[Effect of 5-HT7 receptor agonist on pyramidal neurons in the medial frontal cortex in a rat model of Parkinson's disease].
OBJECTIVE
To investigate the activity of pyramidal neurons in the medial prefrontal cortex (mPFC) of normal and 6-OHDA-lesioned rats and the responses of the neurons to 5-hydroxytryptamine-7 (5-HT(7)) receptor stimulation.


METHODS
The changes in spontaneous firing of the pyramidal neurons in the mPFC in response to 5-HT(7) receptor stimulation were observed by extracellular recording in normal and 6-OHDA-lesioned rats.


RESULTS
Both systemic and local administration of 5-HT(7) receptor agonist AS 19 resulted in 3 response patterns (excitation, inhibition and no change) of the pyramidal neurons in the mPFC of normal and 6-OHDA-lesioned rats. In normal rats, the predominant response of the pyramidal neurons to AS 19 stimulation was excitatory, and the inhibitory effect of systemically administered AS 19 was reversed by GABAA receptor antagonist picrotoxinin. In the lesioned rats, systemic administration of AS 19 also increased the mean firing rate of the pyramidal neurons, but the cumulative dose for producing excitation was higher than that in normal rats. Systemic administration of AS 19 produced an inhibitory effect in the lesioned rats, which was partially reversed by picrotoxinin. Local administration of AS 19 at the same dose did not change the ?ring rate of the neurons in the lesioned rats.


CONCLUSIONS
The activity of mPFC pyramidal neurons is directly or indirectly regulated by 5-HT7 receptor, and degeneration of the nigrostriatal pathway leads to decreased response of these neurons to AS 19.
Department of Physiology, Medical College, Henan University of Science and Technology, Luoyang 471003, China. E-mail: emmafll@163.com.
Ling-Ling
LL
Fan
Bo
B
Deng
Jun-Bao
JB
Yan
Zhi-Hong
ZH
Hu
Ai-Hong
AH
Ren
Yong-Mei
YM
Hu
Dong-Wei
DW
Yang
D000200:Action Potentials; D000818:Animals; D016627:Oxidopamine; D010300:Parkinson Disease / Q000378:metabolism*; D017397:Prefrontal Cortex / Q000166:cytology*; D017966:Pyramidal Cells / Q000187:drug effects*; D051381:Rats; D011985:Receptors, Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*
D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; C104425:serotonin 7 receptor; D016627:Oxidopamine