Cansler Hillary L, Maksimova Marina A, Meeks Julian P
Department of Neuroscience, and.
Neuroscience Graduate Program, Graduate Program of Biomedical Sciences, The University of Texas Southwestern Medical Center, Dallas, Texas 75390.
J Neurosci. 2017 Jul 26;37(30):7240-7252. doi: 10.1523/JNEUROSCI.1031-17.2017. Epub 2017 Jun 28.
Chemosensory information processing in the mouse accessory olfactory system guides the expression of social behavior. After salient chemosensory encounters, the accessory olfactory bulb (AOB) experiences changes in the balance of excitation and inhibition at reciprocal synapses between mitral cells (MCs) and local interneurons. The mechanisms underlying these changes remain controversial. Moreover, it remains unclear whether MC-interneuron plasticity is unique to specific behaviors, such as mating, or whether it is a more general feature of the AOB circuit. Here, we describe targeted electrophysiological studies of AOB inhibitory internal granule cells (IGCs), many of which upregulate the immediate-early gene after male-male social experience. Following the resident-intruder paradigm, -expressing IGCs in acute AOB slices from resident males displayed stronger excitation than nonexpressing neighbors when sensory inputs were stimulated. The increased excitability of -expressing IGCs was not correlated with changes in the strength or number of excitatory synapses with MCs but was instead associated with increased intrinsic excitability and decreased HCN channel-mediated currents. Consistent with increased inhibition by IGCs, MCs responded to sensory input stimulation with decreased depolarization and spiking following resident-intruder encounters. These results reveal that nonmating behaviors drive AOB inhibitory plasticity and indicate that increased MC inhibition involves intrinsic excitability changes in -expressing interneurons. The accessory olfactory bulb (AOB) is a site of experience-dependent plasticity between excitatory mitral cells (MCs) and inhibitory internal granule cells (IGCs), but the physiological mechanisms and behavioral conditions driving this plasticity remain unclear. Here, we report studies of AOB neuronal plasticity following male-male social chemosensory encounters. We show that the plasticity-associated immediate-early gene is selectively expressed in IGCs from resident males following the resident-intruder assay. After behavior, -expressing IGCs are more strongly excited by sensory input stimulation and MC activation is suppressed. -expressing IGCs do not show increased excitatory synaptic drive but instead show increased intrinsic excitability. These data indicate that MC-IGC plasticity is induced after male-male social chemosensory encounters, resulting in enhanced MC suppression by -expressing IGCs.
小鼠副嗅觉系统中的化学感觉信息处理指导着社会行为的表达。在显著的化学感觉接触后，副嗅球（AOB）在二尖瓣细胞（MCs）和局部中间神经元之间的相互突触处经历兴奋和抑制平衡的变化。这些变化背后的机制仍存在争议。此外，MC-中间神经元可塑性是特定行为（如交配）所特有的，还是AOB回路更普遍的特征，目前尚不清楚。在这里，我们描述了对AOB抑制性内颗粒细胞（IGCs）的靶向电生理研究，其中许多细胞在雄性间社交经历后上调即刻早期基因。遵循驻留者-入侵者范式，在来自驻留雄性的急性AOB切片中，表达该基因的IGCs在刺激感觉输入时比不表达的相邻细胞表现出更强的兴奋。表达该基因的IGCs兴奋性增加与与MCs兴奋性突触强度或数量的变化无关，而是与内在兴奋性增加和HCN通道介导的电流减少有关。与IGCs抑制增加一致，MCs在驻留者-入侵者接触后对感觉输入刺激的反应是去极化和放电减少。这些结果表明，非交配行为驱动AOB抑制性可塑性，并表明MC抑制增加涉及表达该基因的中间神经元的内在兴奋性变化。副嗅球（AOB）是兴奋性二尖瓣细胞（MCs）和抑制性内颗粒细胞（IGCs）之间经验依赖性可塑性的位点，但驱动这种可塑性的生理机制和行为条件仍不清楚。在这里，我们报告了雄性间社交化学感觉接触后AOB神经元可塑性的研究。我们表明，与可塑性相关的即刻早期基因在驻留者-入侵者试验后在驻留雄性的IGCs中选择性表达。行为后，表达该基因的IGCs对感觉输入刺激更强烈地兴奋，并且MC激活受到抑制。表达该基因的IGCs没有表现出兴奋性突触驱动增加，而是表现出内在兴奋性增加。这些数据表明，MC-IGC可塑性在雄性间社交化学感觉接触后被诱导，导致表达该基因的IGCs对MC的抑制增强。
