Reserachers at Queensland Brain Insitute in Australia have discovered the class of drugs that increase levels of a neurotransmitter known as ‘norepinephrine’ triggers neurogenesis – the growth of new neurons – in a brain region called the hippocampus. If you block hippocampus neurogenesis, antidepressants no longer work,” lead researcher Dr Dhanisha Jhaveri said. “That suggests antidepressants must up-regulate neurogenesis in order for them to actually have any affect on behavior.”
However, the neuroscientists also found not all antidepressants worked in the same way.  Dr Jhaveri said surprisingly, the class of antidepressants that increase levels of the neurotransmitter called serotonin – Prozac is a common example – fails to stimulate neurogenesis. “Norepinephrine is basically binding directly onto the precursors which then initiate a signal which leads to the production of more neurons,” she said.
Using rodent models the research, published today in the Journal of Neuroscience , established that selectively blocking the re-uptake of norepinephrine directly activated hippocampal stem cells thereby discovering a much larger pool of dormant precursors in the hippocampus than previously thought to exist.
This research may provide insights into treatment for depression and understanding of its underlying etiology.
