Ventromedial septal lesions in rats reduce the effects of inescapable shock on escape performance and analgesia.

Abstract

Lesions of the ventromedial septum reduced or eliminated several effects of exposure to inescapable shock in rats, whereas lesions of the dorsolateral septum did not. Experiment 1 demonstrated that ventromedial septal lesions reduced the loss in body weight produced by inescapable shock and eliminated the subsequent (24 hr later) interference with escape performance (learned helplessness). Experiment 2 demonstrated that ventromedial septal lesions reduced the analgesia that occurs immediately following inescapable shock and the analgesia reinstated by exposure to escapable shocks 24 hr later. These findings, in conjunction with the findings that ventromedial septal lesions also reduce the secretion of corticosterone (Kelsey, 1975) and stomach erosions (Kelsey, Note 1) produced by inescapable shocks, indicate that ventromedial septal lesions reduce several responses to inescapable shock and suggest that possibility that all of these effects may reflect a unitary deficit. It is hypothesized that ventromedial septal lesions reduce these effects of exposure to inescapable shock either by reducing the ability of the rats to learn that their responses and shocks were uncorrelated or by reducing the emotional impact of this lack of correlation.

Nicotinic Receptors in the Brain Links between Molecular Biology and Behavior

“…Administration of nicotine directly into the dorsal hippocampus produces anxiolytic-like effects in both the plus maze (Ouagazzal et al 1999) and social interaction tests (File et al 1998). The behavioral deficits associated with learned helplessness have been prevented by lesions to the hippocampus (Elmes et al 1975) and the ventromedial septum (Kelsey and Baker 1983). Projections from the hippocampus to the amygdala may, therefore, be involved in forming emotional memories associated with learned helplessness-inducing shock.…”

Stress-Induced Analgesia

“…The septo-hippocampal system is highly involved in nociceptive neurotransmission (for review see Aloisi, 1997) and lesions to the ventromedial septum reduce SIA and FCA in rats (Kelsey and Baker, 1983). In a human study by Zhang et al (2003a), electroacupuncture of low and high intensity increased the pain threshold to radiant thermal heat.…”

Ventromedial septal lesions in rats reduce stomach erosions produced by inescapable shock

“…It is suggested that, by disrupting the cholinergic septohippocampal system, ventromedial septal lesions may reduce the ability of rats to learn that shocks are inescapable or may reduce the aversiveness of such knowledge.Lesions of the ventromedial septum in rats reduce or eliminate several physiological and behavioral responses to the stress of inescapable shock. For example, these lesions reduce the enhanced secretion of corticosterone (Kelsey, 1975), the loss of body weight, and the analgesia or decreased pain sensitivity produced by exposure to inescapable shocks (Kelsey & Baker, 1983). In addition to reducing these shortterm responses to inescapable shocks, ventromedial septal lesions also reduce the interfering effects of inescapable shocks on subsequent escape performance (learned helplessness; Kelsey & Baker, 1983).The intent of this study was to explore the generality of these findings by determining if ventromedial septal lesions would also reduce another physiological response to inescapable shock-stomach erosions, commonly referred to as stress ulcers.…”

“…For example, these lesions reduce the enhanced secretion of corticosterone (Kelsey, 1975), the loss of body weight, and the analgesia or decreased pain sensitivity produced by exposure to inescapable shocks (Kelsey & Baker, 1983). In addition to reducing these shortterm responses to inescapable shocks, ventromedial septal lesions also reduce the interfering effects of inescapable shocks on subsequent escape performance (learned helplessness; Kelsey & Baker, 1983).The intent of this study was to explore the generality of these findings by determining if ventromedial septal lesions would also reduce another physiological response to inescapable shock-stomach erosions, commonly referred to as stress ulcers. Indicating that these lesions might reduce gastric erosion formation, Brick, Burright, and Donovick (1979) reported that large septal lesions reduced the length of gastric erosions produced by 3 h of cold restraint.…”

“…Lesions of the ventromedial septum in rats reduce or eliminate several physiological and behavioral responses to the stress of inescapable shock. For example, these lesions reduce the enhanced secretion of corticosterone (Kelsey, 1975), the loss of body weight, and the analgesia or decreased pain sensitivity produced by exposure to inescapable shocks (Kelsey & Baker, 1983). In addition to reducing these shortterm responses to inescapable shocks, ventromedial septal lesions also reduce the interfering effects of inescapable shocks on subsequent escape performance (learned helplessness; Kelsey & Baker, 1983).…”