Biomedical subjects

I Camacho-Arroyo

Publications and source records attributed to I Camacho-Arroyo.

At least 37 records · Page 2Linked to original sources

PubMed1998

Differential effects of 5 alpha-norethisterone on the histomorphology of the oviduct and uterus of the pregnant rabbit.

In this study, the histomorphological changes induced by 5 alpha-norethisterone (5 alpha-NET), a reduced metabolite of the contragestational postcoital agent norethisterone, in the oviduct and the uterus of the pregnant rabbit were determined. Adult fertilized rabbits were treated daily with 5 alpha-NET (1.0, 1.5, 2.5, and 5.0 mg/kg/day) during 7 consecutive days, starting from the first day after coitus. Twenty-four hours after the last administration, the histological analysis of the oviduct and the uterus was performed. It was observed that in the infundibulum-ampullae region as well as in the isthmus of the oviduct, the number of nonsecretory cells (PAS-negative) were decreased, whereas the number of secretory cells (PAS-positive) were increased significantly after 5 alpha-NET administration. The proportion of glandular tissue in the uterus markedly diminished in relation to that of the stromal tissue. This indicates an inhibition of the endometrial transformation observed during normal pregnancy. Interestingly, the highest doses of 5 alpha-NET (2.5 and 5.0 mg/kg/day) induced necrosis in the uterus but not in the oviduct. These results suggest that the molecular antiprogestational effects previously observed after 5 alpha-NET administration are also related to changes in the histomorphology of both the oviduct and the uterus of the pregnant rabbit.

Animals↗

PubMed1998

C-fos expression pattern in the hypothalamus and the preoptic area of the rat during proestrus.

c-fos gene expression in the hypothalamus, the preoptic area, the hippocampus and the frontal cerebral cortex of the rat was determined every two hours from 09:00 h to 19:00 h on the day of proestrus by using reverse transcription coupled to polymerase chain reaction. Rats under a 14:10 h light-dark cycle, with lights on at 06:00 h were used. We found a marked increase in c-fos gene expression in the studied regions but the hippocampus at 13:00 h, followed by a significant diminution in the subsequent hours of proestrus day. The high expression of c-fos gene at 13:00 could be associated to the increase in estradiol seric levels observed both at 11:00 h and at 13:00 h. Our results correlate with the increase in the number of FOS immunoreactive cells in some forebrain areas in proestrus afternoon related to gonadotropin releasing hormone secretion.

Animals↗

PubMed1998

Histomorphometric and progesterone receptor immunohistochemical analysis in the oviduct of newly hatched chicks treated with follicle-stimulating hormone during embryonic development.

In this study we evaluated the histomorphology and ultrastructure of the oviduct of newly hatched chicks, as well as the immunohistochemical expression of progesterone receptor (PR) in this tissue after follicle-stimulating hormone (FSH) treatment on days 13, 15 and 17 of embryonic development. Results indicated a marked difference in the histology of the oviduct of newly hatched chicks treated with FSH. Magnum mucosa from these animals presented a pseudostratified epithelium with evaginations from the lumen into the epithelium and from the latter into the stroma beneath where tubular glands are formed. In contrast magnum mucosa from control animals presented columnar epithelium with no evaginations. In magnum epithelium FSH also induced the formation of cilia and microvilli projections into the lumen as well as an increase in the wall and lumen areas and in the density of nuclei per unitarea. PR immunoreactivity was only observed in the oviduct of FSH treated animals. PR was located in the nucleus of epithelial luminal cells, mucosal stromal cells and smooth muscle cells. These findings suggest that FSH induces an adequate hormonal milieu for the cytodifferentiation and PR gene expression in the chick oviduct.

Animals↗

PubMed1998

Changes in progesterone receptor mRNA content in the rabbit lung during early pregnancy and after sex steroid hormone treatment.

In this work we determined progesterone receptor (PR) mRNA content in female rabbit lung during the first 5 days of pregnancy and in ovariectomized animals after subcutaneous injection of oestradiol benzoate (25 micrograms/kg) for 2 days or oestradiol benzoate (25 micrograms/kg) for 2 days plus a single dose of progesterone (5 mg/kg) on day three. On each day (0-5) of pregnancy and 24 h after the last dose in the case of the treated animals, animals were killed and lung was excised; total RNA was extracted and processed for Northern blot analysis. The results showed three main PR mRNA transcripts (6.1, 4.4 and 1.8 kb) in rabbit lung. The 4.4 kb species was the most abundant. PR mRNA content was markedly increased by oestradiol benzoate and downregulated by progesterone. It significantly increased on the first day of pregnancy and then diminished progressively, reaching its lowest value on day 5. These findings suggest that PR mRNA content in the rabbit lung is regulated by sex steroid hormones and changes according to the physiological concentrations of oestradiol and progesterone.

Animals↗

PubMed1996

Regulation of progesterone receptor gene expression by sex steroid hormones in the hypothalamus and the cerebral cortex of the rabbit.

The effects of estradiol benzoate (EB) and progesterone (P4) upon progesterone receptor (PR) gene expression in the cerebral cortex and the hypothalamus of the rabbit were studied. Ovariectomized adult rabbits were subcutaneously treated with EB (25 micrograms/kg) for 2 days, and with EB (25 micrograms/kg) + a single dose of P4 (5 mg/kg) on day 3. Twenty-four hours after the last dose, the frontal cortex, the hypothalamus and the uterus were excised, total RNA was extracted and processed for reverse transcription-polymerase chain reaction. PR gene expression was induced by EB and down-regulated by P4 both in the frontal cortex and the hypothalamus in a manner similar to that observed in the uterus. The finding that PR gene transcription is regulated by steroid hormones in the cerebral cortex suggests that post-transcriptional processes are involved in the insensitivity of cortical PR protein to steroids regulation previously reported with binding techniques.

Animals↗

PubMed1996

The rabbit submandibular gland: sexual dimorphism, effects of gonadectomy, and variations across the female reproductive cycle.

Sex differences and the effect of various endocrine conditions on the histology of the rabbit (Oryctolagus cuniculus L.) submandibular (chin) gland were investigated. The female gland contained significantly more acini/field than the male gland. The diameter of acini was significantly smaller than those of the male gland. Gonadectomy reduced the number of acini/field and increased their diameter in females but provoked the opposite effect in males. Gonadectomy drastically reduced the percent of acini with crystal bodies in both sexes, and the percent of acini with apocrine secretion only in females. Estrous does showed a significantly higher number of acini/field than pregnant (days 20 and 29) and lactating (day 6) does. Acini containing crystal bodies declined from 22% in estrous females to 8% and 3% in pre-parturient (gestation day 31) and lactating (day 6) does, respectively. By contrast, acini showing apocrine secretion increased from 12% in estrous females to 43% in pre-parturient does and declined to 23% on lactation day 6. In all glands glycoproteins were noted in crystal bodies but not in apocrine secretion. Results show a sexual dimorphism in the rabbit chin gland histology and support the participation of gonadal steroids in its physiological regulation.

Animals↗

PubMed1995

Molecular mechanisms of the antihormonal and antiimplantation effects of norethisterone and its A-ring reduced metabolites.

Norethisterone (NET) has been used as a contragestational postcoital agent. It is biotransformed to 5 alpha dihydro-NET (5 alpha-NET) and 3 beta,5 alpha tetrahydro-NET (3 beta,5 alpha-NET) in target tissues. The participation of these metabolites in NET effects is unknown. We have examined the antiimplantation and antiprogestational effects of NET and its metabolites, in adult mated female rabbits, by assessing the number of implantation sites and the expression products of the uteroglobin (UTG) gene in the uterus, and by comparing them with those of RU-486 and estradiol. Steroids were daily administered s.c. at several doses for 7 consecutive days, starting 24 hr after coitus. To assure that fertilization occurred in all animals, the presence of early pregnancy factor was determined. The results demonstrated that high doses (5 mg/kg) of NET reduced both implantation and the expression of the UTG gene. On the other hand, lower doses (1.5 mg/kg) of 5 alpha-NET produced an antiimplantation effect and suppressed UTG synthesis and its mRNA. These effects were similar to those of RU-486. At lower doses (1 mg/kg), both estradiol and the estrogenic metabolite 3 beta,5 alpha-NET were also effective in inhibiting implantation and UTG gene expression. The overall results suggest that NET metabolites exert antiimplantation and antiprogestational effects through their interaction with progesterone and estrogen receptors, and provide an explanation for the molecular mechanisms involved in the postcoital contraceptive action of NET.

Animals↗

PubMed1995

Norethisterone metabolites modulate the uteroglobin and progesterone receptor gene expression in prepubertal rabbits.

Norethisterone (NET) is a synthetic progestin, used as a contraceptive agent, that is biotransformed at target tissues into 5 alpha-NET and 3 beta,5 alpha-NET, which possess different pharmacological properties. The effects of these metabolites on the expression of uteroglobin (UG) and progesterone receptor (PR) genes, both regulated by progesterone (P4), were evaluated in the uterus of prepubertal female rabbits that were simultaneously treated with P4 (1.0 mg) for 5 consecutive days. As determined by Western and Northern blot analyses, 5 alpha-NET inhibited the P4-induced UG gene expression in a dose-dependent manner. A similar inhibition was observed with the administration of RU-486. The estrogenic agent 3 beta,5 alpha-NET and estradiol at a dose of 1.0 mg also inhibited the UG gene expression induced by P4. Both 5 alpha-NET and 3 beta,5 alpha-NET blocked the PR down-regulation induced by P4 as assessed by Western and Northern blot methods. The inhibition of UG synthesis and PR down-regulation by 5 alpha-NET and 3 beta,5 alpha-NET indicates that these NET metabolites possess antiprogestational properties.

Animals↗

PubMed1995

In vitro molecular assessment of the mechanisms of action of 19-nor progestins used as contragestational agents.

Norethisterone (NET) and levonorgestrel (LNG) are synthetic progestins used as contragestational agents. Both compounds are biotransformed at target tissues into A-ring reduced metabolites which possess different pharmacological properties. The aim of this study was to determine the molecular mechanisms of the progestational and antiprogestational effects of NET, LNG and their metabolites by using a highly efficient, sensitive in vitro molecular assay based on the detection of a reporter gene expression (the bacterial chloramphenicol acetyltransferase (CAT) inserted downstream of a minimal promoter containing two progesterone responsive elements (PRE2) and the TATA box. For this purpose we used CV-1 monkey kidney cells, which do not possess steroid receptors. These cells were cotransfected with a progesterone receptor expression vector and the reporter vector PRE2-TATA-CAT. Data obtained using this model showed that NET and LNG induced CAT activity in a manner similar to that of the potent progestin R5020. NET and LNG metabolites exhibited a weak progestational activity; however, when 5 alpha-NET metabolite was simultaneously administered with R5020, a clear antiprogestational effect similar to that of the antiprogestin RU486 was observed. Therefore, the results clearly demonstrate that the use of the reporter CAT vector containing hormone responsive elements is a suitable assay for the screening and evaluation of new synthetic steroids with agonist or antagonist progestational activities in transfected CV-1 cell line.

Animals↗

PubMed1994

Intracellular progesterone receptors are differentially regulated by sex steroid hormones in the hypothalamus and the cerebral cortex of the rabbit.

The aim of this study was to examine the role of sex steroid hormones in the regulation of intracellular progesterone receptors (PR) in the rabbit central nervous system. We determined PR concentration in cytosol preparations from the hypothalamus, the frontal, tempo-parietal and occipital cortex, by using the specific binding of the synthetic progestin [3H]ORG 2058. PR concentration was higher in the hypothalamus of intact adult females than in that of adult males and prepubertal females, whereas no significant differences were observed in the cerebral cortex of these animals. PR concentration was similar in the three cortical regions analyzed, indicating a homogeneous distribution of PR in the cerebral cortex. The administration of estradiol to ovariectomized animals increased PR concentration in the hypothalamus but not in the cortex. The administration of progesterone to ovariectomized rabbits did not modify PR concentration in any region, however when progesterone was administered after estradiol, it induced a significant diminution in hypothalamic PR concentration without effects in the cortex. These findings suggest that in the rabbit, PR are estrogen regulated in the hypothalamus but not in the cerebral cortex. In the latter, PR are not regulated by progesterone, whereas in the former the estrogen-induced PR are down-regulated by progesterone. Interestingly, hypothalamic PR constitutively expressed in ovariectomized animals are progesterone-insensitive.

Animals↗

PubMed1994

Immunohistochemical localization of intracellular progesterone and glucocorticoid receptors in the rabbit lung.

We have determined the presence and distribution of intracellular progesterone receptors (PRs) and glucocorticoid receptors (GRs) in the lung of adult female rabbits using immunohistochemistry. The effects of ovariectomy and administration of oestradiol benzoate (10 micrograms for 3 consecutive days) upon PR and GR immunoreactivity were also studied. The results demonstrated the presence of both steroid hormone receptors in the female rabbit lung. PR and GR immunoreactivity was predominantly nuclear and located in alveolar epithelial cells and various interstitial cells such as polymorphonuclear leucocytes. Tissue distribution of both receptors was similar in all cases. Oestradiol treatment induced a marked increase in the number of PR immunoreactive cells compared with intact and ovariectomized female animals. Neither ovariectomy nor oestradiol treatment modified the number of GR immunoreactive cells. The presence and localization of intracellular PRs and GRs in several lung cell types suggest that they may play an important role in mediating the effects of progesterone and glucocorticoids in various physiological processes in the rabbit lung. The data also indicated an oestrogen regulation of PRs in the rabbit lung.

Animals↗

PubMed1992

Levels, uptake, and release of glycine and glutamate in the rat pontine reticular formation.

In this work we have determined the levels of glycine, glutamate, and other amino acids in the rat pontine reticular formation (PRF), in addition to some properties of the uptake and release of labeled glycine and glutamate in slices of this region. Glutamate was the most concentrated amino acid in the PRF, although its content was about half that of the striatum. Surprisingly, glycine levels in the PRF were 3.2-fold higher than in the striatum, whereas GABA content was similar in both regions. The uptake of both glycine and glutamate by PRF slices was strictly Na(+)-dependent. Their release was stimulated by K(+)-depolarization, but only the release of glycine was Ca(2+)-dependent. These findings suggest that glycine is a strong candidate for a neurotransmitter role in the PRF and that glutamate might also play such a role in this region.

Animals↗

PubMed1991

Microinjections of muscimol and bicuculline into the pontine reticular formation modify the sleep-waking cycle in the rat.

The role of gamma-aminobutyric acid (GABA) in the sleep-waking cycle was evaluated by means of microinjections of muscimol and bicuculline into the rat pontine reticular formation (PRF). Muscimol (20 ng) produced a marked increase in wakefulness (70%), a decrease in slow-wave sleep (SWS) (35%) and a remarkable delay in the onset of both SWS and paradoxical sleep, without modifying the percentage of the latter. Bicuculline (4 ng) shortened SWS latency by about 70%. These results suggest that GABAergic transmission in the PRF is involved in the regulation of sleep-waking cycle in the rat.

Animals↗

PubMed1991

Release of acetylcholine and GABA, and activity of their synthesizing enzymes in the rat pontine reticular formation.

The aim of this study was to obtain neurochemical information on the possible role of acetylcholine (ACh) and gamma-aminobutyric acid (GABA) as neurotransmitters in the pontine reticular formation (PRF). We studied the uptake of labeled choline and GABA, as well as the release of this amino acid and of ACh, in PRF slices of the rat. In addition, choline acetyltransferase, acetylcholinesterase and glutamate decarboxylase activities were assayed in PRF homogenates. The uptake of GABA was strictly Na(+)-dependent, whereas choline uptake was only partially Na(+)-dependent. The release of both ACh and GABA was stimulated by K(+)-depolarization, but only the former was Ca(2+)-dependent. Choline acetyltransferase activity in the PRF was 74% of that in the striatum, whereas acetylcholinesterase activity was considerably lower. Glutamate decarboxylase activity in the PRF was about half that observed in the striatum. These findings support the possibility that both ACh and GABA may act as neurotransmitters in the rat PRF.

Acetylcholine↗

PubMed1988

The effect of total sleep deprivation on plasma melatonin and cortisol in healthy human volunteers.

Twelve healthy volunteers were included in this study. Baseline curves for melatonin and cortisol were obtained after one night of adaptation to laboratory conditions. From 10:00 p.m. to 6:00 a.m., blood samples were drawn every hour. On the third night, the subjects were kept awake at the sleep unit. Curves for the two hormones were then obtained after 36 h of total sleep deprivation (SD). The levels of these hormones were evaluated by calculating the area under the curve at each hour in both situations (basal and after sleep deprivation). It was found that the melatonin levels were increased after sleep deprivation, whereas the cortisol levels remained the same. These results suggest a mechanism by which a reset of abnormal rhythms can occur in depression.

Adolescent↗

PubMedDate not supplied

Detection and expression of corticosteroid binding protein gene in human pathogenic fungi.

Participation of steroid hormones in the growth of several fungal species has been widely reported. The aim of the present study was to detect the presence and expression of the corticosteroid binding protein (CBP) gene in different pathogenic fungal isolates from human clinical specimens. Genomic DNA and total RNA were obtained from six different pathogenic fungal species and submitted to Southern blot and Reverse Transcription-Polymerase Chain Reaction respectively. The results indicated that all the fungi studied presented and expressed CBP gene. The sequence of a PCR product of CBP gene fragment corresponding to the carboxyl terminal region in Trichophyton mentagrophytes, which presented the highest CBP expression, showed an identity of 98% as compared to the previously reported gene sequence from Candida albicans. The overall results indicate that CBP is a highly conserved gene in fungi and suggest that steroid hormones should play an important physiological role in these eukaryotic organisms.

Adrenal Cortex Hormones↗

PubMedDate not supplied

[Progesterone receptor isoforms: function and regulation].

Progesterone participates in the regulation of several physiological processes in mammals. The biological response to progesterone is mediated by two forms of the progesterone receptor (PR) denominated PR-A and PR-B. The difference between them is that 164 amino acids of N-terminal of PR-B are absent in PR-A. Both PR isoforms are derived from a single gene but are generated from either alternative transcriptional or translational start sites, and are regulated by different estrogen-induced promoters. PR-B acts as a transcriptional activator in different cellular contexts whereas PR-A functions as a strong inhibitor of transcriptional activity. PR isoforms expression and function vary among target tissues such as the uterus, the mammary gland and the brain. The knowledge of the molecular mechanisms involved in the regulation of expression and function of PR isoforms will contribute to the understanding of fundamental biological processes such as sexual behavior and reproduction, and it will open the possibility of alternative therapies in fertility control as well as in the treatment of breast, endometrial and cerebral tumors.

Central Nervous System↗

PubMedDate not supplied

[Progesterone and its metabolites in central nervous system function].

Progesterone (P4) and its metabolites are involved in several functions of the central nervous system (CNS). These steroids participate in neuronal excitability, reproduction and sexual behavior. P4 and its metabolites exert their effects on neurons and glial cells through several mechanisms that include the interaction of the steroids with: 1) intracellular specific receptors; 2) modulatory sites located in neurotransmitter receptors; and 3) ionic channels. By these mechanisms, modifications in gene expression, second messengers' production and ion conductance are induced. The activities of the P4 metabolites have been mainly related to membrane effects, whereas for P4, the transcriptional and translational effects are mediated by intracellular receptors. Thus, these steroids can modify the CNS functions at short (milliseconds), medium (minutes) or long term (hours or days) lapses. The knowledge of the molecular mechanisms involved in the actions of P4 and its metabolites in the CNS will contribute to the understanding of fundamental biological processes such as sexual behavior and reproduction, and it will open the possibility of alternative therapies in the treatment of some neurologic and psychiatric disorders such as epilepsy, anxiety, premenstrual syndrome, and cerebral tumors which possess hormonal regulation.

Animals↗