Researchers at the Marshall University Joan C. Edwards School of Medicine are highlighting the intricate interplay of nicotine’s effects on human brain regions. Their findings, published in eNeuro, explore how nicotine influences the areas associated with reward and aversion and how that varies based on dosage, sex, and distinct brain regions.
The medial habenula (MHb) regulates nicotine aversion. The study discovered that MHb activity experiences fluctuations, either heightened or diminished, based on such factors as the amount of nicotine consumed, dosage variations (with or without menthol), and the sex of the subject. However, the modulation was not mirrored in reward centers like the ventral tegmental area, challenging previous assumptions about the drug’s impact. The conclusion is that nicotine usage affects individuals uniquely.
The study used a vapor-inhalation model of nicotine self-administration in mice—nose poking to earn nicotine vapor deliveries. With patch-clamp electrophysiology, researchers elucidated changes in neuronal excitability in the medial habenula and ventral tegmental area based on dosage and sex. The study underscores the importance of exploring other brain areas controlling the negative aspects of nicotine exposure.
The researchers plan to expand their study to other brain regions, focusing on the interplay between the MHb and the interpeduncular nucleus (IPN). The circuit, called the aversive pathway of nicotine usage, plays a crucial role in limiting nicotine intake and withdrawal symptoms.
