Differential changes in dopamine D2- and D1-receptor mRNA levels induced by hypoxia in the arterial chemoreflex pathway organs in one-day-old and adult rabbits.
This study determined: (1) whether dopamine (DA) D2-receptor (R) and D1-R mRNA levels in the carotid body (CB), petrosal ganglion (PG) and superior cervical ganglion (SCG) are modulated by hypoxia; (2) the role of hypoxia intensity and exposure duration, and (3) whether the pattern of modulation differs between newborn (1-day-old) and adult rabbits. Rabbits were exposed to five FiO2 conditions: 21% (control); 15%/6 h; 15%/24 h; 8%/6 h and 8%/24 h. D2- and D1-R mRNA expression levels were calculated for each hypoxia condition relative to control using RT-PCR analysis. In the CB of 1-day-old rabbits, D2- and D1-R transcript levels increased and decreased after exposure to 15 and 8% O2, respectively. In the adult CB, D2- and D1-R transcript levels decreased independently of hypoxia intensities. Only changes in D1-R mRNA levels were dependent on exposure time. In the PG, both hypoxia intensities decreased the D2-R transcript levels in 1-day-old and adult rabbits; but for the D1-R mRNA levels, hypoxia decreased its level in 1-day-old rabbits and increased it in adults regardless of exposure duration. In the SCG, hypoxia had no determinant effect on the D2-R mRNA levels either in newborn or adult rabbits while it induced a decrease of D1-R transcript levels in 1-day-old rabbits and an increase in adult rabbits. It is concluded that hypoxia affects DA D2- or D1-R mRNA levels in the chemoreflex pathway in an age-dependent and site-specific manner.
D000375:Aging; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development; D001158:Arteries / Q000503:physiopathology*; D002344:Carotid Body / Q000378:metabolism; D002628:Chemoreceptor Cells / Q000503:physiopathology*; D003342:Corpus Striatum / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D017950:Ganglia, Sensory / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D010100:Oxygen / Q000008:administration & dosage; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D017447:Receptors, Dopamine D1 / Q000235:genetics / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism*; D012018:Reflex; D017783:Superior Cervical Ganglion / Q000378:metabolism
D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D010100:Oxygen