Oxytocinergic innervation of the brain of the garden dormouse (Eliomys quercinus L.).

The oxytocinergic innervation of the brain of the garden dormouse (Eliomys quercinus L.) was studied by means of immunocytochemistry. In contrast to the sparse oxytocin innervation of the rat forebrain, dense fibre networks in various cortical and limbic brain areas were demonstrated in this animal. These include, e.g., the prefrontal cortex, the claustrum, the septum, and the hippocampus. A very dense innervation was also seen in the caudal regions of the garden dormouse brain; these regions are already known to have a relatively dense oxytocin fibre network in the rat. A dense innervation of oxytocin fibres is seen in several brain regions which, in the rat, have oxytocin binding sites but no visible oxytocin innervation. This discrepancy suggests that the differences in the oxytocinergic innervation of these two rodent brains may be due to an oxytocin system in the rat brain that is more difficult to detect immunocytochemically.