How does flight training, dietary fat, and dietary anthocyanins
affect the oxidative status of the plasma and metabolic tissues in a
migratory songbird?
To better understand the multifaceted antioxidant system of birds, we
conducted a factorial experiment that manipulated three ecologically
relevant factors (i.e. flight training, dietary fat, dietary
antioxidants) to determine their effects on equivalent measures of lipid
damage and antioxidant capacity in the plasma, liver, and flight-muscle
of a migratory songbird. We tested the following hypotheses:
- Stimulatory effect of flight (H1): Acute flight and
flight-training stimulate the non-enzymatic antioxidant system and
protect against oxidative damage in the plasma, liver, and pectoralis.
- Acute-effect of a long flight : plasma antioxidant capacity
decreases during a given long-duration flight and so enables
circulating oxidative damage levels to remain low.
- Long-term effect of flight-training : a bird’s plasma
non-enzymatic antioxidant capacity (OXY) increases and lipid damage
(d-ROMs) decreases over the course of several weeks of daily flight
training.
- Flight-training effect across multiple tissues : compared to
untrained birds, flying regularly over several weeks increases
non-enzymatic antioxidant capacity (Oxygen radical absorbance
capacity, ORAC in flight muscle and liver; OXY in plasma) and
decreases lipid damage (Lipid hydroperoxides, LPO, in flight muscle
and liver; d-ROMs in plasma) in a consistent manner across tissues.
- Dietary fat effect (H2): migratory songbirds fed diets composed
of more 18:2n-6 PUFA are more susceptible to oxidative damage and thus
preventatively increase antioxidant capacity in the plasma, liver, and
flight-muscle so as to maintain low levels of lipid damage compared to
birds fed diets with less PUFA.
- Dietary antioxidant effect (H3): migratory songbirds fed
dietary anthocyanins have increased non-enzymatic antioxidant
capacity, and lower levels of lipid damage in all three tissues (i.e.,
liver, muscle, plasma) compared to birds not fed anthocyanins.
We also examined whether these three ecologically relevant factors
(flying, fat quality of diet, dietary antioxidants) interacted to affect
key components of the antioxidant system.