Oestrogen and Progesterone Influence on the Release of Prolactin in Ovariectomized Rats

Caligaris, L.; Astrada, J. J.; Taleisnik, S.

doi:10.1677/joe.0.0600205

Cited by 120 publications

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“…Estradiol treatment in ovariectomized (OVX) rats induces daily PRL surges that occur at roughly the same time of day as the proestrous surge (13). Shifting of the light phase results in a coincident shift of the proestrous surge (10), and the estradiol-induced PRL surges of OVX rats free run in constant light (52), but the mechanism regulating the circadian profile of PRL secretion is still unknown.…”

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confidence: 99%

Knockdown of clock genes in the suprachiasmatic nucleus blocks prolactin surges and alters FRA expression in the locus coeruleus of female rats

Poletini¹,

McKee²,

Kennett³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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Poletini MO, McKee DT, Kennett JE, Doster J, Freeman ME. Knockdown of clock genes in the suprachiasmatic nucleus blocks prolactin surges and alters FRA expression in the locus coeruleus of female rats. Am J Physiol Endocrinol Metab 293: E1325-E1334, 2007. First published August 28, 2007; doi:10.1152/ajpendo.00341.2007.-The nature of the circadian signal from the suprachiasmatic nucleus (SCN) required for prolactin (PRL) surges is unknown. Because the SCN neuronal circadian rhythm is determined by a feedback loop of Period (Per) 1, Per2, and circadian locomotor output cycles kaput (Clock) gene expressions, we investigated the effect of SCN rhythmicity on PRL surges by disrupting this loop. Because lesion of the locus coeruleus (LC) abolishes PRL surges and these neurons receive SCN projections, we investigated the role of SCN rhythmicity in the LC neuronal circadian rhythm as a possible component of the circadian mechanism regulating PRL surges. Cycling rats on proestrous day and estradiol-treated ovariectomized rats received injections of antisense or random-sequence deoxyoligonucleotide cocktails for clock genes (Per1, Per2, and Clock) in the SCN, and blood samples were taken for PRL measurements. The percentage of tyrosine hydroxylase-positive neurons immunoreactive to Fos-related antigen (FRA) was determined in ovariectomized rats submitted to the cocktail injections and in a 12:12-h light:dark (LD) or constant dark (DD) environment. The antisense cocktail abolished both the proestrous and the estradiolinduced PRL surges observed in the afternoon and the increase of FRA expression in the LC neurons at Zeitgeber time 14 in LD and at circadian time 14 in DD. Because SCN afferents and efferents were probably preserved, the SCN rhythmicity is essential for the magnitude of daily PRL surges in female rats as well as for LC neuronal circadian rhythm. SCN neurons therefore determine PRL secretory surges, possibly by modulating LC circadian neuronal activity. norepinephrine; PERIOD1; PERIOD2 IN FEMALE RATS, PROLACTIN (PRL) secretion has been proposed to result from synchronization among a circadian neural signal from the suprachiasmatic nucleus (SCN), both inhibitory and stimulatory neurotransmitter actions on the pituitary gland, and modulating effects of ovarian steroids (19). As a consequence of this synchronization, female rats display cyclical increases of PRL secretion characterized by two surges: the preovulatory surge of proestrous afternoon (64) and the secondary surge of estrous afternoon (12,70).The preovulatory surge of PRL depends on the levels of plasma ovarian steroids, because the increase of estradiol titers induces (45) and the increase of progesterone amplifies (76) this surge. Estradiol treatment in ovariectomized (OVX) rats induces daily PRL surges that occur at roughly the same time of day as the proestrous surge (13). Shifting of the light phase results in a coincident shift of the proestrous surge (10), and the estradiol-induced PRL surges of OVX rats free run in constant light (52), but the m...

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confidence: 99%

Knockdown of clock genes in the suprachiasmatic nucleus blocks prolactin surges and alters FRA expression in the locus coeruleus of female rats

Poletini¹,

McKee²,

Kennett³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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“…This increase in L TH can be due to increase in progesterone levels in the blood, which stimulates the release of prolactin as Caligaris et al (1974) found in the rat. The increase in the amount of LTH at this period could prove that corpora lutea in rabbits depend in addition to other physiological activities on prolactin.…”

Section: Discussionmentioning

confidence: 73%

Hormonal Changes During Formation and Involution of Corpus Luteum in Rabbits

Labib¹,

Azab²,

Soliman³

1978

Acta Vet. Brno

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Labib F., E. A. El Azab, F. A. Soliman: Hormonal Changes During Formation and Involution of Corpus Luteum in Rabbits. Acta vet. Brno, 47, 1978: 23-31. A study was made on 30 female Boscat rabbits to reveal the hormonal changes, namely, TSH, FSH, LH and L TH during the formation, maintenance and involution of the corpora lutea. Induction of ovulation was done by using gonadotrophic hormones (PMS and HCG). After HCG injection the animals were devided into 3 groups of 10 animals each. They were slaughtered after 3, 7 and 15 days from HCG injection. The results observed from this experiment are as follows: 3-day old corpus luteumThe rate of synthesis and release of TSH and state of thyroid were considered in a stabilized, balanced euthyroid status. There was increased concentration of FSH in the pituitaries with a relatively low level in the blood. This indicates the inhibition of release of FSH at this stage of development of corpora lutea.The level of L TH in the pituitary was of an average value and low in the serum. 7-days old corpus luteumThe TSH content of the pituitaries was the lowest (decreased synthesis) with a mild change in its level in the blood (non-significant). The thyroids were relatively less active than in the previous group.The FSH content of the pituitaries and blood were significantly decreased (decreased synthesis and release of FSH). The LH content of the pituitaries was increased and the level in the blood was decreased (decreased release of LH).The L TH content of the pituitaries was relatively low, while that of the blood was maximal, indicating increased release of L TH. IS-day old corpus luteumThe TSH content of the pituitaries and blood were highest indicating increased synthesis and release of this hormone. The thyroid gland showed maximum activity as compared to the previous groups.The FSH content of the pituitaries was relatively low while it reached its maximum in the serum (increased rate of release of FSH). The level of LH in the pituitaries was low and that of the blood was the least. The L TH content of the pituitaries was at its maximum and it was the lowest in the blood (increased synthesis of L TH but blocked release into the blood). The results are discussed in the text. LTH, TSH, LH, FSH, pituitary, blood serum.The features of growth and maintenance of the corpus luteum, and its subsequent involution are active processes of extreme importance in regulating reproductive performance of mammals. This includes regulation of the estrous cycle, pregnancy, parturition and milk production.Any disturbance of such processes of the corpus luteum will lead to reproductive disturbances in the farm animals.

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“…Most studies on the hormonal regulation of prolactin (PRL) release have focused on the role of the ovarian steroids (Freeman et al 1972, Caligaris et al 1974, Arbogast & Ben Jonathan 1990. However, accumulated evidence indicates that the adrenal gland is also able to regulate PRL secretion (Brann et al 1990.…”

Section: Introductionmentioning

confidence: 99%

Regulation of prolactin secretion during the estrus in rats: possible role of glucocorticoids

López-Fontana¹,

Maselli²,

Nasso³

et al. 2011

Reproduction

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Mifepristone (MIF) administration to cycling rats at proestrus induces hypersecretion of prolactin (PRL) at the following estrus. We aimed to assess whether this effect is due to the antiprogesterone or antiglucocorticoid action of MIF and to help underscore the nature of the circulating hormone(s) regulating PRL secretion at estrus. Female cycling rats in proestrus were treated with vehicle; the progesterone (Pg) and glucocorticoid receptor antagonists, MIF (5 mg/kg) or ORG-33628 (5 mg/kg); the glucocorticoid agonist dexamethasone (DEX; 27 mg/kg)GMIF; or the inhibitor of steroid synthesis aminoglutethimide (AG; 150 mg/kg)GMIF. The animals' blood was sampled the same day at 1800 h and at 1800 h of the following day to assess for circulating PRL and Pg levels. To distinguish antiglucocorticoid from antiprogesterone effects of MIF, we administered a highly specific neutralizing antibody against Pg. None of the antagonists modified serum PRL values at proestrus but increased PRL levels at estrus. DEX decreased the secretion of PRL at proestrus, yet the effect was entirely blocked by MIF. Furthermore, DEX decreased PRL at estrus in a MIF-reversible manner, suggesting that adrenal corticoids during proestrous may regulate PRL secretion at estrus. AG increased PRL secretion at estrus, whereas its association with MIF produced an even higher response. PRL concentration at estrus was not modified by the antiprogesterone antibody, suggesting that the effect of MIF is a consequence of its antiglucocorticoid effect and not due to its antiprogesterone properties. In conclusion, PRL secretion in the afternoon of the estrus is most likely regulated by glucocorticoids through an inhibitory action.

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Oestrogen and Progesterone Influence on the Release of Prolactin in Ovariectomized Rats

Cited by 120 publications

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Knockdown of clock genes in the suprachiasmatic nucleus blocks prolactin surges and alters FRA expression in the locus coeruleus of female rats

Knockdown of clock genes in the suprachiasmatic nucleus blocks prolactin surges and alters FRA expression in the locus coeruleus of female rats

Hormonal Changes During Formation and Involution of Corpus Luteum in Rabbits

Regulation of prolactin secretion during the estrus in rats: possible role of glucocorticoids

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