Morphine decreases the levels of the gene transcripts of growth hormone receptor and growth hormone binding protein in the male rat hippocampus and spinal cord

In this study we have characterized the nucleotide sequence of the cDNA for the growth hormone receptor (GHR) and examined the effects of morphine on the gene transcripts for GHR as well as GH binding protein (GHBP) in the ma le rat hippocampus and spinal cord. Using reverse transcription-polymerase chain reaction followed by cloning and sequencing, we found that the entire coding region of the GHR mRNA in the spinal cord is identical to that prev iously described in liver. A similar observation was made for the partially sequenced GHR cDNA from hippocampus. Northern blot analysis showed that in both tissues the levels of the transcripts for both GHR and GHBP were sign ificantly decreased 4 h after a single dose of morphine. After 24 h the lev el of both transcripts did not significantly differ from that of control an imals. This result indicates that the opiate does not only affect the recep tor protein as shown earlier by binding studies, but also reduces the expre ssion or turnover of the GHR as well as GHBP at the transcription level. (C ) 2001 Elsevier Science Ireland Ltd. All rights reserved.