Mice, knock-out

Genetically modified animals, in particular knock-out mice, help to understand the role of various factors in blood clotting, thrombolysis, and platelet function. 

They are useful to verify the mode of action of new drugs. 

Bom in normal appearance, 10 % die shortly after birth and another 40 % around 1-2 months after birth due to bleeding, failure of pregnancy, blood samples fail to clot or support platelet aggregation in vitro (Suh etal. 1995). 

Suh TT, Holmback K, Jensen NJ et al. (1995) Resolution of spontaneous bleeding events but failure of pregnancy in fibrinogen-deficient mice. Genes Dev 9 2020-2033 

Partial embryonic lethality 50 % between embryonic day (E) 9.5-11.5 at least 1/4 survive to term, but fatal hemorrhage few days after birth factor II important in maintaining vascular integrity during development as well as postnatal life (Sun et al. 1998 Xu et al. 1998). 

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Cole et al. (1995) reported on knock-out mice with a germ line deletion of GR. They demonstrated that lack of GR leads to perinatal death, atelectasis of the lung, and lack of adrenalin synthesis. To circumvent perinatal lethality, Tranche et al. (1999) and Brewer et al. (2003) generated tissue-specific somatic deletions of GR. This allowed to characterize GR function in the CNS, the immune system, and the liver in more detail. In particular, these approaches revealed novel aspects of organ-specific glucocorticoid physiology such as anxiety-like behavior, growth control, and polyclonal T cell activation. 

Berger et al. (1998) generated MR knock-out mice by gene targeting. Until day 10 after birth, these mice develop normally. Later they show symptoms of pseudohypoaldosteronism, characterized by massive... 

Although drugs may not be able to distinguish between the subclasses of nicotinic receptor the last few years has seen the breeding of knock-out mice in which most of the... 

HT is metabolised primarily by MAO to 5-hydroxyindoleacetic acid (5-HIAA) (Fig. 9.4). In vitro, 5-HT is the preferred substrate for the MAOa, rather than the MAOb isoenzyme (see Chapter 8) and this appears to be the case in vivo since MAOa, but not MAOb, knock-out mice have increased concentrations of 5-HT in the brain. Obviously, because of its indole nucleus, 5-HT is not a substrate for the enzyme COMT which metabolises the catechol derivatives, dopamine and noradrenaline. However, other metabolic products of 5-HT are theoretically possible and one, 5-hydroxytryptophol,... 

Nitric oxide has also been implicated in PD. Thus animals with MPTP-induced Parkinsonism not only show extensive gliosis in the substantia nigra (like humans) in which the glial cells produce NO, but Liberatore and colleagues have found that in iNOS (inducible nitric oxide synthase) knock-out mice the toxicity of MPTP is halved. Since NO releases iron from ferritin and produces toxic peroxinitrate in the presence of superoxide radicals it could accelerate, even if it does not initiate, dopaminergic cell death (see Hirsch and Hunot 2000 for further details). 

There are few specific drugs for D3 receptors but D3 knock-out mice show no behavioural defects. Thus the significance of any DA receptor other than the D2 still remains to be established (see Seeman and Van Tol 1994 Sokoloff and Schwartz 1995 Strange 1994). 

Most cases of AzD show cerebrovascular amyloid deposits and the amyloid protein of senile plaques is the same as that found in blood vessels. It is referred to as )S-amyloid protein and is part of a 695, 751 or 770 amino-acid amyloid precursor protein APP, which is a transmembrane protein and although its precise function is not clear, it is widely distributed and APP knock-out mice show reduced motor function. Normally so-called short 40 amino-acid-soluble derivatives of APP are produced by proteolytic cleavage of APP within the j] (A4) amino-acid sequence but APP can also be cleaved... 

Boutrel, B, Franc, B, Hen, R, Hamon, M and Adrien, J (1999) Key role of 5-HTlB receptors in the regulation of paradoxical sleep as evidenced by 5-HTlB knock-out mice. J. Neurosci. 19 3204-3212. 

The increased dopamine hypothesis is supported by findings of gene induction in the target areas and the indications that individual differences in dopamine receptors and transporters may underlie impulsive and addictive behaviour in humans. Studies in knock-out mice have, however, provided evidence for complex roles of 5-HT in these processes. 

IL-ip is a well documented sleep factor (reviewed by Obal Krueger, 2003). Its administration increases sleep, its blockade decreases sleep and sleep rebound, and its transcription increases during waking. IL-1 receptor knock-out mice sleep less. Local application of IL-1 p in POA also stimulates NREM sleep. We examined the effects of local administration of IL-1 p and an antagonist through microdialytic application adjacent to lateral POA neurons (Alam et at, 2004). Neuronal activity is recorded within 0.5-1.0 mm of a microdialysis membrane in unrestrained rats. IL-ip potently inhibited the activity of 79% of wake-active neurons. The inhibitory response to IL-ip of wake-active neurons could be blocked by pre-treatment with IL-lra, an IL-ip antagonist. IL-ip application also excited some sleep-active neurons, but this response was inconsistent. 

Mochizuki, T., Crocker, A, McCormack, S. et al. (2004). Behavioral state instability in orexin knock-out mice. J. Neurosci 24, 6291-300. 

Boutrel, B Monaca, C., Hen, R., Hamon, M. Adrien, J. (2002). Involvement of 5-HTia receptors in homeostatic and stress-induced adaptive regulations of paradoxical sleep studies in 5-HT1A knock-out mice. J. Neurosci. 22, 4686-92. 

Savelieva, K.V., Caudle, W.M., Findlay, G.S., Caron, M.G., and Miller, G.W., Decreased ethanol preferences and consumption in dopamine transporter female knock-out mice, Alcohol. Clin. Exp. Res., 26, 2002. 

Champtiaux, N., Gotti, C., Cordero-Erausquin, M. et al. Subunit composition of functional nicotinic receptors in dopaminergic neurons investigated with knock-out mice. J. Neurosci. 23 7820, 2003. 

Berrendero, R., Kieffer, B., Maldonado, R. Attenuation of nicotine-induced antinociception, rewarding effects and dependence in mu-opioid receptor knock out mice. J. Neurosci. 22 10935, 2002. 

Fumagalli, F., Gainetdinov, R.R., Wang, Y.M. et al. Increased methamphetamine neurotoxicity in heterozygous vesicular monoamine transporter 2 knock-out mice. J. Neurosci. 19 2424, 1999. 

Sun H, Johnson DR, Finch RA, Sartorelli AC, Miller DW, Elmquist WF. Transport of fluorescein in MDCKII-MRP1 transfected cells and mrpl-knock-out mice. Biochem Biophys Res Com-mun 2001 284(4) 863-869. 

Wess, J. Muscarinic receptor knock out mice novel phenotypes and clinical implications. Ann. Rev. Pharmacol. Toxicol. 44,423-500, 2004. 

Zhang, W., Basile, A. S., Gomeza, J., Volpicelli, L. A., Levey, A. I. and Wess, J. Characterization of central inhibitory muscarinic autoreceptors by the use of muscarinic acetylcholine receptor knock-out mice. /. Neurosci. 22 1709-17, 2002. 

Bonaventure, P., Nepomuceno, D., Kwok, A. et al. Reconsideration of 5-hydroxytryptamine (5-HT)7 receptor distribution using [3H]5-carboxamidotryptamine and [3H]8-hydroxy-2-(di-n-propylamino)tatraline Analysis in brain of 5-HT 1A knock-out and 5-HT1A,1B double knock-out mice. /. Pharmacol. Exp. Ther. 302 240-248, 2002. 

Parmentier, R., Ohtsu, H., Djebbara-Hannas, Z., Valatx, J. L., Watanabe, T. and Lin, J. S. Anatomical, physiological, and pharmacological characteristics of histidine decarboxylase knock-out mice evidence for the role of brain histamine in behavioral and sleep-wake control. /. Neurosci. 22 7695-7711,2002. 

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