Poorer aging trajectories are associated with elevated serotonin synthesis capacity.

The dorsal raphe nucleus (DRN) is one of the earliest targets of Alzheimer's disease-related tau pathology and is a major source of brain serotonin. We used [F]Fluoro-m-tyrosine ([F]FMT) PET imaging to measure serotonin synthesis capacity in the DRN in 111 healthy adults (18-85 years-old). Similar to reports in catecholamine systems, we found elevated serotonin synthesis capacity in older adults relative to young.

Ribosomes in RNA Granules Are Stalled on mRNA Sequences That Are Consensus Sites for FMRP Association.

Local translation in neurons is partly mediated by the reactivation of stalled polysomes. Stalled polysomes may be enriched within the granule fraction, defined as the pellet of sucrose gradients used to separate polysomes from monosomes. The mechanism of how elongating ribosomes are reversibly stalled and unstalled on mRNAs is still unclear.

Chronic pain produces hypervigilance to predator odor in mice.

The adaptive significance of acute pain (to withdraw from tissue-damaging or potentially tissue-damaging external stimuli, and to enhance the salience of the stimulus resulting in escape and avoidance learning) and tonic pain (to enforce recuperation by punishing movement) are well-accepted [1]. Pain researchers, however, generally assert that chronic pain has no adaptive significance, representing instead a pathophysiological state. This belief was recently challenged by the observation [2] that nociceptive sensitization caused by a chronic pain-producing injury reduced predation risk in squid (Doryteuthis pealeii).