FH

Inbr. F33.

Colour: Fawn hooded.

Genet: a, C, h, r.

Origin: Dodds, 1974 from an outbred stock developed by NRF Maier, University of Michigan, Ann Arbor, from a cross between German brown rats and "white Lashley" rats (Tschopp and Zucker 1972). Note that other inbred strains have been developed from the same outbred stock (see FHH and FHL, below), which may have different characteristics.

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Characteristics

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Behaviour

It has been suiggested that FH rats represent a genetic model of depression They have altered serotonergic function (Aulka et al, 1994a), they exhibit differential responses to serotonic agonists and antagonists compared with other strains (Meehan and Schechter, 1994), and long-term treatment with imipramine, clomiprimine and clorgyline produced significant decreases in plasma corticosterone levels, supporting this suggestion (Aulaka et al, 1993). Clonidine increases growth hormone levels in Wistar, but not in FH rats. However, lithium treatment restores clonidine's effect (Aulakh et al 1994b). FH rats show deficits in freezing activity, and are insensitive to naltrexone induced enhancement of freezing activity. They also voluntarily drink large amounts of alcohol (Badishtov et al, 1995), though there is no evidence that alcohol preferring rats are drinking alcohol to reduce high anxiety states (Viglinskaya et al, 1995).

Lifespan and spontaneous disease

Good reproductive performance (Greenhouse et al 1991). Mild bleeding diathesis caused by autosomal dominant (? see below) gene, which is exacerbated by trauma and surgery and increases with age. Variable platelet aggregation defects and reduced platelet ATP, ATP/ADP ratio, and serotonin content and release (Raymond and Dodds 1975). Humoural immunity and compelment activity normal, but aged animals appear susceptible to infection. There is glomerular sclerosis early in life, with proteinurea as early as 10-12 weeks, which gradually progresses with age. At one year, FH rats have kidneys with lesions like those of 2-year old Sprague Dawley or Wistar rats (Kreisberg and Karnovsky 1978, Dodds 1988). Urizar et al (1984) suggest that the platlet defect and the nephropathy are unrelated, and the latter does not seem to be mediated by immune complexes. Moreover, the nephropathy progresses without imparement of renal function. Prieur and Meyers (1984) have shown that the platelet storage pool defect is a pleiotropic effect of the red-eyed dilution gene r, and that both coat colour and the platelet defect are inherited as autosomal recessive (not dominant) characters. Platelets are less reactive to collagen than those of normal rats (Magro et al, 1992).

Outbred Nmh:FAWN HOODED rats developed spontaneous hypertension (Rudofsky and Magro 1982).

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Aulakh C. S., Tolliver T., Wozniak K. M., Hill J. L., and Murphy D. L. (1994b) Functional and biochemical-evidence for altered serotonergic function in the Fawn-Hooded rat strain. Pharmacol. Biochem. Behav. 49, 615-620.

Badishtov B. A., Overstreet D. H., Kashevskaya O. P., Viglinskaya I. V., Kampovpolevoy A. B., Seredenin S. B., and Halikas J. A. (1995) To drink or not to drink - open-field behavior in alcohol-preferring and alcohol-nonpreferring rat strains. Physiol. Behav. 57, 585-589.

Dodds W. J. (1988) Third international registry of animal models of thrombosis and hemorrhagic diseases. ILAR News 30, R1-RR.

Kreisberg J. I. and Karnovsky M. J. (1978) Focal glomerular sclerosis in the fawn-hooded rat. Am. J. Pathol. 92, 637-652.

Magro A., Bizios R., Catalfamo J., Blumenstock F., and Rudofsky U. (1992) Collagen-induced rat platelet reactivity is enhanced in whole-blood in both the presence and absence of dense granule secretion. Thrombosis Research 68, 345-356.

Meehan S. M. and Schechter M. D. (1994) Conditioned place preference aversion to fenfluramine in Fawn-Hooded and Sprague-Dawley rats. Progress in Neuro-Psychopharmacology & Biological Psychiatry 18, 575-584.

Prieur D. J. and Meyers K. M. (1984) Genetics of the fawn-hooded rat strain. J. Hered. 75, 349-352.

Raymond S. L. and Dodds W. J. (1975) Characterization of the fawn-hooded rat as a model for hemostatic studies. Thromb. Diathes. Haemorrh. 33, 361-369.

Rudofsky U. H. and Magro A. M. (1982) Spontaneous hypertension in Fawn-Hooded rats. Lab. Animal Sci. 32, 389-391.

Tschopp T. B. and Zucker M. B. (1972) Hereditary defect in platelet function in rats. Blood 40, 217-226.

Urizar R. E., Cerda J., Dodds W. J., Raymond S. L., Largent J. A., Simon R., and Gilboa N. (1984) Age-related renal, hematological and hemostatic abnormalities in FH/Wjd rats. Am. J. Vet. Res. 45, 1624-1631.

Viglinskaya I. V., Overstreet D. H., Kashevskaya O. P., Badishtov B. A., Kampovpolevoy A. B., Seredenin S. B., and Halikas J. A. (1995) To drink or not to drink - tests of anxiety and immobility in alcohol-preferring and alcohol-nonpreferring rat strains. Physiol. Behav. 57, 937-941.

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