Time-Related Behaviour of Endocrine Secretion: Circannual Variations of FT3, Cortisol,Hgh and Serum Basal Insulin in Healthy Subjects

Four healthy young male volunteers were submitted to the study of circadian and circannual bioperiodicities of several hormones: FT3, FT4, Cortisol, HGH, prolactin, PTh and plasma insulin levels. They were observed for a whole year and their blood samples were collected six times a day, every other month. The results were analyzed by two-way ANOVA macroscopic analysis and Student r-test. Our data registered a circannual variation in the mean circadian plasma levels of the following hormones: Cortisol (peak in December), HGH (peak in April), FT3 (peak in April), insulin (peak in February). FT4, prolactin and PTH showed no cyclic variation during the period of observation.     

Time-Related Behaviour of Endocrine Secretion: Circannual Variations of FT3, Cortisol, Hgh and Serum Basal Insulin in Healthy Subjects

Four healthy young male volunteers were submitted to the study of circadian and circannual bioperiodicities of several hormones: FT3, FT4, Cortisol, HGH, prolactin, PTh and plasma insulin levels. They were observed for a whole year and their blood samples were collected six times a day, every other month. The results were analyzed by two-way ANOVA macroscopic analysis and Student r-test. Our data registered a circannual variation in the mean circadian plasma levels of the following hormones: Cortisol (peak in December), HGH (peak in April), FT3 (peak in April), insulin (peak in February). FT4, prolactin and PTH showed no cyclic variation during the period of observation.     

Circannual Growth Rhythm in a Brown Alga,Pterygophora californica

A circannual rhythm was found in the kelp Pterygophora californica which forms a new blade with a free running period of 7 ? 8 months under constant conditions. Individual plants exposed to cycles of daylength with T = 12, 6, or 3 months performed 1, 2, or 4 growth cycles, respectively, in one calendar year showing the entrainment of the endogenous circannual rhythm. The annual growth cycle also followed a phase shift of the annual cycle of daylength (T = 12 months) by 3 or 6 months.     

Stimulation of Immunoreactive Insulin Release by Glucose in Rat Brain Synaptosomes

The effect of glucose on the release of immunoreactive insulin (IRI) in synaptosomes isolated from rat brain was studied. In the absence of glucose synaptosomes release about 4% (0.77 IU/mg protein) of total content. Glucose increases significantly the IRI released by synaptosomes. Addition of the glycolytic inhibitor iodoacetic acid (IAA), decreased the glucose-induced release of IRI by about 50%, suggesting that glucose metabolism is involved. The observation that glucose provides a concentration related signal for IRI release indicates that this synaptosomal preparation may be useful as a model for research on the mechanism of insulin release in brain.     

Circannual Variations of the Bleeding Time in the Rat

This study was carried out to determine the annual fluctuations of the tail bleeding time in the rat. Bleeding time was determined by transection of the tail of pentobarbital-anesthetized rats. Over a 6-year period, monthly measurement of the tail bleeding time revealed highly reproducible circannual fluctuations. Bleeding times were shortened in the summer (414 ± 18 s in July), being almost half that observed during the winter span (886 ± 32 s in January). The difference between these two time points was highly significant (p > 0.001). This study reports for the first time circannual variations of the bleeding time in the rat.     

Release of Immunoreactive Insulin from Rat Brain Synaptosomes Under Depolarizing Conditions

Synaptosome preparations were utilized to characterize the release and compartmentalization of immunoreactive insulin (IRI) in the adult rat brain. Depolarization of synaptosomes by elevation of the external potassium ion concentration elicited release of IRI from the synaptosomes into the incubation medium. This release was reduced or eliminated under three conditions known to prevent depolarization-induced Ca2+ flux: elevating the external MgCl2, adding CoCl2, and eliminating external Ca2+ with EGTA. Depolarization of synaptosomes by veratridine also elicited release of synaptosomal IRI. This release was inhibited by tetrodotoxin. The amount of IRI released under depolarizing conditions represented 3-7% of that contained in the synaptosomes. High levels of IRI release also were observed upon removal of external Na+ to allow depolarization-independent influx of external Ca2+ into the synaptosomal compartment. The Ca2+ dependency of synaptosomal IRI release suggests IRI is stored in the adult rat brain in synaptic vesicles within nerve endings from which it can be mobilized by exocytosis in association with neural activity.     

Circannual distribution of glioblastoma and anaplastic astrocytoma diagnoses in men and women

Background: circannual variations of incidence may influence human tumors. For example, seasonal distribution of breast cancers suggests an influence of circannual hormonal rhythms. Periodicity of brain tumors has not yet been investigated. The aim of this study was to assess the seasonal variation in glioblastomas and anaplastic astrocytomas. Methods: a large dataset of high-grade gliomas (n = 697) was evaluated with the month of diagnosis as key criterion for time series and seasonal analysis. Circannual and ultra-annual cosinor models were calculated. Results: women suffering from glioblastoma show a peak incidence in fall. No suitable circannual or ultra-annual cosinor model months could be fitted to the data. In women with anaplastic astrocytoma, a peak incidence was detected in summer and fall with a nadir in spring. Here, a significant cosinor model with a period of 8.5 months could be calculated. Conclusion: our data strongly suggest seasonality of diagnosis of high-grade gliomas in women. As gliomas express hormonal receptors, an underlying endocrinal or cell proliferation rhythms may be a possible explanation.     

Circannual Variation in the Incidence of Uterine Cervix Cancer

The impact of uterine cervix cancer (UCC) can be greatly reduced by regular vaginal examination and other preventive measures. With this aim, UCC screening programs had been developed and applied for several years in Mexico and elsewhere. One point still to be considered in such preventive programs is the possible circannual pattern in the morbidity or mortality of UCC. With the aim of identifying a possible circannual pattern of variation in the incidence of UCC, we analyzed the monthly totals of positive detected cases of UCC in the state of Nuevo León (Mexico) between 1978 and 1987. For eliminating bias due to the seasonal variation in the number of preventive check-ups, data were first expressed in percentage of tests done in the same month. The least-squares fit of a 1 -year cosine curve to the data reveals a statistically significant circannual pattern (p = 0.013), with a maximum of relative incidence detected in February. Results indicate UCC incidence higher than the yearly average during the winter, with secondary peaks in August and November. This pattern of variation is similar if one considers separately for analysis the relative incidence of type III, IV, or V UCC (relating to cases suggesting, highly suggesting, or concluding a malignant alteration, respectively). For evaluating the cost-effectiveness of the UCC screening campaign providing these data, the monthly totals of screening check-ups done over the same period were also analyzed. Results reveal a statistically significant circannual rhythm (p > 0.001), with a maximum detected in June. This timing seems to be related to the incidence of most common diseases in Mexico, such as giardiasis and salmonellosis, but not to the UCC morbidity rates. Health educational and screening campaigns for prevention of UCC and other major conditions should be timed during the year according to morbidity and mortality statistics, for which a circannual pattern of variation is documented herein.     

Circannual Variations in Baseline Blood Values of Dogs

Forty-two hematological and biochemical variables routinely measured in dogs as part of a preoperative protocol have been analyzed for circannual changes by analysis of variance (ANOVA) and single cosinor procedures. Data were available from up to 489 adult mongrel dogs of both sexes studied on weekdays over a 5-year span (January 5, 1987 to December 18, 1991). Dogs were housed in individual cages at 24 ± 1 °C with dog chow and tap water available ad libitum and lights on between 06:00 and 18:00 h. A single blood sample/dog was collected by jugular venipuncture between 08:00 and 09:00 h and sent to a commercial laboratory for hematological and biochemical determinations. Data were assigned to date and time of sampling and analyzed for the effect of time of year by ANOVA (across 12 months and 4 seasons), and by the least-squares fit of a precise 1-year cosine. ANOVA and single cosinor described a significant circannual time effect and rhythm for the following: total leukocytes, lymphocytes, hemoglobin, mean corpuscular hemoglobin (MCH), MCH concentration, red cell distribution width, mean platelet volume, creatinine, blood urea nitrogen (BUN), BUN/crea-tinine ratio, amylase, glucose, chloride, uric acid, direct bilirubin, total protein, albumin, globulin, albumin/globulin ratio, lactate dehydrogenase, alkaline phos-phatase, γ-glutamyltransferase, alanine aminotransferase (ALT), and aspartate aminotransferase (AST)/ALT ratio. A significant effect of season by ANOVA only was found for: Ca, Na, phosphorus, total bilirubin, hematocrit, mean corpuscular volume, and neutrophils. No significant time effect could be found at p n%ge 0.05 by either statistical method for: K, Mg, Fe, cholesterol, triglycerides, ASP, red blood cells, monocytes, eosinophils, basophils, or platelets. Acrophases occurred for the most part in either the winter or summer.     

L-丙氨酸对小鼠胰岛分泌胰岛素的急性作用及其葡萄糖依赖性研究

探讨L-丙氨酸刺激小鼠胰岛分泌胰岛素的剂量和葡萄糖依赖性。雌性6~10周NMRI小鼠,苯巴比妥腹腔麻醉,应用胶原酶技术消化胰腺分离胰岛,置于RPMI1640培养皿中在37℃培养箱(5%CO2,95%空气)过夜培养。次日在Krebs-Ringer缓冲液中37℃水浴培养箱预培养30 min,分别把单个胰岛小心放入100 L含有不同浓度葡萄糖和不同浓度L-丙氨酸的改良Krebs-Ringer缓冲液37℃水浴培养箱培养60 min,留取50 L上清液进行胰岛素测定。结果:L-丙氨酸在0.1~20mmol.L-1范围促进了葡萄糖刺激的小鼠胰岛的胰岛素分泌,随剂量增大而增强,在低浓度葡萄糖存在的条件下,10 mmol.L-1L-丙氨酸不能刺激小鼠胰岛的胰岛素分泌,在6.7 mmol.L-1及以上葡萄糖存在的条件下,L-丙氨酸能增加葡萄糖诱导的小鼠胰岛分泌胰岛素。本研究显示L-丙氨酸能增加葡萄糖诱导的小鼠胰岛分泌胰岛素,此作用依赖于一定水平葡萄糖的存在。     

Circannual Variations in Baseline Blood Values of Dogs

Forty-two hematological and biochemical variables routinely measured in dogs as part of a preoperative protocol have been analyzed for circannual changes by analysis of variance (ANOVA) and single cosinor procedures. Data were available from up to 489 adult mongrel dogs of both sexes studied on weekdays over a 5-year span (January 5, 1987 to December 18, 1991). Dogs were housed in individual cages at 24 ± 1 °C with dog chow and tap water available ad libitum and lights on between 06:00 and 18:00 h. A single blood sample/dog was collected by jugular venipuncture between 08:00 and 09:00 h and sent to a commercial laboratory for hematological and biochemical determinations. Data were assigned to date and time of sampling and analyzed for the effect of time of year by ANOVA (across 12 months and 4 seasons), and by the least-squares fit of a precise 1-year cosine. ANOVA and single cosinor described a significant circannual time effect and rhythm for the following: total leukocytes, lymphocytes, hemoglobin, mean corpuscular hemoglobin (MCH), MCH concentration, red cell distribution width, mean platelet volume, creatinine, blood urea nitrogen (BUN), BUN/crea-tinine ratio, amylase, glucose, chloride, uric acid, direct bilirubin, total protein, albumin, globulin, albumin/globulin ratio, lactate dehydrogenase, alkaline phos-phatase, γ-glutamyltransferase, alanine aminotransferase (ALT), and aspartate aminotransferase (AST)/ALT ratio. A significant effect of season by ANOVA only was found for: Ca, Na, phosphorus, total bilirubin, hematocrit, mean corpuscular volume, and neutrophils. No significant time effect could be found at p n%ge 0.05 by either statistical method for: K, Mg, Fe, cholesterol, triglycerides, ASP, red blood cells, monocytes, eosinophils, basophils, or platelets. Acrophases occurred for the most part in either the winter or summer.     

Pinealectomy and LL Abolished Circadian Perching Rhythms but Did Not Alter Circannual Reproductive or Fattening Rhythms in Finches

In the subtropical finch, spotted munia (Lonchura punctulata) circannual rhythms (of gonads, fattening, feeding) have been demonstrated in an information-free environment of continuous illumination (LL), rendering it an ideal model for research on the physiology of the circannual clock. In an attempt to understand the involvement, if any, of the circadian system in the genesis of circannual rhythms, we studied the effect of pinealectomy (LL 15 lux) and strong continuous illumination (LL 300 lux), both known to abolish circadian rhythms, on the circadian perch-hopping rhythm and on the circannual rhythm of reproduction and fattening in the same birds. While both pinealectomy and LL 300 lux treatments abolished the circadian rhythm of motor activity, they had no effect on the circannual rhythms of gonadal size and fattening. If the endogenous circadian rhythm in perch-hopping can be taken to reflect the circadian clock mechanism associated with gonadal functioning, present results suggest that circannual rhythm of reproduction in spotted munia is independent of circadian events.     

Pinealectomy and LL Abolished Circadian Perching Rhythms but Did Not Alter Circannual Reproductive or Fattening Rhythms in Finches

In the subtropical finch, spotted munia (Lonchura punctulata) circannual rhythms (of gonads, fattening, feeding) have been demonstrated in an information-free environment of continuous illumination (LL), rendering it an ideal model for research on the physiology of the circannual clock. In an attempt to understand the involvement, if any, of the circadian system in the genesis of circannual rhythms, we studied the effect of pinealectomy (LL 15 lux) and strong continuous illumination (LL 300 lux), both known to abolish circadian rhythms, on the circadian perch-hopping rhythm and on the circannual rhythm of reproduction and fattening in the same birds. While both pinealectomy and LL 300 lux treatments abolished the circadian rhythm of motor activity, they had no effect on the circannual rhythms of gonadal size and fattening. If the endogenous circadian rhythm in perch-hopping can be taken to reflect the circadian clock mechanism associated with gonadal functioning, present results suggest that circannual rhythm of reproduction in spotted munia is independent of circadian events.     

Circannual cycles in golden-mantled ground squirrels: fall and spring cold pulses

Summary Endogenous circannual rhythms of male golden-mantled ground squirrels (Spermophilus lateralis) exposed to low ambient temperature (6 °C) at various times were compared to the rhythms of a control group kept in a warm room (21 °C) throughout. A 20-week pulse of cold in the spring delayed the subsequent peak body weight and molt offset. However, in the second year after the spring cold pulse, a delay in the rhythm was evident only using peak weight as a phase marker. A 20-week cold pulse in the fall resulted in an earlier peak body weight and earlier onset of pigmented scrotum and descended testes, but there was no evidence from subsequent years that rhythms had been phase advanced. A third of the animals kept continuously at 6 °C remained with pigmented scrotum, descended testes and low body weight for more than a year. Circannual periodicities of animals that continued to display rhythms in the cold room were not significantly longer than those of controls in the warm room. The results suggest that low temperature in the fall can alter the expression of circannual rhythms without much affecting their phasing, while low temperature in the spring produces phase delays which last longer but have not been proved to be persistent.Abbreviation PRC phase response curve     

Circadian and Circannual Rhythms of Hormonal Variables in Elderly Men and Women

A group of fourteen men (73 ± 5 yr of age), and eighteen women (77 ± 7 yr of age) institutionalized at the Berceni Clinical Hospital, Bucharest, Romania, were studied over a 24-hr span once during each season (winter, spring, summer and fall). All subjects followed a diurnal activity pattern with rest at night and ate three meals per day with breakfast at about 0830, lunch at about 1300 and dinner at about 1830. The meals were similar, although not identical for all subjects during all seasons. On each day of sampling blood was collected at 4-hr intervals over a 24-hr span. Seventeen hormonal variables were determined by radioimmunoassay. Statistically significant circadian rhythms were detected and quantitated by population mean cosinor analysis in pooled data from all four seasons in both sexes for ACTH, aldosterone, Cortisol, C-peptide, dehydroepiandrosterone-sulfate (DHEA-S), immunoreactive insulin, prolactin, 17-OH progesterone, testosterone, total T₄ and TSH. In women, estradiol and progesterone also were determined and showed a circadian rhythm during all seasons. Total T, and FSH showed circadian rhythm detection by cosinor analysis in the men only; LH showed no consistent circadian rhythm as group phenomenon in men or women.

A circannual rhythm was detected using the circadian means of each subject at each season as input for the population mean cosinor in the women for ACTH, C-peptide, DHEA-S, FSH, LH, progesterone, 17-OH progesterone and TSH. In the men, a circannual rhythm was detected for ACTH, FSH, insulin, LH, testosterone and T₃. There were phase differences between men and women in ACTH, FSH and LH. In those functions in which both the circadian and circannual rhythms were statistically significant, a comparison of the amplitudes showed in the women a higher circannual rather than circadian amplitude for DHEA-S. In 17-OH progesterone, TSH and C-peptide, the circadian amplitude in women was larger. In men, the circannual amplitude of T₃ was larger than the circadian amplitude and in insulin the circadian amplitude was larger than the circannual amplitude. There was no statistically significant difference between the circadian and circannual amplitudes in the women in ACTH and progesterone and in the men in ACTH and testosterone.     

Evidence for an endogenous circannual component in the control of the annual gonadal cycle in spotted munia

Abstract

For the first time evidence has been provided for a circannual gonadal cycle in any avian species (male spotted munia Lonchura punctulata, Estrildidae) held on continuous light. A model has thus been rendered available in which the “entraining effects” of photoperiod could be clearly distinguished from its direct “driving effects”.     

Seasonal Variations in Socially and Legally Unacceptable Sexual Behaviour

The calendar dates, over the 15-year span 1966-1980, of committed rapes by eight male recidivists and offences of sexually indecent or immoral behaviour by eight other male recidivists were gathered from the files of the Prefecture de Police, Paris, France. Each offender of the first group had committed from two to six rapes, while each offender of the second had committed from two to 16 incidences of indecent behaviour. Although the reported rapes took place during several calendar years, almost all, 18 out of 22 offences, were committed by the eight rape-recidivists during the 4-month span of July-October. Single cosinor analysis of these data revealed a circannual rhythmicity (P<0.03) with ø being 10 August τ 34 days (the 95% CL). The peak time of indecent sexual behaviour, exclusive of rape, against females occurred during September with secondary peaks in February and June; such offences directed against males peaked in October. 'Bootstrap' and 'Jacknife' methods confirmed seasonality within all data sets, except for the offences of indecent behaviour.     

Effects of Artificial Sweeteners on Insulin Release and Cationic Fluxes in Rat Pancreatic Islets

β-l-Glucose pentaacetate, but not -d-galactose pentaacetate, was recently reported to taste bitter and to stimulate insulin release. This finding led, in the present study, to the investigation of the effects of both bitter and non-bitter artificial sweeteners on insulin release and cationic fluxes in isolated rat pancreatic islets. Sodium saccharin (1.0–10.0 mM), sodium cyclamate (5.0–10.0 mM), stevioside (1.0 mM) and acesulfame-K (1.0–15.0 mM), all of which display a bitter taste, augmented insulin release from islets incubated in the presence of 7.0 mM d-glucose. In contrast, aspartame (1.0–10.0 mM), which is devoid of bitter taste, failed to affect insulin secretion. A positive secretory response to acesulfame-K was still observed when the extracellular K⁺ concentration was adjusted to the same value as that in control media. No major changes in ⁸⁶Rb and ⁴⁵Ca outflow from pre-labelled perifused islets could be attributed to the saccharin, cyclamic or acesulfame anions. It is proposed that the insulinotropic action of some artificial sweeteners and, possibly, that of selected hexose pentaacetate esters may require G-protein-coupled receptors similar to those operative in the recognition of bitter compounds by taste buds.     

Genomic Basis of Circannual Rhythm in the European Corn Borer Moth

1. Download : Download high-res image (99KB)
2. Download : Download full-size image