Sialoadenectomized Mice Research Articles

Evidence for physiological function of epidermal growth factor: pregestational sialoadenectomy of mice decreases milk production and increases offspring mortality during lactation period.

Female virgin mice, whose submandibular glands were removed, underwent normal pregnancy and delivery. During the nursing period, however, a substantial number of pups born to and nursed by sialoadenectomized mothers died within 5 days of birth, whereas this did not occur among pups born to normal mothers. Cross-foster nursing experiments indicated that the cause of death of pups was to be found in sialoadenectomized mothers, not in the pups. The capacity of the sialoadenectomized mothers to nurse pups was much less than that of normal mothers, as shown by experiments involving alterations in the number of pups nursed by both sialoadenectomized and normal mothers. The mammary gland of lactating sialoadenectomized mice was smaller in size and produced less milk compared with that of normal mice. No apparent qualitative difference in milk proteins was found in the milk produced by the two groups of mothers. The decreased growth of the mammary gland of sialoadenectomized mice was also manifested during the second half of pregnancy, and mammary explants from those mice synthesized less casein in response to lactogenic stimuli, insulin, cortisol, and prolactin, in an organ culture system, when compared with mammary explants from normal pregnant mice. When epidermal growth factor, a polypeptide hormone that is synthesized and secreted by the submandibular gland, was injected daily at a dose of 5 micrograms into sialoadenectomized pregnant mice, the survival rate of the pups nursed by their mothers increased to the value obtained with normal mothers. The results were discussed in terms of a possible role of the submandibular gland and epidermal growth factor in the development of the mammary gland.

Aggression‐provoked renin release from extrarenal and extrasubmaxillary sources in mice

In submaxillary sialoadenectomized and nephrectomized mice aggressive behaviour provoked 5 to 40-fold increases in plasma renin concentration. The changes in renin concentration with time were different in different groups of confronted mice with only partial correlation between the pattern and the observable degree of fight. The changes were similar in sialoadenectomized mice with untouched kidneys as in sialoadenectomized and nephrectomized, indicating that aggression causes no measurable, if any, renal renin release. Repeated aggression with 2 hourly intervals provoked repeated renin release from extrarenal and extrasubmaxillary sources. The renin concentrations of different organs showed the same mutual relationship as in other mammals, but were about 10-fold higher. Splenectomy was without effect on the aggression-provoked renin release. Antibodies against pure mouse renin neutralized the renin in plasma and organs, which contained only insignificant, if any, pepsin activatable inactive renin. Adrenaline, apomorphine, carbachol and dihydralazine were as isoprenaline and noradrenaline without effect on renin release in sialoadenectomized and nephrectomized mice.

Tumor growth: suppression in mice by submanidibular gland extirpation.

Transplanted A-10 breast adenocarcinomas grew more slowly in young-adult male A/HeJ mice from which the submandibular glands had been extirpated than in sham-operated or unoperated control mice of the same strain. The mitotic index was lower in tumors from experimental animals than in those from controls. Vascularization about the tumor margins was also less prominent. The C1300 neuroblastoma grew more slowly in sialoadenectomized mice than in controls. Modulation of tumor growth by factors of salivary gland origin may have been responsible for these effects.

DIFFERENT EFFECTS ON RENAL AND SUBMAXILLARY RENIN RELEASE AFTER BLOCKADE OF THE RENIN SYSTEM IN MICE

Ingibition of the angiotensin I converting enzyme with SQ 20,881 results in a rapid marked increase in plasma renin concentration in mice. The maximum effect is short-lasting, but the values are still elevated 2 hours after the injection, the time course being similar to that previously found in rats. The relative increase is the same in normal and sialo-adenectomized mice. The plasma renin concentration of nephrectomized mice with their submaxillary glands intact is, however, totally uninfluenced by injection of the blocker. This finding indicates that renin release from the submaxillary glands is not controlled by the plasma angiotensin II concentration as is that of the renin release from the kidneys.