Induction of Precocious Puberty in Female Rats by Prolactin

Clemens, James A.; Minaguchi, Hiroshi; Storey, Robert; Voogt, J.L.; Meites, Joseph

doi:10.1159/000121748

Cited by 74 publications

(16 citation statements)

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“…Increased circulating prolactin levels after hypothalamic lesions [5], pimozide or sulpiride treatment [1,2], pituitary grafts [6,14], or exogenous hormone administration [7,12,13] advance puberty, whereas a delay can be obtained after chronic pro lactin suppression by bromocriptine [3].…”

mentioning

confidence: 99%

Two Possible Mechanisms for Precocious Puberty Induced in Female Rats by Pituitary Grafts

Gonzalez¹,

Fj²,

Je³

et al. 1986

Neuroendocrinology

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Many reports indicate that prolactin has a role in puberty occurrence. The present study was developed to evaluate the action of pituitary grafts on puberty. Female rats grafted on day 21 with ‘adult’ (90 days old) or ‘young’ (21 days old) pituitaries showed precocious vaginal opening and first estrus. The puberty advancement induced by ‘adult’ transplants was due to an increase in plasma prolactin values and can be blocked by bromocriptine treatment. The puberty advancement induced by ‘young’ transplants was not associated with increased prolactin levels and cannot be blocked by bromocriptine. These results suggest the existence of two possible mechanisms in precocious puberty induced by pituitary grafts: a prolactin-dependent one and another one not directly related with prolactin.

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mentioning

confidence: 99%

Two Possible Mechanisms for Precocious Puberty Induced in Female Rats by Pituitary Grafts

Gonzalez¹,

Fj²,

Je³

et al. 1986

Neuroendocrinology

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“…It is also known to have an antigonadotrophic effect in that exogen ous prolactin has a transient inhibitory effect on LH in pre pubertal rat [4], The decreased LH observed at day 30 coin cident with an increased prolactin is supportive of a nor mally occurring antigonadotropin effect of prolactin sug gested by Becket al [4], In addition to its ovarian role during development, pro lactin is postulated to be acting via a central mechanism since ME implants of prolactin advance puberty onset [8]. The AMYG has been shown to have a transient inhibitory role in the onset of puberty [12] since amygdala lesions on day 21 advance the onset of puberty.…”

Section: Discussionmentioning

confidence: 93%

“…Injections of prolactin advance the onset of puberty [1,8,27] partly by an effect on ovarian function [1]. It is also known to have an antigonadotrophic effect in that exogen ous prolactin has a transient inhibitory effect on LH in pre pubertal rat [4], The decreased LH observed at day 30 coin cident with an increased prolactin is supportive of a nor mally occurring antigonadotropin effect of prolactin sug gested by Becket al [4], In addition to its ovarian role during development, pro lactin is postulated to be acting via a central mechanism since ME implants of prolactin advance puberty onset [8].…”

Section: Discussionmentioning

confidence: 99%

Developmental Patterns of Tyrosine Hydroxylase Activity in Discrete Central Nervous System Regions and Serum LH and Prolactin in the Prepubertal Rat

Jimenez¹,

Meyer²,

Murphy³

1984

Neuroendocrinology

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Changes in tyrosine hydroxylase (TH) activity in the whole hypothalamus and discrete nuclear regions of the limbic system were observed to occur from 10 to 40 days of age in the female rat. In the whole hypothalamus, TH activity increased between 10 and 30 days of age then decreased at 40 days of age. In the preoptic (POA) and suprachiasmatic nuclear areas (SCN), TH activity increased to peak values at 20 days then declined to baseline values at 25 days. However, an increase in TH activity of SCN was again noted at 39 days of age. TH activity in the amygdala area (AMYG) increased to peak values at 25 and 30 days with a return to baseline levels at 35 days, while in the median eminence (ME), TH activity increased at 20 days and remained elevated through 39 days of age. These results show that temporally distinct changes in TH activity occur during development in various areas of the brain. These changes may represent maturation of neuronal control systems known to be involved in adult reproductive function.

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“…Since, in these experiments, LH secretion remained unchanged after systemic or i.c.v. administration of AMPA, it is tempting to postulate that the delay of puberty after AMPA treatment is mediated by the decrease in PRL secretion, since it is well known that PRL increased the number of ovarian LH receptors (Advis et al 1981), the responsiveness to gonadotrophins (Advis & Ojeda 1978) and advanced the onset of puberty in female and male rats (Clemens et al 1969, Aguilar et al1988. Experiments are in progress to determine whether activation of AMPA receptors modifies pubertal development in male rats.…”

Section: Discussionmentioning

confidence: 99%

Regulation of prolactin secretion by alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors in male rats

Gonzalez

Pinilla²,

Tena‐Sempere

et al. 2000

Journal of Endocrinology

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The secretion of PRL is controlled by different hypothalamic signals. Depending on the experimental model, PRL secretion increases or decreases after activation of N-methyl--aspartic acid and kainate receptors. Recently we have described that activation of -amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors inhibits PRL secretion in prepubertal male rats. The aim of present study was to examine (1) the physiological relevance of this finding, (2) the possible age-related changes observed after activation or blockade of AMPA receptors, (3) the specificity of the AMPA effect, (4) the hypothalamic and/or pituitary localization of AMPA action, and (5) the mechanism(s) of action of AMPA agonists.In a first set of experiments, neonatal males (5 and 10 days old) and prepubertal (23 days old) male rats were injected with AMPA (1, 2·5 or 5 mg/kg) or the antagonist of AMPA receptors 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo (f) quinoxaline-7-sulfonamide (NBQX; 0·25 or 0·50 mg/kg). Serum PRL concentrations decreased significantly 15 and 30 min after i.p. administration of AMPA in prepubertal male rats, while the inhibitory effect of AMPA was not observed in 5-and 10-day-old males. The effect of AMPA was abolished by NBQX but not by MK-801 (a selective antagonist of NMDA receptors). NBQX alone (0·25 or 0·50 mg/kg) had no effect on PRL release. In vitro, AMPA slightly stimulated PRL secretion by hemipituitaries from prepubertal males, suggesting that the hypothalamus is likely the site of action for the reported inhibitory action of AMPA on PRL release. In this sense, the blockade of AMPA effects in animals pretreated with domperidone (a dopaminergic antagonist) or -methyl-p-tyrosine (an inhibitor of dopamine synthesis) suggests that an increase in the release of hypothalamic dopamine is probably the mechanism involved in the effect of AMPA. In a second set of experiments, the effects of AMPA (2·5 mg/kg i.p.) and NBQX (0·5 mg/kg i.p. and 20 or 40 nmol i.c.v.) were tested in freely moving adult male rats sampled during periods of 2, 3 or 6 h. In contrast with data obtained in prepubertal rats, neither AMPA nor NBQX affected PRL secretion.In conclusion, these data indicate that activation of AMPA receptors inhibits PRL secretion in prepubertal male rats. This effect probably involves the release of dopamine from the hypothalamus and disappears in adulthood.

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Induction of Precocious Puberty in Female Rats by Prolactin

Cited by 74 publications

References 0 publications

Two Possible Mechanisms for Precocious Puberty Induced in Female Rats by Pituitary Grafts

Two Possible Mechanisms for Precocious Puberty Induced in Female Rats by Pituitary Grafts

Developmental Patterns of Tyrosine Hydroxylase Activity in Discrete Central Nervous System Regions and Serum LH and Prolactin in the Prepubertal Rat

Regulation of prolactin secretion by alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors in male rats

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