Regulation of Hypnotic Active Components of Cnidii Fructus on Melatonin Synthesis Rate-limiting Enzyme AANAT in Rats with PCPA-induced Insomnia / 中国实验方剂学杂志

Objective:To observe the effects of Cnidii Fructus hypnotic active components （CHC） on the behaviors of rats with p-chlorophenylalanine （PCPA）-induced insomnia and melatonin （MT） synthesis rate-limiting enzyme arylalkylamine <italic>N</italic>-acetyltransferase （AANAT）， and explore the protective mechanism of CHC on the pineal gland. Method:Male SD rats of SPF grade were randomly divided into a blank control group， a model group， a MT group， and high-， medium-， and low-dose CHC groups with 10 rats in each group. Except for the blank control group， other groups received 4.5% PCPA suspension at 10 mL·kg^-1， intragastric administration， for two consecutive days. After PCPA model of insomnia was established， normal and model groups were gavaged at the same volume of 2% Tween-80， MT control group （10 mg·kg^-1）， CHC was high， medium and low （60， 30， 15 mg·kg^-1）， 10 mL·kg^-1， once a day， for consecutive 7 days. Four days after administration， open field， elevated cross maze， and pentobarbital sodium-induced sleep tests were conducted， respectively. Serum MT was detected by enzyme-linked immunosorbent assay. The mRNA expression level of AANAT was determined by real-time fluorescence-based quantitative polymerase chain reaction （Real-time PCR）. The expression of AANAT protein in the pineal gland was detected by Western blot. Result:Compared with the results in the blank control group， the total distance of open field activity and standing times and duration in the central area were increased （<italic>P</italic><0.05， <italic>P</italic><0.01）， the proportions of open arm entry （OE%） and open arm time （OT%） were decreased （<italic>P</italic><0.05）， and the sleep latency was prolonged （<italic>P</italic><0.01） in the model group. Compared with the model group， no significant difference was observed in the low-dose CHC group， while other groups exhibited reduced total distance of activity （<italic>P</italic><0.05， <italic>P</italic><0.01）， elevated OE% （<italic>P</italic><0.05）， shortened sleep latency， and prolonged sleep time （<italic>P</italic><0.05， <italic>P</italic><0.01）. Compared with the serum MT in the blank control group， that in the model group was decreased （<italic>P</italic><0.01）. Compared with the model group， no significant difference was observed in the low-dose CHC group， while other groups displayed increased serum MT （<italic>P</italic><0.05）. The mRNA and protein expression of AANAT was decreased in the model group as compared with that in the blank control group （<italic>P</italic><0.01）. Compared with the model group， the MT group and the high-dose CHC group showed up-regulated expression （<italic>P</italic><0.05）. Conclusion:CHC improved the behavioral indexes of PCPA-induced insomnia， increased the synthesis and secretion of MT in pineal cells， and elevated the serum MT level， which was related to the up-regulation of the mRNA and protein expression of AANAT in the pineal gland.