Wild red foxes, proverbially cunning carnivores, are investigated for adult hippocampal neurogenesis and morphological characteristics of the dentate gyrus. Adult red foxes harbor almost 15-times more young, doublecortin-positive neurons in their dentate gyrus than domesticated dogs. The number of doublecortin-positive cells corresponds to 4.4% of the total granule cell number, whereas dividing...

Granule cells in the olfactory bulb (OB) are continually produced and added into the neuronal circuit in the adult brain. Sensory input to the OB plays a key role in the survival of newly generated granule cells. Here, we examined in the adult mice whether there is a time window after the generation of new granule cells when their survival is strongly influenced by sensory input. New granule ce...

Recent studies have shown that prolonged stimulation of afferents of the rat fascia dentata in vivo leads to the development of chronic epileptiform activity of the dentate granule cell region, and degeneration of certain cell types in the adjacent hilus. To investigate the development of dentate hyperexcitability and the selective vulnerability of hilar cells, the hippocampal slice preparation...

During development of the cerebellum, sonic hedgehog (Shh) is directly responsible for the proliferation of granule cell precursors in the external germinal layer. We have looked for signals able to regulate a switch from the Shh-mediated proliferative response to one that directs differentiation of granule neurones. Bone morphogenetic proteins (BMPs) are expressed in distinct neuronal populati...

Cbln1, which belongs to the C1q/tumor necrosis factor superfamily, is released from cerebellar granule cells and plays a crucial role in forming and maintaining excitatory synapses between parallel fibers (PFs; axons of granule cells) and Purkinje cells not only during development but also in the adult cerebellum. Although neuronal activity is known to cause morphological changes at synapses, h...

Neuregulin (NRG), a growth and differentiation factor that signals via erbB receptor tyrosine kinases, has been shown to have biological effects in both the CNS and the peripheral nervous system. We report here that erbB4 is expressed in mature cerebellar granule cells, where it appears to be concentrated at the granule cell postsynaptic terminals. We also show that one form of NRG, Ig-NRG, pla...

Nitric oxide (NO) is a multifaceted messenger molecule believed to be involved in neural plasticity and development. Within the cerebellum, the NO synthesizing enzyme, NO synthase (NOS), is expressed exclusively by granule cells and stellate/basket neurons. In the adult cerebellum, levels of NOS expression can be used to define discrete clusters of granule cell populations. Differential express...

A substantial fraction of adult-generated granule cells in the dentate gyrus survive and integrate into the existing neuronal network. These newborn neurons must navigate the environment of the adult brain, a setting that is presumably less optimized for neuronal maturation compared with that in the developing brain. We used EGFP (enhanced green fluorescent protein) expression in newborn granul...

Following status epilepticus in the rat, dentate granule cell neurogenesis increases greatly, and many of the new neurons appear to develop ectopically, in the hilar region of the hippocampal formation. It has been suggested that the ectopic hilar granule cells could contribute to the spontaneous seizures that ultimately develop after status epilepticus. However, the population has never been q...

Temporal lobe epilepsy is usually associated with a latent period and an increased seizure frequency following a precipitating insult. After kainate treatment, the mossy fibers of the dentate gyrus are hypothesized to form recurrent excitatory circuits between granule cells, thus leading to a progressive increase in the excitatory input to granule cells. Three groups of animals were studied as ...