Abstract
Baroreflex control of the heart rate is reduced following CIH in rats. This could be associated with attenuated neurally-mediated circulatory responses at the multiple sites in brain-heart circuitry. However, baroreceptor afferent function is significantly augmented (Gu et al. 2007; EB Abstract). To elucidate such paradoxical findings, F344 rats (3 months) were exposed to either room air (RA) or CIH for 35 days. DiI was injected into the left nodose ganglion to anterogradely label vagal afferents. Vagal axons and terminals were examined using a confocal microscope. Our results indicate: Vagal afferent innervated the anterior and posterior wall of the aortic arch with extensive flower-spray terminals as well as numerous end-nets and free endings. The overall distribution pattern of vagal afferent projections to the aortic arch was similar in RA and CIH rats. The averaged numbers of flower-spray endings were also comparable in RA and CIH rats (RA: 77.2±13.6, CIH: 65.6±12.1, n=6/group, p>0.05). However, salient morphological changes were also found in CIH rats: enlarged axon fibers and terminals, and degenerating ending structures. The area of flower-spray endings in CIH rats was doubled (RA: 4562 ±78 μm2; CIH: 9385 ±432 μm2, p<0.01, n=30 flower-sprays from 6 rats/group). Thus, CIH has significantly altered vagal afferent projections to the aortic arch. This structural reorganization may underlie a neural substrate for the changes of baroreceptor afferent function. Supported by NIH AG-021020, HL-79636, S10RR019391.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
