副腎剔出と電気痙攣ショック (ECS) の塩類溶液選好行動に及ぼす効果

抄録

It is the purpose of these experiments to demonstrate the variation of the preference-aversion functions for NaCl and for KCl among the normal, the adrenalectomized and the convulsed rats subjected to the self-selection. Each solution was presented in a random order. The obtained data are in terms of the mean intake per 24hrs. of each concentration of solution. The intakes of solutions, tap water and food are expressed on a body weight basis (gm. or c.c./100gm. B.W./day/rat).
The results of these experiments are thus as follows:
(1) In the self-selection situation, the normal rats showed a typical preference-aversion function for NaCl and for KCl (Fig. 1). The preference threshold is about 0.05 per cent NaCl and about 0.04 per cent KCl solution. The optimal concentration is about 0.9 per cent NaCl and about 0.1 per cent KCl. The aversion threshold is around 1.5 per cent NaCl and 0.9 per cent KCl solution, where all the rats drank less of each solution than the tap water.
(2) As can be seen in Fig. 2, the bilateral adrenalectomized rats showed an increase of the intake of NaCl after the rest-period of 16 days. Moreover, when given a chance to choose among water, 0.9 per cent NaCl and 0.1 per cent KCl solution, the adrenalectomized rats showed a greater increase in the intake of NaCl and also a greater decrease in that of KCl than the normal rats.
As for the preference-aversion functions, the adrenalectomized rats showed a decrease in the preference threshold (0.02-0.03 per cent) and an increase in the intake of all concentrations of NaCl solution in comparison to the normal rats.
(3) The convulsed rats treated daily with ten ECS administrations showed the preference-aversion functions similar to those of the normal ones, differing only in the amount of intakes, i.e., a decrease in NaCl and an increase in KCl for all concentrations employed (Fig. 3).
(4) There is a significant difference in the level of the physiological need for Na and K between the normal and the adrenalectomized animals (cf. Table 2 and 3).
On the other hand, it is interesting to note that the convulsed rats chose to take significantly less NaCl and more KCl solution in each situation than the normal and the adrenalectomized rats. Therefore, relative Na aversion and K preference by the convulsed animals might result from the functional hypertrophy of the adrenal cortex. This verifies the findings of Rosvold et al., although there is no histological examination of the adrenal gland in this experiment.
(5) The convulsed as well as the adrenalectomized animals showed a decrement in body weight immediately after the treatment and a gradual recovery during the remainder of the experiment. The paralysis in the thoracic region downward appeared in the 33.5 per cent of the convulsed group.
It may be concluded from these findings that the change of the preference-aversion functions under the conditions of the stress suggests some possible mechanisms by which endocrinological and metabolic responses act together to manifest a behavioral disturbance.