Table 2.

Ghrelin and pituitary GH secretion.

Level	Effect
Anterior Pituitary	Direct effect on GH secretion by inhibiting SS action
Arcuate nucleus Periventricular nucleus	Increases GHRH releaseAntagonizes the inhibitory effects of SS on GHRH release
Anterior Pituitary	Inhibits the inhibitory effect of IGF-I on GH secretion
Anterior Pituitary	Acts synergistically with GHRH in inducing GH secretion
Anterior Pituitary	Auto/paracrine induction of GH secretion dependent on GHRH supply.
Anterior Pituitary	> Transcription Na+ channels> NOS/NO+ PLC > > Ca2+

Effects of ghrelin on GH secretion and levels at which it acts. >, Increases. +, Stimulates.