The late positive potential and subjective arousal ratings evoked by negative images vary as a function of oxytocin receptor genotype SNP rs53576.

In the central nervous system the neuropeptide oxytocin mediates a range of behaviors related primarily to emotionality. One factor that influences oxytocinergic communication in the human brain and correlates with emotional behaviors is the single nucleotide polymorphism rs53576 on the oxytocin receptor gene (OXTR). For example, variations in this OXTR genotype are related to parental, altruistic, and other prosocial behaviors. Electroencephalographic waveforms of visually evoked response potentials recorded at the midline parietal electrode site display a prominent component putatively involved with attention allocation called the late positive potential. The magnitude of the late positive potential was found to be significantly higher in homozygous G allele individuals compared with A allele carriers when viewing negative emotionally charged images. Inversely, A allele carriers rated these negative images as more arousing, when measured by the Self-Assessment Manikin rating scale. These data suggest that OXTR functioning contributes to visual processing and subjective experience of negative stimuli.

Continuous intracerebroventricular infusion of the competitive NMDA receptor antagonist, LY235959, facilitates escalation of cocaine self-administration and increases break point for cocaine in Sprague-Dawley rats.

Although escalation of consumption is an important characteristic of cocaine dependence, the neurobiological mechanisms that mediate this phenomenon have not been fully described. In this study, we used male, Sprague-Dawley rats to measure the effects of acute and continuous intracerebroventricular (ICV) administration of the competitive NMDA receptor antagonist, LY235959, on cocaine self-administration behavior under various schedules of reinforcement and access conditions. Single ICV infusions of LY235959 (0.03-0.3 microg/5 microl) produced dose-dependent and statistically significant decreases in the number of cocaine infusions earned under a progressive ratio schedule of reinforcement. In a second experiment, vehicle or LY235959 (0.2-0.3 microg/day) was continuously administered ICV to rats via surgically-implanted subcutaneous osmotic minipump/intracranial cannula assemblies. Both vehicle- and LY235959-treated rats significantly escalated cocaine self-administration over the 10 long access sessions; however, rats treated with LY235959 escalated cocaine self-administration faster and to a greater degree than vehicle-treated rats. There was a statistically significant increase in cocaine infusions earned under the PR schedule in LY235959-treated rats, but not vehicle-treated rats, after 10 long access cocaine self-administration sessions. These data support the hypothesis that escalation of cocaine consumption is mediated by hypo-glutamatergic tone in the central nervous system and this facilitation of escalation is associated with an increase in motivation to respond for cocaine.

Mild forced treadmill exercise enhances spatial learning in the aged rat.

This study addresses whether or not mild, forced treadmill exercise improves learning and increases neurotrophin levels in the basal forebrain (BF). Neurotrophin deficits in the BF have been implicated in Alzheimer's disease, and physical exercise increases neurotrophins. Aged rats exercised for 7 weeks found the hidden platform faster than controls (F(1, 10)=14.6, p<0.05), and swam shorter pathlengths (F(1, 10)=12.6, p<0.05), with no difference in swim speed. Neurotrophins did not differ.

Leverpress escape/avoidance training increases neurotrophin levels in rat brain.

In addition to their well-known role in neural development, the neurotrophins BDNF and NGF help mediate the plasticity that occurs in the brain to promote learning. Exposure to learning procedures often leads to increases in neurotrophins, while exposure to stress often results in decreases. It is unclear how the neurotrophins would respond to an aversive learning task. Therefore, BDNF and NGF content in the dorsal striatum, hippocampus, and basal forebrain was measured following discrete trial lever-press escape/avoidance conditioning. Conditioning significantly increased levels of both neurotrophins in hippocampus and basal forebrain, relative to home cage controls (HCC). Contrary to expectations, the dorsal striatum did not show any significant changes. However, significant correlations were observed between dorsal striatal neurotrophins and aspects of avoidance performance. This may indicate that the dorsal striatum is involved in the performance aspects of the task. Results are discussed in terms of the role of neurotrophins in the acquisition of new information, and the neural structures involved in different types of memory.