Early social enrichment augments adult hippocampal BDNF levels and survival of BrdU‐positive cells while increasing anxiety‐ and “depression”‐like behavior

Abstract

Early experiences affect brain function and behavior at adulthood. Being reared in a communal nest (CN), consisting of a single nest where three mothers keep their pups together and share care-giving behavior from birth to weaning (postnatal day [PND] 25), provides an highly socially stimulating environment to the developing pup. Communal nest characterizes the natural ecologic niche of many rodent species including the mouse. At adulthood, CN reared mice, compared to mice reared in standard nesting laboratory condition (SN), show an increase in BDNF protein levels and longer survival of BrdU-positive cells in the hippocampus. Open field and elevated plus maze results indicate that CN mice, although showing levels of exploratory and locomotor activity similar to those of SN mice, displayed increased anxiety-like behavior, performing more thigmotaxis in the open field and spending less time in the open arms of the plus maze. Furthermore, CN mice displayed higher levels of immobility behavior in the forced swim test. Overall, these findings show that CN, an highly stimulating early social environment, increases adult neuronal plasticity, as suggested by high BDNF levels and augmented number of newly generated cells in the hippocampus, which is associated to an increased anxiety- and "depression"-like behavior. These findings are discussed in the framework of the neurotrophin hypothesis of depression.

Effects of escitalopram on the regulation of brain‐derived neurotrophic factor and nerve growth factor protein levels in a rat model of chronic stress

“…Correlation was calculated with SPSS using Spearman's correlation coefficient (r 5 0.69, P < 0.0001). Barrientos et al, 2003;Pizarro et al, 2004;Roceri et al, 2004), there is a considerable amount of research that denies (Schulte-Herbrüggen et al, 2006) or even opposes (Branchi et al, 2006) the above-mentioned stress-and treatment-related BDNF regulation (for a balanced review see Groves, 2007). Different study outcomes may be due to different stress models, application of acute or chronic stress, dose and time of medication, strain differences, or finally a focus on either BDNF mRNA or BDNF protein levels.…”

Cellular Mechanisms Underlying the Anxiolytic Effect of Low Doses of Peripheral Δ9-Tetrahydrocannabinol in Rats

“…However, as a transcription factor, CREB itself is unlikely to be the molecule acutely affecting behavior. Rather, changes in CREB activity could alter the expression of specific gene products involved in the modulation of anxiety such as neuropeptide Y and brain-derived neurotrophic factor (Heilig, 2004;Branchi et al, 2006). This hypothesis requires further research.…”

Behavioral phenotyping of mouse models of neurodevelopmental disorders: Relevant social behavior patterns across the life span

“…Communally nested adult mice also showed higher neurotrophin levels [nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF)] in selected brain regions. Interestingly NGF increases were further affected by social status, being dramatically more increased in subordinated than in dominants [18,19].…”