Optical control of the hypothalamic arcuate nucleus kisspeptin neuronal network with a photoswitchable peptide that drives luteinizing hormone release in female mice.

Preclinical study involving peptide synthesis, in vitro cell culture, ex vivo electrophysiology, and in vivo animal experiments

“We developed and synthesized a photoswitchable TacR3 agonist (azo‐senktide) and characterized its photochemical and pharmacological properties using UV–Vis spectroscopy, TacR3‐expressing HEK293T cells, electrophysiology in mouse hypothalamic slices, and in vivo optofluidic delivery combined with light stimulation to assess LH secretion in freely moving mice.”

HEK293T cells, mouse hypothalamic slices, and adult female C57BL6J mice

“Adult female C57BL6J mice (8–10 weeks) used for the experiments (n = 7) were purchased from Charles River Laboratories International, Inc.”

7 mice for in vivo experiments, with 6 having successful cannula placement; variable cell counts for in vitro experiments

“We implanted cannulas into seven mice for delivery of azo‐senktide and 365‐nm light. Analysis of histological images acquired from coronal sectioning of the mouse brains showed that six out of seven females had successful cannula placement in the ARH.”

In vivo data collection conducted over 4–6 weeks; in vitro experiments performed over 18–48 hours post-transfection

“Data collection was conducted over a period of 4–6 weeks.”

Azo-senktide reversibly photoisomerizes between inactive (trans) and more potent (cis) conformations, enhancing TacR3-mediated Ca2+ signaling in cells

“Azo‐senktide reversibly photoisomerized between inactive (trans) and more potent (cis) conformations.”

Photostimulation of azo-senktide depolarizes Kiss1ARH neurons and increases firing through the TacR3–TRPC5 signaling pathway

“In brain slices, photostimulation depolarized and increased firing of Kiss1ARH neurons through a mechanism consistent with the established TacR3–TRPC5 signaling pathway.”

The optical stimulation protocol does not fully replicate complex endogenous NKB release patterns, and in vivo experiments in wild-type mice cannot conclusively attribute effects to TacR3 activation specifically in Kiss1ARH neurons

“The optical stimulation protocol was designed to establish proof‐of‐principle that temporally gated TacR3 activation can drive LH pulse release, but it does not fully replicate the complex endogenous patterns of NKB release that occur during natural reproductive cycles.”