Influence of Lesions in the Limbic-Hypothalamic System on Metabolic Response of Acetate to Daily Repeated Immobilization Stress

Abstract

The effects of lesions in the basal medial hypothalamus and limbic structure on the acetate metabolic responses to daily repeated exposure to immobilization stress in the liver of rabbits have been investigated. The experimental results were as follows: (1) The acetate metabolic response to the 1st exposure to immobilization stress (exposure on the 1st day) were considerably altered by lesions in the periventricular arcuate nucleus (ARC) ventromedial hypothalamus (VMH), stria terminalis (ST) and dorsal fornix (FX). (2) The acetate metabolic responses to immobilization stress were completely abolished by seven times repetition of immobilization stress in the rabbits with lesions in ARC, VMH and FX; they were similar to sham-operated groups. (3) In rabbits with ST lesions, the acetate metabolic responses to the 7th exposure (exposure on the 7th day) to immobilization stress were exactly the same as those after the 1st exposure of immobilization stress, but these metabolic responses were completely abolished by the seven times repetition of exposure in the sham-operated animals. (4) These results suggest that firstly, the ARC, VMH, amygdala(AMYG)-ST system and dorsal hippocampus(HPC)-FX system are involved in the acetate metabolic responses to the 1st exposure of immobilization stress, and secondly, that only the AMYG-ST is involved in the disappearance process of acetate metabolic responses to immobilization stress by the daily repetition of immobilization stress.

Influence of Lesions of the Limbic-Hypothalamic System on Metabolic Response of Pyruvate to Daily Repeated Immobilization Stress in Rabbits

“…Thus, the metabolic responses of pyruvate to the ist exposure to 1MO were altered by the ARC lesions, suggesting that the ARC participated in the mechanisms of pyruvate metabolic responses to the ist exposure to 1MO. Our previous findings suggested that the ARC also participated in the mechanisms of adrenocortical and acetate metabolic responses to the ist exposure to 1MO (Seto et al, 1982;Seto et al, 1984). In rabbits with ARC lesions, as in shamoperated animals, the 7th exposure to 1MO had no appreciable effects on the rates of 1C transfer into 002, G, KB, CE, TG, FC, FFA and PL.…”

“…From these findings and our present results, it might be suggested that the ARC was not concerned with the process of establishment of pyruvate metabolic adaptation to daily repeated exposures to 1MO. Our previous findings suggested that the ARC did not participate in the process of adrenocortical and acetate metabolic adaptation to daily repeated 1MO (Seto et al, 1982;Seto et al, 1984). Table 2 shows the effects of VMH lesions on the pyruvate metabolic responses to daily 1MO.…”

“…In rabbits with ST lesions, in contrast, the 7th exposure to 1MO significantly decreased the rates of '4C transfer into CO2, KB, CE, FC, FFA, significantly increased those into TG and PL, but had no appreciable effect on those into G. The fact that the pyruvate metabolic responses to 1MO thus persisted even on the 7th day as on the ist day in rabbits with ST lesions, different from sham-operated animals, suggested a certain participation of the AMYG-ST system in the establishment of pyruvate metabolic adaptation to daily repeated exposures to 1MO. Our previous findings suggested that the AMYG-ST system was also involved in the process of adrenocortical and acetate metabolic adaptation to daily repeated exposures to 1MO (Seto et al, 1982;Seto et al, 1984). Table 4 shows the effects of FX lesions on the pyruvate metabolic responses to daily repeated exposures to 1MO.…”

“…Neither in rabbits with VMH lesions nor in sham-operated animals any appreciable effect was exerted by the 7th exposure to 1MO on the rates of 14C transfer into CO2, 0, KB, CE, TG, FC, FFA and PL, suggesting that the VMH was not concerned with the process of establishment of pyruvate metabolic adaptation to daily repeated exposures to 1MO. Our previous findings suggested that the VMH was not involved in the adaptive process of adrenocortical and acetate metabolic responses to daily repeated exposures to 1MO (Seto et al, 1982;Seto et al, 1984). Table 3 shows the effects of ST lesions on the pyruvate metabolic responses to daily repeated exposures to 1MO.…”

“…Thus, the pyruvate metabolic responses to the ist exposure to 1MO were altered by the VMH lesions, suggesting that the VMH participated in the mechanisms of pyruvate metabolic responses to the ist exposure to 1MO. Our previous findings suggested that the VMH also played some role in the mechanisms of adrenocortical and acetate metabolic responses to the ist exposure to 1MO (Seto et al, 1982;Seto et al, 1984). Neither in rabbits with VMH lesions nor in sham-operated animals any appreciable effect was exerted by the 7th exposure to 1MO on the rates of 14C transfer into CO2, 0, KB, CE, TG, FC, FFA and PL, suggesting that the VMH was not concerned with the process of establishment of pyruvate metabolic adaptation to daily repeated exposures to 1MO.…”