Role of Leptin on Growth Hormone and Prolactin Secretion by Bovine Pituitary Explants

Concentrations of bovine growth hormone (expressed as ng/mg of tissue, mean±SEM) in the medium of pituitary explants treated with 50, 250, or 500 ng/mL of leptin (L50, L250, and L500) after 1, 2, 3, 4, and 5h of incubation. The asterisks indicate significant differences (P<0.05) between treated explants and explants cultured with medium 199 without leptin (control, C) at the same incubation time.

Concentrations of bovine prolactin (expressed as ng/mg of tissue, mean±SEM) in the medium of pituitary explants treated with 50, 250, or 500 ng/mL of leptin (L50, L250, and L500) after 1, 2, 3, 4, and 5h of incubation. The asterisks indicate significant differences (P<0.05) between treated explants and explants cultured with medium 199 without leptin (control, C) at the same incubation time.

A) Representative agarose gel electrophoresis of reverse transcription-PCR analysis of bovine growth hormone (top) and β actin mRNA (bottom) from bovine pituitary explants cultured with different hormonal treatments after 5h of incubation. Lanes: M = standard weight marker; −RT = without cDNA; 1, 2, 3, 4 = explants cultured with medium 199 without hormones (controls); 5, 6, 7, 8 = explants treated with 250 ng/mL of recombinant human leptin. B) Optical density (means±SEM, 15 replicates) of electrophoretic bands expressed in arbitrary units and normalized using the signals generated with β-actin. C = control explants cultured with medium 199 without hormones; L250 = explants treated with 250 ng/mL of recombinant human leptin. ^a,bDifferent letters indicate a significant difference (P<0.01).

A) Representative agarose gel electrophoresis of the reverse transcription-PCR analysis of bovine prolactin (top) and β-actin mRNA (bottom) from bovine pituitary explants cultured with different hormonal treatments after 5h of incubation. Lanes: M = standard weight marker; −RT = without cDNA; 1, 2, 3, 4 = explants cultured with medium 199 without hormones (controls); 5, 6, 7, 8 = explants treated with 250 ng/mL of recombinant human leptin. B) Optical density (means±SEM, 15 replicates) of electrophoretic bands expressed in arbitrary units and normalized using the signals generated with β-actin. C = control explants cultured with medium 199 without hormones; L250 = explants treated with 250 ng/mL of recombinant human leptin.

A) Representative agarose gel electrophoresis of Western blot analysis of bovine growth hormone (bottom) and β-tubulin (top) in bovine pituitary explants cultured with different hormonal treatments. Lanes: M = standard weight marker; 1, 2, 3, 4 = explants cultured with medium 199 without hormones (controls); 5, 6, 7, 8 = explants treated with 250 ng/mL of recombinant human leptin. B) Optical density (means±SEM, 15 replicates) of electrophoretic bands expressed in arbitrary units and normalized using the signals generated with β-tubulin. C = control explants cultured with medium 199 without hormones; L250 = explants treated with 250 ng/mL of recombinant human leptin. ^a,bDifferent letters indicate a significant difference (P<0.01).

A) Representative agarose gel electrophoresis of Western blot analysis of bovine prolactin (bottom) and β-tubulin (top) in bovine pituitary explants cultured with different hormonal treatments after 5h of incubation. Lanes: M = standard weight marker; 1, 2, 3, 4 = explants cultured with medium 199 without hormones (controls); 5, 6, 7, 8 = explants treated with 250 ng/mL of recombinant human leptin. B) Optical density (means±SEM, 15 replicates) of electrophoretic bands expressed in arbitrary units and normalized using the signals generated with β-tubulin. C = control explants cultured with medium 199 without hormones; L250 = explants treated with 250 ng/mL of recombinant human leptin.