Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Formation of olfactory memories mediated by nitric oxide


Sheep learn to recognize the odours of their lambs within two hours of giving birth, and this learning involves synaptic changes within the olfactory bulb1,2. Specifically, mitral cells become increasingly responsive to the learned odour, which stimulates release of both glutamate and GABA (γ-aminobutyric acid) neurotransmitters from the reciprocal synapses between the excitatory mitral cells and inhibitory granule cells1. Nitric oxide (NO) has been implicated in synaptic plasticity in other regions of the brain as a result of its modulation of cyclic GMP levels3,4,5,6,7. Here we investigate the possible role of NO in olfactory learning. We find that the neuronal enzyme nitric oxide synthase (nNOS) is expressed in both mitral and granule cells, whereas the guanylyl cyclase subunits that are required for NO stimulation of cGMP formation8 are expressed only in mitral cells. Immediately after birth, glutamate levels rise, inducing formation of NO and cGMP, which potentiate glutamate release at the mitral-to-granule cell synapses. Inhibition of nNOS or guanylyl cyclase activity prevents both the potentiation of glutamate release and formation of the olfactory memory. The effects of nNOS inhibition can be reversed by infusion of NO into the olfactory bulb. Once memory has formed, however, inhibition of nNOS or guanylyl cyclase activity cannot impair either its recall or the neurochemical release evoked by the learned lamb odour. Nitric oxide therefore seems to act as a retrograde and/or intracellular messenger, being released from both mitral and granule cells to potentiate glutamate release from mitral cells by modulating cGMP contentrations. We propose that the resulting changes in the functional circuitry of the olfactory bulb underlie the formation of olfactory memories.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: a, Photomicrographs of nNOS protein expression in olfactory bulb (OB) mitral (top arrow in top panel) and granule (bottom arrow in top panel) cells, and emulsion autoradiography (bottom two panels) showing the mitral cell layer (arrow) expressing mRNA for the α1 and β1 subunits of guanylyl cyclase.
Figure 2: Glutamate, GABA, noradrenaline, citrulline, nitrite and cGMP levels before, during, and after birth in control animals (dotted line), and in DGG (500 μM; dashed line)- and ODQ (200 μM solid line)-treated animals.
Figure 3: Glutamate, GABA, noradrenaline, citrulline, nitrite and cGMP levels before, during, and after birth in control D-NARG (500 μM solid line)- and L-NARG (500μM dashed line)-treated animals.
Figure 4: a, The effects of drug infusions in the olfactory bulb on acceptance (low-pitch bleating and suckling) and rejection behaviour (butting), as shown by maternal ewes towards their own (white bars) and strange (black bars) lambs.

Similar content being viewed by others


  1. Kendrick, K. M., Lévy, F. & Keverne, E. B. Changes in the sensory processing of olfactory signals induced by birth in sheep. Science 256, 833–836 (1992).

    Article  ADS  CAS  Google Scholar 

  2. Kendrick, K. M. Neurobiological correlates if visual and olfactory recognition in sheep. Behav. Proc. 33, 89–112 (1994).

    Article  CAS  Google Scholar 

  3. Garthwaite, J. & Boulton, C. L. Nitric oxide signalling in the central nervous system. Annu. Rev. Physiol. 57, 683–706 (1995).

    Article  CAS  Google Scholar 

  4. Dawson, T. M. & Snyder, S. H. Gases as biological messengers: nitric oxide and carbon monoxide in the brain. J. Neurosci. 14, 5147–5159 (1994).

    Article  CAS  Google Scholar 

  5. Arancio, O. et al. Nitric oxide acts directly in the pre-synaptic neuron to produce long-term potentiation in cultured hippocampal neurons. Cell 87, 1025–1035 (1996).

    Article  CAS  Google Scholar 

  6. Zhuo, M., Small, S. A., Kandel, E. R. & Hawkins, R. D. Nitric oxide and carbon monoxide produce activity-dependent long-term synaptic enhancement in hippocampus. Science 260, 1946–1950 (1993).

    Article  ADS  CAS  Google Scholar 

  7. Boulton, C. L., Southam, E. & Garthwaite, J. Nutric oxide-dependent long-term potentiation is blocked by a specific inhibitor of soluble guanylyl cyclase. Neuroscience 69, 699–703 (1995).

    Article  CAS  Google Scholar 

  8. Furuyama, T., Inagaki, S. & Takagi, H. Localisations of α-1 and β-1 subunits of soluble guanylate cyclase in the rat brain. Mol. Brain Res. 20, 335–344 (1993).

    Article  CAS  Google Scholar 

  9. Bannerman, D. M., Chapman, P. F., Kelly, P. A. T., Butcher, S. P. & Morris, R. G. M. Inhibition of nitric oxide synthase does not impair spatial learning. J. Neurosci. 14, 7404–7414 (1994).

    Article  CAS  Google Scholar 

  10. Murphy, K. P. S. J., Williams, J. H., Bettache, N. & Bliss, T. V. P. Photolytic release of nitric oxide modulates NMDA receptor-mediated transmission but does not induce long-term potentiation at hippocampal synapses. Neuropharmacology 33, 1375–1385 (1994).

    Article  CAS  Google Scholar 

  11. Kishimoto, J., Keverne, E. B., Hardwick, J. & Emson, P. C. Localization of nitric oxide synthase in the mouse olfactory and vomeronasal system: a histochemical, immunological and in situ hybridization study. Eur. J. Neurosci. 5, 1684–1694 (1993).

    Article  CAS  Google Scholar 

  12. Fujisawa, H. et al. Expression of two types of nitric oxide synthase mRNA in human neuroblastoma cell lines. J. Neurochem. 63, 140–145 (1994).

    Article  CAS  Google Scholar 

  13. Bredt, D. S. et al. Cloned and expressed nitric oxide synthase structurally resembles cytochrome P-450 reductase. Nature 351, 714–718 (1991).

    Article  ADS  CAS  Google Scholar 

  14. Ogura, T., Yokoyama, T., Fujisawa, H., Kurashima, Y. & Esumi, H. Structural diversity of neuronal nitric oxide synthase mRNA in the nervous system. Biochem. Biophys. Res. Commun. 193, 1014–1022 (1993).

    Article  CAS  Google Scholar 

  15. Kendrick, K. M. et al. NMDA and kainate-evoked release of nitric oxide and classical transmitters in the rat stiatum: in vivo evidence that nitric oxide may play a neuroprotective role. Eur. J. Neurosci. 8, 2619–2634 (1996).

    Article  CAS  Google Scholar 

  16. Brennan, P. A. & Keverne, E. B. Impairment of olfactory memory by local infusions of non-selective excitatory amino acid receptor antagonists into the accessory olfactory bulb. Neuroscience 33, 463–468 (1989).

    Article  CAS  Google Scholar 

  17. Martin, L. J., Blackstone, C. D., Levy, A. I., Huganir, R. L. & Price, D. L. AMPA glutamate receptor subunits are differentially distributed in rat brain. Neuroscience 53, 327–358 (1993).

    Article  CAS  Google Scholar 

  18. Garthwaite, J. et al. Potent and selective inhibition of nitric oxide-sensitive guanylyl cyclase by 1H-[1,2,4]oxodiazolo[4,3-a]-1-one. Mol. Pharmacol. 48, 184–188 (1995).

    CAS  PubMed  Google Scholar 

  19. Lévy, F., Locatelli, A., Piketty, V., Tillet, Y. & Poindron, P. Involvement of the main but not the accessory olfactory system in maternal behavior of primiparous and multiparous ewes. Physiol. Behav. 57, 97–104 (1995).

    Article  Google Scholar 

  20. Lévy, F., Gervais, R., Kindermann, U., Orgeur, P. & Piketty, V. Importance of β-noradrenergic receptors in the olfactory bulb of sheep for recognition of lambs. Behav. Neurosci. 104, 464–469 (1990).

    Article  Google Scholar 

  21. Bliss, T. V. P. & Collingridge, G. L. Asynaptic model of memory: long-term potentiation in the hippocampus. Nature 361, 31–39 (1993).

    Article  ADS  CAS  Google Scholar 

  22. Morris, R. G. M. Synaptic plasticity and learning: selective impairment of learning and blockage of long-term potentiation in vivo by N-methyl-D-aspartate receptor antagonist, AP5. J. Neurosci. 9, 3040–3057 (1989).

    Article  CAS  Google Scholar 

  23. Van den Pol, A. N. Presynaptic metabotropic glutamate receptors in adult and developing neurons: autoexcitation in the olfactory bulb. J. Comp. Neurol. 359, 253–271 (1995).

    Article  CAS  Google Scholar 

  24. Doze, V. A., Cohen, G. A. & Maddison, D. V. Synaptic localization of adrenergic disinhibition in the rat hippocampus. Neuron 6, 889–900 (1991).

    Article  CAS  Google Scholar 

  25. Morris, R. G. M., Anderson, G. S., Lynch, M. & Baudry, M. Selective impairment of learning and blockade of long-term potentiation by an N-methyl-D-aspartate receptor antagonist AP5. Nature 319, 774–776 (1986).

    Article  ADS  CAS  Google Scholar 

  26. Koesling, D. et al. The primary structure of the larger subunit of soluble guanylyl cyclase from bovine lung: homology between the two subunits of the enzyme. FEBS Lett. 266, 128–132 (1990).

    Article  CAS  Google Scholar 

  27. Brune, B. & Lapetina, E. G. Phosphorylation of nitric oxide synthase by protein kinase A. Biochem. Biophys. Res. Commun. 181, 921–926 (1991).

    Article  CAS  Google Scholar 

  28. Salter, M., Duffy, C. & Hazelwood, R. Determination of brain nitric oxide synthase inhibition in vivo: ex vivo assays of nitric oxide can give incorrect results. Neuropharmacology 34, 327–334 (1995).

    Article  CAS  Google Scholar 

Download references


This work was supported in part by the Japanese Society for the Promotion of Science (S.O.) and by Consejo Nacional de Ciencia y Technologia y Direccion General del Personal Academico (R.G.)

Author information

Authors and Affiliations


Corresponding author

Correspondence to K. M. Kendrick.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Kendrick, K., Guevara-Guzman, R., Zorrilla, J. et al. Formation of olfactory memories mediated by nitric oxide. Nature 388, 670–674 (1997).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing