The role of histamine in the anterior hypothalamus and its functional interaction with the hippocampus on exploratory behavior in adult male rats

Alvarez, Edgardo O.; Banzán, Arturo M.

doi:10.1016/s0166-4328(05)80148-2

Cited by 16 publications

(13 citation statements)

References 24 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: 78%

“…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: 94%

“…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%

“…Regarding the hippocampal structure, local microinjection of histamine into the ventral hippocampus has been shown to reduce the exploratory activity in a holeboard. Concomitantly, an "indifferent attitude" to the environment was displayed by hippocampus histamine-injected animals (2,3,18). Interestingly, it has been reported that diazepam decreases the turnover rate of histamine in mice (19).…”

Section: Introductionmentioning

confidence: 96%

“…In addition, administration of tetrahydro-ß-carboline, a benzodiazepine ligand, into the hippocampal formation induces a state of "anxiety" in the rat (16). On the other hand, some evidence indicates that the nucleus accumbens, the ventral tegmental area and the hippocampus may be involved in the motivational processes (2,3,8,15,17,18). Regarding the hippocampal structure, local microinjection of histamine into the ventral hippocampus has been shown to reduce the exploratory activity in a holeboard.…”

Section: Introductionmentioning

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: 78%

Section: Discussionmentioning

confidence: 94%

Section: Implantation Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Focus on HTR2C: A possible suggestion for genetic studies of complex disorders

Drago

Serretti

2009

American J of Med Genetics Pt B

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HTR2C is one of the most relevant and investigated serotonin receptors. Its role in important brain structures such as the midbrain, the lateral septal complex, the hypothalamus, the olfactory bulb, the pons, the choroid plexus, the nucleus pallidus, the striatum and the amygdala, the nucleus accumbens and the anterior cingulated gyrus candidate it as a promising target for genetic association studies. The biological relevance of these brain structures is reviewed by way of the focus on HTR2C activity, with a special attention paid to psychiatric disorders. Evidence from the genetic association studies that dealt with HTR2C is reviewed and discussed alongside the findings derived from the neuronatmic investigations. The reasons for the discrepancies between these two sets of reports are discussed. As a result, HTR2C is shown to play a pivotal role in many different psychiatric behaviors or psychiatric related disrupted molecular balances, nevertheless, genetic association studies brought inconsistent results so far. The most replicated association involve the feeding behavior and antipsychotic induced side effects, both weight gain and motor related: Cys23Ser (rs6318) and -759C/T (rs3813929) report the most consistent results. The lack of association found in other independent studies dampens the clinical impact of these reports. Here, we report a possible explanation for discrepant findings that is poorly or not at all usually considered, that is that HTR2C may exert different or even opposite activities in the brain depending on the structure analyzed and that mRNA editing activity may compensate possible genetically controlled functional effects. The incomplete coverage of the HTR2C variants is proposed as the best cost-benefit ratio bias to fix. The evidence of brain area specific HTR2C mRNA editing opens a debate about how the brain can differently modulate stress events, and process antidepressant treatments, in different brain areas. The mRNA editing activity on HTR2C may play a major role for the negative association results.

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Genetic perspectives of histamine and muscarinic receptors in schizophrenia and clozapine response

Mancama

Arranz

Kerwin

2003

Drug Development Research

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The mechanisms that underlie schizophrenia and influence outcome to antipsychotic treatment are unclear, and remain the focus of intense investigation. Genetic studies have been at the forefront of work to delineate the disorders aetiology and have led to the identification of gene variants, predominantly throughout neurotransmitter pathways, that may be important. Prevailing evidence, however, suggests that those variants so far identified confer a relatively limited influence, and in the search to identify the further participants growing evidence has emerged implicating the involvement of histamine and muscarinic receptor pathways. Studies investigating the genetic contribution of these systems in the disorder are relatively nascent, and consequently the extent to which each may be involved is presently unclear. Further work is, therefore, warranted to determine this role, since these pathways potentially offer an unprecedented insight into the disorders aetiology. It is envisaged this knowledge may also contribute to clarifying the mechanisms that moderate antipsychotic efficacy, and could accelerate ongoing efforts to develop new therapies and predictive pharmacogenetic approaches associated with this area of drug treatment. Drug Dev.

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The role of histamine in the anterior hypothalamus and its functional interaction with the hippocampus on exploratory behavior in adult male rats

Cited by 16 publications

References 24 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

Focus on HTR2C: A possible suggestion for genetic studies of complex disorders

Genetic perspectives of histamine and muscarinic receptors in schizophrenia and clozapine response

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