Zinc May Have a Physiological Role in Regulating Pituitary Prolactin Secretion

Login, Ivan S.; Thorner, Michael O.; MacLeod, Robert M.

doi:10.1159/000123568

Cited by 41 publications

(10 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The absence of hypothalamic effect of physiologically relevant zinc concentrations [Login et al, 1983] both on TRH content and TRH release in our experiment is difficult to compare to the previously reported decrease of hypothalamic TRH content in zinc-defi cient rats [Morley et al, 1980], since this effect appears secondary to zinc-dependent deficiency of extrathvroidal production of triiodothyronine.…”

Section: Discussioncontrasting

confidence: 72%

“…since zinc has been previously reported to have an inhibiting ef-feet on basal prolactin release [Labella et al, 1973;Login et al, 1983], a stimulating effect on ACTH and GH release [Labella et al, 1975] and a debated effect for gonadotropin [Labella et al, 1973;Login et al, 1983], Despite this lack of specificity of zinc on TSH release from the pituitary gland, the effi ciency of the zinc physiological concentra tions used (as compared to the pituitary zinc concentration [Merriam et al, 1979]) to in duce both in vitro and in vivo TSH release suggests that this trace clement might be in volved in the regulation of thyrotropin func tion. …”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Zinc May Play a Role in the Regulation of Thyrotropin Function

et al. 1986

View full text Add to dashboard Cite

We studied the in vitro and in vivo influence of physiologically relevant zinc concentrations on the thyrotropin function both at the pituitary and hypothalamic level. Zinc gluconate (Zn Glu) concentrations from 5 to 100 µM decreased basal TSH release from anterior pituitary gland in vitro, but did not affect TSH-stimulated release by TRH, cAMP or high K⁺ concentrations. Zn Glu altered neither the basal nor stimulated production of TRH by hypothalami in vitro. In vivo brain third ventricle injection of Zn Glu decreased serum TSH 30–60 min after injection. The ability of physiological concentrations of zinc to influence TSH secretion both in vitro and in vivo suggest that this trace element might be involved in the regulation of thyrotropin function.

show abstract

Section: Discussioncontrasting

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Zinc May Play a Role in the Regulation of Thyrotropin Function

et al. 1986

View full text Add to dashboard Cite

show abstract

“…Our results support findings from previous studies in cultured adenohypophyseal cells, showing that the inhibition of PPII activity favors TRH‐induced PRL release but not that of TSH (Cruz et al, 2008). Interestingly, Zn addition to cultured adenohypophyseal cells decreases PRL secretion (Login et al, 1983; LaBella et al, 1973). Therefore, in lactating rats Zn deficiency‐induced down‐regulation of PPII favored PRL secretion; an effect that was independent of TRH content, revealing that PPII activity modulation was enough to modify PRL secretion in lactating rats.…”

Section: Discussionmentioning

confidence: 99%

Mediobasal hypothalamic and adenohypophyseal TRH‐degrading enzyme (PPII) is down‐regulated by zinc deficiency

Alvarez-Salas

Alcántara-Alonso

Matamoros-Trejo

et al. 2015

Intl J of Devlp Neuroscience

View full text Add to dashboard Cite

Thyrotropin-releasing hormone (TRH) synthesized in hypothalamic paraventricular nucleus directs hypothalamus-pituitary-thyroid (HPT) axis function, regulating thyrotropin release from adenohypophysis and thyroid hormones serum concentration. Pyroglutamyl aminopeptidase II (PPII), a Zn-dependent metallopeptidase located in adenohypophysis and medial-basal-hypothalamus degrades TRH released from the median eminence and participates in HPT axis function by regulating TRH-induced thyrotropin release from adenohypophysis. It is unknown whether dietary Zn deficiency down-regulates PPII. Our aim was to compare adenohypohyseal and medial-basal-hypothalamic PPII activity and expression of adult rats fed a Zn-deficient diet (2ppm) throughout their lifespan (DD), prenatally (DC) or after weaning (CD) vs. that of animals fed a control diet (20ppm:CC). Female rats consumed a Zn-deficient or control diet from two weeks before gestation and up to the end of lactation. We analyzed adenohypophyseal and medial-basal-hypothalamic PPII activity of dams and male offspring when adults; its relation to median eminence TRH, serum thyrotropin, leptin and thyroid hormones concentration. Offspring ate the same diet as their dams (CC, DD) or were switched from dietary regime after weaning (CD, DC) and until 2.5 months of age. DD males showed decreased adenohypophyseal and medial-basal-hypothalamic PPII activity, along with high thyrotropin serum concentration. Post-weaning Zn-deficiency (CD) decreased PPII activity only in adenohypophysis and increased thyrotropin circulating levels. Zn-replenishment (DC) normalized PPII activity in both regions and serum thyrotropin concentration. Adenohypophyseal PPII activity decreased and prolactin levels increased in Zn-deficient dams. We concluded that long-term changes in dietary Zn down-regulate PPII activity independently of T3, increasing thyrotropin serum concentration, overall resembling sub-clinical hypothyroidism.

show abstract

“…Taneja and Kaur [18,19] have also reported a higher frequency of follicular atresia of type I and VI follicles in virgin female mice fed on zinc-deficient diet, apart from a retardation of ovarian follicular growth with varying degree of atresia, lack of preovulatory Graafian follicles, a reduced and shrunken corpus luteum, and a fragmented zona pellucida and vitelline membrane. The variations observed in the zinc content of goat are correlated to hormonal changes or changes in distribution of specific carrier proteins [21], Variations in plasma albumin [21], regulation of activity or binding of selected hormones [24,25] The follicular atresia associated with low levels of zinc in goat ovary may be due to a decline in number of gap junctions. Only 39% to 49% gap junctions as compared to normal ones have been observed in zinc-deficient rats [26,27].…”

Section: Discussionmentioning

confidence: 99%

Changes in Trace Elements during Follicular Atresia in Goat (Capra hircus) Ovary

Bhardwaj

Sharma

2010

Biol Trace Elem Res

View full text Add to dashboard Cite

Quantitative analysis of follicular fluid and granulosa cells from small, medium and large antral atretic follicles of goat (Capra hircus) ovaries was conducted to study the alterations in trace elements viz zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe). The zinc content was lower in the follicular fluid (0.993 ± 0.001, 0.935 ± 0.002, 1.321 ± 0.001 μg/ml) and granulosa cells (0.867 ± 0.002, 0.801 ± 0.001, 1.073 ± 0.002 μg/mg) of small, medium, and large antral atretic follicles respectively than their respective controls. Copper quantity was higher in the follicular fluid (0.113 ± 0.001, [Formula: see text], 0.224 ± 0.001 μg/ml) and granulosa cells (0.094 ± 0.001, 0.114 ± 0.001, 0.182 ± 0.001 μg/mg) from small, medium, and large antral atretic follicles respectively than their respective controls. Similarly, iron and manganese was also found higher in the follicular fluid and granulosa cells of small, medium, and large antral atretic follicles than their respective controls. The present study provides the basic data on trace elements that can be safely used as atretic marker and will find use in in vitro studies for fertility improvement plan. Thus, help in elevating the number of ovulations and screening of follicles to enhance the success rate in vivo and in vitro fertilization and embryo transfer technology.

show abstract

Zinc May Have a Physiological Role in Regulating Pituitary Prolactin Secretion

Cited by 41 publications

References 15 publications

Zinc May Play a Role in the Regulation of Thyrotropin Function

Zinc May Play a Role in the Regulation of Thyrotropin Function

Mediobasal hypothalamic and adenohypophyseal TRH‐degrading enzyme (PPII) is down‐regulated by zinc deficiency

Changes in Trace Elements during Follicular Atresia in Goat (Capra hircus) Ovary

Contact Info

Product

Resources

About