Table 1.

Central effects of ghrelin.

Central Effects of Ghrelin
Properties	Alzheimer's disease	Addictive disorders	Stress and Anxiety	Schizophrenia	Parkinson's disease
Type of Neuropeptide	Ghrelin mRNA, Acylated ghrelin	Ghrelin mRNA	Ghrelin mRNA, Acylated ghrelin	Ghrelin mRNA	Ghrelin mRNA
Receptors	GHS-R1a, GHS-R1b	GHS-R1a	GHS-R1a	GHS-R1a, GHS-R1b	GHS-R1a
CNS Distribution	Temporal gyrus, Amygdala, Hypothalamus, Pituitary gland	Amygdala, Orbitofrontal cortex, Anterior insula, Striatum, VTA	Amygdala, Hippocampus, Subgenual anterior cingulate cortex, Paraventricular thalamic nucleus	Hippocampus, NPY cells, ARC	Intra-VTA, Substantia nigra, Nigrostriatal system
Biological Actions	Neurogenesis, neural versatility, learning, memory	Mediate the motivation and reinforcing impact of amenable food in both animals and humans	Modulation of in behavior, including such anxiety, mood, and feeding behavior	Decreased elevated level of psychological stress	Attenuate the dopamine in Nigrostriatal system
Molecular Pathways	The phosphatidylinositol-3-kinase (PI3K) extracellular sign managed kinase (ERK 1/2)	GABAergic transmission, NMDA antagonism	Improvement in HPA (stress axis) hormone	Adenylate cyclase – protein kinase A (AC – PKA) system, protein kinase C (PLC – PKC) pathway	Co-expression of GHS-R and dopamine receptor-1 (D1R) in substantia nigra, and D1R-induced cAMP aggregation
Type of Model	AD and MCI Patient	GHSR-1a-KO mice	GHSR-1a-KO mice	Schizophrenic Patient	PD Patient
References	(Bayliss and Andrews, 2013; Walker, 2014)	(Chuang et al., 2011; Cruz et al., 2013; Egecioglu et al., 2011)	(Lodge and Grace, 2011; Walker, 2014)	(Palik et al., 2005; Walker, 2014)	(Jiang et al., 2008; Lee and Koh, 2015)