Table 4.

Summary of negative regulators of pituitary GH.

Molecules	Groups	Roles	References
Catecholamines [norepinephrine (NE), epinephrine and dopamine]	Fish	NE and epinephrine ↓ basal GH release from pituitary cells of goldfish	(106)
	Birds	NE ↓ GHRH–effects in chicken pituitary	(110)
	Mammals	NE ↓ basal and GHRH–stimulated GH release in cultured ovine pituitary cells	(154)
		Dopamine ↓ GH mRNA and secretion in sheep, cattle and human neonates, but opposite role also observed	(143, 155, 156), Table 1
Serotonin	Fish	↓ GH in vitro secretion in goldfish	(157)
	Birds	↓ GH secretion –hypothalamus–dependent– in chicken	(158)
	Mammals	Opposite role observed	Table 1
CCK	Mammals	↓ GH in sheep, but opposite role observed in rat	(159), Table 2
	Fish	Opposite role observed in goldfish	Table 2
Oxytocin	Mammals	↓ GH secretion in rat	(160)
Activin	Fish	↓ GH expression in cultured pituitaries of zebrafish	(96)
		Opposite role observed in goldfish	Table 2
	Mammals	↓ GH mRNA in rat, but opposite role also observed	(161), Table 2
Leptin	Fish	↓ GH mRNA in tilapia	(162)
	Mammals	Opposite role observed	Table 3
Kisspeptin	Mammals	Endogenous kisspeptin can ↓ GH secretion through GPR54 in sheep, but opposite role also observed	(163)
	Fish	Opposite role observed in goldfish	Table 2
Irisin	Fish	↓ GH mRNA and secretion in tilapia in vitro	(164)
Intermedin/Adrenomedullin–2	Mammals	↓ GHRH–stimulated GH release in rat dispersed pituitary cells	(165)
Acetylcholine	Birds	↓ GH secretion –hypothalamus–dependent– in chicken	(168)
	Mammals	Opposite effect observed	Table 1
Nesfatin–1 and NLP	Mammals	↓ GH mRNA and protein in rat pituitary cells	(166)