Growth of prefrontal and limbic brain regions and anxiety disorders in children born very preterm.

BACKGROUND: Children born very preterm (VP) display altered growth in corticolimbic structures compared with full-term peers. Given the association between the cortiocolimbic system and anxiety, this study aimed to compare developmental trajectories of corticolimbic regions in VP children with and without anxiety diagnosis at 13 years. METHODS: MRI data from 124 VP children were used to calculate whole brain and corticolimbic region volumes at term-equivalent age (TEA), 7 and 13 years. The presence of an anxiety disorder was assessed at 13 years using a structured clinical interview. RESULTS: VP children who met criteria for an anxiety disorder at 13 years (n = 16) displayed altered trajectories for intracranial volume (ICV, p < 0.0001), total brain volume (TBV, p = 0.029), the right amygdala (p = 0.0009) and left hippocampus (p = 0.029) compared with VP children without anxiety (n = 108), with trends in the right hippocampus (p = 0.062) and left medial orbitofrontal cortex (p = 0.079). Altered trajectories predominantly reflected slower growth in early childhood (0-7 years) for ICV (ß = -0.461, p = 0.020), TBV (ß = -0.503, p = 0.021), left (ß = -0.518, p = 0.020) and right hippocampi (ß = -0.469, p = 0.020) and left medial orbitofrontal cortex (ß = -0.761, p = 0.020) and did not persist after adjusting for TBV and social risk. CONCLUSIONS: Region- and time-specific alterations in the development of the corticolimbic system in children born VP may help to explain an increase in anxiety disorders observed in this population.

Substance P receptor in the rat indusium griseum during postnatal development.

The presence of substance P (SP) receptor (Neurokinin-1 receptor, NK1R) in the indusium griseum (IG) and anterior hippocampal continuation (AHC) during postnatal development was studied by immunocytochemistry (ICC). NK1R-immunopositive neurons (NK1RIP-n) first appeared in both areas on postnatal day (P) 5. From P5 onward, their distribution pattern was adult-like. In sagittal sections NK1RIP-n formed a narrow strip of neurons and dendrites that were located over the corpus callosum (cc); in coronal sections they were found in a roughly triangular area at the base of the cingulate cortex (Cg) on the dorsal surface of the cc. NK1RIP-n were also found in the AHC, which is considered as a subcallosal extension of the IG, located ventral to the genu of the cc. At all ages studied, IG NK1RIP-n sent dendrites to the contralateral IG, the underlying cc, and the Cg. Moreover, NK1RIP-n located in the Cg and the cc sent dendrites to the IG. The present findings are in line with previous ICC studies describing dopaminergic and serotoninergic afferents to the IG. Together these data suggest that, through NK1R, SP could play an important role in regulating the release mechanisms of these afferents and that it could be an important developmental factor. Notably, IG neurons could be activated by cortical and intracallosal afferents.