Semina: Ciências Agrárias (Jun 2014)

Dopamine action in prepubertal Nelore heifers growth hormone secretion

  • Emiliana Oliveira Santana Batista,
  • Daniel Cardoso ,
  • Guilherme Paula Nogueira

DOI
https://doi.org/10.5433/1679-0359.2014v35n3p1331
Journal volume & issue
Vol. 35, no. 3
pp. 1331 – 1340

Abstract

Read online

The aim of this study was to evaluate the response of dopamine in the growth hormone secretion (GH) during Nellore heifer’s sexual maturation. The animals were randomly assigned into two experimental groups: Sulpiride group (dopamine D2 antagonist, 0.59 mg/kg, S.C.) and control group (saline solution S.C.) at 8, 12 and 16 months of age. Blood samples were collected every 15 min for 10h after drug injection. Growth hormone was quantified by RIA, sensitivity (0.25 ng/mL) and intra and inter-assay variation coefficients were 15% and 17%, respectively. GH concentration was higher in sulpiride group than control group at 8 mo (10.1 ± 0.38 ng/mL vs 4.3 ± 0.34 ng/mL; P 0.05) in total GH secretion area, total peak area and maximum peak amplitude. These results suggested an inhibitory dopamine effect on GH secretion in pre-pubertal Nellore heifers that decreases according to age.

Keywords