Synergistic autonomic nervous regulation of accelerated salivary gland growth in rats

Within 8 days after a submandibular salivary gland is deprived of its parasympathetic nervous innervation, the gland undergoes a marked reduction in weight. After either sympathectomy or parasympathectomy, the increase in gland weight which usually follows incisor amputation or dietary pancreatin is partially inhibited. The gland weight response to these two stimuli is completely inhibited after combined sympathectomy and parasympathectomy. In contrast, the response of the glands to isoproterenol is not dependent upon nervous innervation since administration of the drug still causes glandular enlargement after partial or complete denervation. Compensatory growth of the remaining submandibular gland after removal of one gland and ligation of the ducts of the parotid glands is partially inhibited by section of either nervous branch alone and almost entirely inhibited after complete denervation. A small but definite compensatory response still occurs after complete denervation indicating that humoral as well as nervous factors may be involved in this response. In hypophysectomized rats the response of the submandibular glands to growth hormone administration is not impaired by partial or complete autonomic denervation, indicating that nervous factors do not have a role in this effect of growth hormone.

Cardiovascular Responses Following Immunological Sympathectomy

Sympathetic function and cardiovascular responses were measured in rats treated at birth with an antiserum developed to the sympathetic nerve growth factor. The intact animals exhibited ptosis, miosis, and decreased excretion of norepinephrine in the urine. Electrical stimulation of the sympathetic innervation to the vessels of the perfused hindquarters failed to produce vasoconstriction or vasodilatation in any of the treated rats over a wide range of stimulus parameters. Alterations in vascular reactivity characteristic of sympathetic denervation were noted; responsiveness was increased to norepinephrine but not to other constrictor agents. Chemical stimulation of the sympathetic ganglia with 1,1-dimethyl-4-phenyl-piperazinium iodide (DMPP) did not activate the postganglionic fibers but did promote the release of catecholamines from the adrenal medulla. The treated rats showed elevated resistance to flow in the hindquarters. The results of this investigation thus demonstrate that treatment with the antinerve growth factor effectively abolishes vasomotor function of the fibers of the sympathetic nervous system.

Chromosome Puffs in Drosophila Induced by Ribonuclease

Ribonuclease induces many puffs in salivary gland chromosomes of Drosophila busckii. The left arm of chromosome 2 was analyzed in detail; in this arm seven puffs were induced in a definite sequence.