Pup exposure elicits hippocampal cell proliferation in the prairie vole

Abstract

The onset of parental behavior has profound and enduring effects on behavior and neurobiology across a variety of species. In some cases, mere exposure to a foster neonate (and a subsequent parental response) can have similar effects. In the present experiment we exposed adult male and female prairie voles (Microtus ochrogaster) to two foster pups for twenty minutes and quantified cell proliferation in the dentate gyrus of the hippocampus (DG), medial amygdala (MeA) and cortical amygdala (CorA). Prairie voles are highly social rodents that typically display biparental care and spontaneous parental care when exposed to foster pups. Comparisons were made between the animals that responded parentally or non-parentally towards the pups, as well as control conditions. Cell proliferation was assessed using injections of 5-bromo-2'-deoxyuridine (BrdU) and immunocytochemical localization of this marker. The phenotype of the cells was determined using double label immufluoresence for BrdU and TuJ1 (a neuronal marker). An increase in cell proliferation in the DG was seen in animals exposed to pups. However, animals that responded nonparentally had a greater number of BrdU labeled cells in the DG compared to those that responded parentally. The majority of BrdU labeled cells co-expressed TuJ1 across all groups. These results demonstrate that exposure to a foster pup, and the behavioral reaction to it (parental or non-parental) is associated with site-specific changes in cell proliferation.

Changes in anxiety and cognition due to reproductive experience: A review of data from rodent and human mothers

“…By 2 weeks after weaning, BrdU labeling does not differ between primiparous and nulliparous females. In another rodent species, the biparental prairie vole, exposure to pups increases BrdU labeling in only those foster parents who did not respond parentally (Ruscio et al, 2008). Combined, these studies indicate that the immediate postpartum decrease in cell proliferation may be necessary for proper maternal behavior, and that the decrease is transient.…”

The birth of new neurons in the maternal brain: Hormonal regulation and functional implications

“…Likewise, offspring seem to have a stimulatory effect in virgin females of other rodent species including prairie voles which are biparental and typically display spontaneous parental care when exposed to foster pups. Specifically, Ruscio et al (2008) found that virgin female voles briefly exposed to pups for just 20 min exhibit increased cell proliferation in the DG regardless of whether they behaved parentally. It is important to note however that cell proliferation also increased in response to a control stimulus (i.e.…”

Hippocampal Plasticity during the Peripartum Period: Influence of Sex Steroids, Stress and Ageing

“…Thus, fluctuations in other hormones that occur classically during the peripartum period may also play a major role, such as oxytocin and prolactin, which, as mentioned above, have been shown to influence hippocampal neurogenesis (16, 18). Alternatively differential interactions with pups after restraint stress may contribute to the lack of pregnancy/lactation-induced decrease cell proliferation since as pointed out earlier, pup exposure can increase cell proliferation in nulliparous rats (43, 83). In support of this, restraint stress during the first weeks of lactation increased active nursing behavior in dams for the first two hours after stress compared with control dams (82).…”