Effect of undernutrition on cell generation in the adult rat brain

Cell proliferation in the subependymal layer of the adult mouse in vivo and in vitro

Pulse labelling experiments with [3H] thymidine (dT) and double labelling experiments with [3H]dT and bromodeoxyuridine (BrdUrd) were carried out on cells of the subependymal layer in the brain of adult normal mice in vivo, in vivo/in vitro and in vitro. The results should (i) lead to information about cell cycle parameters of these cells in the brain of adult mice, since these cells have been studied mostly in the rat brain up to now and (ii) answer the question whether results concerning cell proliferation obtained in vivo correspond with those from brain slices incubated in vitro with or without prelabelling in vivo. In vivo an LI of 20.2 +/- 2.7% (mean +/- SEM) and Ts = 7.2 +/- 0.7 h were found. Furthermore, grain count halving experiments led to a surprisingly short cycle time (Tc) of 11.2-14.2 h. The longer Tc values (18-20 h) reported in the literature for subependymal cells in the rat brain seem to be due to evaluations of different areas around the lateral ventricle without considering the migrating behaviour of these cells which is quite different regionally. The in vitro studies (with or without prelabelling in vivo) showed a significantly reduced LI due to the fact that about 20% of the S phase cells, possibly lying in the middle of S, stopped further DNA synthesis after transfer to culture. This was shown by comparing the cell fluxes at the G1/S and S/G2 borders of in vivo vs. in vitro studies.

Prenatal protein malnutrition alters behavioral state modulation of inhibition and facilitation in the dentate gyrus

We have examined the effects of prenatal protein malnutrition on interneuronally mediated inhibition and facilitation in the dentate gyrus of the rat using the paired-pulse technique. Field potentials were recorded in the dentate gyrus in response to paired stimuli delivered to the perforant path. The paired-pulse index (PPI) was used as a measure of the net short-term facilitation or interneuronally mediated inhibition effective at the time of the paired-pulse test and was computed by dividing the amplitude of the second population spike (p2) by the amplitude of the first population spike (p1). PPIs were classified according to p1 in order to compare PPIs between behavioral states and dietary treatments since population spike amplitudes in the dentate gyrus vary in relation to behavioral state. Testing was performed during 4 behavioral states: slow-wave sleep (SWS), paradoxical sleep (REM), immobile waking (IW) and exploratory locomotion (AW) using interpulse intervals (IPI) from 20 to 400 ms. The magnitude and duration of interneuronally mediated inhibition was significantly increased in prenatal protein malnourished animals when compared with controls. Paired-pulse tests performed using an IPI of 20 ms under the high p1 (p1 greater than median) condition showed significantly smaller PPIs in prenatal protein malnourished rats regardless of behavioral state. For IPIs greater than 20 ms PPIs were consistently smaller in prenatal protein malnourished rats during SWS and IW. These data indicate that both the magnitude and duration of interneuronally mediated inhibition are increased in prenatally malnourished rats. No consistent diet-related differences were found during AW and REM using IPIs greater than 20 ms because interneuronally mediated inhibition was relatively suppressed during these behavioral states for both dietary groups. There was no consistent behavioral state modulation of paired-pulse facilitation (IPI = 40 to 80 ms) or late inhibition (IPI = 400 ms) in either diet group. In addition, a new relation between PPI and IPI was found under the low p1 (p1 greater than median) condition. During AW the PPIs observed using IPIs of 40 and 50 ms were smaller than those observed using IPIs of 30 and 60 ms. This depression interrupts what is generally considered the "facilitatory" phase of paired-pulse response and may indicate an interaction between perforant path stimulation and hippocampal theta rhythm which is masked when p1 amplitude is high.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of undernutrition and thyroid state on the ontogenetic changes of D1, D2, and D3 brain-specific proteins in rat cerebellum

Disturbances in metabolic balance brought about by alterations in thyroid state and undernutrition during early life had a marked effect on the concentrations of the brain-specific proteins, D1, D2, and D3 in the developing rat cerebellum. In normal rats, the concentrations of D1 and D3 increased and that of D2 decreased during the first 3 weeks after birth. In the hyperthyroid state a small but consistent advancement was observed in the developmental curves of these proteins. The hypothyroid state caused a marked retardation in the maturational pattern of D1 and D2 but not of D3. In undernutrition, at 6 days the concentrations of D1 and D3 proteins were higher than in controls, but thereafter the developmental increase was markedly delayed for D1 only. The concentration of D2 was normal at 6 days, but after the first week a marked retardation was observed in the maturational pattern of this protein in undernourished rats. In addition, the "anodic-immature" form of D2 predominated in 6-day-old controls, but this was gradually replaced by a "cathodic-mature" form which progressively became the dominant form of D2 in 35-day-old rat cerebellum. The developmental switch in terms of the two forms was also advanced in hyperthyroidism and retarded in thyroid deficiency and undernutrition. Furthermore, daily treatment of hypothyroid rats with physiological doses of thyroxine from birth restored the concentrations of D1 and D2 to normal, but that of D3 was increased above control levels, indicating differences between the proteins in their sensitivity to mechanisms of control by thyroid hormone. Also, the overall effects of undernutrition were markedly different from those of hypothyroidism.

The effects of chlorpromazine and phenobarbital on cerebellar Purkinje cells

The morphological effects of two chemically different neuroactive drugs (chlorpromazine and phenobarbital) on developing Purkinje cells in the rat cerebellum were examined to determine the presence of cytological alterations. Therapeutic dosages of both drugs were chronically administered to separate groups of maternal rats beginning on day 18 postcoitus. Entire litters were sacrificed on postnatal days 13, 15, 18, and 21. Light microscopic quantitation of Purkinje cells demonstrated a statistically significant reduction in total numbers below control levels at all ages examined for both drugs. Pyknotic Purkinje cells, which appeared more numerous in the drug tested groups, had a paucity of synaptic contacts on both the soma and dendritic branches. Both drugs tested produced similar results within the parameters examined. These alterations have been discussed in relation to possible mechanisms and sites of action.

Postnatal quantitative changes in the cerebellar uvula of albino rats

The postnatal quantitative changes in cell diameter, cell density and total number of granule cells in the sublobule IXa of female rats from 6 to 760 days old were examined. There occurs and initial rapid increase in cell density from 1232.00 +/- 91.92 granule cells per 10(-3) mm 3 to 2995.50 +/- 322.07 granule cells per 10(-3) mm 3 and from 3 135 316 +/- 233 937 to more than 24 millions of granule cells between the 6th and 25th postnatal day. After the middle of the 3rd postnatal week, cell density and total number of granule cells decrease. The diameter of the granule cells reaches a maximum at the 6th day post partum and decreases continuously with progressing age. The possible mechanisms of these quantitative changes are discussed.