In vitro brain slices

The development of in vitro brain slice and isolated neuron techniques has greatly facilitated detailed studies of the electrophysiology of a wide range of neuronal types in the adult and neonatal vertebrate central nervous system (CNS). Particularly advantageous are the greater mechanical stability that these preparations provide over in vivo models and the control allowed over the composition of the extracellular environment. In addition, the development of the patch-clamp technique has opened up the possibility of direct access to the intracellular environment via internal patch pipet solutions. In combination, these approaches have enabled detailed investigations of neuronal membrane properties, the cellular actions of neurotransmitters, and synaptic mechanisms. 

Dingledine, R., Dodd, J., and Kelly, J. S., 1980, The in vitro brain slice as a useful neurophysiological preparation for intracellular recording,/. Neurosci. 2 323-362. 

Lynch, G., and Schubert, P., 1980, The use of in vitro brain slices for multidisciplinary studies of synaptic function, Annu. Rev. Neurosci. 3 1-22. 

There are many studies on the induction and spread of spiking in animals both in vivo and in isolated brain slices, generally initiated by the use of GABA antagonists or removal of Mg + ions in vitro). Unfortunately since neither of these events is likely to occur in or around a human epileptic focus the results do not tell us much about how focal activity arises and spreads in humans. This needs to be achieved by the use of human epileptic tissue even though the procedures found to control experimentally induced spiking may well be applicable to humans. 

Nicotine increased DA levels both in vivo11,193 and in vitro. 94 196 Nicotine197 and its metabolites198 were found to both release and inhibit the reuptake of DA in rat brain slices, with uptake inhibition occurring at a lower concentration than that required for DA release. In addition, the (-) isomer was more potent than the (+) isomer.197 However, the effects of nicotine upon DA release and uptake were only apparent when brain slices were utilized because nicotine was unable to affect DA when a synaptosomal preparation was utilized.197 These results indicate that nicotine exerts its effects upon the DAT indirectly, most likely via nicotine acetylcholine receptors. This finding was supported by the results of Yamashita et al.199 in which the effect of nicotine on DA uptake was examined in PC 12 and COS cells transfected with rat DAT cDNA. Nicotine inhibited DA uptake in PC 12 cells that possess a nicotine acetylcholine receptor. This effect was blocked by the nicotinic antagonists hexamethonium and mecamylamine. Additionally, nicotine did not influence DA uptake in COS cells, which lack nicotinic acetylcholine receptors. 

Furukawa T, Manabe S, Watanabe T et al 1999 Daily fluctuation of hepatic P450 mono-oxygenase activities in male rats is controlled by the suprachiasmatic nucleus but remains unaffected by adrenal hormones. Arch Toxicol 73 367-372 Gillette MU 1986 The suprachiasmatic nuclei. Circadian phase-shifts induced at the time of hypothalamic slice preparation are preserved in vitro. Brain Res 379 176-181 Guo YF, Stein K 2003 Circadian rhythm in the cardiovascular system. Chronocardiology. jAm Heart J 145 779-786... 

MPTP decreases glutathione levels and increases the levels of reactive oxygen species and the degree of lipid peroxidation in mouse brain slices in vitro and increases the levels of reactive oxygen species in mouse brain in vivo. MPTP neurotoxicity in vitro is reduced by glutathione. In vitro studies have shown that MPP neurotoxicity can be reduced by vitamin E, vitamin C, coenzyme Q, and mannitol (but not by superoxide dismutase, catalase, allopurinol, or dimethyl sulfoxide). P-Carotene, vitamin C, and /V-acctylcystcine partially protect against the neurotoxic effects of MPTP in mice, as do nicotinamide, coenzyme Q, and the free-radical spin trap A-tert-butyl-a-(sulfophenyl) nitrone. 

Pinnock RD, Reynolds T, Woodruff GN (1994) Different types of bombesin receptors on neurons in the dorsal raphe nucleus and the rostral hypothalamus in rat brain slices in vitro. Brain Res 653 119-124. 

Ihe ATFase In mlcrosones prepared from whole rat brain, from rat cerebral cortex, and from cerebral cortex of-rats that had received 3-qulnuclldlnyl benzllate Intraperltoneally at 1 mg/kg an hour before they were killed was found (196) to be enzymatically competent In all caaes and not to be Inhibited significantly by the addition of 3>4ulnuclldlnyl benzllate In vitro. Furthermore, slices of guinea pig brain cortex Incubated In vitro with 10 4 m 3 ulnuclldli l benzllate hnd the same patterns of loss of and uptake of Na as slices Incubated without the benzllate. Inasmuch as ATPase Is related Intimately to the active transport of the monovalent cation In nervous tissue, the experiment with the brain slices gave an additional Indication that ATPase activity Is not altered by 3-qulnuclldliqrl benzllate. 

Ahmed T, Frey J (2005) Phosphodiesterase 4b (PDE4b) and cAMP-level regulation within different tissue fractions of rat hippocampal slices during long-term potentiation in vitro. Brain Res 1041 212-222... 

In washed brain slices, an in vitro model for the evaluation of effects of membrane-bound enzymes on enkephalin hydrolysis, the main hydrolysis products have been identified as Tyr and Tyr-Gly-Gly. The formation of Tyr-Gly-Gly is dependent on the action of enkephalinase and is reduced in the presence of thiorphan (an enkephalinase inhibitor). In the presence of bestatin (a general aminopeptidase inhibitor), the formation of Tyr is reduced Tyr is also reduced, to a lesser extent, in the presence of puromycin (an aminopeptidase Mil inhibitor). In the presence of thiorphan the formation of Tyr increases whereas in the presence of bestatin there is an increase in formation of Tyr-Gly-Gly. The level of Tyr-Gly in this model is low and is unaffected by either thiorphan or bestatin indicating that the action of DAP is unimportant. Recovery of endogenous enkephalins released by depolarisation of brain slices is enhanced in the presence of thiorphan or bestatin and is complete when both inhibitors are present. This does not occur in the case of puromycin or captopril (an ACE inhibitor) [31]. 

Compound (57) was the most active in inhibiting neuronal uptake of NA and 5-HT in vitro and (somewhat less pronounced) in vivo in a series with NH2, NHMe, and NMcj, and a variable chain length of 2-5 carbon atoms. It also potentiated the L-DOPA response (motor activity in mice) and induced a delayed onset of motor stimulation [160]. Also (58) and analogues showed considerable inhibition of NA-uptake in rat brain slices but were poor inhibitors in vivo. Compounds in this series have little or no effect in vivo or in vitro on 5-HT uptake [161]. 

Bragin, A. G., Zhadina, S. D, Vinogradova, O. S., and Kozhechkin, S. N., 1977, Topography and some characteristics of the dentate fascia-field CA3 relations investigated in hippocampal slices in vitro. Brain Res. 135 55—66. 

Kelly, J. S., Godfraind, J.-M., and Maruyama, S., 1979a, The presence and nature of inhibition in small slices of the dorsal lateral geniculate nucleus of rat and cat incubated in vitro, Brain Res. 168 388-392. 

Schwartzkroin, P. A., and Wester, K., 1975, Long-lasting facilitation of a synaptic potential following tetanization in the in vitro hippocampal slice. Brain Res. 89 107-119. 

Skrede, K. K., and Westgaard, R. H., 1971, The transverse hippocampal slice a well-defined cortical structure maintained in vitro. Brain Res. 35 589-593. 

Yarom, Y., and LlinAs, R., 1979, Electrophysiological properties of mammalian inferior olive neurone in in vitro brainstem slices and in vitro whole brain stem, Neurosci. Abstr. 5 109. 

Cerebrospinal fluid is constantly produced and exchanged, and therefore riboflavin is continuously supplied and crosses the blood-brain barrier. The mechanism of this process was examined in vitro in rabbit brain slices (Speetor 1980a), rat brain endothelial cells (RBE4 cells) (Patel et al. 2010), and isolated rabbit choroid plexus (Speetor and Boose 1979). 

---