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Journal Article 2015; 36(4): 330-336 PubMed PMID: 26454488 Citation  Keywords:  Animals, Embryo Transfer:veterinary, Embryonic Development:physiology, Estrus Synchronization:methods, Female, Insemination, Artificial:veterinary, Laparoscopy, Pregnancy, Seasons, Sheep, Domestic:physiology, Superovulation:physiology,.   

OBJECTIVE: The objective of this study was to investigate the effects of seasonal changes on the superovulation in Black Suffolk ewes, particularly the ovulation rate and embryo quality.

DESIGN: Black Suffolk ewes were superovulated either in May (n=22) or in September (n=21), 2013. After estrus synchronization with CIDR, the donor ewes were superovulated with PMSG and seven decreasing doses of FSH (twice daily at 07:00 and 19:00 for four consecutive days. Then, they were subjected to laparoscopic intrauterine artificial insemination. The viable morula and blastocysts were recovered and immediately transferred to recipients.

RESULTS: Ewes that were superovulated in May had a much higher ovulation rate than those were superovulated in September (16.8 ± 3.23vs. 10.2 ± 2.94, p<0.01); however, the viability rate of the embryo was lower than that of September (56.0 ± 1.92% vs. 92.5 ± 3.26%, p<0.01). There was no significant difference in the survival rate of the transferred viable embryos (33.9 ± 1.00% vs. 36.7 ± 1.64%, p>0.05) and the number of offspring per donor ewe (3.1 ± 0.54 vs. 2.9 ± 0.72, p>0.05) between May and September. In contrast, the offspring/ova ratio of the donor ewes superovulated in May was lower than that of September (18.5 ± 1.64% vs. 32.8 ± 2.14%, p<0.01).

CONCLUSIONS: The superovulation of Black Suffolk ewes may be affected by the seasonal changes. Generallly, The ewe's ovulation rate was higher in May, whereas the viability rate of embryo was higher in September....

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Journal Article 2013; 34(2): 143-153 PubMed PMID: 23645312 Citation  Keywords:  Animals, Circadian Rhythm:physiology, Male, Photoperiod, Pineal Gland:metabolism, Pituitary Gland:metabolism, Rats, Rats, Sprague-Dawley, Seasons, Testis:metabolism, Testosterone:metabolism,.   

BACKGROUND: Photoperiodic changes mediate certain physiological or pathological alterations in organisms. Solstices represent either the longest or shortest photoperiod of a year.

OBJECTIVES: Intact and pinealectomized rats were used to investigate the potential changes of reproductive hormones in the hypothalamus-pituitary-testis (HPT) axis including GnRH, FSH, LH, testosterone and melatonin, and their receptors at summer solstice (SS) and winter solstices (WS).

METHODS: The levels of reproductive hormones in HPT axis and the binding characteristics of their receptors were examined using radioimmunoassay and radioreceptor assay techniques, respectively.

RESULTS: The results indicate that in the intact male rat, GnRH, LH and testosterone are higher at the SS than at the WS. However, FSH exhibited no significant seasonal changes. In the testis, Bmax and Kd of LH receptors are higher at the WS than at the SS while those of FSH receptors are higher at the SS than at the WS. In addition, the melatonin in HPT axis appeared significant differences between WS and SS. Bmax and Kd of melatonin receptors in the hypothalamus and pituitary also showed higher at the WS than at the SS. Moreover, reproductive hormone production lost their seasonal rhythms after pinealectomy.

CONCLUSION: The most important discovery in this study is that we first reported that pinealectomy had profound effects on the binding characteristics of melatonin with its subtype receptors. Especially at the hypothalamus, the dominated melatonin receptors shifted from MT1 to MT2 after pinealectomy at the two solstices....

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Journal Article 2012; 33(3): 314-317 PubMed PMID: 22635091 Citation  Keywords:  Adult, Child, Child Development, Circadian Rhythm, Humans, Infant, Infant, Newborn, Light, Mood Disorders:epidemiology, Neoplasms:epidemiology, Photoperiod, Seasons,.   

: Thought-provoking experimental evidence suggests that perinatal light exposure may imprint circadian clocks with lasting effects on the alignment and the stability of circadian rhythms later in life. Assuming that exposure to light early in life could determine the stability of an individual's circadian system later in life, the present hypothesis proposes that time of year and location of birth (i.e., season and latitude) and thus differential Zeitgeber strengths may be key contributors to a person's susceptibility of developing mood disorders like seasonal affective disorder (SAD) and common internal cancers such as those of breast and prostate. Consequently, when and where people are born might critically predispose them to both mood disorders and internal cancers, and may affect the onset and course of such illnesses. This paper develops a causal framework and presents suggestions for rigorous tests of the associated corollary and predictions. It does not escape our attention that links between the perinatal Zeitgeber strength of light and its effects on the stability of circadian systems later in life could have a role to play in affecting long-term health beyond cancer and mood disorders - mostly in adults but also in children....

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Journal Article 2010; 31(6): 738-742 PubMed PMID: 21196916 Citation  Keywords:  Animals, Circadian Clocks:physiology, Circadian Rhythm:physiology, Cricetinae, Male, Photoperiod, Reproduction:physiology, Seasons, Time Factors,.   

OBJECTIVES AND DESIGN: In European hamsters a circannual clock drives the seasonal changes in the reproductive state. Its resetting by photoperiod is clearly phase dependent. In mid subjective winter a 1-month pulse of long photoperiod (LP) advances the onset of the reproductive phase of animals maintained in constant short photoperiod (SP) by up to 1.5 months. The present study investigated whether shorter pulses, i.e. 8, 4 or 2 days LP-pulses are still effective to phase shift the circannual rhythm.

MAIN FINDINGS: All pulses induced gonadal development after a similar time relative to the offset of the pulse and earlier than in the control group. Thus, they all shared a similar effectiveness.

CONCLUSIONS: In European hamsters a very brief LP-pulse can phase shift the reproductive rhythm but its strength is not determined by its duration at least not in the tested range....

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Journal Article 2010; 31(4): 457-473 PubMed PMID: 20802457 Citation  Keywords:  Animals, Electromagnetic Fields:adverse effects, Female, Kaplan-Meier Estimate, Longevity:radiation effects, Rats, Rats, Sprague-Dawley, Seasons,.   

: During 1997-2008 two long-term (I and II) and two life-long (III and IV) experiments were performed analyzing the effect of chronic exposure to a low-intensity GSM-like signal (900 MHz pulsed with 217 Hz, 100 µW/cm² average power flux density, 38-80 mW/kg mean specific absorption rate for whole body) on health and survival of unrestrained female Sprague-Dawley rats kept under identical conditions. Radiofrequency (RF)-exposure was started at 52-70 days of age and continued for 24 (I), 17 (II) and up to 36 and 37 months, respectively (III/IV). In the first two experiments (1997-2000) 12 exposed and 12 sham-exposed animals each were observed until they were maximally 770 or 580 days old. In experiment I no adverse health effects of chronic RF-exposure were detectable, neither by macroscopic nor detailed microscopic pathological examinations. Also in experiment II no apparent macroscopic pathological changes due to treatment were apparent. Median survival time could not be estimated since in none of the groups more than 50% of the animals had died. In the course of two complete survival experiments (2002-2005; 2005-2008) 30 RF- and 30 sham-exposed animals each were followed up until their natural end or when they became moribund and had to be euthanized. A synoptical data analysis was performed. Survival data of all four groups could be fitted well by the Weibull distribution. According to this analysis median survival was significantly shortened under RF-exposure in both experiments by 9.06% (95% CI 2.7 to 15.0%) (p=0.0064); i.e by 72 days in experiment III and 77 days in experiment IV as compared to the corresponding sham-treated animals (III: 799 days; IV: 852 days). Both groups of animals of experiment III showed reduced median survival times by 6.25% (95% CI -0.3 to 12.4%) (p=0.0604) compared to the corresponding groups of experiment IV (53 days: sham-exposed animals, 48 days: RF-exposed animals) which may be due to the fact that animals of experiment III were born in October and animals of experiment IV in May indicating that the month of birth affects life span. From the results of the last two experiments it has to be concluded that chronic exposure to a low-intensity GSM-like signal may exert negative health effects and shorten survival if treatment is applied sufficiently long and the observational period covers the full life span of the animals concerned. The current data show that survival of rats kept under controlled laboratory conditions varies within certain limits depending on the month of birth. In view of our previous observations regarding an inhibitory or no effect of RF-exposure on DMBA-induced mammary cancer during the 1997-2000 period, an additional modulatory influence on a year-to-year basis should be considered which might be related to changing solar activity during the the 11-years' sunspot cycle. These potentially complex influences of the natural environment modulating the effects of anthropogenic RF-signals on health and survival require a systematic continuation of such experiments throughout solar cycle 24 which started in 2009....

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Journal Article 2008; 29(Suppl 1): 33-64 PubMed PMID: 19029878 Citation  Keywords:  Circadian Rhythm:physiology, Depressive Disorder:therapy, Humans, Light:adverse effects, Phototherapy:adverse effects, Seasonal Affective Disorder:therapy, Seasons,.   

: Bright light is a treatment of choice for seasonal affective disorder. Other indications for bright light therapy have also been tested. These include non-seasonal depression, bipolar depression, chronic depressive disorder, ante- and postpartum depression, late luteal phase dysphoric disorder, circadian phase sleep disorders, jet lag, shift work problems, and behavioral disturbance and insomnia in organic dementia. Future studies should focus on exploring the use of light therapy in combination with sleep deprivation, other classes of antidepressants, and with psychotherapy and their possible combined effect on subtypes of depression or other mentioned diagnoses, light treatment duration, and the applicability and efficacy of adjunct light treatment for in-patients....

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Comparative Study 2005; 26(6): 759-762 PubMed PMID: 16380678 Citation  Keywords:  Austria:epidemiology, Educational Status, Employment, Faculty:statistics & numerical data, Female, Humans, Male, Mothers:statistics & numerical data, Parity, Pregnancy, Reproduction:physiology, Seasons, Sex Ratio, Social Class,.   

OBJECTIVES: Environmental and socio-demographic factors can influence the variation of the human sex ratio at birth (SRB = the ratio of males to males plus females). In particular, findings of seasonal, parental education, birth order, and maternal age effects on the SRB are not always in agreement, and a number of works report minimal variation.

SETTING: Here, we investigated the seasonality of SRB in academic and non-academic mothers employed at the University of Vienna, and who gave birth between 1963 and 2000 (n = 1932 births).

METHODS: All data were available from an anonymous employee database.

RESULTS: Both groups, academic and non-academic mothers do not differ between their overall SRB. In academic mothers the SRB is significantly (P = 0.004) increased during the springtime and decreased during the summertime. Although in non-academic mothers the trend is comparable, it is far less pronounced and not significant (P = 0.345). When a multiple logistic model was applied to the data of academic mothers the only significant influencing factor on the SRB is the season, while birth order of children and mothers' age at childbirth has no effect. None of the three independent variables influence the SRB in non-academic mothers.

MAIN FINDINGS: These findings suggest a more flexible SRB rate in academic mothers than in non-academics within the seasons.

CONCLUSION: We conclude that the significant seasonal variation of the SRB in academic women cannot be merely interpreted as an effect of socio-economic status but more likely as the interaction between socio-economic and environmental working conditions....

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Journal Article 2003; 24(5): 339-340 PubMed PMID: 14647008 Citation  Keywords:  Blood Pressure, Blood Pressure Monitoring, Ambulatory:standards, Circadian Rhythm, Heart Rate, Humans, Hypertension:diagnosis, Seasons,.   

: The diagnoses of summer or winter hypertension in one and the same person can depend upon the clock hour of measurement....

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