Previous in vivo studies revealed that buprenorphine can down-regulate μ and up-regulate δ2 and κ1 opioid receptors in adult and neonatal rat brain. To assess gestational effects of buprenorphine on offspring, pregnant rats were also administered this drug and opioid receptor binding parameters (K(d) and B(max) values) were measured by homologous binding assays of postnatal day 1 (P1) brain membranes. Buprenorphine concentrations of 2.5 mg/kg injected into dams elicited an up-regulation of κ1 opioid receptors as detected with the κ1-selective agonist 3H-U69593. Parallel studies with the μ-selective agonist [D-ala2,mephe4,gly-ol5] enkephalin revealed a buprenorphine-induced down-regulation in receptor density at 0.3, 0.6 or 2.5 mg/kg drug treatment. A greater down-regulation of μ receptors for P1 males than for their female counterparts was observed. Buprenorphine did not cause a reduction in binding affinity in these experiments. Changes in opioid receptor adaptation induced by buprenorphine were further supported by data from cross-linking of 125I-β-endorphin to brain membrane preparations. RT-PCR analysis of opioid receptor expression was also estimated in P1 brains. However, significant changes in neither μ nor κ receptor message were detected in P1 brains as a result of prenatal buprenorphine treatment under the conditions of these experiments. Since buprenorphine is being evaluated in clinical trials for the treatment of heroin abuse, the in utero actions of the drug have ramifications for its use in the treatment of maternal drug abuse.
|Number of pages||8|
|Journal||Developmental Brain Research|
|State||Published - Nov 1 1998|
Bibliographical noteFunding Information:
This work was supported by NIH grants DA05412 (CJC), HL5T32 H207050 (LMB) and NRCIA DA05766 (LMB). We thank Matt Mabery for assistance in densitometric analysis.
- Down- regulation
- Opioid receptor
- mRNA expression
ASJC Scopus subject areas
- Developmental Neuroscience
- Developmental Biology