Novel localizations of TRPC5 channels suggest novel and unexplored roles: A study in the chick embryo brain.

Mammalian TRPC5 channels are predominantly expressed in the brain, where they increase intracellular Ca and induce depolarization. Because they augment presynaptic vesicle release, cause persistent neural activity, and show constitutive activity, TRPC5s could play a functional role in late developmental brain events. We used immunohistochemistry to examine TRPC5 in the chick embryo brain between 8 and 20 days of incubation, and provide the first detailed description of their distribution in birds and in the whole brain of any animal species.

Melanin-concentrating hormone (MCH) neurons in the developing chick brain.

The present study was undertaken because no previous developmental studies exist on MCH neurons in any avian species. After validating a commercially-available antibody for use in chickens, immunohistochemical examinations first detected MCH neurons around embryonic day (E) 8 in the posterior hypothalamus. This population increased thereafter, reaching a numerical maximum by E20.

Activation of state-regulating neurochemical systems in newborn and embryonic chicks.

Coordinated activity in different sets of widely-projecting neurochemical systems characterize waking (W) and sleep (S). How and when this coordination is achieved during development is not known. We used embryos and newborns of a precocial bird species (chickens) to assess developmental activation in different neurochemical systems using cFos expression, which has been extensively employed to examine cellular activation during S and W in adult mammals.