Bilateral lesions of the pedunculopontine tegmental nucleus affect feeding induced by electrical stimulation of the ventral tegmental area.

The pedunculopontine tegmental nucleus (PPN) is anatomically connected with dopaminergic cells in the ventral mesencephalon, which are known to participate in the regulation of various adaptive appetitive behaviours. In the present experiment we studied a possible involvement of PPN in feeding elicited by stimulation of the ventral tegmental area (VTA). It was found that bilateral electrolytic lesioning of the PPN affected VTA-elicited feeding. However, the effects were diverse and showed dependence on the localization of the lesion within the PPN area. Lesions localized anteriorly in the PPN impaired VTA feeding whereas those involving the middle portion of the nucleus facilitated electrically elicited food ingestion. A precise alignment of the lesion and the area activated at the site of stimulation appeared crucial for the effect of the lesion. The results indicate that PPN belongs to the central feeding circuitry and it contains both activating and inhibiting elements directed to the ventral tegmental area.