Ventilatory and cardiovascular actions of centrally administered trout tachykinins in the unanesthetized trout

Jean Claude Le Mével, Frédéric Lancien, Nagi Mimassi, J. Michael Conlon

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10 Citations (Scopus)


The brains of teleost fish contain members of the tachykinin family that are the products of orthologous genes expressed in mammalian nervous tissues, but little is known regarding the physiological effects of these peptides in their species of origin. The present study compares the central actions of trout neuropeptide gamma (NPγ), substance P (SP) and neurokinin A (NKA) (5-250 pmol) on ventilatory and cardiovascular parameters in the unanesthetized rainbow trout Oncorhynchus mykiss. Intracerebroventricular (ICV) injection of NPγ evoked a dose-dependent elevation of the ventilation rate (fV) but a reduction of the ventilation amplitude (VAMP) that was caused by a reduction of the magnitude of the adduction phase of the ventilatory signal. The net effect of NPγ was to produce an hypoventilatory response since the total ventilation (VTOT) was significantly reduced. The minimum effective dose for a significant effect of NPγ on fV and V AMP was 50 pmol. SP evoked a significant elevation of fV, a concomitant depression of VAMP, and a resultant decrease in V TOT but only at the highest dose (250 pmol). NKA was without action on fV but significantly decreased VAMP at only the highest dose tested. In this case also, the net effect of NKA was to reduce V TOT. When injected centrally, none of the three peptides, at any dose tested, produced changes in heart rate or mean dorsal aortic blood pressure (PDA). Intra-arterial injection of the three tachykinins (250 pmol) produced a significant (P<0.05) increase in PDA, but only SP and NKA induced concomitant bradycardia. None of the three peptides produced any change in fV or VAMP. In conclusion, our results demonstrate that centrally injected tachykinins, particularly NPγ, produce a strong hypoventilatory response in a teleost fish and so suggest that endogenous tachykinins may be differentially implicated in neuroregulatory control of ventilation.

Original languageEnglish
Pages (from-to)3301-3310
Number of pages10
JournalJournal of Experimental Biology
Issue number18
Publication statusPublished (in print/issue) - Sept 2007


  • Intracerebroventricular injection
  • Neurokinin A
  • Neuropeptide γ
  • Substance P
  • Teleost
  • Ventilatory control


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