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Growth hormone response to growth hormone-releasing peptide-2 in growth hormone-deficient little mice.

Peroni CN, Hayashida CY, Nascimento N, Longuini VC, Toledo RA, Bartolini P, Bowers CY, Toledo SP - Clinics (Sao Paulo) (2012)

Bottom Line: To investigate a possible direct, growth hormone-releasing, hormone-independent action of a growth hormone secretagogue, GHRP-2, in pituitary somatotroph cells in the presence of inactive growth hormone-releasing hormone receptors.Here, we have demonstrated that lit/lit mice, which harbor a germline mutation in the Growth hormone-releasing hormone gene, maintain a limited but statistically significant growth hormone elevation after exogenous stimulation with GHRP-2.The present data probably reflect a direct, growth hormone-independent effect on Growth hormone S (ghrelin) stimulation in the remaining pituitary somatotrophs of little mice that is mediated by growth hormone S-R 1a.

View Article: PubMed Central - PubMed

Affiliation: Biotechnology Department, National Nuclear Energy Commission, Cidade Universitária, São Paulo, SP, Brazil.

ABSTRACT

Objective: To investigate a possible direct, growth hormone-releasing, hormone-independent action of a growth hormone secretagogue, GHRP-2, in pituitary somatotroph cells in the presence of inactive growth hormone-releasing hormone receptors.

Materials and methods: The responses of serum growth hormone to acutely injected growth hormone-releasing P-2 in lit/lit mice, which represent a model of GH deficiency arising from mutated growth hormone-releasing hormone-receptors, were compared to those observed in the heterozygous (lit/+) littermates and wild-type (+/+) C57BL/6J mice.

Results: After the administration of 10 mcg of growth hormone-releasing P-2 to lit/lit mice, a growth hormone release of 9.3±1.5 ng/ml was observed compared with 1.04±1.15 ng/ml in controls (p<0.001). In comparison, an intermediate growth hormone release of 34.5±9.7 ng/ml and a higher growth hormone release of 163±46 ng/ml were induced in the lit/+ mice and wild-type mice, respectively. Thus, GHRP-2 stimulated growth hormone in the lit/lit mice, and the release of growth hormone in vivo may be only partially dependent on growth hormone-releasing hormone. Additionally, the plasma leptin and ghrelin levels were evaluated in the lit/lit mice under basal and stimulated conditions.

Conclusions: Here, we have demonstrated that lit/lit mice, which harbor a germline mutation in the Growth hormone-releasing hormone gene, maintain a limited but statistically significant growth hormone elevation after exogenous stimulation with GHRP-2. The present data probably reflect a direct, growth hormone-independent effect on Growth hormone S (ghrelin) stimulation in the remaining pituitary somatotrophs of little mice that is mediated by growth hormone S-R 1a.

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Related in: MedlinePlus

The germline ghrh-r Asp60Gly mutation analysis was performed by PCR amplification and direct automated sequencing. The chromatogram traces show the GAT/GAT (wild-type), GAT/GGT (heterozygous mouse) and GGT/GGT (little mouse) statuses, thus characterizing the genotype of the three mice strains used in this study. The forward and reverse traces are shown in the top and bottom panels, respectively.
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f1-cln_67p265: The germline ghrh-r Asp60Gly mutation analysis was performed by PCR amplification and direct automated sequencing. The chromatogram traces show the GAT/GAT (wild-type), GAT/GGT (heterozygous mouse) and GGT/GGT (little mouse) statuses, thus characterizing the genotype of the three mice strains used in this study. The forward and reverse traces are shown in the top and bottom panels, respectively.

Mentions: A germline homozygous ghrhr Asp60Gly mutation was confirmed in the lit/lit mouse, whereas a heterozygous ghrhr Asp60Gly mutation was verified in the lit/+ littermates. Conversely, wild-type (+/+) C57BL/6J mice did not harbor this germline mutation (Figure 1). These data confirmed the genotypes of the three mice lineages used in the present study, respectively: +/+, Asp60Asp; lit/+, Asp60Gly and lit/lit, Gly60Gly (Figure 1).


Growth hormone response to growth hormone-releasing peptide-2 in growth hormone-deficient little mice.

Peroni CN, Hayashida CY, Nascimento N, Longuini VC, Toledo RA, Bartolini P, Bowers CY, Toledo SP - Clinics (Sao Paulo) (2012)

The germline ghrh-r Asp60Gly mutation analysis was performed by PCR amplification and direct automated sequencing. The chromatogram traces show the GAT/GAT (wild-type), GAT/GGT (heterozygous mouse) and GGT/GGT (little mouse) statuses, thus characterizing the genotype of the three mice strains used in this study. The forward and reverse traces are shown in the top and bottom panels, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3297037&req=5

f1-cln_67p265: The germline ghrh-r Asp60Gly mutation analysis was performed by PCR amplification and direct automated sequencing. The chromatogram traces show the GAT/GAT (wild-type), GAT/GGT (heterozygous mouse) and GGT/GGT (little mouse) statuses, thus characterizing the genotype of the three mice strains used in this study. The forward and reverse traces are shown in the top and bottom panels, respectively.
Mentions: A germline homozygous ghrhr Asp60Gly mutation was confirmed in the lit/lit mouse, whereas a heterozygous ghrhr Asp60Gly mutation was verified in the lit/+ littermates. Conversely, wild-type (+/+) C57BL/6J mice did not harbor this germline mutation (Figure 1). These data confirmed the genotypes of the three mice lineages used in the present study, respectively: +/+, Asp60Asp; lit/+, Asp60Gly and lit/lit, Gly60Gly (Figure 1).

Bottom Line: To investigate a possible direct, growth hormone-releasing, hormone-independent action of a growth hormone secretagogue, GHRP-2, in pituitary somatotroph cells in the presence of inactive growth hormone-releasing hormone receptors.Here, we have demonstrated that lit/lit mice, which harbor a germline mutation in the Growth hormone-releasing hormone gene, maintain a limited but statistically significant growth hormone elevation after exogenous stimulation with GHRP-2.The present data probably reflect a direct, growth hormone-independent effect on Growth hormone S (ghrelin) stimulation in the remaining pituitary somatotrophs of little mice that is mediated by growth hormone S-R 1a.

View Article: PubMed Central - PubMed

Affiliation: Biotechnology Department, National Nuclear Energy Commission, Cidade Universitária, São Paulo, SP, Brazil.

ABSTRACT

Objective: To investigate a possible direct, growth hormone-releasing, hormone-independent action of a growth hormone secretagogue, GHRP-2, in pituitary somatotroph cells in the presence of inactive growth hormone-releasing hormone receptors.

Materials and methods: The responses of serum growth hormone to acutely injected growth hormone-releasing P-2 in lit/lit mice, which represent a model of GH deficiency arising from mutated growth hormone-releasing hormone-receptors, were compared to those observed in the heterozygous (lit/+) littermates and wild-type (+/+) C57BL/6J mice.

Results: After the administration of 10 mcg of growth hormone-releasing P-2 to lit/lit mice, a growth hormone release of 9.3±1.5 ng/ml was observed compared with 1.04±1.15 ng/ml in controls (p<0.001). In comparison, an intermediate growth hormone release of 34.5±9.7 ng/ml and a higher growth hormone release of 163±46 ng/ml were induced in the lit/+ mice and wild-type mice, respectively. Thus, GHRP-2 stimulated growth hormone in the lit/lit mice, and the release of growth hormone in vivo may be only partially dependent on growth hormone-releasing hormone. Additionally, the plasma leptin and ghrelin levels were evaluated in the lit/lit mice under basal and stimulated conditions.

Conclusions: Here, we have demonstrated that lit/lit mice, which harbor a germline mutation in the Growth hormone-releasing hormone gene, maintain a limited but statistically significant growth hormone elevation after exogenous stimulation with GHRP-2. The present data probably reflect a direct, growth hormone-independent effect on Growth hormone S (ghrelin) stimulation in the remaining pituitary somatotrophs of little mice that is mediated by growth hormone S-R 1a.

Show MeSH
Related in: MedlinePlus