Expression of the neuropeptide amylin in the nucleus accumbens according to parental effort in zebra finches (Taenopygia guttata).
Most of the studies on the neural bases of parental care in rodents are limited to maternal behaviour. However, many species, including humans, share parental effort between the male and the female. In zebra finches, both sexes incubate the eggs and feed the hatchlings. The neuropeptide amylin is restricted to hypothalamus in rodents and has been shown to influence maternal behaviour, but its role and distribution is more widespread in the avian brain. Its highest expression is in the nucleus accumbens, a region critical for decision making in social situations. In the present study, we correlated the amount of amylin mRNA in the nucleus accumbens of male and female zebra finches with the time spent with incubation of the eggs or feeding the hatchlings. Amylin was labelled on brain sections using in situ hybridization histochemistry. The labelling signal had been quantified and compared among sexes and reproductive statuses. The strongest label was found within the core region of the nucleus accumbens. This subregion also showed sexual dimorphism: males generally expressed more amylin mRNA than females. The more lateral part of the medial striatum, presumably the shell region of the nucleus accumbens showed no sexual dimorphism. The strength of amylin label negatively correlated with the intensity of parental behaviour in males only. Since the brain, amylin expression positively correlates with maternal behaviour in rodents, it is very likely that the amylin in birds has a very different function than those found in mammals.