Effects of handling and vehicle injections on adrenocorticotropic and corticosterone concentrations in Sprague-Dawley compared with Lewis rats.
J Am Assoc Lab Anim Sci
; 54(1): 35-9, 2015 Jan.
Article
in En
| MEDLINE
| ID: mdl-25651089
ABSTRACT
The hypothalamic-pituitary-adrenal (HPA) axis is a key factor in the trajectory of the addiction-like cycle (a pattern of behavior characterized by escalating drug use, withdrawal, and relapse) in preclinical and clinical studies. Concentrations of HPA hormones change in laboratory animals in response to standard experimental procedures, including handling and vehicle injections. We compared HPA activity in adult male Lewis (inbred) and Sprague-Dawley (outbred) rats, 2 common strains in rodent models of addiction, after different schedules of handling and saline injections, to explore the extent to which HPA responses differ by strain and whether interindividual differences underlie addiction vulnerability. The 4 treatment conditions were no, short, or long handling and saline injections. In handled groups, rats were handled for 1 to 2 min for 3 times daily and were euthanized after 7 d (short handling) or 14 d (long handling). The injection schedule in the saline injection group mimicked that in a model of binge-like cocaine exposure. Across all treatment groups, concentrations of adrenocorticotropic hormone were higher in Sprague-Dawley than in Lewis rats. In Sprague-Dawley rats, corticosterone concentrations decreased after continued handling but remained constant in Lewis rats. Interindividual variability in hormone levels was greater in Sprague-Dawley than Lewis rats, although corticosterone variability decreased after continued handling. Prolactin did not differ between groups of either Sprague-Dawley and Lewis rats before or after handling. This study underscores the importance of prolonged handling before experimenter-provided drug-administration paradigms and of strain-associated differences that may affect study outcomes.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Rats, Inbred Lew
/
Rats, Sprague-Dawley
/
Handling, Psychological
/
Injections, Intraperitoneal
Type of study:
Prognostic_studies
Limits:
Animals
Language:
En
Journal:
J Am Assoc Lab Anim Sci
Journal subject:
MEDICINA VETERINARIA
/
TECNICAS E PROCEDIMENTOS DE LABORATORIO
Year:
2015
Document type:
Article
Affiliation country:
United States