GABA and histamine interaction in the basolateral amygdala of rats in the plus-maze test of anxiety-like behaviors.
In the present study, we have investigated the effects and the interaction of the GABAergic and histaminergic systems in the basolateral amygdala (BLA) of rats using the plus-maze test of anxiety-like behaviors. Unilateral injection of different doses of muscimol (GABA(A) receptor selective agonist; 0.01, 0.05 and 0.1 microg/rat) into the BLA (intra-BLA) increased the percentage of open arm time (%OAT) and open arm entries (%OAE) at the doses of 0.05 and 0.1 microg/rat that are representative of an anxiolytic response. Intra-BLA injection of bicuculline (GABA(A) receptor selective antagonist; 0.05, 0.1 and 0.5 microg/rat) decreased %OAT and %OAE at the doses of 0.1 and 0.5 microg/rat showing an anxiogenic-like effect. Intra-BLA administration of histamine (0.05, 0.1 and 0.5 microg/rat) also showed anxiogenic-like effects at the doses of 0.1 and 0.5 microg/rat while intra-BLA administration of pyrilamine (an H1 receptor selective antagonist; 5, 10 and 20 microg/rat) induced anxiolytic effects at the dose of 20 microg/rat. Coadministration of histamine (0.1 microg/rat) with muscimol reversed the anxiolytic effect of muscimol at the dose of 0.1 microg/rat while coadministration of histamine (0.1 microg/rat) with bicuculline increased the anxiogenic effect of bicuculline at the dose of 0.05 microg/rat. On the other hand, coadministration of pyrilamine (10 microg/rat) with bicuculline decreased anxiety-like behaviors of bicuculline at the dose of 0.5 microg/rat while pyrilamine could not affect the anxiolytic effect of muscimol. In conclusion, it seems that both GABAergic and histaminergic systems not only play a part in the modulation of anxiety-like behaviors in the BLA of rats but may also have opposite effects in this brain region.
Hajizadeh Moghaddam
Akbar
A
Department of Biology, Mazandaran University, Babolsar, Iran.
Roohbakhsh
Ali
A
Rostami
Parvin
P
Heidary-Davishani
Ahmad
A
Zarrindast
Mohammad-Reza
MR
D000679:Amygdala / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001007:Anxiety / Q000378:metabolism* / Q000523:psychology; D001522:Behavior, Animal / Q000187:drug effects*; D001640:Bicuculline / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D018682:GABA Agents / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology / Q000502:physiology*; D018494:Histamine Agents / Q000494:pharmacology; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D008845:Microinjections; D009118:Muscimol / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D018682:GABA Agents; D018494:Histamine Agents; D009118:Muscimol; D005680:gamma-Aminobutyric Acid; D006632:Histamine; D011738:Pyrilamine; D001640:Bicuculline