Elsevier

Neuroscience Letters

Volume 257, Issue 1, 20 November 1998, Pages 9-12
Neuroscience Letters

The onset of diffuse noxious inhibitory controls in postnatal rat pups: a C-Fos study

https://doi.org/10.1016/S0304-3940(98)00779-4Get rights and content

Abstract

The development of diffuse noxious inhibitory controls (DNIC) was studied in postnatal rats aged 12, 21 and 42-days-old, using immunoreactive localization of the c-fos protein products induced in the dorsal horn by noxious stimulation. The presence of DNIC was revealed by the reduction in the levels of Fos-like immunoreactivity that are normally induced by a standardized primary pinch stimulus when this stimulus was accompanied by a concurrent noxious stimulus (formalin) to a heterotopic body part. Significant reductions were seen at postnatal day 42 (P42; 15% reduction) and P21 (17% reduction), but concurrent stimulation had no significant effect at P12. These results suggest that the system subserving DNIC is functionally mature by P21, but not effective at P12. This delayed maturation of an inhibitory system may underlie the extreme sensitivity to somatosensory stimulation seen in neonatal pups and premature infants.

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Acknowledgements

Thanks to J. Middleton and S. Beggs for technical support, H. Bester for the gift of the fos antibody. T.B. was supported by an MRC Advanced Course Studentship.

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Present address: Division of Physiology, St Thomas' Hospital Medical School, Lambeth Palace Road, London SE1 7EH, UK.

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