P3.29. NUCLEUS INCERTUS CONNECTIVITY WITH MIDBRAIN CENTRES - IMPLICATIONS FOR STRESS AND REWARD PROCESSING
Joanna Roszkowska1,2, Gniewosz Drwięga1, Magdalena Walczak1, Olga Mierniczek1,2, Martyna Gorkowska-Nosal1,2, Kamil Pradel1,3, Wojciech Solecki4, Tomasz Błasiak1
1 Jagiellonian University, Department of Neurophysiology and Chronobiology, 9 Gronostajowa St., Cracow, Poland
2 Jagiellonian University, Doctoral School of Exact and Natural Sciences, 11 Łojasiewicza St., Cracow, Poland
3 University of Cologne, Institute for Systems Physiology, 39 Robert Koch St., Cologne, Germany
4 Jagiellonian University, Department of Neurobiology and Neuropsychology, 4 Łojasiewicza St., Cracow, Poland
INTRODUCTION: The brainstem nucleus incertus (NI) plays a role in processing aversive stimuli and regulating the stress response. Our previous research has shown that this structure also modulates the activity of midbrain dopaminergic neurons in rats by providing inhibitory input to the ventral tegmental area (VTA). In addition to the VTA, the NI's projections also extend to the rostromedial tegmental nucleus (RMTg), which serves as the primary inhibitory input to the dopaminergic system in the midbrain.
AIM(S): The aim of this study was to better understand the circuit’s anatomy, physiology and function, using advanced neuroscientific research techniques.
METHOD(S): To gain an understanding of the circuit's anatomy, two retrogradely transported viral vectors, each carrying a gene for a different fluorescent protein, were injected unilaterally into the VTA and RMTg of Sprague-Dawley rats. Next, electrophysiological recordings in urethane-anaesthetized rats were conducted after the administration of two viral vectors: one retrograde vector, containing the Cre recombinase gene, was injected into the VTA or RMTg, and another vector, carrying Cre-dependent genes for a light-sensitive opsin, was targeted to the NI. Lastly, preceding behavioural experiments, retrograde viral vectors carrying YFP were injected bilaterally into the animals’ RMTg. Following a stress-induction procedure in operant conditioning chamber, anti-cFos immunostaining was performed.
RESULTS: The results indicate that, in contrast to the VTA, the RMTg receives bilateral input from the NI. Electrophysiological findings further demonstrate functional effects of this NI-derived innervation on both midbrain structures. Additionally, the behavioural data shed light on a potential overlap between the c-fos-reactive NI subpopulation and the neurons projecting to the RMTg.
CONCLUSIONS: Taken together, these findings suggest that NI-derived innervation of midbrain structures constitutes a complex network that plays a role in regulating stress and reward processing.
FINANCIAL SUPPORT: National Science Centre: OPUS 17 2019/33/B/NZ4/03127, Preludium 21 2022/45/N/NZ4/03171