Figure 4

DMT is present in the brain at concentrations comparable to known monoamine neurotransmitters. (A) DMT levels in pineal-intact rats (n = 25) rose following cardiac arrest. DMT, sampled 0.5 hr before cardiac arrest shown (retention time = 7.2 minutes) on a representative raw chromatogram (a, blue tracing), ranged between 0.05–1.8 nM (averaged 0.56 nM; b, blue dots) during baseline. DMT levels increased within one hr of cardiac arrest (a, red tracing), averaging 1.35 nM with maximum 5.01 nM (b, red dots). DMT increase was significant (***p = 0.00027; mean of differences = 0.80; SD = 0.93; 95% CI = 0.41 to 1.18; t(24) = −4.26). (B) DMT levels persisted in brains of pinealectomized rats (n = 11). DMT levels sampled 0.5–1 hr following cardiac arrest shown (retention time = 7.5 minutes) on a representative raw chromatogram (a, blue tracing), ranged between 0.25–2.2 nM (averaged 1.02 nM; b, blue dots) during baseline. DMT levels increased within one hr of cardiac arrest (a, red tracing), averaging 1.83 nM with maximum of 5.11 nM (b, red dots). DMT increase was significant (*p = 0.034; mean of differences = 0.81; SD = 1.10; 95% CI = 0.075 to 1.55; t(10) = 2.45). (C) There was no difference in brain concentrations of DMT at baseline (a) between rats without (−pineal; mean = 1.02 nM; SD, blue bar = 0.63) and with ( + pineal; mean = 0.56 nM; SD, blue bar = 0.49) the pineal gland (p = 0.05, Welch’s unpaired t-test). No difference between brain concentrations of DMT following cardiac arrest (b) without (− pineal; mean = 1.83 nM; SD, red bar = 1.38) and with (+pineal; mean = 1.35 nM; SD, red bar = 1.27) the pineal gland was detected (p = 0.34, unpaired t-test with Welch’s correction). Baseline levels of DMT were about half those of 5-HT levels (c; *p = 0.026; mean of differences = 1.08; SD = 1.37; 95% CI = 0.16 to 2.0; t(10) = −2.62) in the visual cortex of pinealectomized rats (mean DMT = 1.02 nM; SD, blue bar = 0.63; mean 5-HT = 2.10 nM; SD, blue bar = 1.67).