Behavioral effects of GABA in the hippocampal formation: functional interaction with histamine

Alvarez, Edgardo O.; Banzán, Arturo M.

doi:10.1016/0166-4328(90)90088-v

Cited by 21 publications

(17 citation statements)

References 29 publications

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“…Accordingly, these results can be interpreted as supporting the hypothesis that in the hippocampus histamine might be an inhibitory factor of motivation. If this interpretation is true, it may explain the diminished exploratory activity observed in animals microinjected with histamine into the hippocampus in some other experiments described elsewhere (18,29). Interestingly, in the hippocampus histamine appears to have an "anxiolytic effect".…”

Section: Discussionmentioning

confidence: 77%

“…On this basis, the zone of chemical stimulation included a part of the dentate area and the subiculum complex, nearly covering the CA 1 -CA 4 zone. Therefore, the stimulated zone was equivalent to that of previous experiments (18,29,31,32). The major effect of histamine (experiment 2) was a decrease in exploration associated with an increase in the permanency score in the range of 9-45 nmol ( Figure 3B,C).…”

Section: Discussionmentioning

confidence: 95%

“…Animals were anesthetized with ether and unilaterally implanted with steel guide cannulae (23 gauge, 15 mm in length) into the caudal ventral hippocampus, as described elsewhere (18,29,30). After implantation rats were housed individually and allowed to rest for at least 72 h.…”

Section: Implantation Proceduresmentioning

confidence: 99%

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Hippocampal histamine receptors and conflictive exploration in the rat: studies using the elevated asymmetric plus-maze

Ruarte¹,

Orofino²,

Alvarez

1997

Braz J Med Biol Res

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The possible role of histamine receptors in the hippocampal formation on the exploratory motivation and emotionality of the rat was studied. An elevated asymmetric plus-maze composed of 4 different arms (no walls, single high wall, high and low walls and two high walls) arranged at 90 o angles was used. The exploration score, considered to be an index of exploratory motivation, and the permanency score, considered to be an index of emotionality (anxiety), were determined. Histamine was administered locally into the ventral hippocampus at three different doses (9, 45 and 90 nmol). Another group of rats was also microinjected with 45 nmol of pyrilamine (a histamine H 1 receptor antagonist) or ranitidine (a histamine H 2 receptor antagonist) in addition to 9 nmol of histamine in order to identify the possible type of histamine receptor involved. Histamine administration significantly inhibited the exploration score and increased the permanency score at the doses of 9 and 45 nmol in two of four arms. These effects were completely blocked by the administration of either histamine receptor antagonist. The present results suggest that in the hippocampal formation histamine inhibits exploratory motivation and decreases emotionality by activating both types of histamine receptors. Also, the elevated asymmetric plus-maze appears to be a suitable technique to quantify exploration and possibly "anxiety".

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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 95%

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Hippocampal histamine receptors and conflictive exploration in the rat: studies using the elevated asymmetric plus-maze

Ruarte¹,

Orofino²,

Alvarez

1997

Braz J Med Biol Res

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“…There are reports that locomotor activity increases in DBA2 mice and rats after intrahippocampal microinjection of the GABA A receptor agonist muscimol, the GABA degradation inhibitor ␥-vinyl-GABA, or GABA itself (van Abeelen and Boersma, 1984;Alvarez and Banzan, 1990). At 60 d of age, hippocampal KYNA levels and locomotor activity of mKat-2 Ϫ/Ϫ mice converged to values comparable with those measured in WT mice.…”

mentioning

confidence: 69%

Targeted Deletion of the Kynurenine Aminotransferase II Gene Reveals a Critical Role of Endogenous Kynurenic Acid in the Regulation of Synaptic Transmission viaα7 Nicotinic Receptors in the Hippocampus

Alkondon¹,

Pereira²,

Yü³

et al. 2004

J. Neurosci.

124

113

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It has been postulated that endogenous kynurenic acid (KYNA) modulates ␣7* nicotinic acetylcholine receptor (nAChR) and NMDA receptor activities in the brain.a To test this hypothesis, ␣7* nAChR and NMDA receptor functions were studied in mice with a targeted null mutation in the gene encoding kynurenine aminotransferase II (mKat-2 ؊/؊ mice), an enzyme responsible for brain KYNA synthesis. At 21 postnatal days, mKat-2 ؊/؊ mice had lower hippocampal KYNA levels and higher spontaneous locomotor activity than wild-type (WT) mice. At this age, ␣7* nAChR activity induced by exogenous application of agonists to CA1 stratum radiatum interneurons was ϳ65% higher in mKat-2 ؊/؊ than WT mice. Binding studies indicated that the enhanced receptor activity may not have resulted from an increase in ␣7* nAChR number. In 21-d-old mKat-2 ؊/؊ mice, endogenous ␣7* nAChR activity in the hippocampus was also increased, leading to an enhancement of GABAergic activity impinging onto CA1 pyramidal neurons that could be reduced significantly by acute exposure to KYNA (100 nM). The activities of GABA A and NMDA receptors in the interneurons and of ␣3␤4* nAChRs regulating glutamate release onto these neurons were comparable between mKat-2 ؊/؊ and WT mice. By 60 d of age, KYNA levels and GABAergic transmission in the hippocampus and locomotor activity were similar between mKat-2 ؊/؊ and WT mice. Our findings that ␣7* nAChRs are major targets for KYNA in the brain may provide insights into the pathophysiology of schizophrenia and Alzheimer's disease, disorders in which brain KYNA levels are increased and ␣7* nAChR functions are impaired.

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“…This contrariety in the effects of GABA and histamine has also been reported in another study showing that an enhancement in the histaminergic activity potentiated the audiogenic seizure of lorazepam withdrawal [42] . Moreover, Alvarez and Banzan [43] in their study showed that histamine could block the increase in the locomotor activity induced by an increase in the concentration of GABA in the hippocampus. They suggested that a histamine-GABA link in the final expression of GABArelated behaviors exist in the hippocampus.…”

Section: Discussionmentioning

confidence: 96%

GABA and Histamine Interaction in the Basolateral Amygdala of Rats in the Plus-Maze Test of Anxiety-Like Behaviors

Moghaddam

Roohbakhsh

Rostami³

et al. 2008

Pharmacology

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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 µg/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 µg/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 µg/rat) decreased %OAT and %OAE at the doses of 0.1 and 0.5 µg/rat showing an anxiogenic-like effect. Intra-BLA administration of histamine (0.05, 0.1 and 0.5 µg/rat) also showed anxiogenic-like effects at the doses of 0.1 and 0.5 µg/rat while intra-BLA administration of pyrilamine (an H₁ receptor selective antagonist; 5, 10 and 20 µg/rat) induced anxiolytic effects at the dose of 20 µg/rat. Coadministration of histamine (0.1 µg/rat) with muscimol reversed the anxiolytic effect of muscimol at the dose of 0.1 µg/rat while coadministration of histamine (0.1 µg/rat) with bicuculline increased the anxiogenic effect of bicuculline at the dose of 0.05 µg/rat. On the other hand, coadministration of pyrilamine (10 µg/rat) with bicuculline decreased anxiety-like behaviors of bicuculline at the dose of 0.5 µg/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.

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Behavioral effects of GABA in the hippocampal formation: functional interaction with histamine

Cited by 21 publications

References 29 publications

Hippocampal histamine receptors and conflictive exploration in the rat: studies using the elevated asymmetric plus-maze

Hippocampal histamine receptors and conflictive exploration in the rat: studies using the elevated asymmetric plus-maze

Targeted Deletion of the Kynurenine Aminotransferase II Gene Reveals a Critical Role of Endogenous Kynurenic Acid in the Regulation of Synaptic Transmission viaα7 Nicotinic Receptors in the Hippocampus

GABA and Histamine Interaction in the Basolateral Amygdala of Rats in the Plus-Maze Test of Anxiety-Like Behaviors

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