Induction of Daily PRL Surges in Rats by Chronic Treatment with Progesterone

Kawaminami, Mitsumori; Takahashi, Michio

doi:10.1507/endocrj1954.34.37

Cited by 7 publications

(2 citation statements)

References 23 publications

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“…It was published earlier that around the time of puberty females had higher PRL mRNA level than males [49], and the weight and PRL level of anterior pituitary in prepubertal females is significantly higher in females than in males [50]. In ovariectomized rats P implanted in silicone tubes subcutaneously induced nocturnal PRL surge, similar P sensitive central mechanism was not observed in adult male rats [51]. …”

Section: Discussionmentioning

confidence: 97%

Sexual dimorphism in the effect of concomitant progesterone administration on changes caused by long-term estrogen treatment in pituitary hormone immunoreactivities of rats

et al. 2011

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SummaryBackgroundSince in clinical practice long-term estrogen (E) treatment is frequently applied, our aim was to study the effect of concomitant progesterone (P) administration on changes caused by long-term estrogen treatment in the secretion of LH, FSH, PRL and GH.Material/MethodsDiethylstilbestrol (DES), P or both in silastic capsules were implanted under the skin of prepubertal Sprague-Dawley male and female rats. Animals survived for two or five months. We have also studied whether the changed hormone secretion caused by DES can return to normal level 1 or 2 months after removing DES capsule.Results1.) The males more rapidly responded than females with decreasing basal LH release upon treatments. The basal FSH release was decreased only in males. The effect of DES persisted in males; however, in females basal LH and FSH levels were upregulated after removal of DES capsule. 2.) The basal GH levels were low in each group. The body weight and length were depressed by DES in both genders and P little blunted this effect. The body weight and length in males remained low after removal of DES capsule, in females it was nearly similar to intact rats. 3.) There was no sexual dimorphism in the effect of steroids on PRL secretion. In both genders DES extremly enhanced the PRL levels, P prevented the effect of DES. PRL levels returned to intact value after removal of DES influence. 4.) Removal of DES capsule reversed the changes in the immunohisto-chemical appearance of hormone immunoreactivities.ConclusionsThere was sexual dimorphism in the change of basal gonadotropic hormone and GH secretion but not of PRL upon DES and DES+P treatments. P was basically protective and this role may be mediated by P receptors locally in the pituitary gland.

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Section: Discussionmentioning

confidence: 97%

Sexual dimorphism in the effect of concomitant progesterone administration on changes caused by long-term estrogen treatment in pituitary hormone immunoreactivities of rats

et al. 2011

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“…These stimuli may increase the rate of appearance of the long L stage in the first oestrous cycle. Kawaminami & Takahashi (1987) succeeded in inducing the nocturnal surge of prolactin in rats bearing Silastic tubing containing progesterone without taking vaginal smears. We also found in a preliminary experiment that animals showed the long L stage even when vaginal smearing was stopped for 3 days after vaginal opening.…”

Section: Discussionmentioning

confidence: 99%

Plasma progesterone concentrations and length of the first spontaneous oestrous cycle in pubertal rats

Tomogane

Yokoyama²

1990

Reproduction

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Effects of a low-protein diet on prolactin- and growth hormone-producing cells in the rat pituitary gland

et al. 1998

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Background: It is well known that an unbalanced diet induces various changes in the pituitary gland. However, little attention has been paid to the molecular aspects of this perturbation. We studied the influence of a lowprotein diet (LPD) on the prolactin (PRL) and growth hormone (GH) cells in the rat pituitary gland using immunohistochemical staining and in situ hybridization.Materials: Rats aged 20 days were fed a diet containing 27% protein or one with 8% protein (LPD) for 30 days. Pituitary glands were obtained and subjected to either immunohistochemistry or in situ hybridization. Quantitative morphological analysis was then conducted to determine cell number and area as well as the percentage of cells stained by the respective antisera and/or cDNA probe in each experimental group.Results: The average sectional areas of both PRL-and GH-producing cells in the LPD group were smaller in size than those in the controls. The cell numbers per unit area (mm 2 ) of PRL-positive cells and PRL mRNA-positive cells were 3,596.5 and 3,948.6, respectively, in the LPD group, and 3,179.6 and 4,888.5, respectively, in the controls. The numbers per unit area of GHpositive cells and GH mRNA-positive cells in the LPD group were similar (2,252.3 and 2,224.4), as compared to 2,161.3 and 1,684.2, respectively, in the well-fed rats. Whereas PRL-positive cells comprised about 27% of the total number of cells in both animal groups, those given the LPD contained a lower percentage (29%) of PRL mRNA-positive cells as compared to the controls (44%). On the other hand, GH mRNA-positive cells numbered about 15% of the total cell population both animal groups; however, the malnourished rats contained a lower percentage (16%) of GH-positive cells than did their well-fed counterparts (20%).Conclusions: Taken together, these results indicate that in the rat pituitary gland, administration of an LPD reduced the size of PRL-and

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Induction of Daily PRL Surges in Rats by Chronic Treatment with Progesterone

Cited by 7 publications

References 23 publications

Sexual dimorphism in the effect of concomitant progesterone administration on changes caused by long-term estrogen treatment in pituitary hormone immunoreactivities of rats

Sexual dimorphism in the effect of concomitant progesterone administration on changes caused by long-term estrogen treatment in pituitary hormone immunoreactivities of rats

Plasma progesterone concentrations and length of the first spontaneous oestrous cycle in pubertal rats

Effects of a low-protein diet on prolactin- and growth hormone-producing cells in the rat pituitary gland

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