In 2011, the surprising discovery was made that DHEA, as well as DHEA-S, directly bind to and activate the TrkA and p75NTR with high affinity.[3] DHEA was subsequently also found to bind to the TrkB and TrkC with high affinity, though it notably activated the TrkC but not the TrkB.[4] DHEA and DHEA-S bound to these receptors with affinities that were in the low nanomolar range (around 5 nM), although the affinities were nonetheless approximately two orders of magnitude lower relative to the highly potent polypeptide neurotrophins (0.01–0.1 nM).[3][4] In any case, DHEA and DHEA-S were identified as important endogenous neurotrophic factors.[3] These findings may explain the positive association between decreased circulating DHEA levels with age and age-related neurodegenerative diseases.[2]
Subsequently, a series of spiroderivatives of DHEA that had been synthesized and assessed in 2009 as potential neuroprotective agents was re-investigated.[1][2] Of these, BNN-20 was assayed and found to directly bind to and activate the TrkA, TrkB, and p75NTR.[2] In addition, it was found to cross the blood–brain barrier and to have strong neuroprotective effects on dopaminergicneuronsin vivo in a mousemodel of dopaminergic neurodegeneration, which were dependent, at least in part, on activation of the TrkB.[2] Moreover, unlike DHEA, it lacked any hormonal actions.[2] As such, BNN-20 was described as a BDNF mimetic and was proposed as a potential novel treatment for Parkinson's disease and other conditions, particularly of the neurodegenerative variety, like amyotrophic lateral sclerosis.[2][5]
^ abCalogeropoulou T, Avlonitis N, Minas V, Alexi X, Pantzou A, Charalampopoulos I, Zervou M, Vergou V, Katsanou ES, Lazaridis I, Alexis MN, Gravanis A (2009). "Novel dehydroepiandrosterone derivatives with antiapoptotic, neuroprotective activity". J. Med. Chem. 52 (21): 6569–87. doi:10.1021/jm900468p. PMID19845386.
^ abcdefghiBotsakis K, Mourtzi T, Panagiotakopoulou V, Vreka M, Stathopoulos GT, Pediaditakis I, Charalampopoulos I, Gravanis A, Delis F, Antoniou K, Zisimopoulos D, Georgiou CD, Panagopoulos NT, Matsokis N, Angelatou F (2017). "BNN-20, a synthetic microneurotrophin, strongly protects dopaminergic neurons in the "weaver" mouse, a genetic model of dopamine-denervation, acting through the TrkB neurotrophin receptor". Neuropharmacology. 121: 140–157. doi:10.1016/j.neuropharm.2017.04.043. PMID28461162. S2CID5071762.