Change of cholinergic transmission and memory deficiency induced by injection of beta-amyloid protein into NBM of rats

Phenolic Content Analysis of Two Species Belonging to the Lamiaceae Family: Antioxidant, Anticholinergic, and Antibacterial Activities

The Lamiaceae family are utilized as ornamental, medicinal, and food supplements throughout the world. The current study focuses on a comparative analysis of the phenolic compositions and bioactivities (including antioxidant, anticholinergic, and antibacterial activities) of ethanolic extracts derived from the aerial parts of the two species (Lavandula stoechas L. and Thymus sipyleus Boiss). The presence of phenolic compounds and phytochemicals in the plant extracts was identified using the LC-MS/MS technique. The LC-MS/MS analysis revealed that vanillic acid (125,596.66 µg/L) was the most abundant phytochemical in L. stoechas. Kaempferol (8550.52 µg/L) was the most abundant substance in Thymus sipyleus. The assessment of the antioxidant efficacy of the species extracts was conducted using the DPPH (2.2-diphenyl-1-picryl-hydrazyl-hydrate), ABTS (2.2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)), Fe3+-Fe2+ reducing, and CUPRAC (Cu2+-Cu+ reducing) assays. The anticholinergic activity of the samples was determined using the acetylcholinesterase (AChE) inhibition assay. The results of antioxidant activity were higher in the T. sipyleus than in the L. stoechas ethanol extracts. The extracts of L. stoechas exhibited radical scavenging activity ranging from 15 to 18%, while T. sipyleus had activity effects ranging from 34% to 38%. The AChE inhibition potential for L. stoechas and T. sipyleus extracts as IC50 values were 0.221 ± 0.01 mg/mL and 0.067 ± 0.02 mg/mL, respectively. The antibacterial effects of the ethanolic extracts of these species against pathogenic bacteria isolates were determined using the MIC (minimal inhibitory concentration) method. These findings indicated that the extracts from L. stoechas and T. sipyleus possess the potential to be natural antioxidants in the realm of food preservation. Additionally, their antioxidant, anticholinergic, and antimicrobial properties suggest potential therapeutic utility in the management of certain diseases.

Gender-Specific Hippocampal Dysrhythmia and Aberrant Hippocampal and Cortical Excitability in the APPswePS1dE9 Model of Alzheimer's Disease

Alzheimer's disease (AD) is a multifactorial disorder leading to progressive memory loss and eventually death. In this study an APPswePS1dE9 AD mouse model has been analyzed using implantable video-EEG radiotelemetry to perform long-term EEG recordings from the primary motor cortex M1 and the hippocampal CA1 region in both genders. Besides motor activity, EEG recordings were analyzed for electroencephalographic seizure activity and frequency characteristics using a Fast Fourier Transformation (FFT) based approach. Automatic seizure detection revealed severe electroencephalographic seizure activity in both M1 and CA1 deflection in APPswePS1dE9 mice with gender-specific characteristics. Frequency analysis of both surface and deep EEG recordings elicited complex age, gender, and activity dependent alterations in the theta and gamma range. Females displayed an antithetic decrease in theta (θ) and increase in gamma (γ) power at 18-19 weeks of age whereas related changes in males occurred earlier at 14 weeks of age. In females, theta (θ) and gamma (γ) power alterations predominated in the inactive state suggesting a reduction in atropine-sensitive type II theta in APPswePS1dE9 animals. Gender-specific central dysrhythmia and network alterations in APPswePS1dE9 point to a functional role in behavioral and cognitive deficits and might serve as early biomarkers for AD in the future.

Comparative study of the neuroprotective and nootropic activities of the carboxylate and amide forms of the HLDF-6 peptide in animal models of Alzheimer's disease

A comparative study of the neuroprotective and nootropic activities of two pharmaceutical substances, the HLDF-6 peptide (HLDF-6-OH) and its amide form (HLDF-6-NH2), was conducted. The study was performed in male rats using two models of a neurodegenerative disorder. Cognitive deficit in rats was induced by injection of the beta-amyloid fragment 25-35 (βA 25-35) into the giant-cell nucleus basalis of Meynert or by coinjection of βA 25-35 and ibotenic acid into the hippocampus. To evaluate cognitive functions in animals, three tests were used: the novel object recognition test, the conditioned passive avoidance task and the Morris maze. Comparative analysis of the data demonstrated that the neuroprotective activity of HLDF-6-NH2, evaluated by improvement of cognitive functions in animals, surpassed that of the native HLDF-6-OH peptide. The greater cognitive/ behavioral effects can be attributed to improved kinetic properties of the amide form of the peptide, such as the character of biodegradation and the half-life time. The effects of HLDF-6-NH2 are comparable to, or exceed, those of the reference compounds. Importantly, HLDF-6-NH2 exerts its effects at much lower doses than the reference compounds.

Amyloid Beta peptides differentially affect hippocampal theta rhythms in vitro

Soluble amyloid beta peptide (A β ) is responsible for the early cognitive dysfunction observed in Alzheimer's disease. Both cholinergically and glutamatergically induced hippocampal theta rhythms are related to learning and memory, spatial navigation, and spatial memory. However, these two types of theta rhythms are not identical; they are associated with different behaviors and can be differentially modulated by diverse experimental conditions. Therefore, in this study, we aimed to investigate whether or not application of soluble A β alters the two types of theta frequency oscillatory network activity generated in rat hippocampal slices by application of the cholinergic and glutamatergic agonists carbachol or DHPG, respectively. Due to previous evidence that oscillatory activity can be differentially affected by different A β peptides, we also compared Aβ 25-35 and Aβ 1-42 for their effects on theta rhythms in vitro at similar concentrations (0.5 to 1.0  μ M). We found that Aβ 25-35 reduces, with less potency than Aβ 1-42, carbachol-induced population theta oscillatory activity. In contrast, DHPG-induced oscillatory activity was not affected by a high concentration of Aβ 25-35 but was reduced by Aβ 1-42. Our results support the idea that different amyloid peptides might alter specific cellular mechanisms related to the generation of specific neuronal network activities, instead of exerting a generalized inhibitory effect on neuronal network function.

Comparative physiology in China 1984-2007

We briefly summarize the history of the rise of comparative physiology in China, the research work focused on by domestic and international counterparts in the field of comparative physiology of China, and international academic exchange and collaboration during this period. We also introduce some of the interesting model systems used in past and current research. This paper is based on documents in historical materials such as the proceedings of the 1st (August 1988) to 6th (October, 2007) Comparative Physiology Academic Session of the Chinese Association for Physiological Sciences, collected physiological works in commemoration academic papers of the 70th (1926-1999) and 80th anniversary of the Chinese Association for Physiological Sciences (1926-2006), CBP and the Physiology History of China, and the authors' own research experience.