Dietary cholesterol alters memory and synaptic structural plasticity in young rat brain.

Cholesterol plays an important role in synaptic plasticity, learning and memory. To better explore how dietary cholesterol contributes to learning and memory and the related changes in synaptic structural plasticity, rats were categorized into a regular diet (RD) group and a cholesterol-enriched diet (CD) group, and were fed with respective diet for 2 months. Dietary cholesterol impacts on learning and memory, hippocampal synaptic ultrastructure, expression levels of postsynaptic density-95 (PSD-95), synaptophysin (SYP) and cannabinoid receptor type 1 (CB1R) were investigated. We found CD rats had better performances in learning and memory using Morris water maze and object recognition test than RD rats. The memory improvement was accompanied with alterations of synaptic ultrastructure in the CA1 area of the hippocampus evaluated by electron microscopy, enhanced immunoreactivity of SYP, a presynaptic marker in hippocampus detected by immunocytochemistry, as well as increased levels of PSD-95, SYP and decreased level of CB1R in brains of CD rats determined by Western blot. Taken together, the results suggest that the improvement of learning and memory abilities of the young adult rats induced by dietary cholesterol may be linked with changes in synaptic structural plasticity in the brain.

[Effect of low density lipoprotein oxidizing in hyperlipidemia rats after treating with tetrahydrobiopterin].

OBJECTIVE: To explore the oxidative modification effect and its mechanism of low density lipoprotein (LDL) in hyperlipidemia (HL) rats after treating with tetrahydrobiopterin (BH4). METHODS: Fifty four 8-week-old male Wistar rats were used, these 54 rats were randomly divided into control group, high fat diet group (HL group), high fat diet and injected BH4 group (HL + BH4 group), and 18 in each group. The BH4 levels of blood fats and blood serum and its metabolites, the aortic reactive oxygen species, the end product malondialdehyde (MDA) and the LDL oxidation level were all determined by killing 6 experimental rats in each group at the first 8, 16, and 24 weeks of age respectively. RESULTS: Treating with BH4 after 8 and 16 weeks, there was no significant difference in serum lipids among three groups (P > 0. 05); but ROS and MDA decreased significantly (P < 0.01); compared with control and HL groups, the BH4 level of HL + BH4 group increased a lot (P < 0.01); compared with control group, the BH4 content reduced obviously in aortic homogenate of HL group (P < 0.01), but the total petrin levels (TB = BH4 + BH2 + B) had no significant difference (P > 0.05); the serum TBARS formation increased gradually with the increase of week-ages, but compared with HL group, the serum TBARS formation of HL + BH4 group reduced significantly (P < 0. 01). CONCLUSION: Treating with BH4 can reduced the LDL oxidation, the mechanism may be related to the correct of NOS uncoupling, the reduce of ROS generation and the decrease of LDL lipid peroxidation.

[Lipid peroxidation and biomechanical properties of artery in hyperlipemia rats after treating with tetrahydrobiopterin].

OBJECTIVE: To explore the effect of the level of lipid peroxidation and biomechanical properties after chronic treating with tetrahydrobiopterin (BH4) in thoracic aorta of hyperlipemia (HL) rats. METHODS: HL rats were given BH4 chronically. The opening angle in the zero-stress state and the relationship between pressure and diameter (P-D) of mesenteric artery were measured by computer image 8, 16, and 24 week-old respectively. RESULTS: Treating with BH4 chronically from 8 week-old in HL rats, there was a significant increase in the zero-stress state of opening angle of thoracic aorta. The P-D curve of mesenteric artery moved upward. CONCLUSION: Treating with BH4 prevented the structure and function of artery from abnormal changing, and attenuated lipid peroxidation in HL rats.

[Biomechanical properties of artery in spontaneously hypertensive rats after treating with tetrahydrobiopterin].

AIM: To explore the effect of remodeling and biomechanical properties after chronic treating with tetrahydrobiopterin (BH4) in spontaneously hypertensive rats. METHODS: The spontaneously hypertensive rat(SHR) were given with BH4 chronically. The opening angle in the zero-stress state , wall-to-lumen area ratios (W/L) of thoracic aorta and the relationship between pressure and diameter (P-D) of mesenteric artery were measured by computer image analysis in 4, 16, and 26 week-old respectively. RESULTS: Treating with BH4 chronically from 4 weeks-old in SHR, there was a significant decrease in morphometric parameters of the thoracic aorta and an increase in the zero-stress state of opening angle of elastic artery. The P-D curve of mesenteric artery moved upward. CONCLUSION: Treating with BH4 prevented the structure and function of artery from abnormal changing, including to attenuate the resistant vascular hypertrophy and recover the vascular elasticity and expansibility.