Endocannabinoids (eCBs) are lipophilic signals that are produced by postsynaptic neurons in an activity-dependent manner, and signal in a retrograde fashion to modulate neurotransmitter release. As such, eCBs are highly involved in synaptic plasticity, a process that strengthens or weakens synapses. eCB-mediated synaptic plasticity is involved in many brain processes including learning, short-term memory, and adaptive reward, which are processed in the hippocampus and ventral tegmental area (VTA), respectively. However, the expression of eCB biosynthetic enzyme mRNA within hippocampal and VTA neurons, as well as the relationship between these mRNA species and the occurrence of synaptic plasticity, remains unclear. The goal of these studies was to demonstrate the expression pattern of eCB biosynthetic enzyme mRNA within hippocampal and VTA neurons, and to describe the relationship between synaptic plasticity and mRNA expression. Using whole-cell electrophysiology and real-time quantitative PCR, I tested hippocampal and VTA neurons for the presence of eCB biosynthetic enzyme mRNA and described the relationship between these enzymes and synaptic plasticity. The data presented herein demonstrate the importance of eCB signaling within the hippocampus and VTA and the expression patterns of eCB biosynthetic machinery within several neuron types. These data provide evidence that eCB signaling plays a critical role in learning, short-term memory, and adaptive reward.