Systematic review of maternal stress in rodents: are we covering the whole picture?

Abstract We examined the published literature regarding maternal stress in rodents. Rodents have been considered valuable models for studying maternal stress because their neuroendocrine systems, maternal behaviours and developmental responses to stress share important similarities with those of humans, allowing researchers to investigate underlying mechanisms and transgenerational effects. However, research in this area may have been influenced by diverse deviations that could affect the scope of behavioural and physiological outcomes. In an attempt to identify and highlight some of these biases, we performed a systematic literature review focused on the effects of maternal stress on the behavioural and physiological responses of wild rodents’ offspring compared with laboratory ones. This review finds that there has been a notable growth in studies on gestational stress in rodents in recent decades. However, the number of works on wild species is significantly lower than those using laboratory rodent models. In addition, most of these studies in rodent models are carried out with artificial stress factors (e.g. electric shock, noise, cold exposure) and fewer studies applied stressors more related to natural, evolutionary and ecologically relevant conditions, such as exposure to predators or cues indicatives of their presence. Thus, the reduction or absence of genetic variability and lack of environmental challenges can result in model rodents tested in laboratory settings reacting to predatory stress in a more uniform manner than wild species. In consequence, expanding investigations in wild rodents may offer valuable opportunities to understand the ecological and evolutionary bases of maternal stress in mammals.