Hardwick, D. C.

2019-02-15T14:29:06Z

2019-02-15T14:29:06Z

1953

The age carve of histamine in the rat skin exhibits a general, fairly constant level of 10 to 20 microg./g. ap to 500 days. 'I'here are, however, two exceptions, the peak about birth and the peak about weaning. Between these two disturbances values not much above the normal adult figures are obtained. The rise at weaning has been shown to be separable into two parts. Observations on the histamine content of bread and milk (less than 0.5 microg./g.) and of rat cake (about 5 microg./g.) show that these cannot account for the steady rise observed between 16 and 24 days. This may be due to alterations in the intestinal flora on changing from a milk diet to solid food or to hormonal imbalance. These causes probably account, in large measure, for the other irregularities noted in the literature at about this age. Changes in epidermal thickness and tissue fat content may influence the change but are not of prime importance.

The peak observed at 22 days in large but not in small litters is ascribed to the shock of premature weaning. Not weaning . a large litter eliminated this peak and the suggestion is further supported by weaning a small litter prematurely and by the results obtained after traumatic stress. These results indicate that the increase in skin histamine after such treatment may be caused by a relative hypocortism.

Apart from this theoretical aspect the results reported here indicate that careful consideration should he given to weaning schedules to ensure that all litters are, as far as possible, similar. The practice of some authors of allowing the litter to remain with the mother till thirty days has much to recommend it.

The rise before birth may again be related to changes in the thyroid and adrenal glands and forms part of the general metabolic changes at parturition.

An important point arising from Section 4. is that shin not affected directly by the stressing agent did show a change in histamine content. The use of unaffected areas as simultaneous controls i should clearly be used with caution.

It would appear that, in general, changes in the histamine content of the skin indicate a disturbance! of the hormonal balance of the adrenal and thyroid. These changes may also be an indicator of disturbed protein metabolism (133, 134). The gerontological importance of such disturbances has been pointed out in the Introduction, and theory suggests that work on successive stresses might be informative. The results indicate that animals about 50 days old might show differences in their skin histamine reactions which could be related to their previous experience; Such differences do not appear to exist in adult (330 day) animals.

http://hdl.handle.net/1842/34623

The University of Edinburgh

Annexe Thesis Digitisation Project 2019 Block 22

Age and histamine metabolism

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy