The combination of electrophysiology and optogenetics for the in vivo study of the influence of nucleus incertus on the activity of midbrain dopaminergic neurons in the rat

• Autorzy: Pradel K. , Blasiak T.
• Języki publikacji: EN

Abstrakty

EN

The in vivo preparation is commonly used to study electrophysiology of brain circuits. Since the whole brain network is preserved, electrical activity of one brain region can be observed while the other region is being manipulated (e.g. stimulated or inhibited) in order to determine and characterise connectivity be‑ tween these regions. The recently discovered tool of optogenetics is useful for controlling neuronal activi‑ ty, characterized by high specificity to neurons as well as high temporal resolution. We used this tool to de‑ termine if neurons located within the nucleus incer‑ tus (NI), a population of brainstem central gray GAB‑ Aergic neurons involved in stress response, have an impact on the electrical activity of midbrain dopami‑ nergic neurons located within the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). To prepare the tested neuronal circuit for optogenetic manipulations, NIs of Sprague Dawley rats were ste‑ reotaxically injected with adenoviral associated vector (AAV2-hSyn-hChR2(H134R)-eYFP) containing genes for Channelrhodopsin-2 (ChR2; a blue light-sensitive cation channel) and enhanced yellow fluorescent pro‑ tein (eYFP), which are expressed under control of neu‑ ron specific promoter (human synapsin 1). Two weeks after the operation, when ChR2 and eYFP are fully expressed, in vivo electrophysiological experiments were performed on urethane anaesthetised animals. Dopaminergic neurons within the VTA and SNc were recorded, while NI was stimulated using blue laser light (473 nm, 10–20 mW) led to the tissue using fibre optics. After each experiment the expression of eYFP in the NI, optic fibre placement, as well as the localisa‑ tion of recording electrode within the borders of VTA/ SNc were histologically verified. The results revealed that most (59%) of the midbrain dopaminergic neu‑ rons were strongly inhibited by the optogenetic acti‑ vation of the NI. NI-induced inhibition was followed by rebound excitation in the majority (69%) of respon‑ sive neurons. Additionally, numerous eYFP-positive axons originating from the NI were observed within the VTA and SNc. In conclusion, our results show that NI is a source of strong, presumably direct, inhibitory input to the midbrain dopaminergic system. Optoge‑ netic tools can be used to control the activity of neu‑ rons with high temporal and spatial resolution, both in transgenic and wild-type animals.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2018
• Tom: 78
• Numer: Suppl.1
• Opis fizyczny: p.17

Twórcy

autor

Pradel K.

• Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland

autor

Blasiak T.

• Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland