Alteration of electroencephalogram and monoamine concentrations in rat brain following ibogaine treatment

Ibogaine (IBO) is a psychoactive indole alkaloid that has antiaddictive properties. However, treatment with IBO may lead to neurotoxicity, since IBO and its metabolites interact persistently with many neurotransmitter systems. Here, we recorded cortical electroencephalogram (EEG) signals from rats anesthetized with isoflurane. The heart rate (HR) was monitored via electrocardiogram (EKG) electrodes. After the baseline EEG was recorded, rats received one intraperitoneal (i.p.) dose of 50 mg/kg IBO. EEG signals were recorded for 2 hr. Rats were then sacrificed and brains dissected into frontal cortex (FC), caudate nucleus (CN), hippocampus (HIP), and brain stem (BS). The level of dopamine (DA), serotonin (5-HT), and their metabolites were determined by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). Compared with baseline, a decrease in HR immediately after IBO injection and a decrease in delta, theta, alpha and beta power spectra frequency bands (1-4, 4-8, 8-13, 13-32 Hz) during the first 30 min after IBO administration was observed. EEG recovered within the next 15 min. In CN, the level of DA decreased and DA turnover rate increased significantly. The levels of 5-HT increased in FC. The pattern of EKG AND EEG response to IBO may be due to multiple receptor interactions of IBO.

DNA polymerases delta and epsilon in developing and aging rat brain

Our study reveals the presence of DNA polymerases delta and epsilon, participating in DNA replication and repair, along with already known polymerases alpha and beta, in the developing and aging rat brain. This was achieved through a protocol that takes advantage of the reported differential sensitivities of different DNA polymerases towards certain inhibitors such as butylphenyl and butylanilino nucleotide analogs. 2',3'-dideoxythymidine triphosphate, the monoclonal antibody of human polymerase alpha and the use of preferred template primers and proliferating cell nuclear antigen. The results indicate that while polymerase beta seems to be the predominant one, significant levels of polymerases alpha, delta and epsilon are also present at all the postnatal ages studies and that the relative proportion of polymerase epsilon increases with age. The data suggest that the rat brain is equipped with a sustained DNA repair capacity throughout the life span.

Long-term effects of caloric restriction initiated at different ages on DNA polymerases in rat brain

Caloric restriction (CR), has been shown to extend life span and delay both aging and the onset of a number of life-shortening diseases in laboratory animals. Defective DNA repair and DNA damage have been implicated as causal factors in many of these disease processes. CR appears to increase genetic stability by enhancing the DNA repair capacity and reducing the age-related accumulation of certain types of DNA damage. In the present study, we examined the effects of CR, imposed during four discrete periods of the life span of male Wistar rats, on the activity of total DNA polymerases of an aged brain which in turn may have a bearing on the process of aging. Our data indicates that CR had a greater stimulatory response on the activity of total DNA polymerases measured at 28 months of age in rats restricted from 6 to 28 months of age than in those restricted from postnatal day (PND) 7-21 which in turn was higher than those restricted from birth to PND 21. CR had differential effects in different regions of the brain. The enzyme activity of total DNA polymerases was significantly increased in hypothalamus and hippocampus. Cerebral cortex and corpus striatum are the regions which show no significant changes by CR regardless of age or duration of treatment while cerebellum registered a decrease during all periods of restriction. Modification of caloric intake alters total DNA polymerase activity and the extent of modification is both age and tissue dependent. Also, it appears that the effects of CR depend on when the paradigm is initiated, and are not solely a linear function of its duration.

Changes in DNase and DNA-polymerase activities in different tissues of chick with age

The presence of acid and alkaline DNases in nuclei of chick brain cells has been demonstrated. The activities of these two DNases along with those of DNA-polymerases were assessed in chicken tissues with known varied cell proliferative capacities (eg., spleen, kidney and brain) at different ages. The results indicate that the acid and alkaline DNases are probably the 'house keeping' enzymes with a constitutive role in DNA repair process, the former with a DNA-repair process that is linked to cell proliferation (DNA synthesis) while the latter with the basal DNA-repair operations that must go on at all times without any regard to the cell division process. Chicken brain, unlike that of rat, possesses significant levels of aphidicolin sensitive DNA-polymerase(s) that are considered to be more replication oriented enzymes suggesting that the replication potential of adult and old avian brain cells may be different from that of a mammalian brain.