Immunoreactive somatostatin diurnal rhythms in rat pineal, retina and Harderian gland: Effects of sex, season, continuous darkness and estrous cycle

1990 ◽  
Vol 81 (1) ◽  
pp. 63-72 ◽  
Author(s):  
M. A. Peinado ◽  
N. Fajardo ◽  
G. Hern�ndez ◽  
M. Puig-Domingo ◽  
M. Viader ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Harderian Gland ◽  
Diurnal Rhythms ◽  
Continuous Darkness

Autophagic and proteolytic processes in the Harderian gland are modulated during the estrous cycle

2013 ◽  
Vol 141 (5) ◽  
pp. 519-529 ◽  
Author(s):  
M. García-Macia ◽  
A. Rubio-Gonzalez ◽  
B. de Luxán-Delgado ◽  
Y. Potes ◽  
S. Rodríguez-González ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Harderian Gland

Melatonin administration entrains female rat activity rhythms in constant darkness but not in constant light

1988 ◽  
Vol 255 (2) ◽  
pp. R237-R242
Author(s):  
E. M. Thomas ◽  
S. M. Armstrong
Keyword(s):  
Estrous Cycle ◽  
Activity Rhythm ◽  
Onset Time ◽  
Circadian System ◽  
Female Rats ◽  
Male Rats ◽  
Constant Darkness ◽  
Female Rat ◽  
Continuous Darkness ◽  
Activity Rhythms

In female rats the luteinizing hormone (LH) is timed by the circadian system and is followed by a display of intense, estrogen-induced running behavior. This proestrous running on the night of ovulation can be used as a marker of the estrous cycle. Entrainment of the mammalian circadian system by exogenous melatonin (MT) has been demonstrated only in the activity rhythms of male rats. The present experiments were designed to study the effect of daily MT injections on activity rhythms and proestrous running of female rats in 1) continuous dim white light (LL) and 2) continuous darkness (DD). In LL, MT injections (50 micrograms/kg or 1 mg/kg) had no discernible effect on activity rhythms. In DD, four of the six MT-treated rats (100 micrograms/kg) entrained to the injection, and a fifth animal showed phase advances in its activity rhythm when onset of activity passed through injection time. The sixth animal was not injected with MT at activity onset time. None of the six control animals showed either effect. MT had no effect on the length of the estrous cycle. Thus MT injections can entrain circadian rhythms of activity and proestrous running in female rats in DD but not in LL.

scholarly journals Diurnal Rhythmicity of the Clock Genes Per1 and Per2 in the Rat Ovary

Endocrinology ◽  
2006 ◽  
Vol 147 (8) ◽  
pp. 3769-3776 ◽  
Author(s):  
Jan Fahrenkrug ◽  
Birgitte Georg ◽  
Jens Hannibal ◽  
Peter Hindersson ◽  
Søren Gräs
Keyword(s):  
In Situ Hybridization ◽  
Circadian Clock ◽  
Estrous Cycle ◽  
Clock Genes ◽  
Continuous Darkness ◽  
Peripheral Tissues ◽  
Hybridization Histochemistry ◽  
In Situ Hybridization Histochemistry ◽  
Rat Ovary

Circadian rhythms are generated by endogenous clocks in the central brain oscillator, the suprachiasmatic nucleus, and peripheral tissues. The molecular basis for the circadian clock consists of a number of genes and proteins that form transcriptional/translational feedback loops. In the mammalian gonads, clock genes have been reported in the testes, but the expression pattern is developmental rather than circadian. Here we investigated the daily expression of the two core clock genes, Per1 and Per2, in the rat ovary using real-time RT-PCR, in situ hybridization histochemistry, and immunohistochemistry. Both Per1 and Per2 mRNA displayed a statistically significant rhythmic oscillation in the ovary with a period of 24 h in: 1) a group of rats during proestrus and estrus under 12-h light,12-h dark cycles; 2) a second group of rats representing a mixture of all 4 d of the estrous cycle under 12-h light,12-h dark conditions; and 3) a third group of rats representing a mixture of all 4 d of estrous cycle during continuous darkness. Per1 mRNA was low at Zeitgeber time 0–2 and peaked at Zeitgeber time 12–14, whereas Per2 mRNA was delayed by approximately 4 h relative to Per1. By in situ hybridization histochemistry, Per mRNAs were localized to steroidogenic cells in preantral, antral, and preovulatory follicles; corpora lutea; and interstitial glandular tissue. With newly developed antisera, we substantiated the expression of Per1 and Per2 in these cells by single/double immunohistochemistry. Furthermore, we visualized the temporal intracellular movements of PER1 and PER2 proteins. These findings suggest the existence of an ovarian circadian clock, which may play a role both locally and in the hypothalamo-pituitary-ovarian axis.

scholarly journals bHLH-PAS protein RITMO1 regulates diel biological rhythms in the marine diatomPhaeodactylum tricornutum

2019 ◽  
Vol 116 (26) ◽  
pp. 13137-13142 ◽  
Author(s):  
Rossella Annunziata ◽  
Andrés Ritter ◽  
Antonio Emidio Fortunato ◽  
Alessandro Manzotti ◽  
Soizic Cheminant-Navarro ◽  
...  
Keyword(s):  
Gene Expression ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Continuous Light ◽  
Biological Rhythms ◽  
Wide Distribution ◽  
Diurnal Rhythms ◽  
Wild Type ◽  
Continuous Darkness ◽  
Shed Light

Periodic light–dark cycles govern the timing of basic biological processes in organisms inhabiting land as well as the sea, where life evolved. Although prominent marine phytoplanktonic organisms such as diatoms show robust diel rhythms, the mechanisms regulating these processes are still obscure. By characterizing aPhaeodactylum tricornutumbHLH-PAS nuclear protein, hereby named RITMO1, we shed light on the regulation of the daily life of diatoms. Alteration of RITMO1 expression levels and timing by ectopic overexpression results in lines with deregulated diurnal gene expression profiles compared with the wild-type cells. Reduced gene expression oscillations are also observed in these lines in continuous darkness, showing that the regulation of rhythmicity by RITMO1 is not directly dependent on light inputs. We also describe strong diurnal rhythms of cellular fluorescence in wild-type cells, which persist in continuous light conditions, indicating the existence of an endogenous circadian clock in diatoms. The altered rhythmicity observed in RITMO1 overexpression lines in continuous light supports the involvement of this protein in circadian rhythm regulation. Phylogenetic analysis reveals a wide distribution of RITMO1-like proteins in the genomes of diatoms as well as in other marine algae, which may indicate a common function in these phototrophs. This study adds elements to our understanding of diatom biology and offers perspectives to elucidate timekeeping mechanisms in marine organisms belonging to a major, but under-investigated, branch of the tree of life.

scholarly journals Circadian Variation in Basal Plasma Corticosterone and Adrenocorticotropin in the Rat: Sexual Dimorphism and Changes across the Estrous Cycle*

Endocrinology ◽  
1997 ◽  
Vol 138 (9) ◽  
pp. 3842-3848 ◽  
Author(s):  
Helen C. Atkinson ◽  
Brendan J. Waddell
Keyword(s):  
Sexual Dimorphism ◽  
Estrous Cycle ◽  
Circadian Variation ◽  
Sampling Technique ◽  
Plasma Corticosterone ◽  
Male Rats ◽  
Diurnal Rhythms ◽  
Basal Plasma ◽  
Estrous Cycle Stage ◽  
Clear Shift

Abstract Sexual dimorphism in the rat hypothalamic-pituitary-adrenal axis was investigated by determination of plasma corticosterone and immunoreactive (I-) ACTH in males and in females at each stage of the estrous cycle. A serial blood-sampling technique enabled assessment of covariation of the two hormones across the full circadian range of their concentrations within individual animals. Distinct diurnal rhythms in plasma corticosterone were evident in all rats, and the degree and timing of this rhythmicity, determined by cosinor analyses, did not vary with gender or cycle stage. There were, however, marked differences in absolute levels of corticosterone across the estrous cycle, with the average daily concentration (mesor) increasing progressively from a minimum at estrus (129 ± 11 ng/ml) to a maximum 3 days later at proestrus (246 ± 14 ng/ml). The mesor corticosterone value in male rats (102 ± 21 ng/ml) was not different from that in estrous females, but was lower than that in females at all other stages of the cycle. In contrast, no gender- or cycle-related differences were detected in absolute levels of I-ACTH, although distinct diurnal rhythms, synchronous with those for corticosterone, were evident in all groups. Accordingly, a strong and positive within-rat relationship between plasma corticosterone and I-ACTH was observed in all groups, but there was a clear shift in the nature of this relationship across the estrous cycle, such that the slope (i.e. concentration of plasma corticosterone per unit concentration of I-ACTH) was minimal in males and estrous females and maximal in proestrous females. In conclusion, this study shows that the extent of sexual dimorphism in resting plasma corticosterone levels is dependent on estrous cycle stage, being absent at estrus and maximal at proestrus. Moreover, this variation in plasma corticosterone was not accompanied by corresponding changes in plasma I-ACTH, suggestive of cycle-related changes in responsiveness of the adrenal cortex to trophic stimulation.

Mast cells in the Harderian gland of female syrian hamsters during the estrous cycle and pregnancy: effects of the light/dark cycle

1993 ◽  
Vol 25 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Armando Menendez-Pelaez ◽  
Rosa M. Sainz ◽  
Juan C. Mayo ◽  
Maria J. Rodriguez-Colunga ◽  
Julio Vazquez-Rojo ◽  
...  
Keyword(s):  
Mast Cells ◽  
Estrous Cycle ◽  
Harderian Gland ◽  
Dark Cycle ◽  
Syrian Hamsters

scholarly journals Selective autophagy, lipophagy and mitophagy, in the Harderian gland along the estrous cycle: a potential retrieval effect of melatonin

2019 ◽  
Author(s):  
Marina García-Macia ◽  
Adrián Santos-Ledo ◽  
Beatriz Caballero ◽  
Adrián Rubio-González ◽  
Beatriz de Luxán-Delgado ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Harderian Gland ◽  
Mitochondrial Homeostasis ◽  
Perfect Model ◽  
Nrf2 Activation ◽  
Sexual Bias ◽  
The Impact ◽  
Nrf2 Expression ◽  
Retrieval Phase

ABSTRACTSexual dimorphism has been reported in many processes. However, sexual bias in favor of the use of males is very present in science. One of the main reasons is that the impact of hormones in diverse pathways and processes such as autophagy have not been properly addressed in vivo. The Harderian gland is a perfect model to study autophagic modulation as it exhibits important changes during the estrous cycle. The aim of this study is to identify the main processes behind Harderian gland differences under estrous cycle and their modulator. In the present study we show that redox-sensitive transcription factors have an essential role: NF-κB may activate SQSTM1/p62 in estrus, promoting selective types of autophagy: mitophagy and lipophagy. Nrf2 activation in diestrus, leads the retrieval phase and restoration of mitochondrial homeostasis. Melatonin’s receptors show higher expression in diestrus, leading to decreases in pro-inflammatory mediators and enhanced Nrf2 expression. Consequently, autophagy is blocked, and porphyrin release is reduced. All these results point to melatonin as one of the main modulators of the changes in autophagy during the estrous cycle.

scholarly journals A bHLH-PAS protein regulates light-dependent diurnal rhythmic processes in the marine diatomPhaeodactylum tricornutum

2018 ◽  
Author(s):  
Rossella Annunziata ◽  
Andrés Ritter ◽  
Antonio Emidio Fortunato ◽  
Soizic Cheminant-Navarro ◽  
Nicolas Agier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Cell Division ◽  
Cell Cycle Progression ◽  
Marine Diatom ◽  
Diurnal Rhythms ◽  
Biological Processes ◽  
Wild Type ◽  
Continuous Darkness ◽  
Altered Cell

ABSTRACTPeriodic light-dark cycles govern the timing of basic biological processes in organisms inhabiting land as well as the sea, where life evolved. Although prominent marine phytoplanktonic organisms such as diatoms show robust diurnal rhythms in growth, cell cycle and gene expression, the molecular foundations controlling these processes are still obscure. By exploring the regulatory landscape of diatom diurnal rhythms, we unveil the function of aPhaeodactylum tricornutumbHLH-PAS protein,PtbHLH1a, in the regulation of light-dependent diurnal rhythms. Peak expression ofPtbHLH1amRNA occurs toward the end of the light period and it adjusts to photoperiod changes. Ectopic over-expression ofPtbHLH1a results in lines showing a phase shift in diurnal cell fluorescence, compared to the wild-type cells, and with altered cell cycle progression and gene expression. Reduced oscillations in gene expression are also observed in overexpression lines compared to wild-type in continuous darkness, showing that the regulation of rhythmicity byPtbHLH1a is not directly dependent on light inputs and cell division.PtbHLH1a homologs are widespread in diatom genomes which may indicate a common function in many species. This study adds new elements to understand diatom biology and ecology and offers new perspectives to elucidate timekeeping mechanisms in marine organisms belonging to a major, but underinvestigated branch of the tree of life.SIGNIFICANCE STATEMENTMost organisms experience diurnal light-dark changes and show rhythms of basic biological processes such that they occur at optimal times of the day. The ocean harbours a huge diversity of organisms showing light-dependent rhythms, but their molecular foundations are still largely unknown. In this study, we discover a novel protein,PtbHLH1a that regulates cell division, gene expression and the diurnal timing of these events in the marine diatomPhaedoactylum tricornutum. The identification ofPtbHLH1a-like genes in many diatom species suggests a conserved function in diurnal rhythm regulation in the most species-rich group of algae in the ocean. This study unveils critical features of diatom biology and advances the field of marine rhythms and their environmental regulation.

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