Opioid abuse modifies synaptic plasticity, which leads to behavioral changes, such as
morphine dependence, but the mechanism remains poorly understood. Glial cells play an important role in the modulation of synaptic plasticity and are involved in addictive-like behaviors. The indisputable role of
glutamate in
opiate addiction has been shown. Astrocytes, a type of glial cells, which are integral functional elements of synapses, modulate the concentration of
glutamate in the synaptic space. One of the most important mechanisms for
glutamate concentration regulation is its uptake from the synaptic cleft. In this study, we evaluated the role of hippocampal glial
glutamate transporter (GLT-1) in
morphine dependence. Male rats received subcutaneous (s.c.)
morphine sulfate (10 mg/kg) at an interval of 12 h for 9 days. In order to activate GLT-1, animals received an intrahippocampal injection of
ceftriaxone (0.5 mmol/0.5 μl) in the CA1 region of the hippocampus, 30 min before each
morphine administration. Rats were assessed for
morphine dependence by monitoring
naloxone hydrochloride-induced
morphine withdrawal. Our results showed that hippocampal microinjection of
ceftriaxone, as an activator of GLT-1, reduced some signs of
morphine withdrawal, such as activity,
diarrhea, head
tremor, freezing, and ptosis. It seems that hippocampal GLT-1 can be affected by chronic
morphine administration and involved in
morphine dependence. Therefore, its activation may reduce
morphine side effects by reducing hippocampal
glutamate.