Brain biochemical parameters

Of the large number of biochemical parameters in CSF, just a few are suitable for routine diagnostic procedures. Their concentration in CSF depends on the state of the blood-brain barrier (Table 1). 

Our initial studies were carried out on cultures of dissociated cells from brains of one day old mice. Unfortunately these preparations had lower than hoped for activities of certain biochemical parameters of myelination. For example, both the incorporation of 35g0jj into sulfolipids and the activity of the cyclic nucleotide phosphohydrolase attained relatively small activities even at the age (8 to 11 days) of optimum activity in culture (fig. 1 and 2). The dissociated cells from the 1 day old mouse produced parallel developmental patterns of both myelin parameters with peak activities at 8 to 11 days in culture. However cultures prepared from 15 day fetal brains proved to have relatively... 

The biochemical parameters of myelination appear to be controlled in a coordinated manner. That is, the parameters we measured responded in the same direction and degree to a certain condition of growth. For example, the cyclic nucleotide phospho-hydrolase and incorporation of into lipids both were less active in cultures from the newborn mouse than from the 15 day fetus. In addition the developmental pattern of all of the activities measured occurred in parallel and were all highest at about the same growth period. This coordinated control suggests that they are derived from a central source, such as a single cell type (for example, oligodendroglia) of brain. 

The alterations in morphological organization of the brain resulting from hypothyroidism have been documented [10-13]. Numerous biochemical parameters are affected by altered thyroid states (for review see 14-16). Recent biochemical data on the effect of thyroid hormones on nerve cell differentiation indicate that they regulate microtubule assembly by changing the concentration and/or the activity of MAPS (tau fraction) [17]. The critical period of effectiveness of thyroid hormones in brain maturation raises a special problem. The correct organization of... 

Partially thyroidectomized rate dams were maintained on normal laboratory diet with food and water ad libitum in a 12 hour light/dark cycle at SI C constant temperature, mated with normal males and the progeny allowed to grow to 7 months of age. The progeny were then killed and brain regions separated on ice and stored frozen before use. Tissues were thawed, homogenized in 0.32 M sucrose and various biochemical parameters assessed using conventional techniques. Results were compared with matched control animals. 

Age of the animals may or may not influence the effects of lead on a variety of other biochemical parameters. Kolber et al. (1980) reported that isolated brain microvessel preparations from younger rats (treated with 4 mg Pb/g body weight for 2 days before sacrifice at 7 days postnatally) were more sensitive to lead treatment than were microvessel preparations from adults equivalent lead burdens produced a greater increase in passive permeability to 3-0-methylglucose in the younger animals. In contrast, Holtzman et al. (1978) observed that, while lead affected brain mitochondrial respiration (specific effects depended on lead concentrations used), there were no differences in response whether the cerebral or cerebellar mitochondria were from 2-week-old or adult rats. 

Malnutrition during the early life of animals and humans alters the number of brain colls, brain coll size and/or other biochemical parameters, depending upon the time of onset and the duration of the malnutrition. 

Battaglia, G. Yeh, S.Y. and De Souza, E.B. MDMA-induced neurotoxicity Parameters of degeneration and recovery of brain serotonin neurons. Pharmacol Biochem Behav 29 269-274, 1988. 

Numerous studies have been published on the in vivo metabolism of peptides. However, these studies are concerned mainly with assessment of pharmacokinetic parameters such as half-life and clearance. Only seldom is the in vivo biotransformation of peptides that contain only common amino acids investigated in any detail, due to the difficulty of monitoring products of proteolysis that are identical to endogenous peptides and amino acids. More importantly, such studies fail to yield mechanistic and biochemical insights. For this reason, we begin here with a discussion of the metabolism of just a few peptides in some selected tissues, namely portals of entry (mouth, gastro-intestinal tract, nose, and skin), plasma, organs of elimination (liver, kidney), and pharmacodynamic sites (brain and cerebrospinal fluid). These examples serve as introduction for the presentation in Sect. 6.4.2 of the involvement of individual peptidases in peptide metabolism. 

K. Aghajanian, and Eric J. Nestler. 1993. "Lewis and Fischer Rat Strains Display Differences in Biochemical, Electrophysiologica), and Behavioral Parameters Studies in the Nucleus Accumbens and Locus Coeruleus of Drug Naive and Morphine-Treated Animals." Brain Research 611 7-17. 

Brooksbank BW, Atkinson DJ, Balazs R (1981) Biochemical development of the human brain. 11. Some parameters of the GABAergic system. Dev Neurosci 4 188-200... 

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