Galanin-like immunoreactivity in the adult and developing Brazilian opossum brain

The distribution of galanin-like immunoreactivity has been characterized in the brain of the adult and developing Brazilian opossum (Monodelphis domestica). Two commercially available antisera were used to examine the distribution of galanin-like immunoreactive (GAL-IR) cells and fibers. Nuclear groups containing GAL-IR cell bodies and fibers were seen throughout the adult opossum brain. The distribution of GAL-IR elements seen is similar to that reported for other mammals. Based on these findings, we believe that galanin may have similar physiological functions in the adult Brazilian opossum as has been reported for other mammals. In the developing brain, GAL-IR structures were seen as early as 1 day postnatal (PN) in the developing hypothalamus and brainstem. By days 5 and 10 PN, there was a robust expression of galanin-like immunoreactivity in specific regions of the brain. Since neurogenesis and brain morphogenesis are actively occuring postnatally in the opossum, galanin may be playing a role in the differentation of specific regions of the brain.