Assessing the effect of drug tolerance due to chronic administration of morphine and salicylate on synaptic plasticity

Salicylates and opioids are widely used in chronic pain relief. Chronic use of these drugs reorganizes synaptic function, especially experience-dependent plasticity in brain regions. Therefore, in this study the effects of chronic administration of salicylate and morphine on synaptic plasticity were investigated.
in this review, Elsevier, Science Direct, PubMed and Google Scholar databases were searched for the following keywords: salicylate, morphine, drug tolerance, and synaptic plasticity. At the end, 62 of the obtained reports were included in the study.
In addition to induction of tolerance to anti-nociceptive effect and cross-tolerance, chronic salicylate administration as like as morphine has long-lasting effects on hippocampal neuronal networks which are manifested as excitability of neurons and ability of activity and experience-dependent plasticity. Some of these effects can be documented in the hippocampus-related functions such as spatial learning and memory.
Considering the effects of salicylate and morphine on the nervous system and synaptic transmission, the effects of these drugs on the processing of input data and as a result on cognitive functioning would not be unlikely, thus necessitating further behavioral and electrophysiological studies.