Norepinephrine, epinephrine and MHPG levels in chick brain development.

In this study we determined the norepinephrine (NE), epinephrine and methoxy-hydroxy-phenyl-glycol (MHPG) levels in dissected chick telencephalon, diencephalon/mesencephalon and cerebellum in a number of stages from the late embryonic period (E16, E17, E18 and E19) and post-hatching period (P1, P2, P3, P4, P5, P15 and P30) using HPLC coupled with a coulometric detection system. A mobile phase which permits the detection of NE, epinephrine and MHPG simultaneously is also described. During development, NE levels increase dramatically after hatching in all brain structures studied and are not correlated in the same period with an increase in the MHPG/NE ratio. The values obtained for epinephrine and MHPG were significantly lower than the NE values in all the structures and stages studied. Our results support the notion of a specific role for NE during the first days after hatching.