VIP-immunoreactive interneurons within circuits of the mouse basolateral amygdala

2018. július 12.

In cortical structures, principal cell activity is tightly regulated by different GABAergic interneurons (INs). In particular, vasoactive intestinal polypeptide-expressing (VIP+) INs innervate preferentially other INs, providing a structural basis for temporal disinhibition of principal cells. However, relatively little is known about VIP+ INs in the amygdaloid basolateral complex. In this study, the authors report that VIP+ INs have a variable density in the distinct nuclear subdivisions of the mouse BLA. Based on different anatomical, neurochemical and electrophysiological criteria, VIP+ INs could be identified as interneuron-selective INs and basket cells expressing CB1 cannabinoid receptors. Whole-cell recordings of VIP+ interneuron-selective INs revealed 3 different spiking patterns, which did not associate with the expression of calretinin. Genetic targeting combined with optogenetics and in vitro recordings allowed us to identify several types of BLA INs innervated by VIP+ INs, including other interneuron-selective INs, basket and neurogliaform cells. Moreover, light stimulation of VIP+ basket cell axon terminals, characterized by CB1 sensitivity, evoked IPSPs in ~20% of principal neurons. Finally, they show that VIP+ INs receive a dense innervation from both GABAergic, although only 10% from other VIP+ INs, and distinct glutamatergic inputs, identified by their expression of different vesicular glutamate transporters.

In conclusion, the study provides a wide-range analysis of single-cell properties of VIP+ INs in the mouse BLA and of their intrinsic and extrinsic connectivity. The results reinforce the knowledge that VIP+ INs are structurally and functionally heterogeneous and that this heterogeneity could mediate different roles in amygdala-dependent functions.

Thomas Rhomberg*, Laura Rovira-Esteban*, Attila Vikór, Enrica Paradiso, Christian Kremser, Petra Nagy-Pál, Orsolya I Papp, Ramon Tasan, Ferenc Erdélyi, Gábor Szabó, Francesco Ferraguti, Norbert Hájos: VIP-immunoreactive interneurons within circuits of the mouse basolateral amygdala.
J Neurosci. 2018 Jun 28. pii: 2063-17. doi: 10.1523/JNEUROSCI.2063-17.2018

*These authors made an equal contribution to this work.