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This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Majewski, D. Articles by Johnson, S. PubMed Articles by Majewski, D. Articles by Johnson, S.

Frequency plasticity is expressed in turtle hemibrainstems in vitro

Comparative Biosciences, University of Wisconsin, 2015 Linden Drive, Madison, Wisconsin, 53706

ABSTRACT

Thick transverse slices of turtle brainstems in vitro produce rhythmic motor activity that is abolished by DAMGO (µ-opiate receptor agonist) or high pH conditions, suggesting that the turtle respiratory network is composed of oscillatory networks distributed rostrocaudally in the brainstem. Our goal was to test whether hemibrainstems produce respiratory-related motor activity, and whether hemibrainstems express frequency plasticity. Brainstems of adult turtles (Pseudemys) were isolated and suction electrodes attached to XII cranial nerve roots to record respiratory-related motor bursts. Brainstems were completely cut along the midline to produce two hemibrainstems. Burst frequency in hemibrainstems (n=9) was 0.43 ± 0.09 and 0.48 ± 0.09 bursts/min at 2 hr and 6 hr post-hemisection, respectively. In different hemi-brainstems, DAMGO (1 µM; n=4) or high pH (pH=7.8; n=2) reversibly abolished the bursts. During synaptic inhibition blockade with strychnine and bicuculline (50 µM each; n=6), rhythmic bursts persisted for >2 hr. Since the respiratory rhythm of intact turtle brainstems responds almost identically to these perturbations, this suggests that the hemibrainstem rhythm is respiratory-related. When phenylbiguanide (5-HT3 agonist; 20 µM; 60-min) was applied to hemibrainstems (n=6), burst frequency acutely increased by 160 ± 35% above baseline (0.38 ± 0.06 bursts/min) and was 47 ± 10% above baseline after a 2-hr washout period, thereby demonstrating frequency plasticity. Thus, a respiratory-related neural network sufficient to express frequency plasticity is contained within the turtle hemibrainstem.

(Supported by NSF grant # IOB-0517302)

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Majewski, D. Articles by Johnson, S. PubMed Articles by Majewski, D. Articles by Johnson, S.