Developmental profile of cholinergic and purinergic traits and receptors in peripheral chemoreflex pathway in cats

• Published in: Neuroscience 2007-06, Vol.146 (4), p.1841-1853
• Main Authors: Bairam, A, Joseph, V, Lajeunesse, Y, Kinkead, R
• Format: Article
• Language: English
• Subjects: acetylcholine; Adenosine Triphosphate - metabolism; Age Factors; Animals; Animals, Newborn; ATP; Biological and medical sciences; Blotting, Western - methods; carotid body; Carotid Body - growth & development; Carotid Body - metabolism; Cats; Chemoreceptor Cells - growth & development; Chemoreceptor Cells - metabolism; Choline O-Acetyltransferase - metabolism; development; Fundamental and applied biological sciences. Psychology; Ganglia, Parasympathetic - growth & development; Ganglia, Parasympathetic - metabolism; Gene Expression Regulation, Developmental - physiology; Neurology; nicotinic receptors; purinergic receptors; Receptors, Cholinergic - metabolism; Receptors, Purinergic - metabolism; Reverse Transcriptase Polymerase Chain Reaction - methods; RNA, Messenger - biosynthesis; Superior Cervical Ganglion - growth & development; Superior Cervical Ganglion - metabolism; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2007.03.034

Abstract This study describes the developmental profile of specific aspects of cholinergic and purinergic neurotransmission in key organs of the peripheral chemoreflex: the carotid body (CB), petrosal ganglion (PG) and superior cervical ganglion (SCG). Using real time RT-PCR and Western blot analyses, we assessed both mRNA and protein expression levels for choline-acetyl-transferase (ChAT), nicotinic receptor (subunits α3 , α4 , α7 , and β2 ), ATP and purinergic receptors (P2X2 and P2X3 ). These analyses were performed on tissue from 1- and 15-day-old, 2-month-old, and adult cats. During development, ChAT protein expression level increased slightly in CB; however, this increase was more important in PG and SCG. In CB, mRNA level for α4 nicotinic receptor subunit decreased during development (90% higher in 1-day-old cats than in adults). In the PG, mRNA level for β2 nicotinic receptor subunit increased during development (80% higher in adults than in 1-day-old cats). In SCG, mRNA for α7 nicotinic receptor levels increased (400% higher in adults vs. 1-day-old cats). Conversely, P2X2 receptor protein level was not altered during development in CB and decreased slightly in PG; a similar pattern was observed for the P2X3 receptor. Our findings suggest that in cats, age-related changes in cholinergic and purinergic systems (such as physiological expression of receptor function) are significant within the afferent chemoreceptor pathway and likely contribute to the temporal changes of O2 -chemosensitivity during development.