Lipopolysaccharide does not affect acoustic startle reflex in mice

Area of Science:

• Neuroscience
• Behavioral Science
• Immunology

Background:

• Bacterial endotoxin (lipopolysaccharide; LPS) induces sickness behavior in rodents, affecting stress hormones and neurotransmitter systems.
• Sickness behavior involves physiological and behavioral changes to combat infection, but its impact on protective reflexes is not fully understood.
• The acoustic startle reflex (ASR) is a protective response modulated by emotional and physiological states.

Purpose of the Study:

• To investigate the effects of LPS on the acoustic startle reflex (ASR) and prepulse inhibition (PPI) in mice.
• To examine how LPS influences locomotor activity and corticosterone levels in different mouse lines.
• To determine if LPS-induced sickness behavior impairs protective responses to salient environmental stimuli.

Main Methods:

• Intraperitoneal injections of LPS were administered to high (HA) and low (LA) anxiety-related behavior mouse lines.
• Acoustic startle reflex (ASR), prepulse inhibition (PPI), and locomotor activity were measured.
• Blood plasma corticosterone concentrations were analyzed.

Main Results:

• LPS induced sickness behavior in both HA and LA mice, characterized by decreased locomotion, body weight, and elevated corticosterone.
• LPS administration did not alter the magnitude of the acoustic startle reflex (ASR) or prepulse inhibition (PPI) in either mouse line.
• Differences in swim stress-induced analgesia and emotional behaviors between HA and LA lines did not influence the effects of LPS on ASR and PPI.

Conclusions:

• LPS-induced sickness behavior in rodents does not impair the acoustic startle reflex (ASR) or prepulse inhibition (PPI).
• Protective responses to salient environmental stimuli remain intact during LPS-induced sickness behavior.
• These findings suggest that the adaptive nature of sickness behavior may preserve essential protective reflexes.