Changes In Plasma Levels Of Hormones Research Articles

Aortocaval fistula delays gastric emptying of liquid test meal in awake rats

Arteriovenous anastomoses disrupt cardiovascular and renal homeostasis, eliciting hemodynamic adjustments, resetting the humoral pattern, and inducing cardiac hypertrophy. Because acute circulatory imbalance alters gut motor behavior, we studied the effects of arteriovenous fistula placement on the gastric emptying (GE) of a liquid meal in awake rats. After laparotomy, we created an aortocaval fistula (ACF) by aorta and cava wall puncture with a 21-, 23-, or 26-gauge needle. The ACF was not created in the control group, which underwent sham operation. After 12, 24, or 48 h, mean arterial pressure, heart rate, and central venous pressure were continuously recorded, and cardiac output was estimated by thermal dilution. The rats were then gavage fed a test meal (i.e., phenol red in glucose solution), and fractional dye retention was determined 10, 20, or 30 min later. The effect of prior bleeding on ACF-induced GE delay, the role of neuroautonomic pathways, and changes in plasma hormone levels (i.e., angiotensin II, arginine vasopressin, atrial natriuretic peptide, corticosterone, and oxytocin) were evaluated. When compared with the sham-operated group, ACF rats exhibited arterial hypotension, higher (P < 0.05) heart rate, central venous pressure, and cardiac output values and increased (P < 0.05) gastric dye retention, a phenomenon prevented by bilateral subdiaphragmatic vagotomy and hexamethonium treatment. Pirenzepine also impaired the occurrence of gastric delay in subjects with ACF. In addition to causing hyperkinetic circulation, ACF placement delayed the GE of liquid in awake rats, an effect that likely involves a parasympathetic pathway.

Hormone levels are associated with clinical markers and cytokine levels in human localized cutaneous leishmaniasis

Leishmaniasis is a serious health problem in several parts of the world, and localized cutaneous leishmaniasis (LCL) is the most frequent presentation of the tegumentary form of this disease cluster. Clinical presentations of leishmaniasis are influenced by both parasite and host factors, with emphasis on the host immune response. Alterations in plasma hormone levels have been described in many infections, and changes in hormone levels could be related to an imbalanced cytokine profile. In the present work, we evaluated a group of patients with LCL to determine changes in plasma hormone levels (cortisol, DHEA-S, estradiol, prolactin and testosterone) and their association with clinical markers of disease (lesion size, dose used to reach cure and time to cure) and with cytokines produced by PBMC stimulated by SLA (IFN-γ, IL-10 and TNF-α). Individuals with LCL exhibited lower plasma levels of DHEA-S, prolactin and testosterone compared with sex-matched controls, whereas levels of cortisol and estradiol were similar between patients and controls. Plasma levels of cortisol, estradiol or prolactin positively correlated with at least one clinical parameter. Cortisol and prolactin levels exhibited a negative correlation with levels of IFN-γ, whereas no correlation was observed with IL-10 or TNF-α levels. A decrease in DHEA-S levels was observed in male LCL patients when compared to male healthy controls. No other differences between the sexes were observed. Our results indicate a role for neuroendocrine regulation that restricts Th1 responses in human LCL. It is possible that, although impairing parasite killing, such neuroimmunomodulation may contribute to limiting tissue damage.

Changes in plasma hormone levels correlate with fledging in nestling Leach’s storm-petrels

Leach’s storm-petrels accumulate large amounts of body mass throughout the nestling period. Approximately 4 days before fledging, nestlings weigh 50–100% more than adults. In order to shed this excess mass, nestlings engage in behavioral anorexia, and leave the burrow when they are light enough to fly. During this prefledging period, we measured several plasma hormones (corticosterone, thyroxine, and testosterone) to determine whether the behavioral changes associated with fledging are correlated with endocrine changes. In several species, including petrels, corticosterone levels are known to increase near fledging. Reduced food consumption has been shown to elevate corticosterone levels and decrease thyroxine levels in nestling birds. In nestling storm-petrels, levels of both corticosterone and thyroxine increased. Storm-petrels were found to secrete measurable levels of testosterone, but levels did not change during the prefledging period. Increased corticosterone levels might be part of an endocrine signal that initiates changes in feeding behavior, or may result from reduced food intake. Elevated thyroxine levels may be related to metabolic changes involved in mass loss. Future experimental work is needed to ascertain whether the described endocrine changes are responsible for, or result from, prefledging changes in petrel feeding behavior.

Plant Growth Regulator (4-Chlorophenoxy Acetic Acid) Increases Apoptosis in Gonads of Rats without Changing Hormonal Levels

Background/Aims: Plant growth regulators are considered to leave minimal amounts of remnants and therefore cause no significant side effects in humans. In this study, we aimed to investigate the hormonal and histopathological effects of 4-chlorophenoxy acetic acid (4-CPA), a commonly used plant growth regulator, on the gonadal functions of rats. Methods: The study was implemented on 64 Wistar albino rats (20 days old). Forty-eight rats received 4-CPA every day until 50 days of age. The rats were randomized into 4 groups (a control group and three 4-CPA groups with doses of 25, 50 and 100 mg/kg/day); each group was further divided into males and females, making a total of 8 groups. The levels of FSH, LH, testosterone, estradiol, leptin, inhibin-B and neuropeptide-Y were measured. Histopathological examination of the testes and ductus deferens in male rats, and ovaries and uterus of female rats (caspase-3 and -9 immunoreactivity) was performed. Results:Although hormone levels were similar between the groups, rats that received 4-CPA showed significantly higher degrees of apoptosis compared to the control group (p < 0.001) and increased doses of 4-CPA were directly correlated with the amount of apoptosis (p < 0.001). Conclusion: 4-CPA induced apoptosis in the gonads of rats without concurrent changes in plasma hormone levels.

Changes in plasma hormone levels following lipopolysaccharide injection in rabbits

Lipopolysaccharide (LPS) is an endotoxin comprising part of the cell wall of Gram-negative bacteria. It is able to induce a septic state and the release of several pro-inflammatory cytokines that are known to be responsible for hormonal changes in humans and animals. The aim of this study was to evaluate changes in plasma adrenocorticotrophic hormone (ACTH), corticosterone and cortisol levels in a rabbit model in which sepsis was induced by the intravenous administration of LPS. The possible involvement of several protein kinases, namely protein kinase A (PKA), C (PKC) and mitogen-activated protein kinases (MAPKs), and proteasome was also assessed. The results indicated that LPS induced significant increases in plasma ACTH, corticosterone and cortisol concentrations in rabbits. Moreover, protein kinases and proteasome seemed to mediate the hormone response to LPS as treatment with specific inhibitors prior to LPS administration was able to reduce, delay, or, in some cases, inhibit the hormone increases. The findings may help to construct strategies to protect and treat animals with endotoxaemia.

Plasma progesterone levels and cocaine-seeking in freely cycling female rats across the estrous cycle

Previous studies have reported sex and estrous cycle-dependent differences in the reinstatement of cocaine-seeking triggered by cocaine injections or drug-paired cues. However, the relationship between estradiol or progesterone levels and cocaine-seeking in a reinstatement model of relapse has not been explored. Thus, we examined changes in plasma hormone levels during cocaine-taking and -seeking behaviors in gonadally intact female rats. Rats self-administered cocaine (0.5 mg/kg infusion) during daily 2-h sessions, followed by extinction. For reinstatement, cocaine (0, 5, or 10 mg/kg, i.p.) was administered 30 min prior to testing. Vaginal smears and blood samples were collected prior to and during chronic cocaine self-administration, extinction, and reinstatement testing. Relative to non-estrous females, females in estrus showed greater responding during self-administration, extinction, and during cocaine-primed reinstatement. The highest progesterone levels were noted at the time of lowest cocaine-seeking (proestrus) and the lowest levels of progesterone occurred at the time of highest cocaine-seeking (estrus). In contrast, plasma estradiol levels did not show any clear pattern with cocaine-seeking. These data from an animal model of relapse supports recent clinical evidence that progesterone reduces subjective craving in cocaine-dependent women. Overall, these results suggest that progesterone administration may be a useful intervention for reducing the incidence of relapse.

Protein Profiling of Rat Ventral Prostate following Chronic Finasteride Administration

To better understand the effects of antiandrogens on the prostate, we investigated the changes in the proteome of rat ventral prostate (VP) following treatment with a well characterized 5alpha-reductase inhibitor, finasteride. Sprague-Dawley rats were treated daily by gavage with finasteride at 0, 1, 5, 25, and 125 mg/kg/day. Changes in plasma hormone levels as well as the weight and histology of sex accessory tissues were determined after 28 days of treatment and showed a dose-related decrease of VP weights together with a marked atrophy of the tissue visible at the macroscopic and microscopic levels. In addition, significant reductions in seminal vesicle and epididymis weights were noted. VP proteins were analyzed by two-dimensional gel electrophoresis: 37 proteins, mainly involved in protein synthesis, processing, and cellular trafficking and in metabolism, detoxification, and oxidative stress, were identified as modulated by finasteride. The prominent feature of this study is the demonstration of finasteride dose-dependent up-regulation of a protein similar to l-amino-acid oxidase 1 (Lao1). An up-regulation of this protein was also observed with the antiandrogen flutamide. Lao1 expression occurred as early as 48 h after antiandrogen administration and persisted throughout the treatment duration. Immunohistochemistry showed that this protein was only detectable in epithelial cells and secretory vesicles. Altogether these data point to a potential use of Lao1 to reveal antiandrogen-induced prostate injury.

Individual variation in plasma estradiol-17β and androgen levels during egg formation in the European starling Sturnus vulgaris: implications for regulation of yolk steroids

While it is clear that maternal transfer of steroids to egg yolk can have significant effects on offspring phenotype, an unresolved question is whether females can facultatively adjust yolk hormone levels independently of their own plasma levels or whether yolk steroid levels are simply a direct consequence of temporal variation in the female’s hormonal status. In part, this is because we lack detailed information about the day-to-day pattern of changes in plasma hormone levels during the laying cycle for non-domesticated birds. Here, we describe changes in plasma estradiol-17β (E2) and androgens, throughout laying in relation to specific stages of ovarian follicular development in the European starling ( Sturnus vulgaris). Plasma E2 levels increased rapidly from the onset of rapid yolk development (RYD) to reach maximum levels in birds with a complete follicle hierarchy (⩾4 yolky follicles). However, levels decreased linearly throughout the later stages of follicle development returning to pre-breeding values before the final yolky follicle was ovulated. In females with ⩾4 yolky follicles there was 10-fold variation in plasma E2 levels among individual females, but this was not related to plasma levels of the main yolk precursor vitellogenin or to the total mass of yolky follicles developing at the time of blood sampling. In contrast to E2, plasma androgen levels showed only a very gradual linear decline throughout the laying cycle from pre-RYD to clutch completion. Furthermore, androgen levels showed less individual variability: 4-fold variation among females with ⩾4 yolky follicles, although this was also independent of our measures of reproductive function. Data on inter- and intra-individual variation in female hormone levels are important to set-up a priori predictions for, and interpretation of, studies of yolk hormone levels.

Effects of sexual interactions with a male on fos-like immunoreactivity in the female quail brain.

Sexual interactions can cause changes in plasma hormone levels and activate immediate early genes within the mammalian brain. There are marked anatomical differences between the regions activated that relate directly to the sexual specific behaviour and neuroendocrinology of each sex. The aim of this study was to determine if such a sexual dimorphism exists in birds by examining the brain regions stimulated in adult virgin female Japanese quail (Coturnix japonica) during sexual behaviour and comparing this to previously reported data concerning males. Female quail were allowed to freely interact with adult males and both female and male sexual behaviour was recorded. Contrary to previous findings in male quail, no significant induction of Fos-like immunoreactive (FLI) cells was observed following sexual interactions in the preoptic area of females; this area is fundamentally involved in the control of male-type copulatory behaviour. Sexual interactions significantly induced FLI cells in the hyperstriatum ventrale, the part of the archistriatum just lateral to the anterior commissure, and the nucleus intercollicularis. Moreover, prominent activation was detected throughout most of the ventromedial nucleus of the hypothalamus, a region reported to be rich in oestrogen receptors. FLI induction was not a consequence of sexual behaviour induced changes in luteinizing hormone (LH) as plasma LH levels were unaltered. Instead, brain activation must be a consequence of copulation-associated somatosensory inputs or direct stimuli originating from the male. Male quail, like the majority of other birds, lack an intromittant organ (penis) so that the somatosensory inputs to the female are rather different from those in mammals; the precise nature of these inputs is yet to be determined.

Lipid reserves, fasting capability and the evolution of nestling obesity in procellariiform seabirds

Several alternative explanations have been proposed to account for the evolution of nestling obesity in a variety of avian groups. These predict quite different patterns of fat accumulation, storage and use by chicks of different ages. Yet surprisingly few studies have measured changes in body composition during chick development. We tested the applicability of these hypotheses for fulmars, Fulmarus glacialis , by direct measurement of changes in water, lipid and lean dry mass in growing chicks. Lipid and lean dry mass increased until ca. 70% of the way through chick rearing, but then levelled off. Total body water also increased until the same stage, but gradually declined thereafter, and it was this change rather than fat metabolism that resulted in mass recession. The observed pattern of a continued increase in stored lipid, and most importantly, its maintenance all the way through the mass–recession phase until chicks reach fledging, is incompatible with many of the proposed hypotheses. We suggest that the most likely ultimate explanation for large fat deposits is to fuel chicks during the initial critical period away from the nest site while they learn to forage

Reproductive biology and endocrine regulation of final oocyte maturation of captive white bass

The ovarian development, and plasma levels of gonadotropin II (GtH II) and sex‐steroid hormones at the end of vitellogenesis were examined in captive white bass Morone chrysops. The changes in plasma hormone levels and oocyte morphology associated with gonadotropinreleasing hormone agonist (GnRHa)‐induced final oocyte maturation (FOM) were studied. Although plasma 17β‐oestradiol (E2) and oocyte diameter increased, there were no changes in GtH II, testosterone (T), 17,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20β‐P) or 17,20β,21‐dihydroxy‐4‐pregnen‐3‐one (17,20β,21‐P) in non‐hormone‐treated females, and no FOM was observed. Treatment with a sustained‐release GnRHa delivery system (GnRHa implant) induced two FOM cycles separated by about 24 h, with the release of approximately equal numbers of eggs in each spawn. Plasma GtH II levels were elevated significantly throughout FOM, reaching a maximum of 9·07 ± 1·55 ng ml−1 in ovulated fish. Both plasma E2 and T increased soon after the GnRHa treatment, but E2 declined in fish undergoing germinal vesicle (GV) migration. Plasma T increased further during FOM (7·55 ± 2·87 ng ml−1), but declined precipitously at ovulation. A surge in plasma 17,20β‐P and 17,20β,21‐P (4·11 ± 0·97 ng ml−1 and 3·10 ± 0·77 ng ml−1, respectively) was observed in females undergoing GV breakdown (GVBD). Based on the involvement of different sex‐steroid hormones, FOM was separated into two stages. Early FOM included lipid‐droplet coalescence and GV migration, and was associated with elevations in plasma GtH II and T. Late FOM included GVBD and yolk‐globule coalescence, and was associated with elevations in plasma GtH II, 17,20β‐P and 17,20β,21‐P. The results of this study point to the absence of a surge in plasma GtH II as the missing link in the reproductive axis responsible for the failure of captive white bass to undergo FOM at the end of vitellogenesis. Sustained elevation of plasma GtH II via treatment with a GnRHa implant induced two consecutive spawns with an overall egg production two‐ to eightfold higher than previously obtained from captive broodstocks, and similar to annual egg production Values reported for wild fish.

The Influence of Corticosterone and Glucagon on Metabolic Recovery from Exhaustive Exercise in the Desert IguanaDipsosaurus dorsalis

The skeletal muscles of ectothermic vertebrates possess an elevated glyconeogenic capacity that is responsible for a major portion of lactate removal and glycogen resynthesis following exercise. In lizards, changes in plasma hormone levels and the influence of differing hormone levels on muscle metabolism postexercise are poorly understood. We measured the effects of 5 min of exhaustive exercise on plasma levels of glucagon and corticosterone in the desert iguanaDipsosaurus dorsalis.We also determined the extent to which these hormones influence, or are influenced by, postexercise plasma lactate concentrations postexercise. Exercise resulted in the accumulation of 20 mMblood lactate, while plasma glucose levels remained stable throughout 90 min of recovery. Plasma glucagon was elevated sevenfold during 5 min of exercise and returned to resting levels within 45 min of recovery. Glucagon stimulated lactate incorporation into glycogen in isolated red muscle fiber bundles. Plasma corticosterone was also elevated to three times normal resting values, but only after 45 min of recovery. Blocking corticosterone elevation with metyrapone did not alter the kinetics of plasma lactate removal. In lizards, the dramatic rise in plasma glucagon occurs at the same time as previously reported elevated skeletal muscle glyconeogenesis and elevated glucagon stimulates lactate removalin vitro,strongly suggesting a role for glucagon in postexercise skeletal muscle metabolism.

Evaluation of plasma osmolality and hormone responses in elderly chronic hemodialysis patients with excessive interdialytic weight gain.

Elderly patients may exhibit changes in plasma hormone levels, as well as thirst disorders. Two groups of elderly hemodialysis patients were evaluated to determine if excessive interdialytic weight gain was related to differences in postdialysis plasma osmolality or postdialysis measurement of plasma renin activity, or plasma levels of angiotensin II (a dipsogenic hormone), aldosterone, and vasopressin. Patients mean age was 77.0 +/- 8.8 years and patients were divided into groups, I and II, with less than or greater than 2 kg interdialytic weight gain. Postdialysis plasma osmolality was similar in both groups of patients (309.3 +/- 2.3 vs. 309.6 +/- 2.4 mOsm/Kg, p = 0.8) and postdialysis AVP levels also were no different (2.7 +/- 0.6 vs. 2.1 +/- 0.2 pg/mL, p = 0.3). There was also no statistical difference between postdialysis angiotensin II and aldosterone levels in either group of patients. Plasma renin activity (PRA) was also not different in either group (2.3 +/- 1.1 vs. 0.43 +/- 0.1 ng/mL/hr, p = 0.1), but group I patients, with less than 2 kg weight gain, tended to exhibit higher PRA values perhaps reflecting proximity to their dry weight postdialysis. Since excessive fluid intake did not appear to relate to plasma osmolality and hormone levels studied, it might be suggested that excessive drinking could be due to excessive sodium intake associated with personal dietary habits or perhaps other as yet unmeasured factors.

Gamete Ripening and Hormonal Correlates in Three Strains of Lake Trout

Abstract In our 2-year laboratory study of hatchery-reared adult lake trout Salvelinus namaycush of the Seneca Lake, Marquette (Lake Superior Lean), and Jenny Lake strains, we compared gamete ripening times and changes in plasma concentrations of seven hormones. If interstrain differences in these traits were found, such differences might help explain the apparent failure of stocked fish of these strains to develop large, naturally reproducing populations in the Great Lakes. The complex temporal changes in plasma hormone levels that occur during sexual maturation in lake trout have not been previously described. We detected little evidence of temporal isolation that would prevent interbreeding among the three strains. Strain had no effect on ovulation date (OD) in either year. Strain did not affect spermiation onset date (SOD) in year 1 but did in year 2, when the mean SOD of Jenny Lake males was earlier than that of Seneca Lake males but not different from that of Marquette males. Hormonal data were norm...

Control of renal handling of potassium loads in ducks with active salt glands

Domestic ducks adapted to saline of 400 mosmol/kgH2O as their only water supply received intravenous loads of 100 mM KCl for 2 h while being intravenously infused with 200 mM NaCl at 1.0 ml/min to produce simultaneous salt gland secretion and diuresis-natriuresis. K+ loading did not alter the plasma levels of the osmoregulatory hormones arginine vasotocin, angiotensin II, aldosterone, and atrial natriuretic factor but promptly evoked kaliuresis because of a rise from 17 to 155 mM in urinary K+, with a proportional decrease in urinary Na+. Continuous infusion of amiloride (0.04 mg.min.-1.kg body wt-1 iv) further enhanced diuresis and natriuresis and lowered urinary K+, but the kaliuretic response to K+ loading was only moderately reduced because of enhanced diuresis and a rise in urinary K+ from 3 to 33 mM, with a slight decrease in urinary Na+. Changes in plasma hormone levels reflected dehydration due to excessive diuresis but were not related to kaliuresis. Salt gland secretion was not affected directly by amiloride but was secondarily reduced by the induced dehydration. In amiloride-treated ducks, hyperkalemia in response to K+ loading was exaggerated relative to the modest reduction in K+ excretion and may be attributed to moderate metabolic acidosis and/or general effects of amiloride on K+ metabolism. It is concluded that none of the established osmoregulatory hormones is involved in short-term control of renal K+ handling in ducks and that distal tubular K+ excretion involving amiloride-sensitive Na+ channels is quantitatively unimportant in this avian species.

Effect of space flights on plasma hormone levels in man and in experimental animal

An important increase of plasma hormone levels like insulin, TSH and aldosterone was observed in human subjects after space flights, however in the changes of plasma content of ACTH, cortisol, adrenaline and noradrenaline the individual variations were observed in relation to number and duration of space flight. For evaluation of the effects of these changes in plasma hormone levels on metabolic processes also the experiments with small animals subjected to space flights on a board of biosatellite of Cosmos series were running. An elevation of plasma levels of corticosterone, adrenaline, noradrenaline and insulin was found in rats after the space flights of duration from 7 to 20 days. It was demonstrated, that the increase of corticosterone in plasma is followed by the activation of enzymes involved in the aminoacid metabolism in rat liver (tyrosine aminotransferase, tryptophanpyrolase, alanine aminotransferase and aspartate aminotransferase). After a short recovery period (2 to 6 days) the plasma corticosterone concentration and also the activity of liver enzymes returned to control levels. The exposition of animals to stress stimuli during this recovery period showed higher response of corticosterone levels in flight rats as compared to intact controls. The increase of plasma catecholamine levels was not followed by elevation of lipolysis in adipose tissue. This is due to lower response of adipose tissue to catecholamine because a decrease of the stimulation of lipolysis by noradrenaline was observed in animals after space flight. The increase of insulin was not followed by adequate decrease of glucose concentration suggesting a disturbances in glucose utilization similarly as in cosmonauts after a long-term space flight. These results showed that changes in plasma hormone levels, observed after space flight, affected the regulation of metabolic processes in tissues.

Changes in plasma hormone levels during loss of hypoosmoregulatory capacity in mature chum salmon ( Oncorhynchus keta) kept in seawater

Returning chum salmon ( Oncorhynchus keta) in northern Honshu Island, Japan, complete gonadal maturation while in the bay. Mature fish caught in the bay failed to survive in seawater for more than a week, whereas they adapted to fresh water efficiently. Mortality in seawater seems to be due primarily to an increased plasma osmolality. Maladaptation to seawater was more pronounced in the fish caught deep in the bay than those caught outside the bay, and also greater in females than in males. In close correlation with the increased plasma osmolality and electrolyte concentrations, plasma levels of cortisol and growth hormone increased in the fish kept in seawater. Cortisol and growth hormone may be secreted in response to the increased plasma osmolality and would not be the direct cause of the maladaptation to seawater. Plasma prolactin remained low in the seawater fish, indicating that the increased secretion of prolactin, a freshwater-adapting hormone, is not the cause of maladaptation to seawater either. On the other hand, when the fish caught in the river were kept in fresh water, an increase in plasma prolactin concentrations was seen, particularly in females, whereas no significant change was seen in plasma cortisol and growth hormone. Concentrations of 17α,20β-dihydroxy-4-pregnen-3-one in the female and of testosterone in both the male and female were extremely high in the bay fish and decreased slightly but significantly after 7 days in fresh water. The gonadal steroids may have inhibitory effects on osmoregulation in the mature salmon in seawater.

Hypophysectomy does not alter the acinar zonation of gluconeogenesis or the mitochondrial redox state in rat liver.

The biochemical and functional heterogeneity of hepatocytes in different zones of the liver acinus may be related to the concentrations of hormones within the liver acinus. We examined the effects of hypophysectomy, which causes marked changes in plasma hormone levels and in activities of hepatic enzymes that are normally heterogeneously distributed, on the degree of metabolic zonation within the liver acinus. In hypophysectomized rats the activity of alanine aminotransferase was increased, but its normal zonation (predominance in the periportal zone) was preserved. The activity in cultured periportal and perivenous hepatocytes was increased by dexamethasone, but not by glucagon. Periportal hepatocytes from hypophysectomized rats expressed higher rates of gluconeogenesis in culture than did perivenous hepatocytes, irrespective of the absence or presence of dexamethasone, glucagon or insulin. Similar differences in rates of ketogenesis and in the mitochondrial redox state in response to glucagon were observed between periportal and perivenous hepatocytes from hypophysectomized rats as between cell populations from normal rats. Although hypophysectomy causes marked changes in hepatic enzyme activities, it does not alter the degree of zonation of alanine aminotransferase, gluconeogenesis or the mitochondrial redox state within the liver acinus.

Gonadotropin surge during spawning in male goldfish

Changes in plasma hormone levels during spawning were studied in male goldfish. Blood samples were analyzed for gonadotropin (GtH), testosterone, 11-ketotestosterone (11-KT), and 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-diOH-P) in males, and for GtH in females. Spawning was induced by raising water temperature from 12 to 20° in sexually mature goldfish kept in pairs. Plasma GtH levels in males showed a marked increase (GtH surge) which was synchronous with the preovulatory surge in females, and peaked at the onset of spawning. Plasma levels of testosterone and 17α,20β-diOH-P increased almost at the same time as the GtH surge in males, whereas 11-KT levels remained low during the spawning. The small increase in GtH in males could be induced in the absence of females by raising the water temperature, but the levels were significantly enhanced by the presence of ovulatory females. A large amount of milt was observed during spawning, and the amount was correlated with plasma levels of GtH. Increased levels of GtH may be involved in milt production. We can propose that the synchronous GtH surge in both sexes causes ovulation and milt production to occur at the same time, favoring a higher rate of fertilization of the eggs.

Periovulatory hormonal dynamics: relationship of immunoassayable gonadotropins and ovarian steroids to the bioassayable luteinizing hormone surge in rhesus monkeys.

The relationship between ovarian steroids and LH during the midcycle gonadotropin surge is controversial. Recent demonstration of temporal and quantitative differences in immunoassayable LH (I-LH) and bioassayable LH (B-LH) at midcycle have further clouded this issue. To evaluate the relationship of I-LH, FSH, and ovarian steroids to the onset of the midcycle B-LH surge, blood samples were obtained from five chronically catheterized rhesus monkeys at 2-h intervals for 5-6 days. The plasma was assayed for FSH, LH, 17 beta-estradiol (E2), progesterone (P4), and 17 alpha-hydroxyprogesterone (17-OHP) by RIA and for LH by a rat interstitial cell testosterone in vitro bioassay. The initiation of the B-LH surge served as time zero (to) for the temporal analysis of changes in plasma hormone levels. The I-LH and FSH surges were initiated 6.4 +/- 2.2 h (mean +/- SEM) and 5.2 +/- 1.9 h, respectively, after the onset of the B-LH surge. Although the duration of the ascending limb of the surge was similar for B-LH, I-LH, and FSH, the mean +/- SEM total duration of the B-LH surge (34.5 +/- 3.5 h) was significantly longer (P less than 0.025) than those of I-LH (24.4 +/- 5.0 h) and FSH (27.6 +/- 2.3 h). Before the onset of the B-LH surge (to - 4 h), the ratio of B-H to I-LH was unity; however, during the acme of gonadotropin secretion (to + 12-16 h), the B-LH to I-LH ratio approached 6:1. Doubling times for B-LH, I-LH, and FSH were similar during the ascending phase of the surge. Plasma E2 concentrations increased continuously from to - 40 h to to, with a mean +/- SEM doubling time of 32.6 +/- 4.7 h. Peak E2 concentrations occurred within 6 h after the onset of the B-LH surge. Plasma P4 concentrations began to increase at to - 6 h in four monkeys and at to in one monkey. Plasma P4 concentration plateaued from to to to + 24 h, then increased rapidly, with a mean +/- SEM doubling time of 20.5 +/- 2.9 h. Although there were significant individual variations in plasma 17-OHP concentrations, a definite increase in 17-OHP occurred by to - 10 h, and peak concentrations occurred at to + 1 h.(ABSTRACT TRUNCATED AT 400 WORDS)