Arginine induces GH gene expression by activating NOS/NO signaling in rat isolated hemi-pituitaries

Abstract

The amino acid arginine (Arg) is a recognized secretagogue of growth hormone (GH), and has been shown to induce GH gene expression. Arg is the natural precursor of nitric oxide (NO), which is known to mediate many of the effects of Arg, such as GH secretion. Arg was also shown to increase calcium influx in pituitary cells, which might contribute to its effects on GH secretion. Although the mechanisms involved in the effects of Arg on GH secretion are well established, little is known about them regarding the control of GH gene expression. We investigated whether the NO pathway and/or calcium are involved in the effects of Arg on GH gene expression in rat isolated pituitaries. To this end, pituitaries from approximately 170 male Wistar rats (∼250 g) were removed, divided into two halves, pooled (three hemi-pituitaries) and incubated or not with Arg, as well as with different pharmacological agents. Arg (71 mM), the NO donor sodium nitroprusside (SNP, 1 and 0.1 mM) and a cyclic guanosine monophosphate (cGMP) analogue (8-Br-cGMP, 1 mM) increased GH mRNA expression 60 min later. The NO acceptor hemoglobin (0.3 µM) blunted the effect of SNP, and the combined treatment with Arg and L-NAME (an NO synthase (NOS) inhibitor, 55 mM) abolished the stimulatory effect of Arg on GH gene expression. The calcium channel inhibitor nifedipine (3 µM) also abolished Arg-induced GH gene expression. The present study shows that Arg directly induces GH gene expression in hemi-pituitaries isolated from rats, excluding interference from somatostatinergic neurons, which are supposed to be inhibited by Arg. Moreover, the data demonstrate that the NOS/NO signaling pathway and calcium mediate the Arg effects on GH gene expression.

To Unveil the Molecular Mechanisms of Qi and Blood through Systems Biology-Based Investigation into Si-Jun-Zi-Tang and Si-Wu-Tang formulae

“…Estrogen and steroid hormones can promote hematopoiesis 48 , maintain normal menses and the development of fetus in uterus. Arginine is a key player in immune system 49 50 , it can induces growth hormone (GH) gene expression and activate NOS/NO to increase blood flow 51 , so regulating arginine and proline metabolism pathway is benefit for strengthening the ability of anti-infection, promoting human growth and development and increasing blood flow. PPAR signaling plays the important role in lipid metabolism.…”

Amino acid homeostasis in the implementation of adaptive responses in animals with different resistance to tuberculosis infection

“…Воздействие КС на морских свинок сопровождается повышением уровня ФЭА, ЭА в печени, что отражает степень повреждения мембран. Как указывает ряд авторов, высокий уровень GSSG, АФК и ВСА усиливают апоптоз клеток, оказы-вают повреждающее воздействие на их мембраны и структуры ядра [1,4,5,10,14,21]. В то же время повышенный ресурс GSH и его активное включение в механизмы защиты является механизмом антимутагенеза и антиканцерогенеза [3,5,17], следовательно, можно предположить, что в случае заражения микобактериями туберкулеза, сопровождающегося значительным повышением количества глутатиона, у крыс создаются условия для антимутагенеза и антиканцерогенеза.…”

“…Имеются так же сведения, что морская свинка гораздо более устойчива к гипоксическим состояниям, чем крыса [8,9,18]. Эти различия, надо полагать, могут быть обусловлены не только различным количеством, соотношением и обменными процессами перечисленных метаболитов-адаптогенов [17,18,19,21], но и различной стратегией защитно-компенсаторных механизмов у этих животных, что и явилось предметом нашего исследования.…”

Efeitos da suplementação crônica de L-arginina sobre a expressão de proteínas envolvidas na regulação da síntese proteica muscular em ratos treinados em exercícios de alta intensidade

“…Mais recentemente,Olinto et al (2012) realizaram um experimento incubando hemi-hipófises de ratos com três diferentes concentrações de arginina (7,1, 71 e 710 mM) e observaram que houve aumento do conteúdo de GH-mRNA somente na concentração de 71 mM de arginina e que este aumento era notável num período de tempo entre 60 minutos e 120 minutos de incubação. Isso reforça a idéia de que as respostas da suplementação de arginina em relação à secreção de GH dependem da dosagem que são utilizadas nos estudos.Contudo,Collier et al (2006) já haviam constatado que o exercício foi mais eficaz em promover o aumento das concentrações séricas de GH em relação à suplementação de arginina isolada.…”