PE-22-28

PE-22-28 is a synthetic heptapeptide derived from the propeptide of sortilin (also called neurotensin receptor-3/NTSR3). It was developed as an optimized analog of spadin, a natural peptide that blocks TREK-1 potassium channels. TREK-1 (TWIK-Related K+ channel-1, also known as KCNK2/K2P2.1) is a two-pore domain potassium channel expressed in the brain that has been identified as a target for antidepressant research. TREK-1 knockout mice display an antidepressant-like phenotype, and TREK-1 blockade has been investigated as a mechanism for modulating mood-related signaling. PE-22-28 represents a shorter, optimized fragment of the 28-amino acid spadin peptide that retains TREK-1 blocking activity. The peptide has been investigated in preclinical behavioral models where TREK-1 modulation produces effects overlapping with those of conventional antidepressant mechanisms.

PE-22-28 has been investigated for its blockade of TREK-1 potassium channels in neuronal tissue. TREK-1 channels are background leak potassium channels that contribute to resting membrane potential and neuronal excitability. Researchers observed that PE-22-28 interacts with TREK-1 through binding to the sortilin/NTSR3 receptor-associated complex, blocking potassium conductance and increasing neuronal excitability in serotonergic and other mood-relevant neuronal populations. Studies suggest that TREK-1 blockade increases serotonin release in the dorsal raphe nucleus and hippocampus, mimicking the downstream effects of SSRI antidepressants but through an ion channel mechanism rather than reuptake inhibition. In preclinical behavioral models (forced swim test, tail suspension test), researchers observed that PE-22-28 produced effects in as few as 4 days, faster than the typical 2-3 week onset of SSRIs. The peptide also increased hippocampal neurogenesis markers in treated animals, consistent with the neuroplasticity effects associated with TREK-1 deletion.

TREK-1 and Antidepressant Signaling

Mazella et al. (2010) identified spadin (the parent compound) as a natural TREK-1 blocker and demonstrated antidepressant-like effects in behavioral models. This work established the TREK-1 channel as a novel target for mood research [1].

PE-22-28 Optimization

Djillani et al. (2017) characterized PE-22-28 as an optimized spadin analog with improved stability and potency at TREK-1. The researchers demonstrated rapid behavioral effects in preclinical models [2].

TREK-1 Knockout Phenotype

Heurteaux et al. (2006) characterized TREK-1 knockout mice and observed resistance to behavioral despair paradigms, elevated serotonin levels, and increased hippocampal neurogenesis, establishing the rationale for TREK-1 blockade [3].