We have investigated the long-term effects of 15-16 min or 19-20 min of perinatal
asphyxia on D1, D2, and D3 receptors (analyzed by quantitative autoradiography) in the mesotelencephalic
dopamine systems of the 4-week-old rat. Perinatal
asphyxia reduced D1 antagonist binding ([3H]
SCH 23390 in the presence of ketanserine) in the accumbens nucleus, the olfactory tubercle, and the substantia nigra and increased D1 agonist binding ([3H]
dopamine in the presence of
spiperone) in the accumbens nucleus and the olfactory tubercle. No changes in D2 antagonist binding ([123]
iodosulpride) were found, whereas D2 agonist binding ([3H]
N-propylnorapomorphine, [3H]NPA) was reduced in the posterior part of the caudate-putamen, and following 19-20 min of
asphyxia it was also reduced in the accumbens nucleus. D3 agonist binding (R/S-(+/-)-2-(N,N-di[2,3(n)-3H] propylamino)-7-hydroxy-1,2,3,4-tetrahydronaphthalene, [3H]7-
OH-DPAT) was increased in the anterior part of the caudate-putamen following 15-16 min but not 19-20 min of
asphyxia. The results indicate that perinatal
asphyxia reduced the number of D1 receptors and increased D1 agonist affinity in the accumbens nucleus and the olfactory tubercle and reduced the number of D1 receptors in the substantia nigra. The number of D2 receptors was unchanged by
asphyxia, whereas the D2 agonist affinity was reduced in the caudate-putamen and in the accumbens nucleus. D3 agonist binding was increased in the caudate-putamen selectively following 15-16 min of
asphyxia. In conclusion,
asphyxia during birth induces long-term changes in the binding characteristics of
dopamine receptors in the mesotelencephalic
dopamine systems, which may contribute to previously reported behavioral changes.