Interactions of Early-life Temperature Exposure, Offspring Genotype and Maternal Care on Later-life Maternal Care Provisioning in Female Rats

The early-life maternal environment has a profound effect on offspring behaviour, including the transmission of maternal care across generations. Variations in rat maternal care provisioning are associated with alterations in the oxytocinergic and dopaminergic systems in the maternal brain and, in turn, maternal care received by pups can alter oxytocinergic and dopaminergic systems in the rat pup brain. Though there has been progress in elucidating the biological mechanisms underlying the developmental programming of maternal care, the mechanisms that link maternal care received to alterations in the dopaminergic and oxytocinergic systems in the offspring remains to be an active area of research. Previous work has studied the transmission of pup licking across generations, but there are other relevant factors that could interact with pup licking on later-life maternal care provisioning. In this thesis, I review early-life temperature exposure and offspring genotype as important factors also involved in the developmental programming of maternal care. One project directly manipulated early-life temperature exposure and levels of supplemental licking-like tactile stimulation. The second project investigated the main effects of observed early-life inter-individual maternal licking received and interactions with naturally occurring genetic variants in dopamine-related genes. I hypothesized that early-life temperature exposure and offspring genotype would interact with licking-like tactile stimulation or pup licking to alter the oxytocinergic and dopaminergic systems in the offspring and also influence their later-life maternal care provisioning. I found that 1) early-life temperature exposure influenced the epigenetic regulation of the oxytocin gene in week-old female pups with changes in oxytocin transcript abundance and 2) that both early-life temperature exposure and supplemental tactile stimulation affected later-life maternal care provisioning. In addition, I found that a single nucleotide polymorphism in the dopamine receptor 2 gene interacted with inter-individual maternal licking received on 3) later-life performance on dopamine-related tasks and 4) maternal licking provisioning. Moreover, the association between maternal licking received and maternal licking provisioning was mediated by dopamine levels in the nucleus accumbens of the maternal brain. These findings suggest novel biological mechanisms of the developmental programming of maternal care that could be involved with the transmission of maternal care across generations.

Department dc:contributor.department

Cell and Systems Biology

Year dc:date.issued

2021

Author dc:creator

• Lauby, Samantha

Advisor dc:contributor.advisor

• McGowan, Patrick O

Handle dc:identifier.uri

http://hdl.handle.net/1807/106316

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/106316