Macamide B Pretreatment Attenuates Neonatal Hypoxic-Ischemic Brain Damage of Mice Induced Apoptosis and Regulates Autophagy via the PI3K/AKT Signaling Pathway

Abstract

Lepidium meyenii (Maca) is an annual or biennial herb from South America that is a member of the genus Lepidium L. in the family Cruciferae. This herb has antioxidant, anti-apoptotic, and enhances autophagy functions and can prevent cell death, and protect neurons from ischemic damage. Macamide B, an effective active ingredient of maca, has a neuroprotective role in neonatal hypoxic-ischemic brain damage (HIBD), and the underlying mechanism of its neuroprotective effect is not yet known. The purpose of this study is to explore the impact of macamide B on HIBD-induced autophagy and apoptosis and its potential mechanism for neuroprotection. The modi ed Rice-Vannucci method was used to induce HIBD on 7-day-old (P7) macamide B and vehicle-pretreated pups. TTC staining was used to evaluate the cerebral infarct volume of pups, brain water content was measured to evaluate the neurological function of pups, neurobehavioral testing was used to assess functional recovery after HIBD, TUNEL and FJC staining was used to detect cell autophagy and apoptosis, and western blot analysis was used to detect the expression levels of the pro-survival signaling pathway phosphatidylinositol-3kinase/protein kinase B (PI3K/AKT) and autophagy and the apoptosis-related proteins. The results show that macamide B pretreatment can signi cantly decrease brain damage, improve the recovery of neural function after HIBD. At the same time, macamide B pretreatment can induce the activation of PI3K/AKT signaling pathway after HIBD, enhance autophagy, and reduce hypoxic-ischemic (HI)-induced apoptosis.In addition, 3-methyladenine (3-MA), an inhibitor of PI3K/AKT signaling pathway, signi cantly inhibits the increase in autophagy levels, aggravates HI-induced apoptosis, and reverses the neuroprotective effect of macamide B on HIBD. Our data indicate that macamide B pretreatment might regulate autophagy through PI3K/AKT signaling pathway, thereby reducing HIBD-induced apoptosis and exerting neuroprotective effects on neonatal HIBD. Macamide B may become a new drug for the prevention and treatment of HIBD.

Enhanced autophagy interacting proteins negatively correlated with the activation of apoptosis-related caspase family proteins after focal ischemic stroke of young rats

“…Some previous studies proved that rapamycin increased autophagy, decreased apoptosis and significantly alleviated brain injury in neonatal rats after hypoxia–ischemia [ 29 ]. The neuroprotective mechanism of Macamide B on neonatal hypoxic-ischemic brain damage may be related to the activation of the PI3K/AKT signaling pathway, the enhancement of autophagy, and the reduction of apoptosis induced by hypoxia and ischemia [ 35 ]. Chloroquine has been shown to inhibit autophagy and exacerbate neuronal mitochondrial dysfunction and apoptosis in hypoxia rats, thus implying the neuroprotective effects of autophagy in hypoxic-ischemic encephalopathy [ 36 ].…”

Neuroprotective Mechanism of Icariin on Hypoxic Ischemic Brain Damage in Neonatal Mice

“…Subsequently, the cerebral hemispheres were dried in an oven at 106°C for 24 h for dry weight measurement. Percentage of brain water content = (wet weight − dry weight)/wet weight × 100% [ 60 ].…”

“…Neurobehavioral Assessments. On the 1st, 3rd, 5th, and 7th days after HI, two fixed researchers carried out the righting reflex, negative geotaxis, and grip tests on C57BL/6 newborn mice both 8 : 00 AM and 8 : 00 PM without clear grouping and recorded the weights of the pups [60]. All behavioral experiments were conducted in a quiet environment, with few people stirring and gentle movements.…”

“…°C for 24 h for dry weight measurement. Percentage of brain water content = ð wet weight − dry weightÞ/wet weight × 100%[60].2.8. Preparation of Tissue Paraffin Sections.…”

Neuroprotective mechanism of icariin on hypoxic- ischemic brain damage in neonatal mice

“…Under the condition of unclear grouping, two xed researchers performed the righting test, negative geotaxis test, and grip test on C57BL/6 neonatal mice at a xed time, and recorded the body weight of the neonatal mice. The speci c operations can be seen in the previous report [75]. All behavioral experiments should be conducted in a quiet environment, with fewer people moving and gentle movements.…”