Neurogenesis and schizophrenia: dividing neurons in a divided mind?

Forty years after the initial discovery of neurogenesis in the postnatal brain of the rat, convincing evidence has been accrued that functional neurons are generated throughout the entire lifespan, particularly in the dentate gyrus (DG) and the subventricular zone (SVZ). This phenomenon has been termed adult neurogenesis (AN) and while it was detected in all examined mammalian species including humans, the physiological role of this process remains unknown. Although a plethora of animal studies indicate an involvement of AN in the pathophysiology of depression, this view has recently kindled considerable controversy.

Neuronal nitric oxide synthase (NOS-I) knockout increases the survival rate of neural cells in the hippocampus independently of BDNF.

Investigations regarding the regulation of adult neurogenesis, i.e., the generation of new neurons from progenitor cells, have revealed a high degree of complexity.

Influence of different promoters on the expression pattern of mutated human alpha-synuclein in transgenic mice.

Two missense mutations (A53T and A30P) in the gene encoding the presynaptic protein alpha-synuclein (asyn) are associated with rare, dominantly inherited forms of Parkinson's disease (PD) and its accumulation in Lewy bodies and Lewy neurites. As an initial step in investigating the role of asyn in the pathogenesis of PD, we have generated C57BL/6 transgenic mice overexpressing the doubly mutated human asyn under the control of three different promoters; the chicken beta-actin (chbetaactin), the mouse tyrosine hydroxylase 9.6 kb (msTH) and the mouse prion protein (msprp).

Morphological abnormalities in nitric-oxide-synthase-positive striatal interneurons of schizophrenic patients.

Schizophrenia has been suggested to be a neurodevelopmental disorder, and nitric-oxide-synthase (NOS)-positive neurons were shown to be involved in distorted cortical development in schizophrenia. Here we investigated whether nitrinergic neurons in the striatum of schizophrenic patients also display abnormalities regarding distribution or morphology. To do so, postmortem putaminal sections of schizophrenic subjects were examined by means of nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) staining and NOS immunohistochemistry.

A NOS-III haplotype that includes functional polymorphisms is associated with bipolar disorder.

The pleiotropic messenger molecule nitric oxide (NO) has been implicated in a variety of higher CNS functions, including learning, memory, and emotionality. In the human brain, NO is predominantly formed by neuronal NO synthase (NOS-I), while the so-called 'endothelial' isoform NOS-III also contributes to NO generation. We recently reported that NOS-III knockout mice display decreased adult neurogenesis and reduced responsiveness in a learned helplessness paradigm.

Differential effect of endothelial nitric oxide synthase (NOS-III) on the regulation of adult neurogenesis and behaviour.

Although it has been postulated that adult neurogenesis, i.e. the generation of functional neurons from progenitor cells in the mammalian brain, is involved in both the pathogenesis of depressive disorders and the therapeutic effect of antidepressant drugs, its regulation is still poorly understood.