Influence of feelings on the blood-brain barrier (BBB) and drug delivery.

The blood-brain barrier (BBB) is a critical regulator of cerebral homeostasis, displaying high dynamicity of influx and efflux of substances to and from the central nervous system (CNS). In an exploration of the neurochemical pathways through which positive and negative emotions can influence the physiological characteristics of the BBB, this chapter delves into the multifaceted relationship between emotional states and BBB integrity and permeability. Negative emotions exemplified by stress, chronic anxiety, and depression have shown harmful effects on the BBB, suggesting a state of hyperpermeability that compromises the otherwise conferred protection. Few reports in literature examined the exact molecular mechanisms by which negative emotions exhibit signs of damaged and leaky BBB. Although research deciphering those mechanisms is limited, there is consensus that the disruption of tight junction (TJ) protein integrity and expression, along with neuroinflammatory processes, oxidative Stress, and excitotoxicity, plays a role in the induction of BBB damage. Conversely, positive emotions have been shown to exert protective effects, potentially reversing the increased permeability of the BBB. Compared to the research focused on the neural correlates of negative emotions, the neuroscience literature on positive emotions and well-being is still in its infancy. A deeper understanding of the mechanisms by which positive emotions modulate the BBB remains necessary. Additionally, we discuss the therapeutic implications of these findings, considering how emotional well-being can be leveraged in developing treatments for neurological disorders. By integrating neuroscience, psychology, and pharmacology insights, this chapter aims to comprehensively understand the dynamic interplay between emotions and the BBB and its potential to inform novel therapeutic strategies.