Protective effect of astaxanthin against cognitive impairment in offspring prenatally exposed to maternal epilepsy

Objective To investigate the protective effect of prenatal astaxanthin treatment against cognitive impairment in adult offspring induced by exposure to maternal seizures in utero. Methods Female adult Sprague-Dawley rats were randomly divided into four groups: control group, astaxanthin group, kindling group and kindling+astaxanthin group. Each rat was implanted with electrodes. Those in the kindling and kindling+astaxanthin groups were kindled once a day by electrical stimulation of the amygdala. All rats were allowed to mate after one week's amygdala kindling. Rats in the kindling and kindling+astaxanthin groups continued to be treated with electrical stimulation every 48 hours from gestational day 1 to 20, and those in the astaxanthin and kindling+astaxanthin groups were injected intraperitoneally with 30 mg/(kg·d) of astaxanthin simultaneously. Naturally delivered offspring were raised till 12 weeks of age. Morris water maze test was performed to assess the cognitive function of adult offspring. Changes in the morphology of hippocampus were observed with Nissal's staining and transmission electron microscope. Expression of cyclic adenosine monophosphate response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in adult offsprings' hippocampus tissues at protein and mRNA levels were determined using Western-blotting and reverse transcription-polymerase chain reaction. Analysis of variance and LSD test were used as statistical methods. Results Morris water maze test showed that from the 3rd day to the 5th day, the kindling group had significantly longer escape latency [(36.33±7.85), (28.80±8.41), (29.50±11.72) s] than the control [(28.90±7.46), (17.59±9.12), (10.40±3.69) s] and kindling+astaxanthin groups [(28.30±5.75), (18.37±3.39), (15.23±6.63) s] (F=3.601, 9.811 and 14.226, all P<0.05). In probe trials, the kindling group had significantly fewer platform crossings as compared with the control and kindling+astaxanthin groups [(4.40±1.71) vs (7.20±1.62) and (6.50±1.84) times, F=6.586, P=0.001]. The kindling group spent dramatically less time in the target quadrant than the control and kindling+astaxanthin groups [(27.35±7.63) vs (58.29±10.48) and (40.41±7.06) s, F=25.825, P<0.001]. Nissl staining showed that hippocampal neurons of offspring in the control group were normal, but there was hippocampal damage in the kindling group and the damage was more severe than that in the kindling+astaxanthin group. Electron microscope observation showed that neurons and synapses in the hippocampal CA1 area of offspring in the control group were normal. However, obvious damage to neurons and synapses was induced in the kindling group and that was worse than the damage induced in the kindling+astaxanthin group. Expression of CREB and BDNF protein in the kindling group (0.19±0.06 and 0.32±0.04, respectively) were significantly lower than those in the control (0.81±0.11 and 0.93±0.04, respectively) and kindling+astaxanthin groups (0.60±0.07 and 0.80±0.06, respectively) (F were 34.015 and 71.074, both P<0.001). Moreover, the kindling group showed decreased expression of CREB and BDNF mRNA (0.48±0.11 and 0.43±0.08, respectively) as compared with the control (1.02±0.65 and 0.99±0.09, respectively) and kindling+astaxanthin groups (0.89±0.15 and 0.96±0.13, respectively) (F were 13.447 and 21.912, both P<0.01). Conclusion Treatment with astaxanthin could ameliorate the cognitive impairment and pathological damage in hippocampus of adult offspring induced by exposure to maternal seizures in utero through regulating the CREB-BDNF signal pathway. Key words: Pregnancy complications; Epilepsy; Xanthophylls; Oxidative stress; Rats