MNR

Inbr. F79+?.

Colour: Albino.

Genet. A, B, c, h.

Origin: PL Broadhurst, 1954, from a commercial Wistar stock with selection for low defecation response in an open field. To Harrington 1965 at F25 and to National Institutes of Health 1964 at F18+. The strain was apparently inbred as a number of parallel sublines which differ at the agouti locus and major histocompatibility complex (Hansen et al 1982).

---

Characteristics

The strain is widely used in behaviour research, and characteristics have been described by Harrington (1971a,b, 1972, 1979a-i). Long latency to emerge into a familiar (11/12) and novel (12/12) environment in females (Harrington 1971a). Low open field defecation (12/12 males, 11/12 to 9/12 depending on subline in females) (Harrington 1972). High wheel activity (1/12) (Harrington 1971b). Low open-field defecation (8/8) in hybrid offspring (Rick and Fulker 1972). Low blood pressure (23/23), reaching 118_1.1 (SEM) mmHg at 10 weeks of age (Tanase et al 1982). Low 10-week body weight in males (1/23) (Tanase et al 1982). Good breeding performance (3/12) and large litter size (3/12) (Hansen et al 1973). See also MR. An extensive review of the differences between MR and MNR is given by Broadhurst (1975).

Other papers comparing MR and MNR or MR and MNRA include Commissaris et al (1992), Abel et al, (1992), Sara et al, (1993), Buda et al, (1994), Sara et al, (1994), Verbanac et al, (1993)

---

Abel E. L., Altman H. J., and Commissaris R. L. (1992) Maudsley Reactive and Nonreactive rats in the forced swim test - comparison in fresh-water and soiled water. Physiol. Behav. 52, 1117-1119.

Broadhurst P. L. (1975) The Maudsley reactive and non-reactive strains of rats: a survey. Behav. Genet. 5, 299-319.

Buda M., Lachuer J., Devauges V., Barbagli B., Blizard D., and Sara S. J. (1994) Central noradrenergic reactivity to stress in Maudsley rat strains. Neurosci. Let. 167, 33-36.

Commissaris R. L., Franklin L., Verbanac J. S., and Altman H. J. (1992) Maudsley Reactive (MR/Har) and nonreactive (MNRA/Har) rats - performance in an operant conflict paradigm. Physiol. Behav. 52, 873-878.

Hansen C. T., Judge F. J., and Whitney R. A. (1973) Catalogue of NIH Rodents. DREW Publ. No. 74-606. Department of Health, Education, and Welfare, Washington, D.C.: U.S.

Hansen C. T., Potkay S., Watson W. T., and Whitney R. A. Jr. (1982) NIH Rodents: (1980). Catalogue. NIH Publ. No. 83-606. Department of Health and Human Services, Washington, D.C.: U.S.

Harrington G. M. (1971a) Strain differences among rats initiating exploration of differing environments. Psychon. Sci. 23, 348-349.

Harrington G. M. (1971b) Strain differences in rotating wheel activity of the rat. Psychon. Sci. 23, 363-364.

Harrington G. M. (1972) Strain differences in open-field behavior of the rat. Psychon. Sci. 27, 51-53.

Rick J. T. and Fulker D. W. (1972) Some biochemical correlates of inherited behavourial differences. Prog. Brain Res. 36, 105-112.

Sara S. J., Devauges V., and Biegon A. (1993) Maudsley rat strains, selected for differences in emotional responses, differ in behavioral-response to clonidine and in [I-125] clonidine binding in the locus-ceruleus. Behavioural Brain Research 57, 101-104.

Sara S. J., Devauges V., Biegon A., and Blizard D. A. (1994) The Maudsley rat strains as a probe to investigate noradrenergic- cholinergic interaction in cognitive function. Journal of Physiology-Paris 88, 337-345.

Tanase H., Yamori Y., Hansen C. T., and Lovenberg W. (1982) Heart size in inbred strains of rats. Part 1. Genetic determination of the development of cardiovascular enlargement in rats. Hypertension 4, 864-872.

Verbanac J. S., Altman H. J., Dhingra P., Harrington G. M., and Commissaris R. L. (1993) Conflict behavior in Maudsley Reactive and Nonreactive rats - effects of noradrenergic neuronal destruction. Pharmacol. Biochem. Behav. 45, 429-438.

---

INBRED STRAINS OF RATS
Updated 9 Apr. 1998
Michael FW Festing
MRC Toxicology Unit, Hodgkin Building,
University of Leicester, UK