Chronic 13-cis-retinoic acid administration disrupts network interactions between the raphe nuclei and the hippocampal system in young adult mice.
Previously, we showed that chronic administration of 13-cis-retinoic acid (13-cis-RA) induces depression-related behaviors in mice and that 13-cis-RA alters components of the serotonergic system in vitro. Work by others has shown that 13-cis-RA reduces hippocampal neurogenesis in mice and orbitofrontal cortex metabolism in humans. In the current study, we measured cytochrome oxidase activity, a metabolic marker that reflects steady state neuronal energy demand, in various regions of the brain to determine the effects of 13-cis-RA on neuronal metabolic activity and network interactions between the raphe nuclei and the hippocampal system. Brain cytochrome oxidase activity in young adult male mice was analyzed following 6 weeks of daily 13-cis-RA (1 mg/kg) or vehicle injection and behavioral testing. Chronic 13-cis-RA administration significantly decreased cytochrome oxidase activity only in the inferior rostral linear nucleus of the raphe. However, covariance analysis of interregional correlations in cytochrome oxidase activity revealed that 13-cis-RA treatment caused a functional uncoupling between the dorsal raphe nuclei and the hippocampus. Furthermore, a path analysis indicated that a network comprising lateral habenula to dorsal raphe to hippocampus was effectively uncoupled in 13-cis-RA treated animals. Finally, cytochrome oxidase activity in the dentate gyrus of 13-cis-RA treated mice was inversely correlated with depression-related behavior. Taken together, these data show that 13-cis-RA alters raphe metabolism and disrupts functional connectivity between the raphe nuclei and the hippocampal formation, which may contribute to the observed increase in depression-related behaviors.
O'Reilly
Kally C
KC
Institute of Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
Shumake
Jason
J
Bailey
Sarah J
SJ
Gonzalez-Lima
F
F
Lane
Michelle A
MA
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D018891:Dentate Gyrus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D003863:Depression / Q000139:chemically induced; D003879:Dermatologic Agents / Q000009:adverse effects / Q000494:pharmacology*; D003576:Electron Transport Complex IV / Q000187:drug effects* / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D015474:Isotretinoin / Q000009:adverse effects / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D009474:Neurons / Q000378:metabolism; D011903:Raphe Nuclei / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism
D003879:Dermatologic Agents; D003576:Electron Transport Complex IV; D015474:Isotretinoin