Advanced glycation end products (AGEs) have been reported to cause neurodegeneration, senile plaque formation and spatial learning and memory deficits. There is much evidence describing the beneficial effects of aminoguanidine (AG) on the central nervous system; AG is able to inhibit the receptor for AGEs and beta-amyloid (Aβ) deposition in the brain, thus preventing cognitive decline and neurodegeneration. In this study, we investigated whether AG protects against ovariectomy-induced neuronal deficits and Aβ deposition in rats. Animals in the ovariectomy group (OVX) group, and those in the OVX+AG group were treated with AG (100 mg/kg/day) for 8 weeks. Learning and memory were evaluated using the electric Y maze. AGE and Aβ1-40 biochemical assessments were performed using enzyme-linked immunosorbent assay (ELISA) kits. Furthermore, evaluations of brain amyloid precursor protein 695 (APP695) mRNA expression by RT-PCR and AGE expression by immunohistochemistry were carried out. Ovariectomized rats exhibited memory impairment and Aβ production disorder with upregulated APP695 mRNA and AGE expression levels. AG pretreatment relieved the ovariectomy-induced learning and memory disorder and significantly ameliorated the Aβ production disturbance and AGE generation.Additionally, pathological changes in morphology were also significantly recovered. Our data reveal that AG plays a potentially neuroprotective role against ovariectomy-induced learning and cognitive impairment and Aβ production disorder.

The study was carried out in a two-chambered rootbox separated by 37-μm nylon mesh to establish root+hyphae chamber carrying trifoliate orange (Poncirus trifoliata) as the test plant inoculated with Diversispora versiformis and hyphae chamber (without roots). This objective is to evaluate whether exogenous phytohormones regulate mycorrhizal effects on root hairs. Indole butyric acid (IBA), abscisic acid (ABA), and jasmonic acid (JA) (each at 0.1 μM concentration) were weekly applied into hyphae chamber, in total of six times before plant harvest. Mycorrhization strongly stimulated plant growth performance, and exogenous phytohormones, especially IBA, further magnified the mycorrhizal-stimulated growth response. Three exogenous phytohormones significantly decreased mycorrhizal colonization in taproot and first-order lateral roots, but increased in second-and third-order lateral roots, compared with non-phytohormone treatment in mycorrhozal plants. These phytohormones also increased hyphal length in nylon mesh and soil, irrespective of root+hyphae or hyphae chamber. Mycorrhizal inoculation significantly increased root hair density in different root classes, and exogenous hormones further strengthened the mycorrhizal effect. Average root hair length was stimulated by mycorrhization, but all exogenous phytohormones weakened the mycorrhizal response. Mycorrhization in combination with exogenous phytohormones showed no response on root hair diameter. Hence, the result suggested that application of exogenous phytohormones in hyphae chamber strengthened the D. versiformis-induced change in root hair density but weakened in root hair length in trifoliate orange grown in root+hyphae chamber.