Jerlhag et al. (2009b) postulated that the sites of action through which ghrelin acts on alcohol consumption were the VTA and the laterodorsal tegmental area. However, we did not observe any changes in c-Fos immunoreactivity in the VTA after D-Lys3-GHRP-6 either in the DID or systemic studies. Jerlhag et al. (2009b) saw reduced alcohol drinking after injecting their antagonist, BIM28163 intracerebroventricularly. This route of administration does not allow for an exact locus of action, and thus it cannot be conclusively determined that the antagonist was acting in the tegmental areas to affect alcohol consumption. On the other hand, they observed that administering ghrelin, either intracerebroventricularly or into the VTA increased alcohol intake. Since the pIIIu and VTA are located in close proximity, the pIIIu has substantially higher levels of GHSR 1a mRNA expression than VTA, and they injected ghrelin in a relatively large volume (1 µl) it is possible that the injected ghrelin diffused from VTA and affected alcohol intake via the pIIIu.
