Changes In Hormone Profiles Research Articles

Endocrine dysfunction in sepsis: a beneficial or deleterious host response?

Sepsis is a systemic, deleterious inflammatory host response triggered by an infective agent leading to severe sepsis, septic shock and multi-organ failure. The host response to infection involves a complex, organized and coherent interaction between immune, autonomic, neuroendocrine and behavioral systems. Recent data have confirmed that disturbances of the autonomic nervous and neuroendocrine systems could contribute to sepsis-induced organ dysfunction. Through this review, we aimed to summarize the current knowledge about the endocrine dysfunction as response to sepsis, specifically addressed to vasopressin, copeptin, cortisol, insulin and leptin. We searched the following readily accessible, clinically relevant databases: PubMed, UpToDate, BioMed Central. The immune system could be regarded as a "diffuse sensory organ" that signals the presence of pathogens to the brain through different pathways, such as the vagus nerve, endothelial activation/dysfunction, cytokines and neurotoxic mediators and the circumventricular organs, especially the neurohypophysis. The hormonal profile changes substantially as a consequence of inflammatory mediators and microorganism products leading to inappropriately low levels of vasopressin, sick euthyroid syndrome, reduced adrenal responsiveness to ACTH, insulin resistance, hyperglycemia as well as hyperleptinemia. In conclusion, clinical diagnosis of this "pan-endocrine illness" is frequently challenging due to the many limiting factors. The most important benefits of endocrine markers in the management of sepsis may be reflected by their potential to be used as biomarkers in different scoring systems to estimate the severity of the disease and the risk of death.

Decreased glucagon levels and decreased insulin secretion after sitagliptin versus mitiglinide administration with similar glycemic levels following an oral glucose load: a randomized crossover pharmaceutical mechanistic study.

Both sitagliptin (SIT) and mitiglinide (MIT) can lower postprandial hyperglycemia. The purpose of this study was to examine differences in insulin and glucagon secretion after SIT or MIT administration when similar levels of plasma glucose (PG) were achieved for both agents following an oral glucose load. We directly compared the effects of these two agents in 16 type-2 diabetic patients (M/F=10/6, age 66±3years old, HbA1c 6.6±0.5%). Patients received SIT (50mgqd for 1week and 100mgqd for an additional week) or MIT (10mg tid for 2weeks). After 2weeks, patients crossed over to the other treatment. 75-g oral glucose tolerance tests were conducted before the study and after interventions. The area under the curve (AUC) up to 180min for the PG response was similar for both agents. While basal insulin secretion rates (ISR) were similar, incremental AUC of ISR was significantly lower in the SIT treatment (522±108 vs 702±288pmol/minmin, p<0.01), although the difference between the SIT and MIT treatments in the Matsuda index-which reflects insulin sensitivity-remained nonsignificant. Glucose-stimulated insulin secretion was similarly increased by the MIT and SIT treatments. Suppression of the AUC for glucagon was observed in the SIT treatment, while MIT treatment failed to suppress the glucagon concentration (-432±2322 vs MIT 1116±2520pg/mlmin, p<0.05). The basal proinsulin/insulin ratio was lower in the SIT treatment (0.23±0.04 vs MIT 0.26±0.36, p<0.05). Although either SIT or MIT can be employed to reduce postprandial hyperglycemia, SIT induces changes in hormonal profiles that are more favorable to islet functions than MIT does.

Hypoxia acclimation protects against oxidative damage and changes in prolactin and somatolactin expression in silver catfish (Rhamdia quelen) exposed to manganese

The aim of this study was to assess the Mn toxicity to silver catfish considering Mn accumulation and oxidative status in different tissues, as well as pituitary hormone expression after acclimation to hypoxia. Silver catfish acclimated to hypoxia for 10 days and successively exposed to Mn (9.8mgL−1) for an additional 10 days exhibited lower Mn accumulation in plasma, liver, kidneys and brain and prevented the hematocrit decrease observed in the normoxia group. Hypoxia acclimation also modified Mn-induced oxidative damage, which was observed by lower reactive species (RS) generation in gills and kidneys, decreased lipid peroxidation (LP) levels in gills, liver and kidneys and decreased protein carbonyl (PC) levels in liver, kidneys and brain. Manganese accumulation showed positive correlations with LP levels in gills and kidneys, as well as with PC levels in gills, liver and brain. In addition, hypoxia acclimation and Mn exposure increased catalase (CAT) activity in gills and kidneys and Na+/K+-ATPase activity in gills, liver and brain. Silver catfish that were acclimated under normoxia and exposed to Mn displayed increased pituitary prolactin (PRL) and decreased somatolactin (SL) expression. Interestingly, hypoxia acclimation prevented hormonal fluctuation of PRL and SL in fish exposed to Mn. These findings indicate that while the exposure of silver catfish to Mn under normoxia was related to metal accumulation and oxidative damage in tissues together with endocrine axis disruption, as represented by PRL and SL, hypoxia acclimation reduced waterborne Mn uptake, thereby minimizing oxidative damage and changes in hormonal profile. We hypothesized that moderate hypoxia is able to generate adaptive responses, which may be related to hormesis, thereby ameliorating Mn toxicity to silver catfish.

Short-term changes in hormonal profiles after laparoscopic ovarian laser evaporation compared with diagnostic laparoscopy for PCOS

Which reproductive endocrine changes are attributed exclusively to laparoscopic ovarian drilling in polycystic ovarian syndrome (PCOS)? Laser evaporation-specific endocrine effects were the prevention of an immediate increase in inhibin B and a sustained decrease in testosterone, androstenedione and anti-Müllarian hormone (AMH). All ovarian drilling procedures result in reproductive endocrine changes. It is not known which of these changes are the result of ovarian drilling and which are related to the surgery per se. This prospective controlled study was performed at an outpatient academic fertility clinic. Between 2007 and 2010, a total of 21 oligo- or amenorrheic PCOS patients were included. Included were oligo- or amenorrheic PCOS patients with all three of the Rotterdam criteria and luteinizing hormone (LH) >6.5 U/l. All PCOS patients had an indication for diagnostic surgery due to subfertility. There were 12 PCOS patients who chose to undergo ovarian laser evaporation (CO2 laser, 25 W, 20 times/ovary) and 9 PCOS who chose a diagnostic laparoscopy only (controls). Reproductive endocrinology was measured before, and until 5 days after, surgery, and four gonadotrophin-releasing hormone (GnRH) 'double pulse' tests were included. The main outcome measures were changes in reproductive endocrinology and pituitary sensitivity/priming to GnRH after laser evaporation compared with diagnostic laparoscopy only. In the first hours after surgery, both groups showed an increase in LH, follicle stimulating hormone, estrogen and a decrease in testosterone, androstenedione, AMH and insulin growth factor-1 (P < 0.05). Inhibin B increased in the laparoscopy only group (P < 0.05). In the first days after surgery, testosterone, androstenedione and AMH remained at lower than baseline levels exclusively in the laser group (P < 0.05). Pituitary sensitivity/priming to GnRH was not altered after either laser evaporation or laparoscopy only. The limitations of this study are the short follow-up period and the relatively small groups. The strength of this study is the integrally measured endocrine profiles in combination with an optimal control group of PCOS patients undergoing diagnostic laparoscopy only. Interestingly, most of the immediate endocrine changes after laser evaporation could be related to the surgical context and not to the ovarian drilling procedure itself. The study was funded by the Foundation of Scientific Research in Obstetrics and Gynaecology and the study medication, Lutrelef, was donated by Ferring, The Netherlands, Hoofdorphe There were no conflicts of interests mentioned by the authors.

Pathogenetic substantiation of the correction of placental dysfunction associated with iron-deficiency anemia

The study aims to investigate the pathogenetic correction of placental dysfunction associated with iron deficiency anemia. It is shown that placental dysfunction associated with iron deficiency is characterized by moderate changes in hormonal profile in the form of reduced production of progesterone and prolactin and placental dysfunction is closely related to manifestations of syderopenic syndrome. The results of multimodality therapy of placental dysfunction in women with iron deficiency anemia have been analysed, the main directions of pathogenesis-based therapies for these patients were determined.

Changes in hormonal profile and seminal parameters with use of aromatase inhibitors in management of infertile men with low testosterone to estradiol ratios

To compare the effects of 2.5 mg letrozole with those of 1 mg anastrazole daily on the hormonal and semen profiles of a subset of infertile men with low T/E(2) ratios. Prospective, nonrandomized study. Reproductive medicine clinic. The study group consisted of 29 infertile men with a low serum T/E(2) ratio (<10). Patients were divided into two groups. Group A included 15 patients treated with 2.5 mg letrozole orally once daily for 6 months, and Group B consisted of 14 patients treated with 1 mg anastrazole orally every day for 6 months. Hormonal evaluation included measurement of serum FSH, LH, PRL, T, and E(2). In all sperm analyses pretreatment and posttreatment total motile sperm counts (ejaculate volume × concentration × motile fraction) were evaluated. The use of aromatase inhibitors (either letrozole or anastrazole) in cases of infertile men with low T/E(2) ratios improved both hormonal and semen parameters. This study suggests that some men with severe oligospermia, low T levels, and normal gonadotropin concentration may have a treatable endocrinopathy.

Randomized Controlled Trial on the Effects of Tualang Honey and Hormonal Replacement Therapy (HRT) on Cardiovascular Risk Factors, Hormonal Profiles and Bone Density Among Postmenopausal Women: A Pilot Study

Results of recent trial have shown some negative effects of HRT on postmenopausal women. Therefore, there has been a need to search for an alternative treatment and honey is one of the well known traditional remedies used in minimizing postmenopausal problems. The objectives of the study were to investigate the effects of Tualang honey on the cardiovascular risk factors, changes in hormonal profiles and also effect on the bone. A randomized controlled trial comparing the effects of Tualang honey 20 g/day and HRT for a 4-month intervention period among healthy postmenopausal Malay women aged 45-60 years old was conducted. The primary outcome measures were changes from baseline on the cardiovascular risk profiles, hormonal profiles and effect on bone. Tualang honey compared with low dose HRT, consumed for 4 months by postmenopausal women had no demonstrable effects on the parameters examined such as blood pressure measurement, body mass index and waist circumference. There was no significant difference in the lipid profile, blood sugar profile and bone density between the two groups at the end of the study period.

Changes in hormonal profile, gonads and sperm quality of Argyrosomus regius (Pisces, Scianidae) during the first sexual differentiation and maturation

In the present study, sexual gonadal differentiation and first sexual maturation of Meagre (Argyrosomus regius) was studied, based upon the annual changes in gonadosomatic index (GSI), gonadal histology, and the plasma steroid hormones, testosterone (T), 11-ketotestosterone (11-KT), and estradiol (E2). In addition, spermatozoa characteristics were evaluated by measuring sperm motility and morphology. Results demonstrated that Meagre completes sex differentiation at 10 to 12 mo of age, and are group-synchronous spawners, which reach puberty at 2 (mean length 26.8 ± 0.7 cm, mean weight 920 ± 75 g; N = 10) and 3 (mean length 35.8 ± 0.8 cm, mean weight 1610 ± 89 g; N = 10) years of age for males and females, respectively. In males, during the sex differentiation period, T levels were significantly higher with respect to those of 11-KT; this suggests that T has a key role in the early phases of the sex differentiation. During the spawning season an increase in plasma concentrations of all hormones was observed with 11-KT levels being significantly higher that those of T. In females, during the sex differentiation period, there was an increase in E2 plasma levels, while during the first spawning season, a significant increase of T and E2 levels were measured. Regarding sperm characteristics, the measured curvilinear velocity (VCL) and straight-linear velocity (VSL), resulted in the same order of magnitude with respect to those measured in other marine fish, while the average path velocity (VAP) was similar to that measured in the European Eel. The head of Meagre spermatozoa presents as oval shaped with a surface area of approximately 3.66 μm2 and a perimeter of approximately 6.65 μm. All these findings represent an important basis for further investigation on the reproductive biology of this specie and may assist the farmers to improve seed production in aquaculture.

Endocrine mechanisms mediating temperature-induced reproductive behavior in red-sided garter snakes (Thamnophis sirtalis parietalis)

We investigated the mechanisms by which temperature induces seasonal reproductive behavior in red-sided garter snakes (Thamnophis sirtalis parietalis). Specifically, we addressed whether elevated temperatures during winter dormancy influence (1) diel melatonin and corticosterone rhythms; (2) sex steroid hormone and corticosterone profiles; and (3) the expression of reproductive behavior following emergence. Elevated hibernation temperatures (i.e. 10 degrees C versus 5 degrees C) significantly increased overall melatonin and decreased corticosterone concentrations of snakes. The temperature-induced differences in melatonin rhythms between the 5 degrees C and 10 degrees C treatment groups persisted even after both groups were again acclimated to 10 degrees C, indicating that cold temperature exposure has a lasting influence on melatonin rhythms. Elevated hibernation temperatures also significantly altered androgen and corticosterone profiles of snakes, providing a potential mechanism to explain reported annual variation in steroid hormones. Although previous studies indicate that male red-sided garter snakes exhibit a dissociated reproductive strategy, we demonstrate the presence of intersexual variation in sex steroid hormone profiles, as estradiol concentrations of female snakes increased significantly prior to spring mating activity. Importantly, the percentage change in body mass did not differ significantly between snakes in the hibernation treatments, indicating that the observed changes in hormone profiles are indeed temperature induced and not simply an indirect result of significant changes in the energy balance of snakes. Finally, in males maintained at 10 degrees C during winter dormancy the onset of courtship behavior following emergence was delayed. Our results suggest that environmental temperatures induce reproductive behavior, in part, via changes in diel melatonin and/or corticosterone rhythms in this seasonally breeding reptile.

Changes in cerebral perfusion hormone profile and cerebrospinal fluid flow across the third ventriculostomy after endoscopic third ventriculostomy in patients with aqueductal stenosis: a prospective study

The object of the present study was 3-fold: 1) to study regional cerebral perfusion before and after endoscopic third ventriculostomy (ETV) in patients with obstructive hydrocephalus by using (99m)Tc ethyl cysteinate dimer SPECT: 2) to study any correlation between clinically successful third ventriculostomy and CSF flow across the third ventriculostomy; and 3) to determine any changes in hormone profile following ETV. The authors prospectively studied 15 patients with aqueductal stenosis who underwent ETV during the last 2 years. All the patients underwent pre- and postoperative MR imaging, brain (99m)Tc ethyl cysteinate dimer SPECT, and hormone profile studies. Eight patients were infants. The mean follow-up duration was 17.6 months. Thirteen patients (86.7%) exhibited clinical improvement after surgery. In all patients with clinical improvement the studies documented CSF flow through the ventriculostomy site. Clinical progress could be correlated with SPECT changes in 14 cases (93.3%). In the 13 clinically successful cases, 12 were substantiated by improvement on SPECT scans, whereas in the 2 failed cases, SPECT images revealed no improvement of perfusion defects. Hormone analysis conducted in 14 patients revealed hyperprolactinemia in 8, low triiodothyronine values in 2 patients, and hypocortisolemia in 1, which was reversed after ETV. Clinical improvement is not well correlated with a decrease in ventricular size following ETV. Brain SPECT is a valuable tool for the follow-up of patients with hydrocephalus after ETV, particularly in cases in which MR imaging findings are not clear. There are subtle hormonal changes in patients with hydrocephalus that may improve following ETV.

Should luteal phase support be introduced in ovarian stimulation/IUI programmes? An evidence-based review

World-wide, intrauterine insemination (IUI) is still one of the most applied techniques to enhance the probability of conception in couples with longstanding subfertility. The outcome of this treatment option depends on many confounding factors. One of the confounding factors receiving little attention is the quality of the luteal phase. From IVF studies, it is known that ovarian stimulation causes luteal phase deficiency. Based on the best available evidence, this short review summarizes the indications for mild ovarian stimulation combined with IUI and the optimal stimulation programme. While it has been established that stimulated IVF/intracytoplasmic sperm injection cycles have deficient luteal phases, the question remains whether the quality of the luteal phase when only two or three corpora lutea are present (as is the case in stimulated IUI cycles) is impaired as well. There are too few large non-IVF trials studying luteal phase quality to answer this question. Recently a randomized trial has been published that investigated luteal phase support in an IUI programme. This study is discussed in detail. It is recommended to apply luteal phase support in stimulated IUI cycles only when proven cost-effective. Further trials are mandatory to investigate both endometrial and hormonal profile changes in the luteal phase after mild ovarian stimulation, and the cost-effectiveness of luteal support in IUI programmes.

Changes in endocrine profiles during ovsynch and ovsynch plus norprolac treatment in Murrah buffalo heifers at hot summer season

The aim of this study was to compare the changes in hormonal profiles during ovsynch and ovsynch plus norprolac treatment in Murrah buffalo heifers following timed artificial insemination (TAI) at stressful summer months, through intensive endocrine analysis. The norprolac (an anti-prolactin drug) at the dose rate of 10.0 mg/animal /day effectively suppressed the level of prolactin upto 30 hours. The hormones quantified in blood plasma samples collected before, during and after ovsynch and ovsynch plus norprolac treatment were LH, prolactin, progesterone, estradiol-17beta and total estrogens. The plasma prolactin and progesterone concentrations were negatively correlated (r = - 0.24) during summer estrous cycle, which indicated prolactin-induced suppression of progesterone secretion through poor luteal development. The ovsynch treatment reduced the incidence of anestrous from 45% before treatment to only 18% after treatment. The norprolac induced prolactin suppression improved the efficiency of ovsynch treatment upto 100% cyclicity after treatment in comparison to 36% acyclicity before treatment. In both the treatments 45% and 55% of animal became pregnant after TAI, respectively. The high prolactin secretion contributed to poor fertility by lowering gonadal hormones (estradiol-17beta, total estrogens and progesterone) production in summer months. This finding of endocrine changes suggests that ovsynch protocol for estrus synchronization has potential application for improvement of fertility in repeat breeding buffaloes even during extreme summer months through suppression of prolactin secretion.

Key Role of Aldosterone and Pericryptal Myofibroblast Growth in Colonic Permeability

When sodium intake diminishes, both the kidney and distal colon contribute directly to sodium homeostasis. In response to a diet with low amounts of sodium, the body hormonal profile changes to produce different effects on crypt-colon permeability and absorption and in the pericryptal sheath surrounding distal colonic crypts. This adaptation produces an increase in Na absorption, a decreased crypt-wall permeability, and an activation of the growth of pericryptal myofibroblasts. The separate roles of the 2 main hormones implicated in the process, aldosterone and angiotensin II, until now have been unclear. Experiments conducted on adrenalectomized rats on low- and high-sodium diets, implanted with osmotic pumps perfusing either aldosterone or angiotensin II, allow us to discriminate between the effects of these hormones. In the distal colon, aldosterone acts as a trophic agent on the myofibroblasts layer and is the key hormone controlling colonic permeability, but angiotensin II alone has no discernable direct role in the process.

Assessment of human oocyte developmental competence by cumulus cell morphology and circulating hormone profile

The predictive value of the morphology of the cumulus–oocyte complex (COC) has not yet been explored as a possible factor contributing to the success of human in-vitro maturation (IVM). In the present study, development-supporting competency of oocytes encircled in a large (≥5) (grade A), moderate (3∼4) (grade B) or small (≤2) (grade C) number of cumulus cell layers was assessed, together with changes in hormonal profile following a truncated course of 150 IU pure FSH administration for 3 days prior to aspiration on laparoscopy indicated for endometriosis. FSH priming increased the number of COC aspirated without changing the proportion of the three morphological types of COC, which were then subjected to IVM in the presence of 200 mIU/ml FSH plus 1000 mIU/ml human chorionic gonadotrophin, followed by intracytoplasmic sperm injection. The highest development-supporting competence was observed not with oocytes in grade A COC harvested from natural cycles, but with oocytes in grade B COC from FSH-primed cycles. Hormonal profiles in patients bearing grade B COC were characterized by moderate response in oestradiol and progesterone production following FSH, with LH/FSH ratio being below 1.0. It is concluded that an optimal window of hormonal profile(s) may exist for follicle aspiration to obtain grade B COC in FSH-stimulated human IVM cycles.

A double-blind randomised trial to evaluate the effect of anastrozole for the treatment of non-toxic multinodular goitre

Multinodular goitre (MNG) is a common clinical finding, particularly in females and is usually asymptomatic. When symptoms occur because of local pressure-related effects the only treatment is surgical involving partial or total thyroidectomy. A number of epidemiological observations and experimental data have suggested that oestrogen aromatase activity may be involved in the pathogenesis of MNG. This study examines the effect of anastrozole, a non-steroidal aromatase inhibitor that inhibits the peripheral conversion of testosterone to oestradiol, in reducing the size of MNG. Thirty-two post-menopausal female patients, median age 63 years (range 42-84) were randomised in a double-blind fashion to receive either anastrozole 1 mg daily or placebo for 3 months. Ultrasonographic measurement of each thyroid lobe and isthmus together with complete biochemical and hormone profiles were performed at the start and end of treatment. There was no significant reduction in the goitre size for patients in the anastrozole group (p = 0.246) or the placebo group (p = 0.418). There were no significant changes in hormone profiles (including throglobulin concentration) within each group between the start and end of the study. We conclude that the use of anastrozole in the treatment of MNG does not appear to have any effect in reducing the size of MNG.

Menopause transition: Annual changes in serum hormonal patterns over the menstrual cycle in women during a nine-year period prior to menopause.

To examine the hormonal characteristics of menstrual cycles in healthy women approaching menopause, serum hormone profiles were investigated annually in this longitudinal study of 13 healthy women between 4 and 9 yr before menopause and the year of the menopause. Serum FSH, LH, estradiol, progesterone, total inhibin, inhibins A and B, and prolactin were determined in blood samples collected annually three times weekly for 4 wk beginning with the onset of menses. Menstrual bleeding diaries covering this 4- to 9-yr period were also collected allowing the prospective identification of the final menstrual period. A change in serum hormone patterns was observed in cycles approaching menopause, exemplified by an increasing number of cycles of prolonged length with a prolonged follicular phase resulting in a failure to detect a luteal phase rise in serum progesterone within the 4-wk collection period. These prolonged cycles (designated B cycles based on a previous work) were analyzed separately and compared with the remaining ovulatory (D) cycles. No B cycles were identified in any women earlier than 27 cycles from menopause. The proportion of B cycles increased as menopause approached, reaching 62% in the last 10 cycles. The proportion of D cycles decreased accordingly. The B cycles during the initial 4-wk collection period were characterized by elevated FSH, LH, FSH/inhibin A and FSH/inhibin B ratios, and longer duration, although cycle length/subject was not significantly different presumably due to the small number of B cycles. The D cycles showed no changes in hormonal profiles over the 4- to 9-yr time period. These data indicate that there is a time-related change in the character of menstrual cycles as menopause approaches, with an increasing proportion of cycles observed with prolonged follicular phases that may either be delayed ovulatory cycles or anovulatory cycles. The increase in the proportion of B cycles with elevated early follicular phase FSH levels and low inhibin/FSH ratios toward menopause provides a basis for the apparent early increase in serum FSH and decrease in serum inhibins observed previously in studies of the menopause transition based on sampling confined to the follicular phase only. The data amplify and clarify current concepts of the endocrine basis of the menopause transition.

Effect of high altitude on sensitivity to the taste of phenylthiocarbamide

Sensitivity to the taste of phenylthiocarbamide (PTC) was studied using the Harris-Kalmus method in healthy human volunteers at sea level and then subsequently at an altitude of 3500 m over a period of 3 weeks, after which they were brought back to sea level. Blood sugar, insulin and blood cortisol levels were estimated weekly. The results indicated that, out of 51 subjects studied, 26 (55%) were PTC tasters at sea level. Eight of those unable to taste PTC at sea level tested as tasters at high altitude, and 2 of them reverted to being non-tasters on return to sea level. In the blood, an increase in cortisol and blood insulin levels was seen without any significant change in sugar levels. All the changes recorded at high altitude tended to return to basal values after re-induction to sea level. The study suggests that high-altitude hypoxia in some way, possibly involving changes in hormonal profile among other factors, causes an alteration in sensitivity to the taste of PTC, resulting in some of the individuals shifting to lower PTC sensitivity.

Simulated weightlessness-induced attenuation of testosterone production may be responsible for bone loss.

This study examined the effects of simulated weightlessness on serum hormone levels and their relationship to bone mineral density (BMD). The tail-suspended (i.e., hindlimb suspended, HLS) rat model was used to simulate weightless conditions through hindlimb unloading to assess changes in hormonal profile and the associated bone loss. In the first study, 24 adult male rats were assigned to two groups with 12 rats being HLS for 12 d, and the remaining 12 rats serving as ground controls. On d 0, 6, and 12, blood samples were taken to estimate circulating hormone levels. HLS rats had significant reductions in testosterone, 1,25 (OH)2 vitamin D, and thyroxine levels by d 6 (p<0.01); their testosterone levels were almost undetectable by d 12 (p<0.001). Serum cortisol levels in these rats were elevated on d 6 (p<0.02), but returned to normal levels by d 12. No changes were observed with serum ionized calcium and other hormones examined, as well as the body weights, and weights of thymus, heart, and brain. In the second study, eight rats were ground controls, while an additional eight rats were HLS for 12 d before being removed from tail-suspension and maintained for a further 30 d. Blood samples were collected every 6th d for 42 d. This study showed that both serum thyroxine and 1,25(OH)2 vitamin D levels returned to normal levels soon after hind limb unweighting, while serum testosterone levels matched normal levels only after a further 3-4 wk. These studies showed a significant decrease of femur weights, but not weights of humeri in HLS rats suggesting that this is a specific effect on unloaded bones. On d 12 in both studies, a significant reduction in the lumbar spine (p<0.05) and the femoral neck (p<0.01) BMD appeared in HLS rats. This was confirmed in the second study, where HLS led to a significant decrease in BMD even extending to d 42. Previous studies have shown that space flight and tail-suspension lead to marked reductions in bone formation with little effect on bone resorption. Recently, we reported that androgen replacement can indeed prevent bone losses in this animal model. Therefore, it seems logical to propose that the significant decreases of serum testosterone observed in these tail-suspended animals are, at least in part, responsible for the losses of BMD seen in their affected weight-bearing bones (i.e., lumbar spine and the femur). Considering that 1. testosterone is anabolic to osteoblasts and also decreases the rate of bone turnover 2. serum testosterone levels are markedly suppressed in simulated weightlessness, and 3. testosterone replacement therapy prevented the bone loss in HLS rats, we propose that the testosterone deficiency in this animal model is related to their bone loss.

Erythrocyte metallothionein in relation to other biochemical zinc indices in pregnant and nonpregnant women.

Erythrocyte metallothionein (E-MT) is considered a promising index of zinc status in humans, since it may be more sensitive than other biochemical indices to changes in dietary zinc. However, conditions of high zinc demand with substantial redistribution of tissue zinc and specific changes in hormone profile, such as pregnancy, may have an influence on E-MT levels in addition to dietary zinc. In this study, we compared E-MT concentrations in relation to other biochemical zinc indices in healthy pregnant women at delivery (n = 40) and non-pregnant women (n = 22) with similar habitual dietary zinc intakes (average 13.3 mg/d). Pregnant women had lower serum zinc and albumin-bound serum zinc, but higher levels of alpha 2-macroglobulin-bound serum zinc than the nonpregnant women. Erythrocyte zinc (E-Zn) was similar in both groups, but E-MT (mean +/- SE) was slightly but significantly (p < 0.05) higher in the pregnant women (2.9 +/- 0.09 nmol/g protein) compared to nonpregnant women (2.6 +/- 0.06 nmol/g protein). A significant correlation was observed between E-MT and E-Zn in the nonpregnant women (r = 0.70; p < 0.001), consistent with the role of intracellular zinc in the regulation of metallothionein synthesis. However, such correlation was not observed in the pregnant women, suggesting that E-MT levels in pregnancy may be influenced by factors related to the pregnant state.

Changes in hormonal profiles during the estrous cycle in old lactating beef cows

Patterns of concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), progesterone (P 4) and estradiol-17β (E 2) during an estrous cycle were compared between 15 lactating beef cows 5 to 7 years of age (young) and 15 cows ≥ 12 years of age (old). Length of estrous cycle did not differ between young and old cows (P = .06). No differences due to age were found for LH. Patterns of concentrations of P 4 during the first 15 days of the cycle, of FSH during days 6 through 12 and of E 2 during the follicular phase differed with age (P < .05). An earlier (P < .025) midcycle elevation of FSH was associated with an earlier rise and greater concentration of E 2 (P < .05) during the follicular phase in old than in young cows. Differences in FSH and P 4, although subtle, were consistent with an earlier or more advanced follicular development in old cows, leading to greater secretion of E 2 from the preovulatory follicle.