Novel Etiological and Therapeutic Strategies for Neurodiseases: Epigenetic Understanding of Gene–Environment Interactions

Increasing the quality of life from womb to grave: the importance of pregnancy and birth cohorts

Epigenetics is revealing how "nature is nurtured", with environmental factors such as nutrition, environmental neurotoxicants, and psychological stress influencing DNA expression. In this current opinion paper, we argue that understanding the dynamic interplay between the genome acquired at conception and environmental exposures throughout life requires pregnancy and birth cohorts, and that greater Canadian national commitment to the infrastructure needed for sustaining such cohorts is warranted. We present a framework that is now being implemented in Alberta.

Possible involvement of histone acetylation in the development of emotional resistance to stress stimuli in mice

Recent reports have implied that aberrant biochemical processes in the brain frequently accompany subtle shifts in the cellular epigenetic profile that might underlie the pathogenic progression of psychiatric disorders. Furthermore, certain antidepressants or mood stabilizers have been reported to have the ability to modulate epigenetic parameters. We previously reported that pretreatment of mice with 5-HT(1A) receptor agonists 24 h before testing suppressed the decrease in emotional behaviors induced by exposure to acute restraint stress. Based on this finding, the aim of the present study was to examine the association between the development of emotional resistance to stress stimuli and the modulation of an epigenetic parameter, particularly histone acetylation. We found that acetylated histone H3 was increased in the hippocampus of mice that had developed resistance to emotional stress by pretreatment with flesinoxan (1 mg/kg, i.p.) 24 h before testing. On the other hand, pretreatment with benzodiazepine anxiolytic diazepam (1 mg/kg, i.p.) did not have similar effects. Interestingly, similar to flesinoxan, the histone deacetylase inhibitor trichostatin A also protected against the emotional changes induced by acute restraint stress, as well as histone H3 acetylation. The present findings suggest that the epigenetic mechanisms of gene regulation may play an important role in the development of emotional resistance to stress stimuli.

Preventive effects of an enriched environment on rodent psychiatric disorder models

Interplay between genetic and environmental factors plays a key role in psychiatric disorders, as well as other brain diseases, cancer, and metabolic syndrome. In accordance with epidemiological findings, animal studies have pointed out the importance of a variety of environmental factors, such as viral infection during pregnancy or infancy, early parental loss or separation, and physical or sexual abuse in early life, in the etiology of psychiatric disorders. Conversely, positive effects of environmental factors against the pathogenesis of psychiatric disorders are also demonstrated, in which most of the animals are exposed to an "enriched environment". This review summarizes recent progress of research in this field focusing on the preventive effects of an "enriched environment" against the expression of behavioral abnormalities in rodent models of psychiatric disorders.