Regulation of growth hormone secretion by amino acid neurotransmitters in the goldfish (I): Inhibition by N-methyl-D, L-aspartic acid.
High levels of the amino acid neurotransmitter glutamate were found in the goldfish hypothalamus and pituitary using high performance liquid chromatography with fluorometric detection. A specific polyclonal antibody to glutamate was generated in the rabbit for immunocytochemistry. Localization studies demonstrated that glutamatergic neurons of undetermined origin innervate the particular part of the goldfish adenohypophysis where somatotrophs and gonadotrophs are located. Intraperitoneal and brain third ventricle injection of the glutamate agonist N-methyl-D,L-aspartic acid (NMA) inhibited GH release in vivo. The gonadal steroid estradiol plays an important role in regulating GH secretion by stimulating basal serum GH levels and enhancing the inhibitory effects of NMA on GH secretion. Taken together, these results demonstrate that glutamate is an important regulator of GH secretion in goldfish.
Trudeau
V L
VL
Department of Zoology, University of Aberdeen, Scotland.
Sloley
B D
BD
Kah
O
O
Mons
N
N
Dulka
J G
JG
Peter
R E
RE
D000818:Animals; D004958:Estradiol / Q000494:pharmacology; D018698:Glutamic Acid / Q000032:analysis / Q000494:pharmacology*; D006054:Goldfish / Q000502:physiology*; D013006:Growth Hormone / Q000378:metabolism*; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D016202:N-Methylaspartate / Q000008:administration & dosage / Q000494:pharmacology*; D010902:Pituitary Gland / Q000737:chemistry
D018698:Glutamic Acid; D004958:Estradiol; D016202:N-Methylaspartate; D013006:Growth Hormone