Effects of peptidic growth hormone secretagogue receptor (GHS-R) antagonist [D-Lys3] on some of serum hormonal and biochemical parameters in Wistar rat model

Abstract

Objective: The present study investigated the effects of different dosages of a GHS-R antagonist on some serum hormonal (cortisol, T 3 and T 4 ) and biochemical parameters in a rat. Materials and methods: Thirty-six 60-day-old male rats were assigned to four treatments. [D--Lys3]-GHRP-6 solutions were infused via intraperitoneal injections. Blood was collected and analyzed. Results: The large dosages of a GHS-R antagonist (200 ng/kg BW) caused increases in cortisol, whereas no significant changes occurred when low dosages were injected. There were no significant changes in T 3 and T 4 following the administration of the GHS-R antagonist, but a considerable increase was observed in blood glucose levels of the groups (G50, G100, and G200 ng/kg BW). There was a significant increase in total protein when the greatest dose was administrated (G200 ng/kg BW). However, total cholesterol, triglycerides, and albumin showed no significant changes. Conclusions: Exogenous GHS-R antagonist can cause an increase in glucose and moderate increases in cortisol and total protein, yet it has no significant effect on T 3 and T 4 levels or on the concentrations of serum lipids. The effect of GHS-R antagonist is not completely adverse to the effects of ghrelin. Further molecular studies are necessary to identify the physiological effects of the peptidic GHS-R antagonist. Arq Bras Endocrinol Metab. 2014;58(3):288-91 Keywords Ghrelin receptor; GHS-R; GH-releasing; regulatory peptide; peripheral infusion RESUMO Objetivo: O presente estudo investigou os efeitos de diferentes doses do antagonista do GHS-R [D-Lys3] sobre alguns parâmetros hormonais (cortisol, T 3 e T 4 ) e bioquímicos em ratos. Materiais e métodos: Trinta e seis ratos machos com 60 dias de idade foram alocados para quatro tratamentos. Soluções de [D-Lys3]-GHRP-6 foram administradas por meio de injeções intraperitoneais e foram coletadas e analisadas amostras. Resultados: Doses altas de antagonista de GHS--R (200 ng/kg PC) levaram a aumento do cortisol, enquanto não houve diferença significativa quando foram injetadas doses baixas. Não houve alterações significativas em T 3 e T 4 depois da administração do antagonista do GHS-R, mas foi observado aumento considerável nos níveis de glicose sanguínea dos grupos (G50, G100 e G200 ng/kg PC). Houve aumento significativo na proteína total quando foi administrada a maior dose (G200 ng/kg PC), entretanto, não foram observadas alterações no colesterol total, nos triglicérides e na albumina. Conclusões: O antagonista do GHS-R exógeno pode causar aumento da glicose e aumento moderado do cortisol e proteína total, embora não haja efeitos significativos nos níveis de T 3 e T 4 ou na concentração de lipídios séricos. O efeito do antagonista de GHS-R não é completamente adverso aos efeitos da grelina. Devem ser feitos outros estudos moleculares para se identificar os efeitos fisiológicos do peptídeo antagonista do GHS-R. Arq Bras Endocrinol Metab. 2014;58(3):288-91 DescritoresReceptor da grelina, GHS-R, liberação de GH, peptídeo re...

Effects of peripheral administration of ghrelin antagonist [D-Lys<sup>3</sup>]-GHRP-6 on growth performance and blood biochemical indices in broiler chickens

“…Khazali and Mahmoudi (2009) found that the injection of another GHS-R antagonist (analog of substance P) in rats increased mean plasma TSH, T 3 and T 4 concentrations based on dosage but was different in the control group (normal level), which is in agreement with Khazali and Mahmoudi (2009), who argued that T 3 and T 4 decreased after the central infusion of ghrelin. Aghdam Shahryar and Lotfi (2014) reported that the peripheral administration of [D-Lys 3 ]-GHRP-6 did not result in any considerable increases in T 3 or T 4 in rats. In other words, GHS-R antagonist seems to have more pronounced impact on thyroid hormones in chickens.…”

“…If ghrelin is assumed to be an endocrine peptide which has numerous endocrine effects, blocking its receptors may change endocrine and metabolic body profile. As a case in point, Aghdam Shahryar and Lotfi (2014) conducted a simple study on peripheral infusion of ghrelin antagonist [D-Lys 3 ]-GHRP-6 in rats. They found that infusion of exogenous GHS-R antagonist may increase serum glucose and cortisol concentration; however, this effect was not completely different from the ghrelin effect.…”