Differential expression of a(2a), A(1)-adenosine and D(2)-dopamine receptor genes in rat peripheral arterial chemoreceptors during postnatal development

Brain Res. 2000 Jul 28;872(1-2):1-10. doi: 10.1016/s0006-8993(00)02314-3.


The sensitivity of peripheral arterial chemoreceptors in the carotid body to hypoxia increases with postnatal maturation. Carotid sinus nerve activity is augmented by adenosine binding to A(2a)-adenosine receptors and attenuated by dopamine binding to D(2)-dopamine receptors. In this study, we used in situ hybridization histochemistry to determine the change in the levels of mRNA expression for A(2a) and A(1)-adenosine receptors and D(2)-dopamine receptors in the rat carotid body. We also investigated the cellular distribution and possible colocalization of these receptor mRNAs and tyrosine hydroxylase (TH) mRNAs during the first 2 weeks of postnatal development. By using immunohistocytochemistry, we detected A(2a)-adenosine receptor protein in the carotid body and petrosal ganglion. We found that A(2a)-adenosine receptor mRNA and protein are expressed in the carotid body in animals at 0, 3, 6 and 14 postnatal days. The level of A(2a)-adenosine receptor mRNA expression significantly decreased by 14 postnatal days (P<0.02 vs. day 0) while D(2)-dopamine receptor mRNA levels significantly increased by day 3 and remained greater than D(2)-dopamine receptor mRNA levels at day 0 (P<0.001 all ages vs. day 0). TH mRNA was colocalized in cells in the carotid body with A(2a) adenosine receptor and D(2)-dopamine receptor mRNAs. A(1)-adenosine receptor mRNA was not expressed in the carotid body at any of the ages examined. In the petrosal ganglion, A(1)-adenosine receptor mRNA was abundantly expressed in numerous cells, A(2a)-adenosine receptor mRNA was expressed in a moderate number of cells while D(2)-dopamine receptor mRNA was seen in a few cells in the rostral petrosal ganglion. In conclusion, using in situ hybridization histochemistry, we have shown that mRNA for both the excitatory, A(2a)-adenosine receptor, and the inhibitory, D(2)-dopamine receptor, is developmentally regulated in presumably type I cells in the carotid body which may contribute to the maturation of hypoxic chemosensitivity. Furthermore, the presence A(1)-adenosine receptor mRNAs in cell bodies of the petrosal ganglion suggests that adenosine might also have an inhibitory role in hypoxic chemotransmission.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Arteries / innervation
  • Arteries / metabolism*
  • Carotid Body / cytology
  • Carotid Body / growth & development
  • Carotid Body / metabolism
  • Chemoreceptor Cells / cytology
  • Chemoreceptor Cells / growth & development
  • Chemoreceptor Cells / metabolism*
  • Ganglia, Sensory / cytology
  • Ganglia, Sensory / growth & development
  • Ganglia, Sensory / metabolism
  • Gene Expression
  • RNA, Messenger / analysis*
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Adenosine A2A
  • Receptors, Dopamine D2 / biosynthesis
  • Receptors, Dopamine D2 / genetics*
  • Receptors, Purinergic P1 / biosynthesis
  • Receptors, Purinergic P1 / genetics*
  • Tyrosine 3-Monooxygenase / genetics
  • Tyrosine 3-Monooxygenase / metabolism


  • RNA, Messenger
  • Receptor, Adenosine A2A
  • Receptors, Dopamine D2
  • Receptors, Purinergic P1
  • Tyrosine 3-Monooxygenase