Indole hallucinogens

Using tactile startle, bufotenin, a hallucinogen that does not cross the blood-brain barrier readily, also produced biphasic dose-response effects when given intraventricularly (76). After systemic administration, however, low doses of indole hallucinogens have not been reported to increase tactile startle (73). Thus LSD (20-80 Mg/kg), DMT (0.25-1.0 mg/kg), and psilocin (2.5-5.0 mg/kg) did not increase tactile startle. A slightly higher dose of LSD (100 Mg/kg) did increase startle toward the end of the test session, perhaps because of blocking habituation (see below). 

In contrast to the rather weak effects produced by these indole hallucinogens, another indole hallucinogen, 5-MeODMT, produces a marked increase in acoustic startle (44). In this case, the excitatory effect is monotonically related to the dose over a range from 0.03 to 8 mg/kg. In fact, 5-MeODMT is one of the most efficacious drugs we have found in increasing acoustic startle. Thus far, the effects of 5-MeODMT on tactile startle have not been tested. 

The idea that indole hallucinogens might increase startle by interacting with presynaptic autoreceptors has received some experimental support. Davis and Sheard (49) found that lesions of the dorsal and median raphe nuclei blocked the usual excitatory effect of a low dose (40 jtg/kg) of LSD on acoustic startle. Moreover, other treatments that decreased raphe cell firing rates also blocked the excitatory effects of LSD on startle. For example, pretreatment with chlor-imipramine (CIMI), which decreases raphe cell firing indirectly by blocking 5-HT reuptake (153), blocked the usual excitatory effect of LSD on startle without preventing the entry of LSD into the brain (47). These data were consistent with the disinhibition hypothesis. 

Meltzer, H. Y., Fang, V. S., Gudelsky, G., Manov, G., Simonovic, M., and Wiita, B. (1981) Effect of indole hallucinogens on neuroendocrine function in man and laboratory animals. Abstract, p. 47, Annual Meeting of the American College of Neuropsychopharmacology, Coronado, California. 

Ibogaine, discovery of, 7 Imagery, hallucinogen-induced, 15-16 Indole hallucinogens, effects of on spinal reflexes, 38-39 on startle reflexes, 43-44 Indolealkylamines... 

Psilocybin and psilocin are believed to work through mechanisms similar to LSD and other indole hallucinogens. Similar to LSD, chronic psilocybin in take also down-regulates 5-HT2 receptors, which parallels the development of behavioral tolerance (Buckholtz et al. 1990). 

Mushrooms are the most important natural psychedelics of southern Mexico, used in ceremonies so sacred that Indians carefully concealed them from Europeans until the present century. It wasn t until the 1950s that descriptions of Mexican mushrooms came to the attention of the world. Soon after, botanists began to identify the mushrooms in use, and chemists found that their psychoactive properties came from psilocybin, an indole hallucinogen similar to LSD but with a shorter duration of action four to six hours. 

Iboga, 94, loi Ibogame, loi Ibotenic acid, 135 "Ice" metharnphetamme, 49 Identity, drug use to establish, 21 Imipramine (Tofranil), 144 Indole hallucinogens, 95—103 Inhalants. See Nitrite inhalants Injection of drugs, 23, 31, 83, 103 amphetamines, 49 angel dust, 137 barbiturates, 69, 70 cc.,aine, 45... 

Since they are tryptamine derivatives, the indolic hallucinogens are structurally related to the neurohumoral factor serotonin (5-hydroxytryptamine). Serotonin is widely distributed in warmblooded animals. It accumulates in the brain, where it plays a role in the biochemistry of nervous regulations. Consequently, it seems that certain tryptamine structures which occur so frequently in hallucinogens, as well as in the neurohormone serotonin, may be biochemically important in the metabolism of psychic functions. . . ... 

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