, Volume 115, Issue 1–2, pp 141–146 | Cite as

Alphaxalone, a steroid anesthetic, inhibits the startle-enhancing effects of corticotropin releasing factor, but not strychnine

  • Neal R. Swerdlow
  • Karen T. Britton
Original Investigations


Corticotropin releasing factor (CRF) is a 41 amino acid peptide implicated in the expression of stress-and fear-enhanced behaviors. CRF potentiates the amplitude of the startle reflex, and this effect is reversed by benzodiazepines (BDZ), suggesting that the startle-enhancing effects of CRF are modulated by changes in the GABA/BDZ receptor complex. In the present study, CRF-potentiated startle is inhibited by alphaxalone, a pregnane steroid anesthetic that is thought to act via the GABA/BDZ receptor complex. Alphaxalone (ALX) does not reduce CRF-potentiated startle by producing a generalized reduction in reactivity, since blockade of CRF-stimulated startle was not accompanied by an ALX-induced reduction in baseline startle amplitude, and ALX does not reduce strychnine-potentiated startle. The effects of alphaxalone on CRF-potentiated startle may not be generalized to all CRF-stimulated behaviors, since alphaxalone failed to disrupt CRF-stimulated locomotor activity. CRF-potentiated startle is a useful assay for studying the effects of novel anxiolytic agents, and alphaxalone appears to be a steroid anesthetic with anxiolytic properties in this assay.

Key words

Alphaxalone Corticotropin releasing factor Fear Startle Stress Strychnine 


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Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Neal R. Swerdlow
    • 1
  • Karen T. Britton
    • 1
  1. 1.Department of PsychiatryUCSD School of MedicineLa JollaUSA

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