Hypothyroidism increases prolactin secretion and decreases the intromission threshold for induction of pseudopregnancy in adult female rats

Tohei, Atsushi; Taya, Kazuyoshi; Watanabe, Gen; Voogt, J.L.

doi:10.1016/s0031-9384(00)00224-9

Cited by 13 publications

(7 citation statements)

References 46 publications

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“…The activity of the rate-limiting enzyme in dopamine synthesis, tyrosine hydroxylase, was unaltered in hypothalamic tuberoinfundibular dopaminergic neurons after PTU-induced hypothyroidism (37); correspondingly, we observed no difference in the hypothalamic dopamine production in our Pax8 Ϫ/Ϫ mice when compared with control.…”

Section: Discussionmentioning

confidence: 46%

Analysis of Hypertrophic Thyrotrophs in Pituitaries of Athyroid Pax8−/− Mice

et al. 2009

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Thyroid hormone is important for pituitary development and maintenance. We previously reported that in the Pax8(-/-) mouse model of congenital hypothyroidism, lactotrophs are almost undetectable, whereas the thyrotrophs exhibit hyperplasia and hypertrophy. Because the latter might be caused by an overstimulation of thyrotrophs with TRH, we analyzed TRH-R1(-/-)Pax8(-/-) double-knockout mice, which miss a functional thyroid gland and the TRH transducing receptor-1 at pituitary target sites. Interestingly, in these double mutants, the hypertrophy and hyperplasia of the thyrotrophs still persist, suggesting that the phenotype is rather a direct consequence of the athyroidism of the animals. The increased expression of TSH in the Pax8(-/-) mice was paralleled by a strongly up-regulated expression of deiodinase type 2 (Dio2) in thyrotrophic cells. Moreover, coexpression of TSH and Dio2 could also be demonstrated in the pituitary of wild-type mice, underlining the important role of this enzyme in the negative feedback regulation of TSH by thyroid hormone. As another consequence of the athyroidism in the mutant mice, tyrosine hydroxylase mRNA expression was found to be also highly up-regulated in thyrotrophic cells of the pituitaries from Pax8(-/-) mice, whereas the transcript levels in the hypothalamus were not affected. Accordingly, tyrosine hydroxylase protein levels, enzyme activities, and ultimately dopamine concentrations were found to be strongly increased in the pituitaries of Pax8(-/-) mice compared with wild-type animals. These findings may explain in part the reduced number of lactotrophs found in the pituitary of athyroid Pax8(-/-) mice and suggest a novel paracrine regulatory mechanism of lactotroph activity.

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Section: Discussionmentioning

confidence: 46%

Analysis of Hypertrophic Thyrotrophs in Pituitaries of Athyroid Pax8−/− Mice

et al. 2009

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“…Pituitary concentrations of VIP increased in hypothyroid female rats. This increased level of VIP likely affects PRL secretion in a paracrine or autocrine manner, inducing hyperprolactinemia in hypothyroid female rats [60]. In female rat, thus, inhibition of gonadal function in hypothyroid rats mediated by hyperprolactinemia in addition to hypersecretion of endogenous CRH.…”

Section: Discussionmentioning

confidence: 99%

Studies on the Functional Relationship between Thyroid, Adrenal and Gonadal Hormones

Tohei

2004

J. Reprod. Dev.

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Abstract. In order to clarify the functional relationship between thyroid, adrenal and gonadal hormones, hypothyroidism was induced by administration of thiuoracil in adult male and female rats, and the effects of hypothyroidism on the adrenal and the gonadal axes were investigated in the present study. 1. The functional relationship between thyroid and adrenal hormones: Adrenal weights and corticosterone were lowered, whereas the secretion of ACTH, corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) increased in hypothyroid rats compared to euthyroid rats. These results indicate that hypothyroidism causes adrenal dysfunction directly and results in hypersecretion of CRH and AVP from the hypothalamus. 2. The functional relationship between thyroid and gonadal hormones: The pituitary response to LHRH was lowered, whereas the testicular response to hCG was not changed in hypothyroid rats. Hypothyroidism suppressed copulatory behavior in male rats. These results suggest that hypothyroidism probably causes dysfunction in gonadal axis at the hypothalamic-pituitary level in male rats. In adult female rats, hypothyoidism inhibited the follicular development accompanied estradiol secretion, whereas plasma concentrations of progesterone and prolactin (PRL) increased in hypothyroid female rats. Hypothyroidism significantly increased the pituitary content of vasoactive intestinal peptide (VIP) though it did not affect dopamine synthesis. These results suggest that hypothyroidism increases pituitary content of VIP and this increased level of VIP likely affects PRL secretion in a paracrine or autocrine manner. In female rats, inhibition of gonadal function in hypothyroid rats mediated by hyperprolactinemia in addition to hypersecretion of endogenous CRH.

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“…The present data suggest that TCS-induced hypothyroidism presents the same scenario, as the elevated levels of serum PRL, TSH and TRH in 10-TCS mice were corrected by L-T4 administration. Hypothyroidism can also induce elevation in vasoactive intestinal peptide, which is capable of increasing PRL secretion (Tohei et al, 2000 ). On the other hand, PRL can regulate its own release by acting on the hypothalamic dopaminergic systems via a “short loop feedback”, which is mostly responsible for the maintenance of PRL homeostasis.…”

Section: Discussionmentioning

confidence: 99%

“…The treatment with TCS in pregnant rats decreases total serum triiodothyronine (T3) and T4 (Rodríguez and Sanchez, 2010 ). This decrease in thyroid hormone results in reduced negative feedback on the hypothalamus-pituitary axis enhances thyroid releasing hormone (TRH) secretion, which would in turn promote excess prolactin (PRL) secretion (Tohei et al, 2000 ). PRL elevation was found in 21% of patients with overt hypothyroidism, and 8% of patients with subclinical hypothyroidism (Goel et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Impact of Triclosan on Female Reproduction through Reducing Thyroid Hormones to Suppress Hypothalamic Kisspeptin Neurons in Mice

Cao

Xiong

et al. 2018

Front. Mol. Neurosci.

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Triclosan (TCS), a broad-spectrum antimicrobial agent, is widely used in clinical settings and various personal care products. The aim of this study was to evaluate the influence of TCS on reproductive endocrine and function. Here, we show that the exposure of adult female mice to 10 or 100 mg/kg/day TCS caused prolongation of diestrus, and decreases in antral follicles and corpora lutea within 2 weeks. TCS mice showed decreases in the levels of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and progesterone, and gonadotrophin-releasing hormone (GnRH) mRNA with the lack of LH surge and elevation of prolactin (PRL). TCS mice had lower kisspeptin immunoreactivity and kiss1 mRNA in anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC). Moreover, the estrogen (E2)-enhanced AVPV-kisspeptin expression was reduced in TCS mice. In addition, the serum thyroid hormones (triiodothyronine (T3) and thyroxine (T4)) in TCS mice were reduced with increases in levels of thyroid stimulating hormone (TSH) and thyroid releasing hormone (TRH). In TCS mice, the treatment with Levothyroxine (L-T4) corrected the increases in PRL, TSH and TRH; the administration of L-T4 or type-2 dopamine receptors agonist quinpirole inhibiting PRL release could rescue the decline of kisspeptin expression in AVPV and ARC; the treatment with L-T4, quinpirole or the GPR45 agonist kisspeptin-10 recovered the levels of serum LH and FSH and progesterone, and GnRH mRNA. Furthermore, TCS mice treated with L-T4 or quinpirole resumed regular estrous cycling, follicular development and ovulation. Together, these results indicate that exposing adult female mice to TCS (≥10 mg/kg) reduces thyroid hormones causing hyperprolactinemia that then suppresses hypothalamic kisspeptin expression, leading to deficits in reproductive endocrine and function.

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Hypothyroidism increases prolactin secretion and decreases the intromission threshold for induction of pseudopregnancy in adult female rats

Cited by 13 publications

References 46 publications

Analysis of Hypertrophic Thyrotrophs in Pituitaries of Athyroid Pax8−/− Mice

Analysis of Hypertrophic Thyrotrophs in Pituitaries of Athyroid Pax8−/− Mice

Studies on the Functional Relationship between Thyroid, Adrenal and Gonadal Hormones

Impact of Triclosan on Female Reproduction through Reducing Thyroid Hormones to Suppress Hypothalamic Kisspeptin Neurons in Mice

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