in adult tissues of both male and female rats. Relatively high levels of AR were detected in tissues of the male urogenital tract and in the adrenal glands and gonads of both sexes. Another group of tissues, including the male levator ani/bulbocavernosus muscles, preputial gland, scrotal skin, and vagina, had low, but detectable, levels of AR. In a third group of tissues, including the uterus, kidney, spleen, liver, gut, heart, lung, pituitary, and hypothalamus, AR was undetectable. In some androgen target tissues, such as the penis, androgens cause an apparent disappearance of AR from the tissue, and in other tissues, such as the ventral prostate, androgen therapy increases the amount of detectable AR. We compared the effect of androgen on AR levels in the adrenal gland and ventral prostate, tissues that differ markedly in their trophic responses to androgen. Castration appeared to have no effect on the amount of detectable AR in the adrenal gland, whereas it caused a profound decrease in AR levels in the ventral prostate. By contrast, 7 days after hypophysectomy, AR levels declined in both the adrenal gland and the ventral prostate. The effects of hypophysectomy plus castration were similar to those of hypophysectomy alone. Administration of ACTH to hypophysectomized rats for 7 days did not reverse the effects of hypophysectomy on adrenal AR, nor did treatment with levothyroxine, dexamethasone, rat GH, or rat PRL. Treatment of hypophysectomized rats with 5alpha-dihydrotestosterone for 7 days caused a dramatic increase in the amount of detectable AR in both the ventral prostate and the adrenal gland, but had a trophic effect only in the ventral prostate. These findings suggest that the amount of immunoreactive AR detected in both the adrenal gland and the ventral prostate is enhanced by androgens: testicular androgens in the case of the ventral prostate and adrenal androgen in the case of the adrenal glands.     

Androgen regulation of the insulin-like growth factor-I and the estrogen receptor in rat uterus and liver

For the first time testosterone is shown to be an important regulator of the insulin-like growth factor-I (IGF-I) in the rat uterus under in vivo conditions. In this study the regulation of IGF-I and the estrogen receptor (ER) by gonadal steroids in the uterus and liver of female rats was monitored. The ER level was assayed by hormone binding after treatment with testosterone, 5 alpha-dihydrotestosterone or estradiol and specific mRNA species were analyzed by a solution hybridization/RNase protection assay using 35S-labeled RNA probes. Ovariectomized rats restored uterine weight after treatment with testosterone. Uterine IGF-I mRNA was more than 20-fold higher in testosterone treated rats compared to untreated ovariectomized controls after 48 h treatment. The effects of testosterone on ovariectomized animals was followed in a timecourse study. Testosterone administration increased uterine IGF-I mRNA expression during the first 48 h and the maximally induced level was maintained throughout the duration of the experiment (168 h). Since induction of IGF-I mRNA by estrogen is transient, these data indicate that androgen and estrogen increase IGF-I mRNA by different mechanisms. Regulation of IGF-I mRNA by gonadal steroids was also studied in hypophysectomized animals. The rats were given either testosterone, 5 alpha-dihydrotestosterone or estradiol, and uterine IGF-I mRNA was measured after 1 week of treatment. At this timepoint estrogen treated rats showed levels of IGF-I mRNA not significantly different from those of hypophysectomized controls. In contrast testosterone and 5 alpha-dihydrotestosterone increased the IGF-I mRNA level 30 and 40 times, respectively, relative to hypophysectomized control animals. Since 5 alpha-dihydrotestosterone is not convertable to estrogen, the induction by testosterone was considered to be a true androgenic phenomenon.