Slower growth of tumours in sympathetically denervated murine skin

In order to examine tumour growth in sympathetically denervated murine skin, two breast cancer tumour lines were employed, i.e. M3 tumours, of a relatively high local growth and low metastatic capacity, and MM3-LN tumours, that grew locally at a slower rate but disseminated early to the lung. Mice subjected to unilateral superior cervical ganglionectomy or sham-operation 2 weeks earlier were used. M3 or MM3-LN tumours were implanted in the ipsilateral ear to the surgical procedure. Tumour size was assessed every 2-6 days, starting from the 7th day after tumour implantation. Growth of M3 and MM3-LN tumours was significantly slowed by a previous sympathetic denervation of the skin territory. There were no significant differences in the number or size of pulmonary metastases at autopsy between mice subjected to ganglionectomy or to sham-operation. Ganglionectomy increased significantly ipsilateral submaxillary lymph node ornithine decarboxylase activity by 62% and decreased noradrenaline content to 8% of the innervated contralateral lymph node. The present results indicate a local inhibitory modulation of tumour growth by the sympathetic nervous system.