Table 1.

Summary of the relation between the relative expression of isoforms

Manipulation	Relative Homer expression in mPFC	Basal glutamate content		Cocaine-stimulated release		Cocaine reward	Cocaine locomotion
Manipulation	Relative Homer expression in mPFC	mPFC	NAC	mPFC	NAC	Cocaine reward	Cocaine locomotion
Repeated i.p. cocaine	Homer2 > Homer1^{^a}	—^{^b}	↓^{^c}	↑^{^b}	↑^{^c}	↑^{^d}	↑^{^e}
Repeated i.v. cocaine	Homer2 > Homer1^{^f,^g}	↓^{^h}	↓^{^c}	↑^{^g}	↑^{^c}	↑^{^c}	Mixed^ⁱ
Homer1 KO	Homer2 > Homer1	↑^{^j,^k}	↓^{^l}	↓^{^j,^k}	↑^{^l}	↑^{^l}	↑^{^j,^k,^l}
mPFC cDNA-H2b	Homer2 > Homer1	↑	↓	↓	↑	↑	—
mPFC shRNA-H1c	Homer2 > Homer1	n.d.	↓	n.d.	↑	↑	—
Homer2 KO	Homer2 < Homer1	—^{^l}	↓^{^l,^m}	—^{^l}	↑^{^l}	↑^{^l}	↑^{^l}
mPFC shRNA-H2b	Homer2 < Homer1	↓	—	↑	—	—	—
mPFC cDNA-H1c	Homer2 < Homer1	↓^{^k}	n.d.	↑^{^k}	n.d.	n.d.	—^{^k}

Data are reported as the relative expression of mPFC Homer1 versus Homer2 isoforms produced by either repeated cocaine experience (intraperitoneal or intravenous administration) or transgenic manipulations of Homer protein expression within drug-naive animals; and (1) the levels of basal extracellular glutamate within the mPFC and the NAC; (2) the change in extracellular glutamate levels within the mPFC and NAC produced by a cocaine challenge injection; (3) indices of cocaine reward or reinforcement (i.e., conditioned place-preference or intravenous cocaine self-administration); and (4) cocaine-stimulated locomotor behavior or locomotor sensitization. ↑ and ↓, Increase and decrease, respectively, relative to animals treated acutely with drug (for repeated intraperitoneal or intravenous cocaine administration), WT controls (for Homer1 and Homer2 KO mice), or animals infused with a control AAV (for cDNA and shRNA-infused animals); —, no change from aforementioned controls; cDNA-H2b, AAV carrying Homer2b cDNA; n.d., not determined.
↵^aAry and Szumlinski (2007).
↵^bWilliams and Steketee (2004).
↵^cBaker et al. (2003).
↵^dLett et al. (1989).
↵^eVanderschuren and Kalivas (2000).
↵^fGould et al. (submitted).
↵^gBen-Shahar et al. (2012).
↵^hBen-Shahar et al. (2013).
↵ⁱBen-Shahar et al. (2004).
↵^jSzumlinski et al. (2005a).
↵^kLominac et al. (2005).
↵^lSzumlinski et al. (2004).
↵^mSzumlinski et al. (2005b).