Effects of pentobarbital anesthesia on nociceptive processing in the medial and lateral pain pathways in rats.
OBJECTIVE
To investigate the effects of pentobarbital anesthesia on nociceptive processing in the medial and lateral pain pathways.


METHODS
Laser stimulation was employed to evoke nociceptive responses in rats under awake or anesthetic conditions. Pain-related neuronal activities were simultaneously recorded from the primary somatosensory cortex (SI), ventral posterolateral thalamus (VPL), anterior cingulate cortex (ACC), and medial dorsal thalamus (MD) with 4 eight-wire microelectrode arrays.


RESULTS
Compared with the awake state, pentobarbital anesthesia significantly suppressed the neural activities induced by noxious laser stimulation. Meanwhile, the pain-evoked changes in the neuronal correlations between cortex and thalamus were suppressed in both medial and lateral pain pathways. In addition, the spontaneous firing rates in all the 4 areas were altered (including inhibition and excitation) under the condition of anesthesia.


CONCLUSIONS
The nociceptive processing in the brain can be dramatically changed by anesthesia, which indicates that there are considerable differences in the brain activities between awake and anesthetized states. It is better to employ awake animals for recording neural activity when investigating the sensory coding mechanisms, especially pain coding, in order to obtain data that precisely reflect the physiological state.
Wang
Ning
N
Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China.
Zhang
Yang
Y
Wang
Jin-Yan
JY
Gao
Ge
G
Luo
Fei
F
D000200:Action Potentials / Q000187:drug effects; D000758:Anesthesia; D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000503:physiopathology*; D006179:Gyrus Cinguli / Q000187:drug effects / Q000503:physiopathology; D007834:Lasers; D008297:Male; D008839:Microelectrodes; D009433:Neural Inhibition / Q000187:drug effects; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000188:drug therapy* / Q000503:physiopathology*; D010424:Pentobarbital / Q000494:pharmacology*; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000187:drug effects / Q000503:physiopathology; D013788:Thalamus / Q000187:drug effects / Q000503:physiopathology; D014851:Wakefulness / Q000187:drug effects / Q000502:physiology
D000777:Anesthetics; D010424:Pentobarbital