DSP-4, a noradrenergic neurotoxin, produces sex-specific effects on pairing and courtship behavior in zebra finches

• The role of norepinephrine in forming a pair relationship is poorly understood.
• Males treated with a noradrenergic neurotoxin (DSP-4) sang less than control males.
• DSP-4 treated females showed mate preference deficits in a two-choice test.
• DSP-4 decreased DBH-ir densities in song, auditory, and affiliative brain regions.
• DBH-ir expression explained variation in several courtship and pairing behaviors.

Norepinephrine (NE) is involved in a variety of behaviors across vertebrate species. In songbirds, NE is involved in singing and auditory perception, fundamental components of pair formation. Mechanisms of pairing remain poorly understood in avian species. NE is likely involved given its role in vocal communication and perception. Here, we tested the hypothesis that DSP-4 treatments (a noradrenergic neurotoxin that decreases NE) decreases singing in males, song perception in females and pairing in both sexes using a naturalistic paradigm. Females were tested for preferences of either control or DSP-4 males in a two-choice paradigm using live males. Both sexes were then tested for courtship and pair formation in aviaries. In the two-choice paradigm, control females showed a significant preference for control males over DSP-4 males, whereas DSP-4 females showed no such preference. In the aviary tests, DSP-4 males engaged in less courtship behavior, showed decreased pairing behaviors and increased pair latencies compared to control males. In females, DSP-4 treatments did not alter courtship or pairing behavior. Lower neural densities of noradrenergic fibers in song, auditory, and affiliative regions were observed in DSP-4 animals of both sexes. Furthermore, DBH-ir densities in these regions explained variations in courtship and pairing behaviors, as well as pairing status. Our results extend previous findings to naturalistic contexts, provide evidence that DBH-ir densities in specific regions correlate with pairing-related behaviors, and inform us of sex differences in the role of NE in pairing.