Irritant‐drinking behaviour can be modified by gravity‐stress loaded in developing but not in adult rats

Abstract

It is generally accepted that taste and taste‐related trigeminal chemical sensation bring up emotions that are essential for animal living and for a good quality of life, and that stress may modify sensory systems related to emotionality. The purpose of this study was to clarify (1) the effects of stress on taste and trigeminal irritant sensations, (2) effects of stress at a developing stage on these sensations. Male Wistar albino rats received 1G, 2G or 3G stimulation. Hyper‐gravity was applied with a centrifugal apparatus. The two‐bottle preference test was performed to measure chemical sensation. Adult rats received 1G (control), 2G (moderate) or 3G (strong) gravity loading every 10 min/day during 32 days. Developing rats received 3G gravity loading every 10 min/day during 45 days and were compared with 1G controls. As test solutions, taste solutions (sucrose, saccharin, citric acid, NaCl, monosodium glutamate, quinine and caffeine) and a trigeminal irritant solution (capsaicin) were used. In developing rats, but not in adult rats, hyper‐gravity stimulation increased the intake volume of sucrose, saccharin, NaCl, quinine and capsaicin, and the preference ratio for quinine, caffeine and capsaicin. It is suggested that the life stage where stress is loaded is critical for determining changes in emotionality as well as in emotion‐related sensory systems. Copyright © 2010 John Wiley & Sons, Ltd.

Sex Differences in Antinociceptive Effects Induced by Gravity Stress in Rats

“…Therefore, it is presumed that stress-modified trigeminal pain sensation may strongly depend on sex. A similar interaction has been reported in relation to taste sensation during food intake [40].…”

Hypergravity Conditioning on Ileal Movements in Rats

“…The animals were moved in pairs from the colony room to the centrifuge room and loaded into the centrifuge. A centrifugal apparatus (H26-F, Kokusan, Tokyo, Japan) was used, as described elsewhere (10). The arm length of the centrifuge was 15 cm, and to produce hyperG, the speed of rotation was set to 108 rpm (resulting in an acceleration vector of 2.2 G).…”

“…However, careful consideration on possible side-effects of centrifugation on all bodily functions and systems should be carried out before it can be used in a regular basis. Previous animal studies have shown general effects of hypergravity in the body, such as changes in body weight and gustatory sensation in rats (9,10).…”

Sex Differences in Ileal Somatostatin-Response after Stress Conditioning in Rats

“…3G stress was loaded by a centrifugal apparatus (H26-F, Kokusan, Tokyo, Japan) every day at 10:00 AM for 10 min during 30 days, as described elsewhere [20]. During gravity-loading, rats were placed in the mesh case of the centrifuge with a head-central orientation.…”

“…Nevertheless, the relationship between stress and somatostatin is still controversial. Further, sex differences are usually observed in stress responses, including changes in digestive function and feeding behavior [20][21][22].…”