Differential housing and novelty response: Protection and risk from locomotor sensitization

Abstract

High novelty seeking increases the risk for drug experimentation and locomotor sensitization. Locomotor sensitization to psychostimulants is thought to reflect neurological adaptations that promote the transition to compulsive drug taking. Rats reared in enrichment (EC) show less locomotor sensitization when compared to rats reared in isolation (IC) or standard conditions (SC). The current research study was designed to test if novelty response contributed locomotor sensitization and more importantly, if the different housing environments could change the novelty response to protect against the development of locomotor sensitization in both adolescence and adulthood. Experiment 1: rats were tested for their response to novelty using the inescapable novelty test (IEN) and pseudorandomly assigned to enriched (EC), isolated (IC), or standard (SC) housing conditions for 30 days. After housing, they were tested with IEN. Rats were then administered amphetamine (0.5 mg/kg) or saline and locomotor activity was measured followed by a sensitization test 14 days later. Experiment 2: rats were tested in the IEN test early adulthood and given five administrations of amphetamine (0.3 mg/kg) or saline and then either stayed in or switched housing environments for 30 days. Rats were then re-tested in the IEN test in late adulthood and administered five more injections of their respective treatments and tested for locomotor sensitization. Results indicate that IC and SC increased the response to novelty. EC housing decreased locomotor response to amphetamine and saline, and SC housing increased the locomotor response to amphetamine. Mediation results indicated that the late adult novelty response fully mediates the locomotor response to amphetamine and saline, while the early adulthood novelty response did not. Conclusions Differential housing changes novelty and amphetamine locomotor response. Novelty response is altered into adulthood and provides evidence that enrichment can be used to reduce drug vulnerability.

Environmental Enrichment During Adolescence Mitigates Cognitive Deficits and Alcohol Vulnerability due to Continuous and Intermittent Perinatal Alcohol Exposure in Adult Rats

“…On the other hand, in our experimental conditions, declarative memory performance of p-IAD EE rats was not different from their SE counterparts’ one, suggesting that the abnormalities in declarative memory formation due to the perinatal intermittent exposure to alcohol are not rescued by the EE. Besides, the repeated exposure to environmental stimuli has been reported to decrease the incentive value of novelty (Cain et al, 2006 ; Garcia et al, 2017 ), suggesting that a lower interest in the novel object may explain its lower exploration by the EE offspring. Interestingly, our data show that EE mitigated the spatial learning and reference memory deficits induced by the perinatal intermittent alcohol paradigm.…”

Environmental Enrichment During Adolescence Acts as a Protective and Therapeutic Tool for Ethanol Binge-Drinking, Anxiety-Like, Novelty Seeking and Compulsive-Like Behaviors in C57BL/6J Mice During Adulthood

“…The present data are consistent with and support previous studies pointing to the negative impact of losing EE on drug intake. Switching mice from EE to SE conditions caused an increase in cocaine rewarding properties (Nader et al, 2012 ), a marked depressive-like phenotype characterized by low mobility in the forced swim test (Smith et al, 2017 ), and increased locomotor responses to amphetamine and saline when compared with chronically EE housed animals (Garcia et al, 2017 ).…”

“…Taken together, present data are consistent, and complement previous studies reporting positive EE effects on repetitive compulsive-like behavior (Bechard and Lewis, 2016 ; Bechard et al, 2016 ). Thus, EE-housed rats switched to isolated conditions increased novelty-seeking responses in the inescapable novelty test (IEN; Garcia et al, 2017 ), switching rats from isolated to enriched conditions decreased novelty-seeking responses (Garcia et al, 2017 ), and housing rats in enriched conditions from weaning to adulthood reduced novelty-seeking behavior in the OF test and locomotor activity cages (de Carvalho et al, 2010 ). Strong evidence supports head dipping in HB as a valid novelty-seeking trait measure (Vaglenova et al, 2004 ; Abreu-Villaça et al, 2006 ; Kliethermes and Crabbe, 2006 ; Mateos-García et al, 2015 ), however, some authors have suggested that the number of head dips might be indicative of a neophobic, rather than neophilic, response (Brown and Nemes, 2008 ).…”

Voluntary ethanol consumption during early social isolation and responding for ethanol in adulthood

“…Limited literature exists that formally compares post-weaning social isolation effects between rat strains. However, after postweaning social isolation Lister Hooded rats exhibit hyperlocomotion in an open-field testan effect which is inconsistent in Sprague-Dawley rats (Garcia, Haddon, Saucier, & Cain, 2017;Green, Cain, Thompson, & Bardo, 2003;Leng, Feldon, & Ferger, 2004;Lukkes, Mokin, Scholl, & Forster, 2009;Lukkes, Vuong, Scholl, Oliver, & Forster, 2009;Weiss, Pryce, Jongen-Rêlo, Nanz-Bahr, & Feldon, 2004). Thus, the current study used Long-Evans rats; a strain which tends to voluntarily consume alcohol under intermittent access conditions (Simms et al, 2008;Simms, Bito-Onon, Chatterjee, & Bartlett, 2010) and tends to achieve higher blood ethanol concentrations (BECs) when drinking similar amounts of ethanol compared to other outbred strains (Carnicella, Ron, & Barak, 2014).…”