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The Journal of Neuroscience, May 9, 2007, 27(19):5023-5032; doi:10.1523/JNEUROSCI.1194-07.2007
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Development/Plasticity/Repair
Postnatal Generation of Neurons in the Ventrobasal Nucleus of the Rat Thalamus
Sandra M. Mooney1,2 andMichael W. Miller1,2,3 1Department of Neuroscience and Physiology, State University of New York–Upstate Medical University, Syracuse, New York 13210, 2Developmental Exposure Alcohol Research Center, Binghamton, New York 13902 and Syracuse, New York 13104, and 3Research Service, Veterans Affairs Medical Center, Syracuse, New York 13210
Correspondence should be addressed to Dr. Sandra M. Mooney, Department of Neuroscience and Physiology, State University of New York–Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210. Email: mooneys{at}upstate.edu
Most CNS systems, including the trigeminal–somatosensory system, develop via a hierarchical order (from the periphery and up the neuraxis). We tested the hypothesis that development of the trigeminal system can proceed via a nonhierarchical mechanism (i.e., that neuronogenesis can occur postnatally). Preweanling rats were perfused, and brain sections were stained with cresyl violet or immunolabeled with NeuN (for neuronal counts), or processed for acetylcholinesterase (AChE) activity or p75 immunoreactivity [to identify boundaries of the ventrobasal nucleus (VB)]. Neuronal number decreased during the first postnatal week but increased 2.5-fold over the next 3 weeks. To determine whether this remarkable rise resulted from the generation of new neurons, preweanlings were given injections of bromodeoxyuridine (BrdU) on postnatal day 6 (P6) or P21. BrdU-positive VB cells were apparent on both days. Cumulative BrdU labeling showed that the cell cycle was 17.3 h on P6. Moreover, Ki-67, a protein elaborated throughout the cell cycle, was expressed by 25.8–29.3% of all VB cells on P6–P15, falling to 7.7% by P21. BrdU-positive VB cells coexpressed neuronal markers: NeuN, HuC/D, microtubule-associated protein 2, and a dextran placed in the somatosensory cortex. Note that postnatal neuronal generation was also evident in other thalamic nuclei (e.g., the lateral geniculate nucleus). Thus, the developing VB experiences two periods of neuronal generation. Prenatal neuronogenesis is part of hierarchical trigeminal–somatosensory development. Postnatal nonhierarchical neuronogenesis is intrathalamic and matches changes in neuromodulatory systems (exemplified by AChE activity and p75) and the arrival of corticothalamic afferents.
Key words: bromodeoxyuridine; lateral geniculate nucleus; neural stem cells; neurogenesis; proliferation; acetylcholinesterase (AchE)
Received June 16, 2005; accepted March 22, 2007.
Correspondence should be addressed to Dr. Sandra M. Mooney, Department of Neuroscience and Physiology, State University of New York–Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210. Email: mooneys{at}upstate.edu
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Endocrinology, December 1, 2009; 150(12): 5520 - 5529.
[Abstract] [Full Text] [PDF]
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