In vivo oxymetric analysis of mild hypercapnia upon cerebral oxygen, temperature and blood flow: markers of mood as proposed by concomitant bupropion challenge and electrochemical analysis?

Scientific interest has increased the influence of temperature in neurodegenerative and psychiatric disorders, and according to the monoamine hypothesis, depression is a neurochemical disorder arising from hypofunctioning of brain monoamine systems. Here, in vivo flow-oxymetry is applied to verify relationships between cerebral oxygen tension (pO2), blood flow (CBF), that are markers of brain metabolism, and temperature (T), while in vivo voltammetry is concomitantly applied in the medial prefrontal cortex of anaesthetized rats to monitor monoamine levels such as dopamine (DA) and serotonin. An induced mild hypercapnia via increasing exogenous carbon dioxide (CO2) concentration resulted in increased pO2, CBF and T in discrete brain areas. Concomitant in situ voltammetric analysis of extracellular levels of serotonin and DA has revealed significant changes in the latter, only. Parallel treatment with antidepressant bupropion has confirmed its described central thermogenic properties and its positive influence on dopaminergic activity. CBF was also enhanced by such antidepressant. Altogether these data support direct relationships between markers of brain metabolism such as pO2, CBF, T and brain monoamine[s], indicating the coupled in vivo methodology: oxymetry-voltammetry as a rapid in vivo tool for analyses of such indicators in psychiatric disorders.