Developmental pattern of diacylglycerol lipase-α (DAGLα) immunoreactivity in brain regions important for song learning and control in the zebra finch (Taeniopygia guttata)

Abstract

Zebra finch song is a learned behavior dependent upon successful progress through a sensitive period of late-postnatal development. This learning is associated with maturation of distinct brain nuclei and the fiber tract interconnections between them. We have previously found remarkably distinct and dense CB1 cannabinoid receptor expression within many of these song control brain regions, implying a normal role for endocannabinoid signaling in vocal learning. Activation of CB1 receptors via daily treatments with exogenous agonist during sensorimotor stages of song learning (but not in adulthood) results in persistent alteration of song patterns. Now we are working to understand physiological changes responsible for this cannabinoid-altered vocal learning. We have found that song-altering developmental treatments are associated with changes in expression of endocannabinoid signaling elements, including CB1 receptors and the principal CNS endogenous agonist, 2-AG. Within CNS, 2-AG is produced largely through activity of the α isoform of the enzyme diacylglycerol lipase (DAGLα). To better appreciate the role of 2-AG production in normal vocal development we have determined the spatial distribution of DAGLα expression within zebra finch CNS during vocal development. Early during vocal development at 25 days, DAGLα staining is typically light and of fibroid processes. Staining peaks late in the sensorimotor stage of song learning at 75 days and is characterized by fiber, neuropil and some staining of both small and large cell somata. Results provide insight to the normal role for endocannabinoid signaling in the maturation of brain regions responsible for song learning and vocal-motor output, and suggest mechanisms by which exogenous cannabinoid exposure alters acquisition of this form of vocal communication.

Song-associated reward correlates with endocannabinoid-related gene expression in male European starlings ( Sturnus vulgaris )

“…We examined the relationship between undirected song production and endocannabinoid-related genes in Area X, because CB 1 is expressed in Area X (Soderstrom and Tian, 2006) and cannabinoid exposure during development alters songbird vocal production (Soderstrom and Johnson, 2003), leading to long-term impairment of the endocannabinoid system (Soderstrom et al, 2011). It has also been proposed that DAGLɑ and CB 1 in Area X have a role in vocal learning (Soderstrom and Tian, 2006; Soderstrom and Wilson, 2013). Our results are consistent with this previous research suggesting that the endocannabinoid system has a role in songbird vocal development and production; we found significant positive correlations between how much song a bird produced and FABP5 (an intracellular transporter) and DAGLα (the synthesizing enzyme for 2-AG) expression in Area X.…”

Song practice as a rewarding form of play in songbirds

“…Studies on brain regions in which cannabinoids impact song practice have mostly focused on regions involved in vocal learning and production, rather than in motivation and reward (e.g., (Soderstrom et al, 2011;Soderstrom and Tian, 2006;Soderstrom et al, 2004;Soderstrom and Wilson, 2013)). However, recently we conducted a study examining relationships between song-associated reward and endocannabinoid expression in VTA and mPOA.…”