Synergistic neuroprotective action of prolactin and 17β-estradiol on kainic acid-induced hippocampal injury and long-term memory deficit in ovariectomized rats

PURPOSE

The neuroprotective actions of the ovarian hormone 17β-estradiol (E2) against different brain lesions have been constantly confirmed in a variety of models including kainic acid (KA) lesions. Similarly, the pituitary hormone prolactin (PRL), traditionally associated with lactogenesis, has recently been linked to a large diversity of functions, including neurogenesis, neuroprotection, and cognitive processes. While the mechanisms of actions of E2 as regards its neuroprotective and behavioral effects have been extensively explored, the molecular mechanisms of PRL related to these roles remain under investigation. The current study aimed to investigate whether the simultaneous administration of PRL and a low dose of E2 prevents the KA-induced cognitive deficit and if this action is associated with changes in hippocampal neuronal density.

METHODS

Ovariectomized (OVX) rats were treated with saline, PRL, and/or E2 in the presence or absence of KA. Neuroprotection was assessed by Nissl staining and neuron counting. Memory was evaluated with the novel object recognition test (NOR).

RESULTS

On their own, both PRL and E2 prevented short- and long-term memory deficits in lesioned animals and exerted neuroprotection against KA-induced excitotoxicity in the hippocampus. Interestingly, the combined hormonal treatment was superior to either of the treatments administered alone as regards improving both memory and neuronal survival.

CONCLUSION

Taken together, these results point to a synergic effect of E2 and PRL in the hippocampus to produce their behavioral, proliferative, and neuroprotective effects.

Hormone-Related Cancer and Autoimmune Diseases: A Complex Interplay to be Discovered

Neoplasic transformation is a continuous process that occurs in the body. Even before clinical signs, the immune system is capable of recognizing these aberrant cells and reacting to suppress them. However, transformed cells acquire the ability to evade innate and adaptive immune defenses through the secretion of molecules that inhibit immune effector functions, resulting in tumor progression. Hormones have the ability to modulate the immune system and are involved in the pathogenesis of autoimmune diseases, and cancer. Hormones can control both the innate and adaptive immune systems in men and women. For example androgens reduce immunity through modulating the production of pro-inflammatory and anti-inflammatory mediators. Women are more prone than men to suffer from autoimmune diseases such as systemic lupus erythematosus, psoriasis and others. This is linked to female hormones modulating the immune system. Patients with autoimmune diseases consistently have an increased risk of cancer, either as a result of underlying immune system dysregulation or as a side effect of pharmaceutical treatments. Epidemiological data on cancer incidence emphasize the link between the immune system and cancer. We outline and illustrate the occurrence of hormone-related cancer and its relationship to the immune system or autoimmune diseases in this review. It is obvious that some observations are contentious and require explanation of molecular mechanisms and validation. As a result, future research should clarify the molecular pathways involved, including any causal relationships, in order to eventually allocate information that will aid in the treatment of hormone-sensitive cancer and autoimmune illness.

17beta-estradiol does not protect cerebellar granule cells from excitotoxicity or apoptosis

Mounting evidences have suggested that 17beta-estradiol (E2) could have a neuroprotective action in the CNS. In the present study, we wanted to study whether this estrogen was able to protect cerebellar granule cells (CGCs) from apoptosis or excitotoxicity. Our results suggest that E2 has no anti-apoptotic effect in CGCs cultures. The lack of phosphoinositide 3-kinase/Akt pathway activation in CGCs cultures could be on the basis of the failure of estradiol to protect CGCs from potassium-deprivation and ceramide-mediated apoptosis. Moreover, E2 does not protect CGCs from glutamate-mediated death despite activating the extracellular signal regulated kinase kinase/extracellular signal regulated kinase pathway, which suggests that extracellular signal regulated kinase kinase/extracellular signal regulated kinase pathway activation is not sufficient to sustain an estrogen-mediated neuroprotective effect in CGCs cultures. By contrast, we found that the estrogen had a significant neuroprotective effect against hydrogen peroxide-mediated neuronal death. This effect was due to the antioxidant properties of the chemical structure of estradiol, as the biological inactive isomer 17alpha-estradiol was also able to reduce hydrogen peroxide-mediated neuronal death.

Protective effect of testosterone on early apoptotic damage induced by streptozotocin in rat pancreas

Beta-cell apoptosis is responsible for the development of insulin-dependent diabetes mellitus in the streptozotocin (STZ) rat model. It has been demonstrated that steroid hormones possess antioxidant and protective antiapoptotic effects in many tissues. The aim of the present study was to investigate the early apoptotic damage induced by STZ in rat pancreas, and the effect of testosterone in preventing apoptosis of pancreatic beta cells. Intact and castrated adult male Wistar rats were subjected to a unique injection of STZ 60 mg/kg (body weight) in citrate buffer, and the kinetics of apoptosis in beta cells was assessed. Insulin and glucose were measured by RIA and a glucometer respectively, and in pancreatic tissue by immunohistochemistry. At 6 h after STZ injection, a marked increase in apoptotic beta cells was detected; however, glucose and insulin serum levels were not significantly different from the controls. The castrated animals presented higher percentages of apoptotic beta cells (65.75 +/- 5.42%) than intact males (20.6 +/- 4.38%) and castrated, testosterone-substituted males (30.66 +/- 1.38%). The decrease in apoptotic beta cells induced by testosterone was reversed by the antiandrogen flutamide (67.69 +/- 3.45%). The overall results indicate that early apoptotic damage produced by STZ in castrated animals was reversed by testosterone, suggesting that this hormone exerts a natural protective effect in rat pancreas. This effect could help to explain some sexual differences in diabetes mellitus incidence in man, reinforcing the idea that new approaches in steroid hormone therapies should be considered for treatment of this disease.

Differential expression of AP-1 transcription factor genes c-fos and c-jun in the helminth parasites Taenia crassiceps and Taenia solium

Homologues of c-fos and c-jun from total DNA of Taenia crassiceps and Taenia solium were cloned and sequenced. The amino acid alignment analysis revealed that c-fos DNAs from T. crassiceps and T. solium were highly homologous (96%), and both have high homology compared to several mammalian c-fos proteins (93% to mouse, 96% to rat and 86% to human). The c-jun protein alignment showed higher homology (T. crassiceps and T. solium have 98%), when compared with mouse, rat and human, being 92%, 98% and 93% respectively. RT-PCR amplification of the parasite's total RNA, showed that T. crassiceps expressed both AP-1 complex genes, while T. solium only expressed c-fos. Southern blot hybridization analysis confirmed the true origin of each amplified gene. AP-1 transcription gene expression is regulated by oestradiol in the same fashion as their mammalian counterparts only in T. crassiceps. To study if AP-1 genes are involved in a physiological function of the cyst, reproduction was studied in vitro. Oestradiol treatment stimulated reproduction in T. crassiceps but not in T. solium cysticerci. This is the first report of the detection and functionality of AP-1 transcription factor genes in any species of helminth parasite.

Remote sensing of intraperitoneal parasitism by the host's brain: regional changes ofc-fosgene expression in the brain of feminized cysticercotic male mice

Experimental intraperitonealTaenia crassicepscysticercosis in mice exhibits distinct genetical, immunological and endocrinological features possibly resulting from the complex interactive network of their physiological systems. Very notable is the tendency of parasites to grow faster in hosts of the female sex. It is also remarkable in the feminization process that the infection induces in chronically infected male mice, characterized by their estrogenization, deandrogenization and loss of sexual and aggressive patterns of behaviour. The proto-oncogenec-fosis a sex steroid-regulated transcription factor gene, expressed basally and upon stimulation by many organisms. In the CNS of rodents,c-fosis found expressed in association to sexual stimulation and to various immunological and stressful events. Hence, we suspected that changes inc-fosexpression in the brain could be involved in the feminization of the infected male mice. Indeed, it was found thatc-fosexpression increased at different times during infection in the hypothalamus, hippocampus, less so in the preoptic area and cortex, and not in several other organs. The significant and distinctive regional changes ofc-fosin the CNS of infected mice indicate that the brain of the host senses intraperitoneal cysticercosis and may also announce its active participation in the regulation of the host–parasite relationship. Possibly, the host's CNS activity is involved in the network that regulates the estrogenization and deandrogenization observed in the chronically infected male mice, as well as in the behavioural and immunological peculiarities observed in this parasitic infection.

Histomorphological changes in the oviduct epithelium of the rabbit during early pregnancy

In this study, we determined the histomorphological changes in different regions of the oviduct (fimbriae, infundibulum, ampullae and isthmus) during early pregnancy (days 1-4) of the rabbit. It was observed that the number of secretory cells (PAS-positive cells) diminished in the fimbriae during the first 4 days of pregnancy with the corresponding increase in the number of non-secretory cells (PAS-negative cells). In contrast, there was an increase in the number of PAS-positive cells in the isthmus during early pregnancy. In both the infundibulum and the ampullae the number of PAS-positive cells was increased on day 3. A significant decrease in the height of the epithelium was observed in the fimbriae during early pregnancy. On the contrary, a significant increase in this parameter was observed in the isthmus during the first 3 days of pregnancy. A slight decrease in the height of the epithelium was observed in the infundibulum on day 4 of pregnancy, while in the ampullae it was significantly increased on days 1 and 3. The overall results indicate that during early pregnancy there is a selective modification in the histomorphological characteristics of the different regions of the rabbit oviduct.

Differential p53 protein expression level in human cancer-derived cell lines after estradiol treatment

BACKGROUND

p53 has a remarkable number of biological activities, including a central role in cell cycle checkpoints, apoptosis, senescence, and maintenance of genomic integrity. Its expression is modified by estradiol in some epithelial cancer-derived cell lines from the reproductive tract. The aim of this study was to evaluate the effect of low and high doses of estradiol in p53 gene expression in epithelial cancer-derived cell lines from the reproductive tract.

METHODS

p53 gene expression was assessed by Northern and Western blot methods in three human epithelial cancer-derived cell lines after estradiol treatment.

RESULTS

These indicated that no changes in p53 mRNA content occurred after estradiol treatment at both low (10 nM) and high (1 micro M) doses of estradiol in HeLa, CaLo, and C-33 cell lines. p53 protein content was nearly constant in HeLa and C-33 cell lines at administration of 10 nM of estradiol. However, when estradiol was administered at a higher dose (1 micro M), an increase in p53 protein was observed over time in HeLa and CaLo cell lines. In contrast, estradiol was without variations in C-33.

CONCLUSIONS

Overall results indicate that estradiol induces variations of p53 protein levels in epithelial cancer-derived cell lines from the reproductive tract in vitro and that this effect may be related with status p53 and/or presence of E6/E7 from human papillomavirus.

Evidence that steroid 5alpha-reductase isozyme genes are differentially methylated in human lymphocytes

The synthesis of dihydrotestosterone (DHT) is catalyzed by steroid 5alpha-reductase isozymes 1 and 2, and this function determines the development of the male phenotype during embriogenesis and the growth of androgen sensitive tissues during puberty. The aim of this study was to determine the cytosine methylation status of 5alpha-reductase isozymes types 1 and 2 genes in normal and in 5alpha-reductase deficient men. Genomic DNA was obtained from lymphocytes of both normal subjects and patients with primary 5alpha-reductase deficiency due to point mutations in 5alpha-reductase 2 gene. Southern blot analysis of 5alpha-reductase types 1 and 2 genes from DNA samples digested with HpaII presented a different cytosine methylation pattern compared to that observed with its isoschizomer MspI, indicating that both genes are methylated in CCGG sequences. The analysis of 5alpha-reductase 1 gene from DNA samples digested with Sau3AI and its isoschizomer MboI which recognize methylation in GATC sequences showed an identical methylation pattern. In contrast, 5alpha-reductase 2 gene digested with Sau3AI presented a different methylation pattern to that of the samples digested with MboI, indicating that steroid 5alpha-reductase 2 gene possess methylated cytosines in GATC sequences. Analysis of exon 4 of 5alpha-reductase 2 gene after metabisulfite PCR showed that normal and deficient subjects present a different methylation pattern, being more methylated in patients with 5alpha-reductase 2 mutated gene. The overall results suggest that 5alpha-reductase genes 1 and 2 are differentially methylated in lymphocytes from normal and 5alpha-reductase deficient patients. Moreover, the extensive cytosine methylation pattern observed in exon 4 of 5alpha-reductase 2 gene in deficient patients, points out to an increased rate of mutations in this gene.

Progesterone receptor isoforms expression pattern in human astrocytomas

Progesterone receptors (PR) have been detected in human astrocytomas; however, the expression pattern of PR isoforms in these brain tumors is unknown. Progesterone receptor isoforms expression was studied in 13 biopsies of astrocytomas (6 grade III, and 7 grade IV) from adult Mexican patients by using reverse transcription-polymerase chain reaction and immunohistochemistry. Progesterone receptor expression was observed at mRNA and at protein levels in 66% and 83% of astrocytomas grade III, respectively, whereas 100% of astrocytomas grade IV expressed PR. Almost all PR mRNA content in astrocytomas grades III and IV corresponded to PR-B. The number of immunoreactive cells expressing PR-B was higher than that expressing PR-A in 73% of the cases. Estrogen receptor-alpha protein was only observed in 33% of astrocytomas grade III, whereas no astrocytomas grade IV expressed it. These data suggest that PR-B is the predominant isoform expressed in human astrocytomas grades III and IV, and that estrogen receptor-alpha is not expressed in astrocytomas grade IV.

Insulin gene expression pattern in rat pancreas during the estrous cycle

Sex steroid hormones influence insulin homeostasis and glucose metabolism, estradiol (E2) and progesterone (P4) induce changes in both fasting and postprandial insulinemia in rodents, however, insulin gene expression during estrous cycle is unknown. The aim of the present study was to determine an insulin gene expression pattern during the estrous cycle in the rat. Groups of 6 adult rats in each day of the estrous cycle were used. Serum P4, E2, testosterone (T) and insulin concentrations were determined by radioimmunoassay (RIA). A Northern blot analysis was performed to assess insulin gene expression in pancreatic tissue. We found a marked variation in insulin gene expression during the estrous cycle. The highest insulin expression was observed during the proestrus day. Interestingly, E2 and P4 but not T levels were correlated with changes in insulin mRNA content. The variations in serum insulin during the cycle were correlated with its mRNA content in pancreas. The overall results showed variations in serum insulin and insulin gene expression during estrous cycle of the rat that correlated with circulating E2 and P4 levels.

[Tumor suppressor gene p53: mechanisms of action in cell proliferation and death]

Normal development is a balance process, which includes proliferation and cell death. Indeed both proliferation and apoptotic cell death are very complex process that involves the participation of many genes. In both events, the tumor suppressor p53 is one of the most important and studied genes. This transcription factor activates several genes, which results in the arrest of the cellular cycle and cellular repair or apoptosis. Many are the signals that activate p53 function including: DNA damage by gamma or ultraviolet radiation and chemical agents and hypoxia, among others. When p53 is activated it can either induces the expression of p21 (Waf1, Cip-1), which participates in the cellular arrest between G1-S transition, or the expression of bax, PIGs, IGF-BP3, Fas, FasL and DR5. The former genes participate in the cascade of events that induce apoptosis. Cellular arrest or apoptosis depends of the degree of cellular damage. The final outcome of the different mechanisms of action of p53 is to maintain the genomic stability of the cell. Thus, the absence of this protein contributes to genomic instability, the accumulation of mutations and increased tumorigenesis. It has been demonstrated that p53 present mutations in 50-55% of all types of reported human cancer. These mutations are primary located in DNA binding domain of the protein, which results in the loss of its biological activity. Frequently, tumors that present wild type p53 have a better response towards therapy than those that present p53 mutations. This review is focused on the knowledge of the normal p53 cellular pathways and their alterations in cancer. It is clear that the understanding of p53 function in the development of this pathology may give new insights in future therapeutic strategies including gene therapy for cancer.

Progesterone receptor isoforms expression in the prepuberal and adult male rat brain

Progesterone receptor (PR) isoforms expression was determined in several regions of the prepuberal and adult male rat brain by using reverse transcription coupled to polymerase chain reaction. Rats under a 14:10-h light-dark cycle, with lights on at 0600 h were used. We found that in the hypothalamus of prepuberal animals the expression of both PR isoforms was similar, whereas PR-A expression was higher than that of PR-B in adults. In the cerebellum PR-B expression was predominant in both prepuberal and adult rats. In both ages PR-A and PR-B exhibited a non-significant tendency to be predominant in the hippocampus and the preoptic area respectively. In the frontal cortex and the olfactory bulb PR isoforms were expressed at a similar level. These results indicate a differential expression pattern of PR isoforms in the male rat brain and suggest that the tissue-specific expression of PR-A and PR-B is important for the appropriate response of each cerebral region to progesterone.

Progesterone receptor isoforms expression pattern in human chordomas

Steroid hormone receptors are involved in the regulation of tumor growth. Two progesterone receptor (PR) isoforms have been identified in humans: a larger form (PR-B) and the N-terminally truncated one (PR-A). PR isoforms can exert opposite functions and are differentially regulated by estrogens. PR have been detected in several brain tumors including chordomas, however, it is unknown which PR isoform is expressed in brain tumors. The aim of this study was to determine by reverse transcription-polymerase chain reaction (RT-PCR) and by immunohistochemistry the expression pattern of PR isoforms in chordomas as well as its correlation with the expression of estrogen receptor a (ER-alpha). All studied chordomas expressed both PR and ER-alpha. PR-B was the predominant isoform in chordomas both at the mRNA and at the protein level. These data suggest that PR-B should be the predominant PR isoform expressed in human chordomas.

c-Fos gene expression pattern in the hypothalamus and the preoptic area of defeminized rats

The object of the present study was to determine the c-fos gene expression pattern in the hypothalamus (HYP) and the preoptic area (POA) after estradiol and testosterone priming during the critical period of sexual differentiation of the rat brain. Three-day-old female rats were injected s.c. with a single dose of 17beta-estradiol (200 microg), testosterone enantate (200 microg) or vehicle (corn oil). HYP and POA were dissected 2 h, 24 h and 14 days after treatments and on the day of vaginal opening (VO). Other animals, previously treated as above, were acutely injected with 17beta-estradiol (5 microg) on the day of VO; HYP and POA were obtained 3 h later. Total RNA was extracted and processed for semiquantitative RT-PCR. We observed that c-fos gene expression was markedly increased in POA of the animals treated with estradiol or testosterone 2 h after treatments, while a non-significant increase in c-fos gene expression was observed in the HYP of these animals. We found a significant increase in c-fos expression in HYP and POA on the day of VO in both estradiol and testosterone defeminized rats. Interestingly, the acute estradiol administration on the day of VO did not induce c-fos gene expression in either HYP or POA of defeminized animals, instead a diminution in its expression was observed in animals treated with testosterone in POA. The overall results suggest that estradiol and testosterone imprinting during critical postnatal period of sexual differentiation of the brain permanently modifies the regulation of c-fos gene expression.

Mating modifies c-fos expression in the brain of male and female rabbits

Copulation in rabbits provokes behavioral and neuroendocrine changes in both sexes. To investigate if the activity of particular brain regions is modified accordingly we quantified, by the reverse transcription-polymerase chain reaction method, c-fos expression in the preoptic area, hypothalamus, hippocampus, and frontal cortex of male and female rabbits before mating, immediately afterwards, and 1 h later. Mating immediately increased c-fos expression in the hypothalamus of both sexes, the frontal cortex of females, and the preoptic area of males. c-fos expression did not change in the hippocampus after mating in either sex but decreased in the preoptic area of females following mating. Results show that mating provokes changes in brain activity, in a gender- and region-specific manner, which may underlie the behavioral and endocrine consequences of copulation in rabbits.

Progesterone receptor isoforms expression pattern in the rat brain during the estrous cycle

Progesterone receptor (PR) isoforms expression was determined in the hypothalamus, the preoptic area, the hippocampus and the frontal cerebral cortex of the rat at 12:00 h on each day of the estrous cycle 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 that PR-B isoform was predominant in the hypothalamus, the preoptic area and the frontal cerebral cortex. Both PR isoforms were similarly expressed in the hippocampus. The highest PR-B expression was found on proestrus day in the hypothalamus; on metestrus in the preoptic area; and on diestrus in the frontal cortex. We observed no changes in PR isoforms expression in the hippocampus during the estrous cycle. These results indicate that PR isoforms expression is differentially regulated during the estrous cycle in distinct brain regions and that PR-B may be involved in progesterone actions upon the hypothalamus, the preoptic area and the frontal cortex of the rat.

Tissue damage in the male murine reproductive system during experimental Taenia crassiceps cysticercosis

Chronic infection with Taenia crassiceps cysticerci in male mice increases the level of estradiol in serum, whereas it reduces that of testosterone. In addition, male mice lose their typical male reproductive behavior. The effects of cysticerci infection on the histomorphology of male reproductive tissues are unknown. The present study was undertaken to determine the histological changes in testes, seminal vesicles, and prostate of male mice infected with T. crassiceps cysticerci. At 16 wk of infection, all tissues exhibited high inflammatory infiltrate. Tissue lesions included marked dilation and peripheral fibrosis. In the testes, a diminution of spermiogenesis was observed. The overall results indicated that the histological changes in chronically parasitized male mice occurred with changes in hormone levels, simultaneously with the high inflammatory immune response.

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.

Immunocytochemical detection of estrogen and progesterone receptors in the rabbit submandibular gland

Rabbit submandibular glands produce secretions involved in olfactory communication. The histology of these glands and their secretory activity are: sexually dimorphic; vary across the female reproductive cycle; and are modified by gonadectomy. This suggests that gonadal steroids regulate the structure and function of such glands. To further support this idea we assessed by immunocytochemistry the presence of estrogen and progesterone receptors in male and female rabbit submandibular glands. Immunoreactivity was detected only in the nucleus of acini cells. The number of estrogen receptor-immunoreactive cells/field varied among estrus (26 +/- 6; mean +/- S.E.), ovariectomized (19 +/- 2), and ovariectomized-estrogen-treated animals (13 +/- 3). Intact males showed a significantly smaller number of estrogen receptor-immunoreactive cells/field (12 +/- 1) than estrous females. Interestingly, progesterone receptor-immunoreactive cells were more abundant in estrous (32 +/- 7) than in ovariectomized animals (7 +/- 1). Estradiol benzoate (5 micrograms daily for 5 days) increased the number of progesterone receptor-immunoreactive cells/field in ovariectomized females (17 +/- 1). Intact males showed fewer progesterone receptor-immunoreactive cells/field (16 +/- 2) than estrous females. Results show that the rabbit submandibular gland is a target for estrogen and progesterone and support the idea that these hormones participate in regulating the physiology of this gland.

Modified expression of steroid 5 alpha-reductase as well as aromatase, but not cholesterol side-chain cleavage enzyme, in the reproductive system of male mice during (Taenia crassiceps) cysticercosis

Infection with Taenia crassiceps cysticerci in male mice produces an increase in serum estradiol levels, whereas serum testosterone is abolished. Concomitantly, complete atrophy of the reproductive tract of infected male mice is observed. The present study was under-taken to determine the expression pattern of three key steroidogenic enzymes in the reproductive tissues of normal and infected male mice. In infected mice, serum estradiol levels were increased 97 times as compared with control mice of the same age. Testosterone and dihydrotestosterone levels were completely inhibited. The expression of 5 alpha-reductase in the reproductive tract was markedly reduced, whereas aromatase mRNA levels were highly elevated in the testes of parasitized mice. No change in the mRNA content for cholesterol side-chain cleavage enzyme was evident. The overall results suggest that the change in the normal production of sex steroids in infected male mice is produced concomitantly by the inhibition of expression of the 5 alpha-reductase enzyme and the activation of aromatase gene expression. This induces a preferential metabolism from testosterone toestradiol instead of the normal metabolism from testosterone to dihydrotestosterone.

Variations of progesterone receptor and c-fos gene expression in the rat uterus after treatment with norethisterone and its A-ring reduced metabolites

It has been suggested that some contraceptive derivatives of 19-nor-testosterone possess estrogenic activity that may facilitate the development of breast cancer. The aim of this work was to investigate the estrogenic properties of norethisterone (NET) and its A-ring-reduced derivatives by determining progesterone receptor (PR) and c-fos mRNA content of two estrogen-regulated genes in the uterus of ovariectomized rats. mRNA content was evaluated by Northern blot 1-6 h after 17 beta-estradiol administration. The highest PR and c-fos mRNA content was observed 3 h and 2 h after 17 beta-estradiol administration, respectively. NET did not modify either PR or c-fos mRNA content. In contrast, 5 alpha- and 3 beta, 5 alpha-NET significantly increased mRNA content of both genes. The increase in c-fos mRNA content induced by these reduced compounds was lower than that found with estradiol treatment. The overall results indicate that NET administration can indirectly induce estrogenic effects through the action of its 5 alpha-dihydro and 3 beta, 5 alpha-tetrahydro derivatives.

Progesterone receptor isoforms are differentially regulated by sex steroids in the rat forebrain

We studied the effects of estradiol (E2) and progesterone (P4) on expression of genes coding for PR isoforms in the forebrain of ovariectomized rats by RT-PCR analysis. In the hypothalamus the expression of both PR isoforms was induced by E2 and down-regulated by P4. In the preoptic area these changes were only observed in the PR-B isoform. In contrast, in the hippocampus PR induction by E2 was only observed for PR-A. In this region P4 did not modify the expression of any PR isoform. These results indicate that PR isoforms expression is differentially regulated by sex steroid hormones in distinct forebrain regions and suggest that the tissue-specific regulation of either PR-A or PR-B may be involved in the physiological actions of P4 upon the rat brain.

Differential expression of the estrogen-regulated proto-oncogenes c-fos, c-jun, and bcl-2 and of the tumor-suppressor p53 gene in the male mouse chronically infected with Taenia crassiceps cysticerci

Chronic infection with Taenia crassiceps cysticerci produces a 200-fold increase in serum estradiol levels in male mice. The aim of this study was to investigate the expression pattern of c-fos and c-jun, two estradiol-regulated genes, as well as that of p53 and bcl2 in the testes, spleen, and thymus of male mice infected with T. crassiceps cysticerci. In parasitized animals the c-fos mRNA content was significantly increased in all tissues studied, whereas the c-jun mRNA content was increased only in the thymus. The p53 mRNA content was markedly reduced in all tissues of the parasitized animals analyzed, whereas bcl-2 gene expression was abolished in the thymus. On the other hand, thymic cell analysis performed by flow cytometry showed a diminution in the content of CD3+, CD4+, and CD8+ subpopulations in the parasitized mice. Our results suggest that the increase in estradiol levels of the host should change the expression pattern of several genes that participate in apoptosis regulation in the thymus of male mice during chronic infection with T. crassiceps cysticerci.

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.

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.

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.

Differential methylation in steroid 5 alpha-reductase isozyme genes in epididymis, testis, and liver of the adult rat

DNA methylation has been largely involved in the regulation of tissue-specific gene expression. The aim of the study was to determine the methylation pattern of steroid 5 alpha-reductase genes 1 and 2 in two reproductive tissues (testis and epididymis) and a nonreproductive tissue (liver) that exhibit different contents of steroid 5 alpha-reductase isozymes. These isozymes induce the bioconversion of testosterone to dihydrotestosterone that in mammals is a key molecule for external genitalia development. Genomic DNA from the testis, the epididymis, and the liver from normal adult rats was used to determine cytosine and adenine methylation pattern of steroid 5 alpha-reductase genes 1 and 2 by restriction fragment length polymorphism (RFLP) analysis using restriction enzymes sensitive to adenine (Mbo I and Sau3A I) and cytosine (Hpa II and MSP I) methylation. We also evaluated the expression of both steroid 5 alpha-reductase genes by northern blot. When genomic DNA was digested with Hpa II or Msp I, we found that steroid 5 alpha-reductase gene 2 was less cytosine methylated in the epididymis and in the testis than in the liver. In contrast, when genomic DNA was digested with Mbo I or Sau3A I, we observed that gene 2 was more adenine methylated in the epididymis and in the testis than in the liver. 5 alpha-Reductase gene 1 presented the same adenine- and cytosine-methylation pattern in the studied tissues. We also found a differential expression of steroid 5 alpha-reductase genes. Gene 2 was expressed both in the testis and the epididymis but not in the liver; whereas gene 1 was only expressed in the latter. Our results suggest that the differential methylation pattern in 5 alpha-reductase gene 2 in reproductive and nonreproductive tissues should be involved in the regulation of its expression.

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.

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.

[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.

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.

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.

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.

[An epidemic of primary bacteremia due to an endemic strain of Serratia marcescens in an intensive care unit]

An outbreak of Serratia marcescens bacteremia detected in the intensive care unit (ICU) of a tertiary care center on the last days of October, 1985, is described. The rate of primary S. marcescens nosocomial bacteremia during the pre-epidemic period (January-September 1985) was 6.25 per cent; and for the post-epidemic period compared with the epidemic were significantly different (p < 0.0001). The outbreak strains belonged to the biotype A8b, which has been endemic in our hospital. The responsible organism exhibited an unusual antimicrobial resistance pattern associated to the presence of a specific plasmid (greater than 50 kilobases), which showed similar fragments after restriction endonuclease digestion. No specific risk factors were identified in the case-control study. The outbreak was probably related to a greater influx of infected patients, resulting in less careful infection control measures, due to the emergency situation which suffered the hospital after the earthquakes in 1985. The unusual high rate of blood isolation of S. marcescens at the ICU was the first sign of the outbreak. The prompt reinforcement of infection control policies facilitated its resolution.

Endometrial expression of progesterone receptor and uteroglobin genes during early pregnancy in the rabbit

The progesterone receptor (PR) plays a pivotal role in the maturation process of the secretory endometrium, implantation and maintenance of pregnancy in rabbits. To determine the dynamics of PR gene expression and its physiological significance, the endometrial expression of PR and PR mRNA were evaluated and compared with the expression of the progesterone-regulated uteroglobin (UG) gene during 0-5 days post-coitus in rabbits. The results of immunoblot experiments indicated the presence of PR in endometrial cell extracts from days 1-4 of pregnancy with maximum PR immunostaining on day 2, followed by a marked diminution until its complete disappearance on day 5. When endometrial PR mRNA content was assessed by Northern blots, the results were similar to those of PR immunostaining, with maximal concentrations on the second day after mating. However, PR mRNA levels were still high on day 3, despite the concomitant decrease in immunostainable PR. Endometrial UG gene expression, on the other hand, exhibited a different time sequence. Thus, the UG content in uterine flushings progressively increased from day 3 after mating, reaching maximal levels on the fifth day. The endometrial UG mRNA content presented a similar profile, as its maximum concentration occurred on days 4-5. The overall results indicate that endometrial PR is down-regulated at both the mRNA and protein levels, possibly by endogenous progesterone during early pregnancy. The striking observation that maximal expression of endometrial UG gene products occurred when PR and its mRNA are no longer detectable suggests an important role for this progesterone-binding uterine protein during the preimplantation period.

Mechanisms of hormonal and antihormonal action of contraceptive progestins at the molecular level

19-Nor synthetic progestins undergo extensive metabolism at the target cells. The resulting metabolic conversion products interact with putative steroid receptors within the cells, and through those interactions, they may exert either agonistic, synergistic and antagonistic hormonal effects. Studies conducted in our laboratories have disclosed that norethisterone (NET) and D-(1) norgestrel (LNG), two widely used contraceptive progestins, are biotransformed to several A-ring reduced (dihydro and tetrahydro) derivatives. The resulting metabolites 5 alpha-dihydro NET (5 alpha-NET) and 5 alpha-dihydro LNG bind with relative high affinity to the progesterone and androgen receptors. To gain insight into the underlying molecular events mediating the mode of action of NET and its neutral metabolites, we have examined the expression of their biological effects at target organs by using the rabbit uteroglobin gene model and the beta-glucuronidase activity of the mouse kidney. The results of a series of experiments seem to indicate that the enzyme-mediated formation of the 5 alpha (trans A/B ring junction) NET derivative results in a significant diminution of its progestational and androgenic potencies. Furthermore, 5 alpha-NET acquire a potent anti-progestational/contragestational effect as assessed in the female rabbit. These results demonstrated that 5 alpha-reduction of 19-nor progestins exerts a paradoxical effect, at least in terms of their hormone-like effects. The overall data are in line with the concept that metabolism of synthetic progestins at hormone-sensitive organs modulates their mechanisms of action.

Variable expression of the uteroglobin gene following the administration of norethisterone and its A-ring reduced metabolites

Enzyme-mediated A-ring reduction of norethisterone (NET) results in the transformation of a molecule with potent intrinsic progestational activity into neutral derivatives with estrogen-like effects. To ascertain whether these structural modifications of NET are able to modify the uteroglobin (U) gene (G) expression, a series of experiments assessing the UG products after the administration of NET and its reduced A-ring metabolites were conducted in prepubertal female rabbits. Synthesis of endometrial uteroglobin and its specific mRNA were studied in animals following the administration of NET, 5 alpha-dihydro NET,3 beta,5 alpha-tetrahydro NET and progesterone. Animals treated with either estradiol or vehicle alone served as controls. The uteroglobin content in uterine flushings and cytosols was determined by immunodiffusion and polyacrilamide gel electrophoresis techniques and by a specific double-antibody radioimmunoassay, while the U mRNA synthesis was assessed by its molecular hybridization to [alpha 32P]d-ATP uteroglobin cDNA. NET induced a significant increase of the uterine content of uteroglobin similar to that observed with progesterone with a simultaneous increase on U mRNA synthesis. On the contrary, 5 alpha-NET and 3 beta,5 alpha-NET induced very little, if any uteroglobin synthesis with a concomitantly low U mRNA production as compared with NET; thus exhibiting a similar effect to that observed in estradiol-treated animals. The overall results were interpreted as demonstrating that the enzyme mediated structural changes of NET which occur at the target organs induce variable expression of the uteroglobin gene. The data indicate that the rabbit uteroglobin gene products are suitable molecular markers to evaluate the hormonal potency of contraceptive synthetic progestins and their derivatives.

Oestrogen-insensitive progestin receptors in the central nervous system: physicochemical and immunoreactive characteristics

Abstract The intracellular effects of progesterone in the central nervous system are exerted via two distinct receptors: The classical oestrogen-regulated progestin receptor and the non-oestrogen-inducible progestin receptor. To assess whether the oestrogen-insensitive receptor is related to the oestrogen-dependent receptor or whether it is a different binding macromolecule, its physicochemical and immunoreactive characteristics (immunoprecipitation with polyclonal anti-uterine progesterone receptor antisera) were studied in neural tissues of the female rat. The results disclosed that the dissociation constant (K(d), 0.4-0.5 +/- 10(-9) M), stereospecificity and sedimentation coefficient (7-8 S) in linear sucrose gradients of the oestrogen-insensitive progestin receptor were identical to those reported for the oestrogen-regulated progestin receptor, although its saturation binding capacity was significantly lower. Results of in vitro nuclear acceptor assays revealed that the progestin receptor complexes from cerebellum and cerebral cortex, were able to specifically bind to cell nuclei preparations in a fashion similar to that observed with the uterine progestin receptor, although to a lesser extent. Interestingly, a similar nuclear uptake of receptor complexes was noticed when standardized cerebellum and uterus cytosol preparations with a similar receptor content were used. The anti-uterine progesterone receptor immunoglobulins used in the immunoprecipitation studies were able to specifically recognize the progestin receptor populations of the anterior pituitary and hypothalamus (oestrogen-regulated receptors) as well as those of the cerebellum and cerebral cortex (oestrogen-insensitive receptors). The results presented show that both the oestrogen-sensitive and the oestrogen-insensitive cytosol progestin receptors in brain bind the same progesterone-like molecules used as radioligands and also react with the same antibody when tested in an immunoprecipitation radioassay. The striking similarities found in binding kinetics, physicochemical characteristics and immunoreactive behaviour in the two progestin receptors studied demonstrated that both macromolecules belong to the same family of proteins in spite of their different sensitivity to oestrogens. The overall data seem to suggest a common origin of the two progestin receptor populations in brain but with different mechanisms of hormonal regulation.

Plasma prolactin increase following electric stimulation of the amygdala in humans

Plasma levels of PRL, GH, FSH, LH, and TSH were studied at various intervals after electric stimulation of the amygdala, in 5 patients in whom electrodes had been chronically implanted in the course of their evaluation for surgical treatment of uncontrollable, temporal lobe seizures. Electric stimulation, but not sham stimulation, elicited in all cases a significant rise in plasma PRL. Plasma GH rose only in 1 patient and TSH in another. No significant changes in plasma FSH or LH were detected. It is suggested that a fine control mechanism of the hypothalamic hypophyseal final common pathway for the control of PRL secretion, may be mediated either by the ventral amygdalohypothalamic pathway or via the stria terminalis.

Serum thyrotrophin, triiodothyronine and thyroxine levels by radioimmunoassay during childhood and adolescence

Serum thyrotrophin (TSH), triiodothyronine (T3) and thyroxine (T4) were measured by radioimmunoassay in 165 boys and 171 girls, clinically healthy, aged 6.1 to 16.0 years with normal weight and height, grouped at 12 months' intervals. The TSH values in boys ranged from 5.0 ± 0.6 to 6.1 ± 0.6 μU/ml without significant age differences. In girls, TSH level was 5.3 ± 0.5 μU/ml at the age of 6.0 to 7.0 and 7.4 ± 0.5 μU/ml at the age of 10.1 to 11.0 (P < 0.001). Girls had higher values than boys from 9.1 to 11.0 years (P < 0.025). In boys the T3 level was 182 ± 10 ng/100 ml at age 6.0 to 7.0 and 230 ± 15 ng/100 ml at age 11.1 to 12.0 (P < 0.025). Girls had higher values from the age of 9.1 on (215 ± 12 ng/100 ml), but after 13.1 years they decreased (P < 0.025). Girls had higher T3 levels than boys at age 10.1 to 11.0 (P < 0.025), but this difference disappeared when T3 concentrations in girls of this age were compared to boys aged 11.1 to 12.0. In boys and girls, T4 levels tended to be lower with increasing age (r = −0.860, P < 0.01) and there was a significant difference between the values seen up to 9.0 years and those after 13.1 years (P < 0.025 − < 0.001). Girls had lower values than boys at the age of 8.1 to 9.0; however, this difference disappeared when girls of this age were compared to boys 9.1 to 10.0 years old.

It is concluded that previous to and around puberty initiation in both sexes, there is a rise in T3, followed by a progressive decrease in T4 with a rise in TSH only in girls. These changes occurred one year earlier in girls than in boys. These observations may represent transient adaptation responses to the increasing energy needs during periods of rapid growth.