Role of the thalamic intergeniculate leaflet and its 5-HT afferences in the chronobiological properties of 8-OH-DPAT and triazolam in syrian hamster.
The 5-HT(1A/7) receptor agonist 8-hydroxy-2-[di-n-propylamino]-tetralin (8-OH-DPAT) has chronobiological effects on the circadian system and, in the Syrian hamster, it is known that serotonergic (5-HT) projections connecting the median raphe nucleus to the suprachiasmatic nuclei (SCN) of the hypothalamus are a prerequisite for the expression of 8-OH-DPAT-induced phase advance of locomotor activity rhythm. We examined the possible involvement of the thalamic intergeniculate leaflet (IGL) in the phase-shifting properties of 8-OH-DPAT injections at CT7. Bilateral electrolytic lesions of the IGL blocked phase-shift responses to 8-OH-DPAT of the activity rhythm. Phase changes induced by injections of 8-OH-DPAT at CT7 and triazolam (Tz), a short-acting benzodiazepine, at CT6 were also studied after bilateral chemical lesion of the 5-HT fibres connecting the dorsal raphe nucleus (DR) to IGL. Destruction of 5-HT fibres within the IGL blocked the phase-shift response to Tz, but not the phase-shift response to 8-OH-DPAT. In conclusion, (a) IGL is essential for the phase-shifting effect of peripheral 8-OH-DPAT injections; (b) 5-HT fibres connecting DR to IGL are necessary for the expression of the phase-shifting effect of Tz but not of 8-OH-DPAT.
Schuhler
S
S
Laboratoire de Neurobiologie des Fonctions Rythmiques et Saisonnières, CNRS-UMR 7518, Université Louis Pasteur, 12 rue de l'Université, F-67000, Strasbourg, France.
Pitrosky
B
B
Saboureau
M
M
Lakhdar-Ghazal
N
N
Pévet
P
P
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology; D006224:Cricetinae; D003891:Desipramine / Q000494:pharmacology; D005829:Geniculate Bodies / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008647:Mesocricetus; D009478:Neuropeptide Y / Q000032:analysis; D011985:Receptors, Serotonin / Q000502:physiology; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin / Q000502:physiology*; D013787:Thalamic Nuclei / Q000187:drug effects / Q000502:physiology*; D014229:Triazolam / Q000494:pharmacology*
D009478:Neuropeptide Y; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D014229:Triazolam; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D003891:Desipramine