Maristela de Oliveira Poletini

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Melanopsin has been implicated in the mammalian photoentrainment by blue light. This photopigment, which maximally absorbs light at wavelengths between 470 and 480 nm depending on the species, is found in the retina of all classes of vertebrates so far studied. In mammals, melanopsin activation triggers a signaling pathway which resets the circadian clock(More)
Oscillations of gene expression and physiological activity in suprachiasmatic nucleus (SCN) neurons result from autoregulatory feedback loops of circadian clock gene transcription factors. In the present experiment, we have determined the pattern of PERIOD1 (PER1), PERIOD2 (PER2), and CLOCK expression within neuroendocrine dopaminergic (DAergic) neurons(More)
In female rats, estradiol (E(2)) and suckling induce prolactin (PRL) secretion. This involves inhibition of hypothalamic dopaminergic tone and stimulation by a PRL-releasing hormone, possibly oxytocin (OT). Infusing an OT antagonist (OTA) i.v., we evaluated the role of OT on suckling- and E(2)-induced PRL secretion. Three days after parturition at 0900 h,(More)
The role of norepinephrine (NE) in regulation of LH is still controversial. We investigated the role played by NE in the positive feedback of estradiol and progesterone. Ovarian-steroid control over NE release in the preoptic area (POA) was determined using microdialysis. Compared with ovariectomized (OVX) rats, estradiol-treated OVX (OVX+E) rats displayed(More)
Stress has been proposed to stimulate prolactin release if its prestress levels are low, or to inhibit it if they are elevated, but the role of ovarian-steroid fluctuations in the prolactin stress response is not yet clearly understood. Because the noradrenergic nucleus locus coeruleus has been implicated in stress responses and generation of prolactin(More)
Since locus coeruleus (LC) lesion blocks preovulatory prolactin surge, the aim of this study was to determine if this lesion would also block prolactin surges induced by steroids in ovariectomized rats and would modify basal prolactin secretion. To determine the time of the steroid-induced prolactin surges, ovariectomized rats treated with estradiol (OVE)(More)
Cervical stimulation induces two daily rhythmic prolactin surges, nocturnal and diurnal, which persist for several days. We have shown that a bolus injection of oxytocin initiates a similar prolactin rhythm, which persists despite low levels of oxytocin after injection. This suggests that oxytocin may trigger the cervical stimulation-induced rhythmic(More)
In female rats, stimulation of the uterine cervix during mating induces two daily surges of prolactin. Inhibition of hypothalamic dopamine release and stimulation of oxytocin neurons in the paraventricular nucleus (PVN) are required for prolactin secretion. We aim to better understand how stimulation of the uterine cervix is translated into two daily(More)
Internal temporal organisation properly synchronised to the environment is crucial for health maintenance. This organisation is provided at the cellular level by the molecular clock, a macromolecular transcription-based oscillator formed by the clock and the clock-controlled genes that is present in both central and peripheral tissues. In mammals,(More)
BACKGROUND/AIMS Cervical stimulation induces a circadian rhythm of prolactin secretion and antiphase dopamine release. The suprachiasmatic nucleus (SCN) controls this rhythm, and we propose that it does so through clock gene expression within the SCN. METHODS To test this hypothesis, serial blood samples were taken from animals injected with an antisense(More)