Startle responses, heart rate, and temperature in 5-HT1B receptor knockout mice

Neuroreport. 2000 Dec 18;11(18):4097-102. doi: 10.1097/00001756-200012180-00037.


Relative to wildtype mice, mice lacking 5-HT1B receptors (5-HT1B KO) exhibit exaggerated heart rate and body temperature responses to environmental stimuli. In contrast, acoustic startle reactivity is reduced in 5-HT1B KO mice. We combined heart rate and temperature measurement with startle response paradigms in order to elucidate this apparent contradiction. Habituation and footshock-induced sensitization paradigms modulate startle reactivity. Reduced startle reactivity and unaltered habituation in 5-HT1B KO mice were replicated. Heart rate and temperature were unaffected by startle stimuli, but increased markedly in response to transportation and handling procedures. Footshocks caused a mild startle-sensitization and tachycardia in both genotypes. The physiological hyper-reactivity in 5-HT1B KO mice is a subtle phenotypic difference that contrasts with the phenotypic decrease in startle reactivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation / adverse effects
  • Adaptation, Physiological / genetics
  • Animals
  • Behavior, Animal / physiology
  • Body Temperature / genetics*
  • Brain / cytology
  • Brain / metabolism*
  • Electric Stimulation / adverse effects
  • Habituation, Psychophysiologic / physiology
  • Heart Rate / genetics*
  • Male
  • Mice
  • Mice, Knockout / physiology*
  • Phenotype
  • Receptor, Serotonin, 5-HT1B
  • Receptors, Serotonin / deficiency*
  • Receptors, Serotonin / genetics
  • Reflex, Startle / genetics*


  • Receptor, Serotonin, 5-HT1B
  • Receptors, Serotonin