| Alzheimer’s disease(AD)is a common neurodegenerative disease characterized by cognitive decline.Clinical manifestations of AD include memory impairment,language impairment,and cognitive impairment.The patient’s cognitive ability and emotional control ability decline,the quality of life is seriously affected.It also causes a huge burden on the family.AD is pathologically characterized by powder-like protein β(Aβ)deposition in the brain,inflammatory responses caused by hyperphosphorylation of Tau protein to form neurofibrillary tangles(NFTs),neuronal damage,neuronal apoptosis,synapse loss,and oxidative stress.Current AD treatments only provide limited relief of cognitive and functional decline in the early stages of the disease,so far there is no cure,and can lead to a series of adverse effects,the treatment of AD remains an area of unmet need.Global anti-AD drugs have repeatedly failed in clinical practice but the clinical success rate is extremely low.Drugs acting on a single pathway is unlikely to alleviate the complex pathological cascade of AD.So researchers are increasingly focusing on multi-pathway,multi-targeted therapeutic approaches.In recent years,phytocannabinoids have attracted extensive attention as potential therapeutic targets in central nervous system diseases.Cannabis(Cannabis sativa Linn.)is an annual herb of the Moraceae(Moraceae)cannabis genus(Cannabis Linn.).For thousands of years,cannabis has been detailly recorded in many ancient herbal medicine books as a medicinal plant.The "Compendium of Materia Medica" records that cannabis "treats forgetfulness and trauma".They are involved in various physiological processes such as memory,learning,and immunity.Phytocannabinoids can protect neurons and promote nerve regeneration.Therefore,these compounds have the potential to become new treatments for AD.drug.Over 130 cannabinoids have been isolated from cannabis dry matter and fresh cannabis leaves in recent studies,with addictive ingredient cannabidiol(THC)and nonaddictive ingredient cannabidiol(CBD)showed highest content level.CBD has clinically confirmed anti-epileptic,anti-spasmodic,anti-anxiety,and anti-inflammatory effect among other effects.At present,a number of new drugs with CBD as the main component have been developed.In vitro experimental studies have shown that CBD is related to various processes of AD disease progression,participates in neuroprotection,prevents hippocampal and cortical neurodegeneration,has anti-inflammatory and antioxidant properties,and becomes a potential drug in AD treatment.However,the specific mechanism of CBD’s anti-AD effect is still unclear.The pathogenesis of AD is related to the metabolic disturbance of various neurotransmitters.Aβ can seriously damage the neurotransmitter system,such as the loss of cholinergic neurons and the destruction of glutamatergic neurotransmission,and the deposition of A(3 results in impaired synaptic transmission and abnormal release of neurotransmitters such as monoamines,amino acids,and acetylcholine.Aβ and hyperphosphorylated Tau protein interfere with the release of neurotransmitters in the synaptic cleft,causing neurotransmitter disorders,and thereby,leads to the impairment of learning and memory functions.Studies have shown that reduced level of acetylcholine(Ach)have deleterious effects on learning and memory functions.For example,increased release of excitatory transmitters such as glutamate(Glu)can lead to excitotoxicity.Inhibitory transmitters such as gamma-aminobutyric acid(GABA)Sex transmitters exert postsynaptic mode inhibition function and participate in the process of delayed neuronal damage.Also,dopamine(DA)secretion is reduced at the sites of A(3 deposition and NFTs.Overall,abnormal neurotransmitters are considered to be one.of the important causes of cognitive,memory,and learning impairments in AD.So far,there is no research on the direct effects of CBD on the glutamatergic and cholinergic systems in the field of AD.In this study,CBD’s effects on neurotransmitter changes in specific nuclei of AD model mice induced by Aβ were studied.Due to the strong fat solubility of CBD,the solubility in various pH solutions is extremely low,the absorption process of insoluble drugs in the body is complicated,and different solvents have a great impact on the bioavailability of drugs.Using CBD powder with a purity of 99.9%provided by Heilongjiang Zhongsheng Biotechnology Co.,Ltd.,this subject investigated the pharmacokinetics(PK)behavior of Tween 80 as a solubilizer to dissolve CBD in rats.To sum up,this topic conducted a Morris water maze(MWM)experiment to explore the cognitive function improvement effect of CBD on AD after long-term administration of CBD to APP/PS1 transgenic model mice,and to investigate the effect of CBD on neuronal pathological morphology,neuroinflammation and other functions;the LC-MS determination method of CBD in serum was established,and the pharmacokinetic differences of CBD in different solvent were investigated;and AD was induced by Aβ.A mouse model to investigate the differences in the effects of different dosage forms of CBD on neurotransmitters in the brain.The main experimental methods and results are as follows:a.Established an LC-MS method for the determination of cannabidiol(CBD)in serum of SD rats,and to study the pharmacokinetic characteristics of CBD in normal rats.The linear relationship of CBD in serum is good,the extraction recovery rate is 103.3%～115.7%,the intra-day and inter-day precision RSD is less than 15.0%,and the sample is stable at-80℃.CONCLUSION:Compared with the existing literature,this analytical method has shorter time-consuming,less sample injection,specificity and sensitivity that can meet the pharmacokinetics determination of rat serum.The Tmax of CBD Tween solution is only 2 hours,which can be rapidly distributed in the blood,and the Tmax of CBD oil is 9 hours.Both of them quickly pass through the blood-brain barrier and enter the brain within 30 minutes after administration,and are metabolized out of the body within 48 hours.b.In this paper,the APP/PS1 transgenic mice were used as the research object to investigate the effect of CBD on its behavior and pathology.Morris water maze(MWM)test and immunohistochemistry were performed after 21-day of CBD gavage.The experimental results showed that APP/PS1 mice had obvious memory deficits.CBD significantly shortened the escape latency of APP/PS1 mice(p<0.05),and increased the number of crossing platforms,platform retention time,and movement distance(p<0.05).The memory,learning,and motor abilities of the mice were improved.The escape latency line graph from day 1 to day 6 confirmed the memory deficit of APP/PS1 mice.The line graphs of the CBD treatment group are all closer to the normal group;proving effectiveness of CBD treating cognition dysfunction.The results of Iba1 immunohistochemistry showed that the model group had a large number of deep-stained positive cells,with clear cell shapes,enlarged cell bodies,and branched meshes.The CBD dose groups and the positive group had different degrees of reduction,suggesting that CBD may functions by reducing the activation of microglia,and reducing the inflammatory response.c.In this paper,the AD mouse model was induced by intracerebral injection of Aβ.The effect of CBD on neurotransmitters such as monoamines,amino acids and acetylcholine in the hippocampus and cortex was investigated based on LC-MS/MS technology.The experimental results are as follows:I Compared with the normal group,the content of Glu in the hippocampus and cortex of the model group was significantly decreased,with a significant difference(p<0.05),and the content of GABA in the model group had an increasing trend;Glu and GABA data of the Tween and oil blank vehicle group and the model group No significant difference.Compared with the model group,the positive group could decrease the content of Glu in the cortex and hippocampus(p<0.01),increase the content of GABA(p<0.05),and the value of Glu/GABA in the hippocampus was significantly decreased(p<0.001).Compared with the model group,CBD could restore Glu levels in the hippocampus and cortex(p<0.01),and there was a doseeffect relationship in the hippocampus.There was no significant difference between the medium-dose and high-dose groups of CBD in different vehicles and the positive group.Each administration group could adjust the level of GABA in the hippocampus to varying degrees(p<0.05),while the medium-dose and high-dose groups of different vehicles failed to restore the GABA level in the cortex.The Glu/GABA values were significantly decreased in each CBD dose group with different vehicles(p<0.001).This suggests that CBD affects cognitive function by reducing excitotoxicity in the brain and avoiding neuronal loss or death.CBD can significantly restore acetylcholine levels in the hippocampus and cortex of mice.The Ach level in the model group was significantly lower than that in the normal group(p<0.01).The vehicle had no effect on the Ach levels in the hippocampus and cortex,and the positive drugs significantly increased the Ach content,which was in line with the efficacy of acetylcholinesterase(AchE)inhibitors.Both medium and high-dose CBD of different vehicles could restore the Ach level in the hippocampus of model mice(p<0.01),and each dose group could restore the Ach level in the cortex of model mice(p<0.01).It can significantly increase the Ach content in the hippocampus and cortex(p<0.05),and there is a dose correlation in the hippocampus,suggesting that CBD may improve learning and memory in mice by restoring Ach levels ability to improve cognitive impairment.CBD affected 5-HT,5-HIAA,DA,dopac levels in mouse cortex and hippocampus.The levels of 5-HT and 5-HIAA in the hippocampus and intracortical model group were significantly lower than those in the normal group(p<0.001).The positive drug group could restore the levels of 5-HT and 5-HIAA in the hippocampus of the model mice(p<0.05,p<0.001);there was no significant difference in the content of 5-HT in the cortex compared with the model group,but the content of 5-HIAA was significantly increased(p<0.001).Compared with the model group,different CBD dose groups increased the levels of 5-HT and 5-HIAA in the hippocampus and cortex(p<0.05),and decreased the value of 5-HT/5-HIAA in the hippocampus and cortex(p<0.05).p<0.05,p<0.05).The contents of DA and dopac in the hippocampus and cortex of the model group were significantly lower than those of the normal group(p<0.01),and the vehicle had no effect on the levels of transmitters.The positive drug group could restore the contents of DA and dopac in the hippocampus and cortex of the model mice(p<0.01),but there was no significant difference in the content of DA in the hippocampus compared with the model group.Compared with the control group,the contents of DA and dopac in the cortex increased in different CBD solvent and dose groups(p<0.01,p<0.01);in the hippocampus,the CBD Tween solvent high-dose group and the CBD oil dose groups The content of DA increased(p<0.05),the content of dopac increased in the CBD Tween medium and high dose groups and the CBD oil low and medium dose groups(p<0.05).In the hippocampus,the DA/dopac values in the low and high dose CBD oil groups were significantly increased(p<0.05,p<0.05);in the cortex,the CBD oil low,medium and high dose groups and the CBD oil low and high dose groups DA/dopac Values have different degrees of recovery,and there is a significant difference(p<0.001).It shows that CBD may effectively increase neuronal activity and improve cognitive function by promoting the synthesis of 5-HT and DA. |
