Table 1.

Supporting and refuting evidence regarding the central synthesis of ghrelin.

	Technique(s)	Findings Summary	Species	Reference(s)
Supporting Evidence	RT PCR	Ghrelin transcript detected in the brain	Rat	[20]
	RT PCR	Ghrelin transcript detected in the arcuate nucleus (ARC)	Rat	[24]
	RT PCR	Ghrelin transcript detected in the hypothalamus (HYP) of wild-type (WT) but not ghrelin knockouts (KOs)	Mouse	[22]
	RT PCR	Ghrelin mRNA detected in HYP	Rat	[215]
	RT PCR	Ghrelin mRNA detected in cerebral cortex and HYP	Rat	[214]
	RT PCR	Hypothalamic expression of ghrelin significantly lower in clock mutants	Mouse	[217]
	RT PCR	Hypothalamic expression of ghrelin and ghrelin O-acyltransferase (GOAT) mRNA increases following a 48 h fast	Rat	[56]
	RT PCR and transgenics	Detected ghrelin and enhanced green fluorescent protein (EGFP) transcripts in the HYP of transgenic mice that were engineered to express EGFP in cells that produce ghrelin (i.e., inserted the gene for EGFP in the regulatory region of the ghrelin gene)	Mouse	[225]
	Immunohistochemistry	Ghrelin-immunoreactive neurons detected in the ARC	Rat	[20,24,220,221,223]
	Immunohistochemistry	Numerous ghrelin immunoreactive cell bodies and axons found within the HYP;small number of ghrelin immunoreactive processes found within extrahypothalamic brain regions (e.g., BNST, NA, cortex)	Mouse	[22]
	Immunohistochemistry	Detected ghrelin immunoreactivity in the HYP	Human	[224]
	Immunohistochemistry	Ghrelin immunoreactive neurons were detected in the HYP and cerebral cortex	Rat	[214]
	Immunohistochemistry	HYP ghrelin was detected in sham operated rats but not in those that underwent a pinealectomy	Rat	[220]
	Immunohistochemistry and transgenics	EGFP fluorescence detected in ARC of transgenic ghrelin reporter mice (inserted the gene for EGFP in the regulatory region of the ghrelin gene)	Mouse	[225]
	Reverse phase high performance liquid chromatography and ghrelin radioimmuneassays	Detected ghrelin radioimmunoreactivity in the ARC	Rat	[24]
	Reverse phase high performance liquid chromatogra-phy and ghrelin radioimmuneassays	Detected ghrelin radioimmunoreactivity in the HYP	Rat	[215]
	Behavioural tests	Chronic central GOAT knockdown (via ICV infused amorpholino antisense oligonucleotides) significantly decreased weight gain of rats fed a high fat diet	Rat	[56]
Refuting Evidence	RT PCR and transgenics	Failed to detect ghrelin immunoreactivity or ghrelin mRNA (via in situ hybridization) within the brain of WT or ghrelin-hrGFP BAC transgenic reporter mice	Mouse	[25]
	Immunohisto-chemistry	Strong ghrelin immunoreactive signals from the stomach but no specific immunoreactivity for either ghrelin or des-acyl ghrelin in the central nervous system (e.g., HYP, medulla oblongata, and spinal cord) using four separate well characterized anti-ghrelin antibodies	Mouse and Rat	[23]
	Immunohisto-chemistry and transgenics	Evident β-galactosidase staining within the stomach and intestine but no positive staining within the HYP of transgenic ghrelin deficient mice (ghrl−/−) engineered to express a lacZ reporter gene in the place of the functional ghrelin gene WT and ghrelin deficient mice show negligible and indistinguishable hypothalamic ghrelin immunoreactivity despite having very different stomach ghrelin immunoreactivity profiles	Mouse	[218]
	Immunohisto-chemistry and transgenics	Failed to detect GFP fluorescence in the brain but demonstrated clear GFP expression in the stomach using two separate transgenic ghrelin reporter mice (i.e., ghrelin-hrGFP BAC transgenic mice), in which humanized Renilla reniformis GFP expression was driven by different lengths of the ghrelin promotor	Mouse	[25]