In Vivo Cerebral Blood Flow Modulation by Serotonin and Histamine (2012)
Undergraduates: Kevin Wood, Anna Belle
Faculty Advisor: Mark Wightman
Department: Biology
Blood flow within the brain is highly regulated, but the mechanism of blood flow control is poorly understood. Glutamate is known as the major transmitter regulating it. Better understanding of the neurochemical basis for blood flow resulting oxygen changes will clarify the analysis of human neuroimaging scans (PET and fMRI) and aid our understanding of its disruption which can lead to headaches, ischemia, and neuronal death. We believe that other neurotransmitters including histamine and serotonin control blood flow in the substantia nigra pars reticulata and nucleus accumbens of the rat brain. Increasing serotonin, but not dopamine, in the entire brain attenuates oxygen levels in both regions. Local applications of histamine increased blood flow in the nucleus accumbens and substantia nigra, while serotonin was shown to increase blood flow in the substantia nigra. Both serotonin and histamine increased blood flow in a dose-dependent manner. Locally applying dopamine did not significantly alter blood flow in either region. Finally, pharmacologically induced serotonin syndrome greatly increased serotonin levels, attenuated stimulated oxygen, and eventually led to cardiac arrest. The results indicate that serotonin and histamine modulate cerebral blood flow in the rat brain and that its dysregulation can be deleterious.