BIMU-8 is a drug which acts as a 5-HT4 receptor selective agonist. BIMU-8 was one of the first compounds of this class.[1][2] The main action of BIMU-8 is to increase the rate of respiration by activating an area of the brain stem known as the pre-Botzinger complex.
The most obvious practical use of BIMU-8 is to combine it with opioid analgesic drugs in order to counteract the dangerous respiratory depression which can occur when opioids are used in excessive doses.[3] BIMU-8 does not affect the pleasurable or painkilling properties of opiates, which means that if combined with BIMU-8, large therapeutic doses of opiates could theoretically be given to humans without risking a decrease in breathing rate. Studies have shown BIMU-8 to be effective in rats at counteracting the respiratory depression caused by the potent opioid fentanyl,[4] which has caused many accidental deaths in humans. However, no human trials of BIMU-8 have yet been carried out.
Other studies have suggested a role for 5-HT4 agonists in learning and memory,[5] and BIMU-8 was found to increase conditioned responses in mice, so this drug might also be useful for improving memory in humans.
Some other selective 5-HT4 agonists such as mosapride and tegaserod (the only 5-HT4 agonists currently licensed for use in humans) have been found not to reduce respiratory depression.[6] On the other hand, another 5-HT4 agonist, zacopride, does inhibit respiratory depression in a similar manner to BIMU-8.[7]
This suggests that either the anti-respiratory depression action is mediated via a specific subtype of the 5-HT4 receptor which is activated by BIMU-8 and zacopride, but not by mosapride or tegaserod, or alternatively there may be functional selectivity involved whereby BIMU-8 and zacopride produce a different physiological response following 5-HT4 binding compared to other 5-HT4 agonists. Another alternative to this is that the 5-HT4 agonist currently available for use in humans do not have great enough potency or bioavailability in the brain to elicit the same effects.[6]
Along with several other 5-HT4 ligands, BIMU-8 was also found to possess significant affinity for the sigma receptors, acting as a σ2 antagonist.[8][9][10] It is unclear as yet what contribution this additional activity makes to the pharmacological profile of BIMU-8 and other 5-HT4 ligands that also show sigma affinity.
^Turconi M, Nicola M, Quintero MG, Maiocchi L, Micheletti R, Giraldo E, Donetti A (August 1990). "Synthesis of a new class of 2,3-dihydro-2-oxo-1H-benzimidazole-1-carboxylic acid derivatives as highly potent 5-HT3 receptor antagonists". Journal of Medicinal Chemistry. 33 (8): 2101–2108. doi:10.1021/jm00170a009. PMID1695682.
^Dumuis A, Sebben M, Monferini E, Nicola M, Turconi M, Ladinsky H, Bockaert J (March 1991). "Azabicycloalkyl benzimidazolone derivatives as a novel class of potent agonists at the 5-HT4 receptor positively coupled to adenylate cyclase in brain". Naunyn-Schmiedeberg's Archives of Pharmacology. 343 (3): 245–251. doi:10.1007/bf00251122. PMID1650917. S2CID3173348.
^ abLötsch J, Skarke C, Schneider A, Hummel T, Geisslinger G (September 2005). "The 5-hydroxytryptamine 4 receptor agonist mosapride does not antagonize morphine-induced respiratory depression". Clinical Pharmacology and Therapeutics. 78 (3): 278–287. doi:10.1016/j.clpt.2005.05.010. PMID16153398. S2CID45695450.
^Meyer LC, Fuller A, Mitchell D (February 2006). "Zacopride and 8-OH-DPAT reverse opioid-induced respiratory depression and hypoxia but not catatonic immobilization in goats". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 290 (2): R405–R413. doi:10.1152/ajpregu.00440.2005. PMID16166206. S2CID224414.
^Bonhaus DW, Loury DN, Jakeman LB, Hsu SA, To ZP, Leung E, et al. (October 1994). "[3H]RS-23597-190, a potent 5-hydroxytryptamine4 antagonist labels sigma-1 but not sigma-2 binding sites in guinea pig brain". The Journal of Pharmacology and Experimental Therapeutics. 271 (1): 484–493. PMID7965749.
^Weatherspoon JK, Gonzalez-Alvear GM, Werling LL (May 1997). "Regulation of [3H]norepinephrine release from guinea pig hippocampus by sigma2 receptors". European Journal of Pharmacology. 326 (2–3): 133–138. doi:10.1016/S0014-2999(97)85407-6. PMID9196265.
^Liu X, Nuwayhid S, Christie MJ, Kassiou M, Werling LL (June 2001). "Trishomocubanes: novel sigma-receptor ligands modulate amphetamine-stimulated [3H]dopamine release". European Journal of Pharmacology. 422 (1–3): 39–45. doi:10.1016/S0014-2999(01)01071-8. PMID11430911.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction