l-Menthol increases extracellular dopamine and c-Fos-like immunoreactivity in the dorsal striatum, and promotes ambulatory activity in mice

Socially-mediated activation in the snake social-decision-making network

Brain areas important for social perception, social reward, and social behavior - collectively referred to as the social-decision-making network (SDN) - appear to be highly conserved across taxa. These brain areas facilitate a variety of social behaviors such as conspecific approach/avoidance, aggression, mating, parental care, and recognition. Although the SDN has been investigated across taxa, little is known about its functioning in reptiles. Research on the snake SDN may provide important new insights, as snakes have a keen social perceptual system and express a relatively reduced repertoire of social behaviors. Here, we present the results of an experiment in which ball pythons (Python regius) interacted with a same-sex conspecific for one hour and neural activation was investigated through Fos immunoreactivity. Compared to controls, snakes that interacted socially had higher Fos counts in brain areas implicated in social behavior across taxa, such as the medial amygdala, preoptic area, nucleus accumbens, and basolateral amygdala. Additionally, we found differential Fos immunoreactivity in the ventral amygdala, which facilitates communication between social brain areas. In many of these areas, Fos counts differed by sex, which may be due to increased competition between males. Fos counts did not differ in early sensory (i.e., vomeronasal) processing structures. As ball python social systems lack parental care, cooperation, or long-term group living, these results provide valuable insight into the basal functions of the vertebrate social decision-making network.

Neuromodulatory and neurotoxic effects of e-cigarette vapor using a realistic exposure method

The most direct effects of inhaled harmful constituents are the effects on the airways. However, inhaled compounds can be rapidly absorbed and subsequently result in systemic effects. For example, e-cigarette vapor has been shown to evoke local effects in the lung, although little is known about subsequent effects in secondary target organs such as the brain. Traditionally, such effects are tested using in vivo models. As an alternative, we have combined two in vitro systems, which are Air-Liquid-Interface (ALI) cultured alveolar cells (A549) and rat primary cortical cultures grown on multi-well microelectrode arrays. This allows us to assess the neurological effects of inhaled compounds. We have used exposure to e-cigarette vapor, containing nicotine, menthol, or vanillin to test the model. Our results show that ALI cultured A549 cells respond to the exposure with the production of cytokines (IL8 and GROalpha). Furthermore, nicotine, menthol, and vanillin were found on the basolateral side of the cell culture, which indicates their translocation. Upon transfer of the basolateral medium to the primary cortical culture, exposure-related changes in spontaneous electrical activity were observed correlating with the presence of e-liquid components in the medium. These clear neuromodulatory effects demonstrate the feasibility of combining continuous exposure of ALI cultured cells with subsequent exposure of neuronal cells to assess neurotoxicity. Although further optimization steps are needed, such a combination of methods is important to assess the neurotoxic effects of inhaled compounds realistically. As such, an approach like this could play a role in future mechanism-based risk assessment strategies.