Table 2.

Summary of histological observations

Protein/mRNA	Function	Human/monkey	Zonation/subdivision	References
mGlur1a	G-protein-coupled receptors for glutamate	M	None reported	Kuwajima et al. (2004)
mGlur5	G-protein-coupled receptors for glutamate	M	None reported	Kuwajima et al. (2004)
GAD	Glutamate decarboxylase, catalyzes the conversion of glutamate to GABA	H	None reported	Levesque and Parent (2005)
GAT1	GABA transporter 1	H	None reported	Augood et al. (1999)
GABA-A receptor	Ligated ion channels	M	None reported	Kultas-Ilinsky et al. (1998)
GABA-B receptor	G-protein-coupled receptors	M	None reported	Charara et al. (2000)
TH	Tyrosine hydroxylase, rate-limiting enzyme in catecholamine production	H	None reported	Hedreen (1999)
DR2	Dopamine Receptor	H	None reported, expression in STN is controversial	Hurd et al. (2001); Augood et al. (2000)
SERT	High affinity serotonin reuptake transporter	H	More staining in anterior STN as compared to posterior	Parent et al. (2011)
5HT	Serotonin	M	Highest density in medial and ventral part of the STN	Mori et al. (1985)
ppEnkB	prepro-Enkephalin B encodes Endogenous opioid	M	None reported	Aubert et al. (2007)
Parvalbumin	Calcium-binding protein	H	Clear zonation, higher dorsolateral expression	Parent et al. (1996); Augood et al. (1999)
Calretinin	Calcium-binding protein	H	Clear zonation, higher ventromedial expression	Parent et al. (1996); Augood et al. (1999)