Abstract by Jefferson Novaes Gomes

Opioids are powerful pain-relieving drugs, but repeated use can lead to dependence and addiction. This PhD thesis explores how opioids affect the laterodorsal tegmental nucleus (LDT), a brain region traditionally associated with sleep and arousal that also communicates with the brain’s reward system. Using electrophysiological recordings from individual neurons, this PhD thesis characterises how the three major opioid receptors—mu, delta, and kappa—alter neuronal activity in the LDT and examine how these effects vary with sex and age. The thesis further investigates how chronic morphine exposure reshapes LDT function and whether a ketogenic diet can modify these adaptations. Together, the findings identify the LDT as an important component of opioid-sensitive brain circuitry.