Background: The purpose of this study was to evaluate whether or not dopami
ne (DA) can penetrate to the central nervous system (CNS) from the blood in
the infantile period in rats.
Methods:ln a preliminary experiment, we administered a 50 mg/kg dose of DA
hydrochloride, intraperitoneally, to 7-day-old rats (DA 50 mg/kg group), ob
taining cerebrospinal fluid (CSF) both before and at 5, 10, 20, 30, 60 and
120 min after administration. The CSF levels of DA and its main metabolites
, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were
then measured. Next, we investigated the DA transfer from blood to the CNS
by administering doses of 1, 5, 10 and 30 mg/kg DA hydrochloride (DA 1, 5,
10 and 30 mg/kg groups). In these groups, CSF samples were obtained only at
10 and/or 60 min after DA administration, based on the results of the DA 5
0 mg/kg group.
Results: The DA concentrations in CSF significantly increased compared with
values before DA administration in the DA 50 mg/kg group. The DA concentra
tions in the DA 30 mg/kg group, DOPAC concentrations in the DA 5, 10 and 30
mg/kg groups, and HVA concentrations in all groups were significantly high
er than in the control (saline injection) group.
Conclusions: These findings suggest easy DA transfer from blood to the CNS
and immaturity of the blood-blain barrier for DA in the infantile period in