Mammary gland sympathetic innervation is a major component in type 1 deiodinase regulation
- 45 Downloads
Recent observations have shown that in lactating rats previously deprived of suckling, either suckling stimulus or ip injection of norepinephrine was capable of increasing mammary deiodinase type 1 (M-D1) mRNA content and enzyme activity. In the present work, we show that intact efferent sympathetic mammary innervation is required to restore both mammary D1 mRNA content and enzyme activity, whereas suckling-induced secretion of catecholamines from the adrenal glands does not seem to participate in M-D1 enzyme regulation. The data also indicate that the sympathetic reflex activation in response to suckling involves two complementary autonomic components: (1) activation, presumably through mammary segmental arrangement affecting neighboring mammary glands; and (2) an individual reflex regulatory mechanism capable of maintaining M-D1 activity within each mammary gland. In addition to these findings, we show that the suckling-induced sympathetic activation of M-D1 activity could be blocked by prior activation of ductal mechanoreceptors. This set of regulatory and counterregulatory mechanisms seems to ensure the optimal control of mammary energetic expenditure according to litter size.
Key WordsThyroid hormone metabolism deiodinases sympathetic innervation mammary gland lactation
Unable to display preview. Download preview PDF.
- 2.Oppenheimer, J. H. and Samuels H. H. (eds.) (1983): Molecular Basis of Thyroid Hormone Action. Academic: New York.Google Scholar
- 4.Aceves, C., Navarro, L., Ramirez del Angel, A., Luna, M., and Valverde-R, C. (1994), Endocrine 2, 547–551.Google Scholar
- 7.Valverde-R, C. and Aceves, C. (1989), Endocrinology 124, 1340–1344.Google Scholar
- 8.Aceves, C., Morales, T., Pineda, O., Rodón-Fonte, C., Navarro, L., Valverde-R, C., and Mena, F. (1996). 5th International Symposium Hormonal Bioactive Substances in Milk. Slovak Republic.Google Scholar
- 10.Mena, F., Clapp, C., Martínez-Escalera, G., Pacheco, P., Grosvenor, C. E. (1985). In: Oxytocin: Clinical and Laboratory Studies, Amico, J. A. and Robinson, A. G. (eds.), Elsevier: Amsterdam.Google Scholar
- 11.Grosvenor, C. E. and Mena, F. (1982). In: Neuroendocrine Perspectives, vol. 1, Muller, C.E.E. and McLeod, R. M. (eds.), Elsevier: Amsterdam.Google Scholar
- 12.Deis, R. P. (1968), J. Physiol. (Lond.) 197, 37–46.Google Scholar
- 15.Memphan, T. B. (1987), Physiology of Lactation, Open University Press: Philadelphia.Google Scholar