Environmental enrichment alters LPS-induced changes in BDNF and PSD-95 expressions during puberty

Pubertal stress in male rats: Effects on juvenile play behavior and adult sexual partner preference

Puberty is a period of brain organization impacting the expression of social and sexual behaviors. Here, we assessed the effects of an acute pubertal stressor (immune challenge) on the expression of juvenile play (short-term) and sexual partner preference (long-term) in male rats. Juvenile play was assessed over ten trials at postnatal days (PND) (31-40) with age- and sex-matched conspecifics, and at PND35 males received a single injection of lipopolysaccharide (LPS, 1.5 mg/kg i.p.) or saline. Then, sexual partner preference was assessed at PND 60, 64, and 68, in a three-compartment chamber with a sexually receptive female and a male as potential partners simultaneously. The results confirmed that a single injection of LPS during puberty induced sickness signs indicative of an immune challenge. However, juvenile play was not affected by LPS treatment during the following days (PND36-40), nor was sexual behavior and partner preference for females in adulthood. These findings highlight that, while other studies have shown that LPS-induced immunological stress during puberty affects behavior and neuroendocrine responses, it does not affect juvenile play and sexual behavior in male rats. This suggests a remarkable resilience of these behavioral systems for adaptation to stressful experiences mediated by immune challenges during critical periods of development. These behaviors, however, might be affected by other types of stress.

Environmental Enrichment Cage for Laboratory Mice: A Downloadable Alternative

Environmentally enriched housing (EE) provides a stimulating and species-typical environment that enhances brain plasticity and cognition, while reducing disease severity in laboratory animals. However, standardizing EE protocols has been challenging due to issues such as variability, high pricing, or limited laboratory space. To address these challenges, we present a replicable and cost-efficient cage protocol that is accessible to researchers with limited resources and space constraints. The protocol is designed to provide a stimulating and species-typical environment for the animals. It incorporates elements such as social interaction, physical exercise, cognitive stimulation, manipulable objects, environmental variability, and sensory stimulation. As evidenced in our previous studies using our protocol, users can expect to observe similar neuroplastic and health-wise benefits that accompany EE experimental paradigms. These included straightforward step-by-step guide, which allows for construction of functional EE cages in under 8 hr. Basic knowledge of 3D printing and laser cutting is required, but no advanced skills are necessary. The protocol enables researchers to create stimulating and replicable environments that promote animal welfare, enhance brain plasticity, and yield valuable experimental results for low cost. © 2024 Wiley Periodicals LLC. Basic Protocol: An effective and cost-efficient environmental enrichment cage designed to encourage standardization amongst laboratory protocols.

Gestational environmental enrichment prevents chronic social stress induced anxiety- and ethanol-related behaviors in offspring

Epidemiological surveys have shown a strong relationship between maternal stress and offspring's mood disorders. Growing evidence suggested that environmental enrichment (EE) improves cognitive function in models of psychiatric and neurological disorders. However, the potential protective effects of gestational EE on social stress-elicited mood disorders in offspring have not been studied. Knowing that the undeveloped brain is more sensitive to gestational environmental stimuli, we hypothesized that initiating cognitive stimulation, during gestation, would protect against social stress-induced behavioral alterations in adulthood. Therefore, the present study aimed to investigate the effects of gestational EE on social stress-elicited anxiety- and ethanol-related behaviors in adult offspring. EE consisted of free access, of dams, to tubular devices of different shapes, colors, and sizes that were changed regularly. After birth and weaning, young adult offspring were exposed to 19 days of social stress and anxiety-like behavior was evaluated by elevated plus maze, open field, and marbles burying tests. The two-bottle choice (TBC) drinking paradigm was used to assess stress-induced ethanol intake. Results showed that gestational EE prevented social stress-elicited anxiogenic-like effects with no differences in spontaneous locomotor activity. Moreover, in the TBC paradigm, mice pre-exposed to EE consistently showed a significantly decreased consumption and preference for ethanol with no effects on tastants' intakes. Interestingly, gestational EE increased serum BDNF levels, which showed a correlation with measures of anxiety- and ethanol-related behaviors. These findings indicate that some neurodevelopmental changes associated with prenatal EE may counteract adult social stress-induced behavioral alterations through a BDNF mechanism. Therefore, we propose that gestational EE has significant protective and beneficial effects on social stress-induced cognitive impairment. It can also alleviate anxiety-like behavior and subsequent excessive alcohol consumption.

Environmental enrichment initiated in adolescence restores the reduced expression of synaptophysin and GFAP in the hippocampus of chronically stressed rats in a sex-specific manner

This study aims at investigating whether environmental enrichment (EE) initiated in adolescence can alter chronic unpredictable stress (CUS)-associated changes in astroglial and synaptic plasticity markers in male and female rats. To this end, we studied possible alterations in hippocampal glial fibrillary acidic protein (GFAP) and synaptophysin (SYN) in CUS rats previously housed in EE. Wistar rats on postnatal day (PND) 23 were housed for 10 weeks in standard housing (SH) or enriched conditions. On PND 66, animals were exposed to CUS for 4 weeks. SYN and GFAP expressions were evaluated in CA1 and CA3 subfields and dentate gyrus (DG). CUS reduced the expression of SYN in all hippocampal areas, whereas lower GFAP expression was evident only in CA1 and CA3. The reduced expression of SYN in DG and CA3 was evident to male SH/CUS rats, whereas the reduced GFAP expression in CA1 and CA3 was limited to SH/CUS females. EE housing increased the hippocampal expression of both markers and protected against CUS-associated decreases. Our findings indicate that the decreases in the expression of SYN and GFAP following CUS are region and sex-specific and underline the neuroprotective role of EE against these CUS-associated changes.

Multisensory Stimulation Reverses Memory Impairment in Adrβ3KO Male Mice

Norepinephrine plays an important role in modulating memory through its beta-adrenergic receptors (Adrβ: β₁, β₂ and β₃). Here, we hypothesized that multisensory stimulation would reverse memory impairment caused by the inactivation of Adrβ₃ (Adrβ₃KO) with consequent inhibition of sustained glial-mediated inflammation. To test this, 21- and 86-day-old Adrβ₃KO mice were exposed to an 8-week multisensory stimulation (MS) protocol that comprised gustatory and olfactory stimuli of positive and negative valence; intellectual challenges to reach food; the use of hidden objects; and the presentation of food in ways that prompted foraging, which was followed by analysis of GFAP, Iba-1 and EAAT2 protein expression in the hippocampus (HC) and amygdala (AMY). The MS protocol reduced GFAP and Iba-1 expression in the HC of young mice but not in older mice. While this protocol restored memory impairment when applied to Adrβ₃KO animals immediately after weaning, it had no effect when applied to adult animals. In fact, we observed that aging worsened the memory of Adrβ₃KO mice. In the AMY of Adrβ3KO older mice, we observed an increase in GFAP and EAAT2 expression when compared to wild-type (WT) mice that MS was unable to reduce. These results suggest that a richer and more diverse environment helps to correct memory impairment when applied immediately after weaning in Adrβ₃KO animals and indicates that the control of neuroinflammation mediates this response.