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This Article Full Text Full Text (PDF) All Versions of this Article: 576/3/903    most recent jphysiol.2006.114850v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zabka, A. G. Articles by Behan, M. Search for Related Content PubMed PubMed Citation Articles by Zabka, A. G. Articles by Behan, M. Related Collections Respiratory

¹ Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA

Sex hormones modulate plasticity in the central nervous system, including respiratory long-term facilitation (LTF), a form of serotonin-dependent respiratory plasticity induced by intermittent hypoxia. Since gonadectomy (GDX) attenuates LTF in male rats, we tested the hypotheses that: (1) testosterone replenishment restores LTF in gonadectomized male rats, and (2) that the conversion of testosterone to oestradiol (under the influence of aromatase) is required for these effects. Intact and sham operated male F344 rats were compared to gonadectomized rats implanted with Silastic tubing containing testosterone (T), T plus an aromatase inhibitor (ADT), or 5-dihydrotestosterone (DHT), a form of testosterone not converted to oestradiol. Seven days postsurgery, LTF was studied in anaesthetized, neuromuscularly blocked and ventilated rats while monitoring integrated phrenic and hypoglossal (XII) motor output. LTF was elicited by three 5 min hypoxic episodes (P_a,O2 = 35 – 45 mmHg). Although significant phrenic and XII LTF were observed in all rat groups, GDX reduced both phrenic and XII LTF, an effect reversed by T. In contrast, LTF was not restored in T + ADT or DHT-treated gonadectomized rats. We conclude that the conversion of testosterone to oestradiol modulates phrenic and XII LTF in male F344 rats.

(Received 6 June 2006; accepted after revision 21 August 2006; first published online 24 August 2006)
Corresponding author M. Behan: Department of Comparative Biosciences, School of Veterinary Medicine, 2015 Linden Drive, Madison, WI 53706, USA. Email: behanm{at}svm.vetmed.wisc.edu

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