Queensland researchers have identified two distinct types of cells that give rise to new neurons in a region of the brain known as the hippocampus, which may have implications for the treatment of learning- and mood-related disorders.
Dr Dhanisha Jhaveri from the Queensland Brain Institute (QBI) and the lead author of the study, explained that for the first time researchers have been able to identify and isolate these cells to purity.
‘Neurons are created from stem cells and precursor cells, the activity of which is influenced by stimuli as diverse as physical exercise, antidepressants, stress and ageing,’ Dr Jhaveri said.
‘In adults, we have previously shown that the hippocampus contains a large population of dormant precursor cells. Because of a lack of unique and specific markers, different subtypes of these stem and precursor cells had never been identified,’ she said.
Purification of these cells revealed that the hippocampus harbours two dormant precursor subtypes that are activated by different mechanisms and generate new cells that differ in their gene expression. The discovery was made using state-of-the-art cell-sorting and DNA technologies available at QBI.
‘Our findings suggest that the two precursor cell types may give rise to new neurons that have different functions in the brain,’ Dr Jhaveri said.
The two cell groups are located in different regions of the hippocampus. Recent research suggests that distinct areas within the hippocampus control spatial learning versus mood.
‘In mice spatial learning, for example, is regulated by neurons in the anterior hippocampus whereas anxiety and mood are regulated by cells in a more posterior part of this structure,’ she said.
Professor Perry Bartlett, Director of QBI, said the discovery solves a longstanding mystery about neurogenesis, or the birth of new nerve cells, in the hippocampus.
‘Previously, the neurons in the hippocampus were all thought to be identical, so it wasn’t understood how the region is able to regulate divergent behaviours,’ he said.
‘The existence of distinct precursor cell populations suggests that they may give rise to different types of neurons, which explains the varied functions of the hippocampus in regulating learning and memory as well as mood.’
The study, ‘Purification of neural precursor cells reveals the presence of distinct, stimulus-specific subpopulations of quiescent precursors in the adult mouse hippocampus’, published in The Journal of Neuroscience, was funded by the National Health and Medical Council, the Australian Research Council Special Research Initiative in Stem Cells, and the Estate of Dr Clem Jones AO.
Dr Jhaveri is a member of Stem Cells Australia's Neural Regeneration and Repair theme.