Chronic morphine exposure induces degradation of receptive field properties of LGN cells in cats.
OBJECTIVE
To investigate the effect of chronic morphine exposure on the receptive field properties of lateral geniculate nucleus (LGN) neurons in cats.


METHODS
Cats were injected with morphine (10 mg/kg) or saline twice daily, for 10 d. Subsequently, extracellular single-unit recording techniques were used to examine the sensitivity of LGN neurons to visual stimuli in chronic morphine-treated and saline-treated cats.


RESULTS
Compared with saline-treated cats (as controls), LGN neurons in morphine-treated cats had decreased signal-to-noise ratios (1.9 vs 3.1), and orientation and direction sensitivity (0.103 vs 0.135 and 0.074 vs 0.10, respectively), accompanied by significant increases in spontaneous (27.4 vs 17.5) and evoked activity (preferred: 42.2 vs 38.1; average: 28.1 vs 22.3).


CONCLUSIONS
Chronic morphine exposure can lead to the functional degradation of LGN neurons in cats, which might result from the effects of chronic morphine exposure on inhibitory neurotransmission.
He
Li-hua
LH
Hefei National Laboratory for Physical Sciences at Microscale and School of Life Science, University of Science and Technology of China, Hefei 230027, China.
Li
Guang-xing
GX
Li
Xiang-rui
XR
Zhou
Yi-feng
YF
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002415:Cats; D005829:Geniculate Bodies / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000009:adverse effects*; D009294:Narcotics / Q000008:administration & dosage / Q000009:adverse effects*; D009433:Neural Inhibition / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009949:Orientation / Q000187:drug effects*; D010775:Photic Stimulation
D009294:Narcotics; D009020:Morphine