Research Paper Volume 9, Issue 3 pp 880—899

Functional decline at the aging neuromuscular junction is associated with altered laminin-α4 expression

Figure 1. Altered transmission properties at lama4-/- neuromuscular junctions were maintained throughout adulthood to aging. (A) Sample traces from intracellular recordings of 10 consecutive mEPPs and 10 consecutive EPPs for WT and lama4-/- NMJs at 3MO in diaphragm muscle. Prolonged mEPP decay time was observed as indicated on sample traces. Stimulus artefacts have been omitted from EPP traces for clarity. (B) mEPPs frequency, (C) failures in evoked release and (D) quantal content were measured across all ages investigated. (E) Normalized binomial parameter analysis displayed decreased quantal content (m) at 3MO lama4-/- NMJs, which was resulted from lower number of active sites (n) with normal probability release of neurotransmitters (p). Binomial parameter analysis is normalized to 3MO WTs, as represented by dashed lines at 100%. (F) Sample traces from extracellular recordings of 10 averaged consecutive mEPCs and 10 averaged consecutive EPCs for WT and lama4-/- NMJs at 3MO. (G, H) amplitudes of (G) spontaneous release (mEPCs) and (H) evoked release (EPCs) across all age groups. For all graphs, n = 4-6, NMJs = 25-45 per genotype at each age. Statistical analyses were performed using Student’s t-test; values are presented as mean ± SEM (* P < 0.05, ** P < 0.01, *** P < 0.001 and **** P < 0.0001).