Altered Phosphorylation of the Proteasome Subunit Rpt6 Has Minimal Impact on Synaptic Plasticity and Learning.

Dynamic control of protein degradation via the ubiquitin proteasome system (UPS) is thought to play a crucial role in neuronal function and synaptic plasticity. The proteasome subunit Rpt6, an AAA ATPase subunit of the 19S regulatory particle (RP), has emerged as an important site for regulation of 26S proteasome function in neurons. Phosphorylation of Rpt6 on serine 120 (S120) can stimulate the catalytic rate of substrate degradation by the 26S proteasome and this site is targeted by the plasticity-related kinase Ca/calmodulin-dependent kinase II (CaMKII), making it an attractive candidate for regulation of proteasome function in neurons.

Proteasome phosphorylation regulates cocaine-induced sensitization.

Repeated exposure to cocaine produces structural and functional modifications at synapses from neurons in several brain regions including the nucleus accumbens. These changes are thought to underlie cocaine-induced sensitization. The ubiquitin proteasome system plays a crucial role in the remodeling of synapses and has recently been implicated in addiction-related behavior.

Methylphenidate enhances acquisition and retention of spatial memory.

Psychostimulants containing methylphenidate (MPH) are increasingly being used both on and off-label to enhance learning and memory. Still, almost no studies have investigated MPH's ability to specifically improve spatial or long-term memory. Here we examined the effect of training with 1 or 10mg/kg MPH on hidden platform learning in the Morris water maze.

Inhibition of PKC disrupts addiction-related memory.

The atypical PKC isoforms, PKMζ and PKCλ have been proposed as integral substrates of long-term memory (LTM). Inhibition of these isoforms has recently been demonstrated to be sufficient for impairing the expression and maintenance of long-term potentiation. Additionally, the pseudosubstrate inhibitor, zeta inhibitory peptide (ZIP), which effectively blocks PKMζ and PKCλ, has previously been shown to disrupt associative memory; very little is known about its effects on pathological nonassociative forms of memory related to addiction.

Animal model of methylphenidate's long-term memory-enhancing effects.

Methylphenidate (MPH), introduced more than 60 years ago, accounts for two-thirds of current prescriptions for attention deficit hyperactivity disorder (ADHD). Although many studies have modeled MPH's effect on executive function, almost none have directly modeled its effect on long-term memory (LTM), even though improvement in LTM is a critical target of therapeutic intervention in ADHD. We examined the effects of a wide range of doses of MPH (0.