Cortex Of Neonatal Rats Research Articles

Changes in protein content of developing brain synaptic membranes, mitochondria and myelin

The development of myelin, synaptosomal plasma membranes (SPM) and mitochondria in neonatal rat cortex has been followed by examining the electrophoretic profiles of protein in brain subcellular fractions. The appearance of the myelin proteins parallels the time course of myelination and confirms previous reports of the order of appearance of the proteins. Few changes occur in mitochondria during the developmental period. Plasma membranes in the SPM fraction show a progressive change from an ante-synaptogenesis profile to that characteristic of adult SPM. Tubulin, which is the major synaptic junctional protein, reaches its adult level in the developing SPM earlier than other SPM proteins, indicating that it may be involved in establishing the basic framework of the junction.

Postlesion Axonal Growth Produces Permanent Functional Connections

Lesions of the entorhinal cortex in neonatal rats cause the commissural projections to the dentate gyrus to spread from their normal location in the inner molecular layer into the outer molecular layer, a region normally occupied by afferents from the entorhinal cortex. These lesions also cause the short-latency response to commissural stimulation to spread into the outer molecular layer, a result suggesting that these abnormally located connections are operative.

Adenyl cyclase and phosphodiesterase activity in cerebral cortex of normal and undernourished neonatal rats

Adenyl cyclase and cyclic nucleotide phosphodiesterase were measured in homogenates of cerebral cortex from well-fed and undernourished rats at 3, 10, and 19 days after birth and in homogenates from normal adult rats. The specific activities of both enzymes increased progressively between 3 and 19 days postpartum, and were the same in cortical homogenates from well-fed and undernourished rats. In the adult, adenyl cyclase was approximately half the value observed at 19 days of age. Activities of adenyl cyclase in whole homogenates of cerebral cortices were, in part, dependent upon the presence of low concentrations of a soluble, heat stable cellular component.

Developmental changes in frontocortical morphology and neurochemistry of neonatal rats following gestational nicotine exposure

Exposure of the embryo or foetus to nicotine during development results in some forms of neurological deficits later in life. The current study aimed at determining the effects of prenatal nicotine administration during the 1st and 2nd gestational weeks on the frontal cortex of neonatal Wistar rats. For each week of gestation, pregnant Wistar rats were assigned to 3 groups: a control group (1), and two treated groups (2 and 3), and were given intra-peritoneal nicotine at 6.88 mg/ kg and 13.76 mg/kg doses respectively. The weights of the litters were taken at birth and at postnatal day 4; the whole brain and frontal cortical weights were also assessed. Tissues for histological demonstration were fixed in freshly prepared formol calcium, while specimen for biochemical studies were homogenised and processed for the determination of alkaline phosphatase (ALP) and malondialdehyde (MDA) activities. Findings in the treated animals showed low birth weights, raised ALP but reduced MDA, with corresponding alterations in the cortical cytoarchitecture, which could explain some of the pathological basis for the neurobehavioural problems associated with offspring of women smokers.Keywords: Prenatal nicotine, Frontal cortex, Morphology, Histology, ALP, MDA