, 2008). Retrogradely labeled MePD cells were mainly located in deeper layers and varied markedly

in number in the different cases. In BSTp 762 and MPN 783 cases, a particularly heavy retrograde labeling was observed in the MePD, especially in its dorsal extent (Figs. 11C1, D1, C2, D2). In contrast, in LA 181 and BMP 737 cases, the MePD contained RG7204 concentration a much smaller number of faintly labeled cells (Figs. 9C1, D1, C2, D2). The present investigation provides the first detailed description of MeAV projections using anterograde and retrograde tract tracing techniques in the rat. The results suggest that the MeAV displays a relatively simple pattern of projections, innervating prominently a few targets it shares with the MeAD and/or the MePV, namely the ventromedial hypothalamic nucleus, especially the dorsomedial and central parts, the amygdalostriatal transition area, the lateral and posterior basomedial amygdaloid nuclei and the intraamygdaloid part of the BST. Overall, they reinforce the view that the MeAD, MeAV and MePV are interrelated and differ markedly from

the MePD, as proposed by Canteras et al. (1995). Importantly, in contrast to the MeAD and MePV, the MeAV sends only light Talazoparib molecular weight inputs to the medial extended amygdala, main olfactory system and components of the reproductive hypothalamic network. A similar pattern of projections was observed in hamsters after Me injections restricted to the MeAD or involving the MeAD and MeAV (Coolen and Wood, 1998 and Gomez and Newman, 1992) however, in rats, these injections were

found to originate distinctive outputs to the ventromedial hypothalamic nucleus, ending in the shell and core (the dorsomedial and central divisions) regions, respectively (Canteras et al., 1995; present findings). The existence of a massive MeAV projection to the ventromedial hypothalamic nucleus is also supported by retrograde tracing evidence in rats (Berk and Finkelstein, 1981; present data) and mice (Choi et al., 2005). In particular, Choi et al. (2005), using exquisitely localized injections, showed in mice that MeAV neurons projecting Orotidine 5′-phosphate decarboxylase to the ventromedial hypothalamic nucleus express the Lhx5 gene of the LIM homeodomain and target the dorsomedial rather than the ventrolateral part. Moreover, in accord with the present results, Gomez and Newman (1992) noted in a case with a PHA-L injection primarily confined to the hamster MeAV that the projections of the MeAV, although similar to, are not as extensive as those of the MeAD, particularly in view of the absence of fiber labeling in the thalamus and nucleus of the horizontal limb of the diagonal band.