Seasonal Changes in the Activity of the Adrenal Medulla of Viscacha (Lagostomus maximus maximus)
Article first published online: 30 APR 2013
Copyright © 2013 Wiley Periodicals, Inc.
The Anatomical Record
Volume 296, Issue 7, pages 1089–1095, July 2013
How to Cite
Rodriguez, H., Filippa, V. P., Penissi, A., Fogal, T., DomÍnguez, S., Piezzi, R. S. and Scardapane, L. (2013), Seasonal Changes in the Activity of the Adrenal Medulla of Viscacha (Lagostomus maximus maximus). Anat Rec, 296: 1089–1095. doi: 10.1002/ar.22707
- Issue published online: 14 JUN 2013
- Article first published online: 30 APR 2013
- Manuscript Accepted: 21 MAR 2013
- Manuscript Received: 17 DEC 2012
- Universidad Nacional de San Luis (UNSL) . Grant Number: Proyecto 22/Q003
- adrenal medulla;
- chromaffin granules;
Animals living in nontropical climates modify their physiology and behavior to adapt to seasonal environmental changes. Part of this adaptation involves the release of catecholamine from sympathetic nerve endings and the adrenal medulla, which play a major role in regulating energy balance. The aim of this work was to investigate whether adult male viscachas in their natural habitat exhibits structural changes in the adrenal medulla during the annual seasonal cycle. In August–September, chromaffin granules revealed ultrastructural changes suggestive of piecemeal degranulation. Quantitative morphometric analysis by transmission electron microscopy showed a significantly lower percentage of resting chromaffin granules and a higher percentage of altered granules and empty containers in August–September (late winter) compared to February–March (late summer), suggesting an increased secretory process of catecholamines in August–September. The mechanism of piecemeal degranulation might amplify this process, encouraging the adaptive response to winter environmental conditions. Tissue levels of epinephrine, norepinephrine, and dopamine (analyzed by high-performance liquid chromatography) changed throughout the year, reaching maximum values in February–March and minimum values in August–September. These results demonstrate morphological and biochemical seasonal variations of the adrenal medulla, suggesting that epinephrine might promote energy mobilization, which allow the Lagostomus to cope with adverse environmental conditions and thus to survive during winter season. Anat Rec, 296:1089–1095, 2013. © 2013 Wiley Periodicals, Inc.