Neurogenesis persists in the mammalian subventricular zone after birth, producing various populations of olfactory bulb (OB) interneurons, including GABAergic and mixed dopaminergic/GABAergic (DA) neurons for the glomerular layer. While olfactory sensory activity is a major factor controlling the integration of new neurons, its impact on specific subtypes is not well understood. In this study we used genetic labeling of defined neuron subsets, in combination with reversible unilateral sensory deprivation and longitudinal in vivo imaging, to examine the behavior of postnatally born glomerular neurons. We find that a small fraction of GABAergic and of DA neurons die after 4 weeks of sensory deprivation while surviving DA-neurons exhibit a substantial decrease in tyrosine hydroxylase (TH) expression levels. Importantly, after reopening of the naris, cell death is arrested and TH levels go back to normal levels, indicating a specific adaptation to the level of sensory activity. We conclude that sensory deprivation induces adjustments in the population of glomerular neurons, involving both, cell death and adaptation of neurotransmitter use in specific neuron types. Our study highlights the dynamic nature of glomerular neurons in response to sensory deprivation and provide valuable insights into the plasticity and adaptability of the olfactory system.

Olfactory sensory activity is a main factor factor controlling intergration and survival of neurons in the olfactory bulb. However, its impact on specific neuronal subtypes is unclear. Using reversible unilateral naris closure in concert with longitudinal in vivo imaging we show here that newborn GABAergic interneurons undergo significant cell death under sensory deprivation. In contrast, dopaminergic OB neurons survive under deprivation, but react with a reversible downregulation of tyrosine hydroxylase expression.long abstractNeurogenesis persists in the mammalian subventricular zone after birth, producing various populations of olfactory bulb (OB) interneurons. These include GABAergic and mixed dopaminergic/GABAergic double neurotransmitter neurons for the glomerular layer. While olfactory sensory activity is one of the main factors controlling newborn neuron integration, its effect on specific neuronal subtypes is far less clear. Here we use a reversible unilateral deprivation paradigm in combination with longitudinal in vivo imaging to characterize the behavior of newborn glomerular neurons. We find that a substantial fraction of purely GABAergic neurons die after four weeks of sensory deprivation. Tyrosine Hydroxylase (TH) positive dopaminergic/ GABAergic neurons show no signifficant cell death under deprivation, but react with an important decrease in TH expression levels. Importantly, this effect reverses after naris reopening, pointing to a specific adaptation of this neuron population to the level of sensory activity. We conclude that sensory deprivation induces adjustments in the excitation/inhibition balance of the OB implicating cell death and adaptation of neurotransmitter use in specific neuron types.