Abstract\r<br />Background: Previous studies by our group suggest that extracellular dopamine (DA) and noradrenaline (NA) may be\r<br />co-released from noradrenergic nerve terminals in the cerebral cortex. We recently demonstrated that the concomitant\r<br />release of DA and NA could be elicited in the cerebral cortex by electrical stimulation of the locus coeruleus (LC). This\r<br />study analyses the effect of both single train and repeated electrical stimulation of LC on NA and DA release in the medial\r<br />prefrontal cortex (mPFC), occipital cortex (Occ), and caudate nucleus. To rule out possible stressful effects of electrical\r<br />stimulation, experiments were performed on chloral hydrate anaesthetised rats.\r<br />Results: Twenty min electrical stimulation of the LC, with burst type pattern of pulses, increased NA and DA both in\r<br />the mPFC and in the Occ. NA in both cortices and DA in the mPFC returned to baseline within 20 min after the end of\r<br />the stimulation period, while DA in the Occ reached a maximum increase during 20 min post-stimulation and remained\r<br />higher than baseline values at 220 min post-stimulation. Local perfusion with tetrodotoxin (TTX, 10 µM) markedly\r<br />reduced baseline NA and DA in the mPFC and Occ and totally suppressed the effect of electrical stimulation in both\r<br />areas.\r<br />A sequence of five 20 min stimulations at 20 min intervals were delivered to the LC. Each stimulus increased NA to the\r<br />same extent and duration as the first stimulus, whereas DA remained elevated at the time next stimulus was delivered,\r<br />so that baseline DA progressively increased in the mPFC and Occ to reach about 130 and 200% the initial level,\r<br />respectively.\r<br />In the presence of the NA transport (NAT) blocker desipramine (DMI, 100 µM), multiple LC stimulation still increased\r<br />extracellular NA and DA levels.\r<br />Electrical stimulation of the LC increased NA levels in the homolateral caudate nucleus, but failed to modify DA level.\r<br />Conclusion: The results confirm and extend that LC stimulation induces a concomitant release of DA and NA in the\r<br />mPFC and Occ.\r<br />The different time-course of LC-induced elevation of DA and NA suggests that their co-release may be differentially\r<br />controlled.
Devoto Paola, Flore Giovanna, Saba Pierluigi, Fà Mauro, & Gessa Gian Luigi. (2005). Co-release of noradrenaline and dopamine in the cerebral cortex elicited by single train and repeated train stimulation of the locus coeruleus. BMC Neuroscience. Retrieved from http://download.springer.com/static/pdf/532/art%253A10.1186%252F1471-2202-6-31.pdf?originUrl=http%3A%2F%2Fbmcneurosci.biomedcentral.com%2Farticle%2F10.1186%2F1471-2202-6-31&token2=exp=1490294114~acl=%2Fstatic%2Fpdf%2F532%2Fart%25253A10.1186%25252F1471-220