Abstract
The effects of gamma oryzanol (γ-OZ) a ferulic acid of triterpene alcohol, on the synthesis and release of the growth hormone (GH) and prolactin (PRL) in vitro and turnover rates of hypothalamic catecholamines were investigated. A single subcutaneous injection of 20mg/kg of γ-OZ suppressed GH synthesis and PRL release 1 hour after the injection. γ-OZ increased medial basal hypothalamic (MBH) dopamine (DA) content, and the DA content was decreased by a treatment of α-methyl-p-tyrosine (αMpT), a tyrosine hydroxylase inhibitor, indicating increased synthesis and release of DA in MBH by γ-OZ. γ-OZ did not alter norepinephrine (NE) content in MBH, while the NE content was significantly de-creased, indicating unchanged synthesis and increased release of NE in MBH by γ-OZ. These results may explain the previous data concerning the changes in serum levels of GH and PRL by γ-OZ and also suggest that γ-OZ can affect the synthesis and/or release of at least two hypothalamic neurotransmitters, DA and NE, resulting in the alterations of anterior pituitary hormone synthesis and/or release.
