Fig. 4.
Capsaicin (Cap) modulates excitatory neurotransmission of transient receptor potential vanilloid type 1 (TRPV1)-expressing neurons. A–C: Cap increased (A), decreased (B), or did not affect (C) the frequency of miniature excitatory postsynaptic currents (mEPSCs) in TRPV1Cre/tdTom neurons in the dorsomedial hypothalamic nucleus (DMH). Representative recordings of mEPSCs from TRPV1Cre/tdTom neurons in the DMH show increase (A1), decrease (B1), or no response (C1) to Cap application. TTX, tetrodotoxin. Bar graphs demonstrate increase (A2), decrease (B2), and no response (C2). D: in the presence of a TRPV1 antagonist, 5′-iodoresiniferatoxin (5′-IRTX), Cap did not increase mEPSC frequency (D1) and amplitude (D2); however, 5′-IRTX alone decreased mEPSC amplitude. E: in the presence of fluorocitrate, Cap increased mEPSC frequency in a small subset of TRPV1-expressing DMH neurons (E1), without altering the overall mEPSC frequency (E2). Numbers indicate number of neurons. ○, recording was conducted in female mice; ●, recording was conducted in male mice. **Significance (P < 0.01).