Impact of parental ethanol exposure on offspring memory: Sex differences in spatial and passive avoidance tasks

Abstract

The impact of parental alcohol exposure on subsequent generations recently gained significant attention. Ethanol, widely consumed by humans, is known for its anxiolytic effects upon initial use. However, repeated ethanol consumption leads to cognitive dysfunction, dependence, and other physical abnormalities. In line with recent publications from our group, this study investigated the role of parental ethanol exposure—10 days prior to gestation—on learning and memory, which are critical cognitive abilities, in male and female offspring.

Adult male and female Wistar rats (n = 12) were exposed to ethanol (in drinking water) for 30 days, followed by a 10-day ethanol-free period. Each rat was then paired to mate with either an ethanol-naïve (control, n = 12) or ethanol-exposed rat, resulting in four distinct groups: (1) control male and female, (2) ethanol-exposed male and control female (P.EE), (3) ethanol-exposed female and control male (M.EE), and (4) ethanol-exposed male and female (P + M.EE). Adult male and female offspring were tested for spatial learning and memory (Morris Water Maze) and passive avoidance memory. Additionally, brain-derived neurotrophic factor (BDNF) levels in the cerebrospinal fluid were evaluated.

Results showed that spatial memory was negatively affected by parental ethanol consumption in both male and female offspring, while spatial learning was impaired only in female offspring of ethanol-exposed dams. In the passive avoidance paradigm, memory retrieval was impaired in ethanol-exposed male offspring, whereas in females, only the P + M.EE group showed a deficit in memory retention. While BDNF levels decreased in male offspring, an enhancement in BDNF was observed in female offspring of the P. EE group.

In conclusion, our findings suggest that parental ethanol exposure before conception has differential impacts on learning and memory, depending on the offspring's sex and the type of memory tested. Spatial memory was affected in both sexes (except for females in the P. EE group), while memory retrieval in the passive avoidance task remained unaffected in female offspring of the P. EE and M. EE groups. Conversely, male offspring of ethanol-exposed sires and dams exhibited deficits in passive avoidance memory. This may suggest that in memory tasks involving inhibitory cues, such as passive avoidance, female offspring of ethanol-exposed dams or sires are more resilient to memory deficits compared to male offspring. This resilience could possibly be attributed to their higher anxiety levels relative to males.