**Author details**

*Behavioral Pharmacology - From Basic to Clinical Research*

Regarding the response to pharmacological treatments, our group reported that the minimum anxiolytic effective dose of diazepam for animals of 21 PND is 0.5 mg/kg, being half of the minimum effective dose for adults [29]. While the use of selective serotonin reuptake inhibitors (SSRIs) like fluoxetine (first-line treatment in clinical practice [62]) shows diverse results, ranging from the absence of anxiolytic effects of fluoxetine with acute and chronic treatment [69] until paradoxical anxiogenic effects [70], possible explanation for diverse unexpected fluoxetine effects on infant and juvenile anxiety is based on mechanism of action of fluoxetine and the treatment duration. At first, on acute treatment fluoxetine increases extracellular serotonin levels for inhibition of reuptake, and the neurotransmitter remains free to stimulate postsynaptic receptors explaining the transitory increase in anxiety levels when fluoxetine treatment begins [71]. Later with chronic fluoxetine, high concentrations of serotonin inhibit serotonergic neurons in

the dorsal raphe nucleus, reducing serotonin production and anxiety [71].

could prevent adult high incidence of this clinical and disabling condition.

Based on preclinical findings, stressors produce human-like alterations before adulthood. The consequences are brain changes that impact behavioral performance generating anxiety. These effects are studied in the field of the experimental anxiety to probe pharmacological substances in order to extend knowledge of mechanism of action of new molecules or their combination with other drugs. This chapter described some aspects of brain function during early postnatal development which involves a critical period of vulnerability to psychiatric conditions. Child and adolescent anxiety preclinical research must be extended in order to improve the

This chapter was partially supported by Cátedras CONACYT Grant #1840 (National Council for Science and Technology) to Gabriel Guillén-Ruiz. Ana Karen Limón-Vázquez and Margarita Hernández-Mixteco received fellowships from

Some limitations that researchers face are the differences in experimental conditions, age, and even strains, which can explain the variability of the results obtained by diverse research groups. Of course the transition of preclinical findings to human condition should be modest and responsible, so generalizations should be avoided. With this brief review, it is clear that the expression of anxiety depends on age and represents a challenge but also an opportunity to generate knowledge that increases the scope of preclinical research. The advantages to study preclinical anxiety may consist in the opportunity to know the neurobiology of the developing brain under stress and pharmacological conditions. These manipulations on an organ with a great plasticity at early stages would lead to better results with potential reversible effects before reaching adulthood. Future studies must be encouraged to extend literature of infant and juvenile anxiety from preclinical to clinical approach, which

**132**

**6. Conclusion**

knowledge of this clinical condition.

CONACYT (Reg: 480040 and 452396, respectively).

The authors declare no conflict of interest.

**Acknowledgements**

**Conflict of interest**

Gabriel Guillén-Ruiz1 \*, Blandina Bernal-Morales2 , César Soria-Fregozo3 , Emma Virginia Herrera-Huerta4 , Ana Karen Limón-Vázquez<sup>5</sup> , Margarita Hernández-Mixteco5 and Abraham Puga-Olguín<sup>5</sup>

1 Laboratory of Neurofarmacology, Cátedras CONACYT, Institute of Neuroetology, Universidad Veracruzana, Xalapa, Veracruz, Mexico

2 Laboratory of Neurofarmacology, Institute of Neuroetology, Universidad Veracruzana, Xalapa, Veracruz, Mexico

3 Laboratory of Biomedical Sciences/Histology, University Center of Los Lagos, University of Guadalajara, Lagos de Moreno, Jalisco, Mexico

4 Faculty of Chemical Sciences, Universidad Veracruzana, Orizaba, Veracruz, Mexico

5 Postgraduate Studies in Neuroethology. Institute of Neuroethology, Universidad Veracruzana, Xalapa, Veracruz, Mexico

\*Address all correspondence to: gguillen@uv.mx

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
