Brain activation changing levels

Environment, effect on changes in locomotor activity and brain 5-HT levels, 48-50 with LSD, 50-51... 

Motor activity changes were also observed in rats administered doses of FireMaster FF-1 as low as 1 mg/kg/day for 4 weeks (Geller et al. 1979). In this experiment, neither learning nor performance of a simple discrimination task was affected by 1, 3, or 6 mg/kg/day dosage levels, but increased motor activity was observed at 1 mg/kg/day. No changes were apparent at 3 mg/kg/day and decreased motor activity was apparent at 6 mg/kg/day, compared with controls. Weakness of the hind limb was noted in rats treated with 10 mg/kg/day FireMaster FF-1 for 6 months compared with control rats (Cabe and Tilson 1978). Histological examination of brain and/or spinal nerve tissue found no FireMaster FF-l-related alterations in rats or mice administered up to 10 mg/kg/day for 25 weeks (NTP 1983) or 3.9 mg/kg/day for up to 105 weeks (NTP 1992). 

Romero G, Perez MP, Carceller A, Monroy X, Farre AJ, et al. 2000. Changes in phosphoinositide signalling activity and levels of the alpha subunit of G(q/ll) protein in rat brain induced by E-5842, a sigma(l) receptor ligand and potential atypical antipsychotic. Neurosci Lett 290 189-192. 

The problem is that 40%-65% of those people receiving placebos also report improvement of their physical or mental conditions. Just the anticipation of relief, and the care by others, is enough to alleviate suffering. There is evidence that the placebo effect is centered in the brain and changes the activity levels of areas associated with pleasant and unpleasant sensations. Brain imaging has shown that metabolism of these different areas changes when cure is expected. History is full of medicines and medical devices that were claimed to effect cures, but only did so because of the placebo effect Giving people hope is one of the most powerful medicines available. 

In contrast, there have been other reports that morphine does alter brain levels of 5-HT, with sometimes an increase [246] and sometimes a decrease [247,248] this confusion is tempered slightly by the knowledge that the effects of morphine on brain levels of DA and NA, as well as of 5-HT, are modified significantly by the dose of opiate employed [249]. Thus, there appears to be no simple monophasic type of relationship between morphine-induced changes in brain biogenic amine levels and antinociceptive activity. 

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