Possible role for the 5-HT1A receptor in the behavioral effects of REM sleep deprivation on free-operant avoidance responding in rat.
BACKGROUND
REM sleep deprivation (REMSD) has been shown to increase rates of free-operant avoidance responding. Depletion of 5-hydroxytryptamine (5-HT, serotonin) levels produces similar effects on responding.


OBJECTIVE
We studied whether the pharmacological activation of the 5-HT1A receptor would produce effects on avoidance responding similar to REMSD and depleted 5-HT levels.


METHODS
Rats were trained to lever press on a free-operant avoidance task. Dose-effect functions were established for 8-OH-DPAT (a 5-HT1A receptor agonist) (0.1-1.0 mg/kg) and WAY 100635 (a 5-HT1A receptor antagonist) (0.1-1.0 mg/kg). Rats were then exposed to REMSD (48 h) or equivalent control conditions, and then administered 8-OH-DPAT (0.6 mg/kg) and/or WAY 100635 (0.025-0.1 mg/kg).


RESULTS
Injections of 8-OH-DPAT increased rates of avoidance responding in a dose-dependent manner, while WAY 100635 did not alter responding. The effect of 8-OH-DPAT was antagonized by pre-injection of WAY 100635. REMSD and injections of 8-OH-DPAT increased rates of avoidance responding and the effects of both manipulations were reversed by pre-injection of WAY 100635.


CONCLUSIONS
Activation of the 5-HT1A receptor may be a mechanism by which REMSD increases rates of free-operant avoidance responding.
Harvey
Mark T
MT
John F. Kennedy Center on Human Development, Vanderbilt University, Nashville, TN 37203, USA.
Smith
Randy L
RL
May
Michael E
ME
Caruso
Mary
M
Roberts
Celeste
C
Patterson
Tina G
TG
Valdovinos
Maria
M
Kennedy
Craig H
CH
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology*; D058825:Serotonin 5-HT1 Receptor Agonists; D012892:Sleep Deprivation / Q000503:physiopathology / Q000523:psychology; D012895:Sleep, REM / Q000187:drug effects / Q000502:physiology*
D058825:Serotonin 5-HT1 Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin