Role of zinc in regulating the testicular function. Part 1. Effect of dietary zinc deficiency on serum levels of gonadotropins, prolactin and testosterone in male albino rats

Hafiez, A. A.; El‐Kirdassy, Z. H. M.; Mansour, Mohy S.; Sharada, Hayat M.; El-Zayat, Emad

doi:10.1002/food.19890331007

Cited by 15 publications

(9 citation statements)

References 16 publications

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“…In several studies, there was an increase in the secretion of gonadotrophins, presumably as a consequence of the loss of negative feedback to the hypothalamo-hypophyseal system (Lei et al, 1976;Root et al, 1979;Prasad, 1985). In the study by Hafiez et al (1989), however, the serum concentrations of gonadotrophins were not affected.…”

Section: Introductionmentioning

confidence: 52%

“…In 1969, Underwood & Somers suggested that there may be two deficiency (5-17 pg Zn g~') where there are no clinical symptoms and body growth is normal, but testicular development and sperm production are markedly reduced. This contrast between the responses of the reproductive and other tissues suggests that 'mild' deficiency specifically affects the hormonal systems controlling testicular growth. A similar situ¬ ation has been suggested for the male rat and human, in which the effects of zinc deficiency appear to be expressed in the testis, specifically within the pathways controlling steroidogenesis, so that the secretion of androgens is reduced (McClain et al, 1984;Prasad, 1985;Hafiez et al, 1989). In several studies, there was an increase in the secretion of gonadotrophins, presumably as a consequence of the loss of negative feedback to the hypothalamo-hypophyseal system (Lei et al, 1976;Root et al, 1979;Prasad, 1985).…”

Section: Introductionmentioning

confidence: 90%

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Effects of dietary zinc deficiency on gonadotrophin secretion and testicular growth in young male sheep

Martin

White²

1992

Reproduction

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Summary. The hypothesis that the secretion of gonadotrophins would be reduced by zinc deficiency was tested in five groups of four young Merino rams (initial liveweight 22 kg). Four groups were fed ad libitum with diets containing 4, 10, 17 or 27 \ g=m\ g Zn g \ m=-\ 1. The effects of loss of appetite on the deficient diet was controlled by feeding a fifth group (pair-fed control) at a rate of 27 \g=m\g Zn g \ m=-\ 1, but the amount of feed offered was restricted to that eaten voluntarily by the deficient (4 \ g=m\ g Zn g\ m=-\ 1) group. Blood was sampled every 20 min for 32 h on two occasions before the treatments were imposed and 96 days later, at the end of the experiment. The rams were injected with gonadotrophin-releasing hormone (GnRH; 10 ng kg \ m= -\ 1 i.v.) after each serial sampling, and with naloxone (1 mg kg\m=-\ 1 i.v.) 24 h after the end of the final GnRH test.In the group that were fed the diet with the lowest zinc content, the concentration of zinc in blood plasma was reduced to 18% of that in the pair-fed controls (P < 0\m=.\05) and was within the deficient range. The appetite of the deficient rams was half that of the controls fed 27 \g=m\g Zn g\m=-\1 ad libitum and there was no increase in liveweight or testicular diameter during pubertal development. Similar, but smaller, effects were observed in the pair-fed controls. There were no significant differences between pair-fed and deficient groups in the frequency of the luteinizing hormone (LH) pulses or in the concentration of follicle-stimulating hormone (FSH), but the secretion of gonadotrophins was markedly lower in both groups than in the control rams fed ad libitum. The response to GnRH was not affected by treatment, but the increase in LH pulse frequency evoked by naloxone was lower in the deficient animals than in other groups.The animals fed zinc at intermediate rates (10\p=n-\17 \ g=m\ g\ g=m\ \ m=-\ 1) showed similar responses to the controls fed ad libitum.It is concluded that the specific effects of zinc deficiency on testicular function were small. Most of the reduction in testicular growth in rams fed a deficient diet was not specifically related to the trace element, but was due to the fall in energy and protein intake caused by the loss of appetite. This leads to a reduction in the frequency of GnRH pulses secreted by the hypothalamus, and to low rates of gonadotrophin secretion by the pituitary gland.

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Section: Introductionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 90%

Effects of dietary zinc deficiency on gonadotrophin secretion and testicular growth in young male sheep

Martin

White²

1992

Reproduction

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“…Zinc also induces the activity of 3␤-OH steroid dehydrogenase, which is the key enzyme used for testosterone biosynthesis [41]. Hafiez et al [42] also showed that zinc deficiency causes decreased levels of serum testosterone. In the present study an increase in testosterone and estradiol was observed after zinc supplementation.…”

Section: Discussionmentioning

confidence: 97%

Antioxidant role of zinc in PCB (Aroclor 1254) exposed ventral prostate of albino rats

Venkataraman

Sridhar²,

Dhanammal

et al. 2004

The Journal of Nutritional Biochemistry

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“…Hpogonadismus kann bei männlichen Zn‐Mangelratten die Folge eine Mangels oder Verlustes bzw. einer verminderten Funktion an Leydig‐Zellen sein (L ei et al 1976; M ansour et al 1989). Möglicherweise ist es aber auch ein Sekundäreffekt, der durch die verminderte Futteraufnahme und dem damit verbundenen Energie‐ und Proteinmangel zu einer geringeren Wachstumsrate sowie einer allgemeinen Schwächung der Tiere führt.…”

Section: Diskussionunclassified

Einfluß von Zinkmangel auf die Gehalte von Gonadotropinen, Prolactin und Testosteron im Serum von künstlich ernährten männlichen Ratten

Roth

Kirchgeßner

1997

Animal Physiology Nutrition

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Zusammenfassung 24 männliche Sprague‐Dawley Ratten mit einer durchschnittlichen Lebendmasse von 108 g, wurden in 2 Gruppen zu je 12 Tieren eingeteilt. Beiden Gruppen wurden 12 Tage lang viermal täglich über eine Schlundsonde künstlich ernährt. Gruppe 1 erhielt eine Zn‐Mangeldiät (1,2 mg Zn/kg T) in einer Menge von 11,6 g pro Tag und Gruppe 2 die Kontrolldiät (22 mg Zn/kg T) in derselben Menge. Mit dieser Schlundsondentechnik war es möglich, auch die Zn‐Mangelratten über den gesamten Versuchszeitraum zur gleichen Zeit mit derselben Diätmenge entsprechend den Kontrolltieren ausreichend mit Nährstoffen zu versorgen. Nach 12 Versuchstagen wurde der Einfluß von alimentärem Zinkmangel per se auf die Serumgehalte von Gonadotropinen, Prolactin und Testosteron bestimmt. Zur Beurteilung des Zn‐Versorgungsstatus der Tiere wurde die Zn‐Konzentration und die Aktivität der alkalischen Phosphatase im Serum ermittelt. Die Zn‐Konzentration und die Aktivität der alkalischen Phosphatase war im Serum der Zn‐Mangelratten im Vergleich zu den Kontrolltieren signifikant um 56% bzw. 47% erniedrigt, was auf einen ausgeprägten alimentären Zn‐Mangel dieser Tiere hinweist. Die Gehalte an Testosteron und Dihydrotestosteron im Serum wurden durch die Zn‐Mangelernährung innerhalb der Versuchszeit nicht signifikant beeinflußt. Dagegen war im Serum der Zn‐Mangelratten die Konzentration an Follikelstimulierendem Hormon um 25% signifikant reduziert, während das luteinisierende Hormon und Prolactin um 22% bzw. über 100% signifikant erhöht waren. Summary Influence of zinc deficiency on serum levels of gonadotropins, prolactin and testosterone in force‐fed male rats Twenty‐four male Sprague‐Dawley rats with an average liveweight of 108 g were divided into two groups of 12 animals each. Both groups were force‐fed by intra‐gastric tube four times each day (0800, 1200, 1700, 2200 h) over 12 experimental days. Group 1 received a zinc‐deficient diet [1.2 mg Zn/kg dry matter (DM)] in a total amount of 11.6g DM per day and per animal. Group 2 received the control diet (22 mg Zn/kg DM) in the same amount. This technique made it possible to supply even the zinc‐deficient rats with sufficient nutrients over the whole experimental period in the same manner as for the control rats, at the same time and with the same dietary amounts. After 12 experimental days the influence of alimentary zinc deficiency per se on the concentrations of gonadotropins, prolactin and testosterone in serum were estimated. For assessment, the zinc status of the rats covered both serum zinc concentration and alkaline phosphatase activity. The serum zinc concentration and alkaline phosphatase activity were significantly reduced in the zinc‐deficient rats by 56 and 47%, respectively, in comparison with control animals, indicating a severe alimentary zinc‐deficiency status of the animals. Within the experimental time the serum concentrations of testosterone and dihydrotestosterone were not significantly influenced by the zinc‐deficient nutrition. On the other hand the serum concentration of ...

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Role of zinc in regulating the testicular function. Part 1. Effect of dietary zinc deficiency on serum levels of gonadotropins, prolactin and testosterone in male albino rats

Cited by 15 publications

References 16 publications

Effects of dietary zinc deficiency on gonadotrophin secretion and testicular growth in young male sheep

Effects of dietary zinc deficiency on gonadotrophin secretion and testicular growth in young male sheep

Antioxidant role of zinc in PCB (Aroclor 1254) exposed ventral prostate of albino rats

Einfluß von Zinkmangel auf die Gehalte von Gonadotropinen, Prolactin und Testosteron im Serum von künstlich ernährten männlichen Ratten

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