The effect of cannabinoids on the number of nuclear membrane-attached ribosomes in infant rat brain

The pharmacologically active cannabinoids Δ⁹-THC, Δ⁹-THC and 11-OH-Δ⁹, -THC each caused a highly significant reduction in nuclear membrane-attached ribosomes of infant rat brain cells. The pharmacologically inactive agents cannabinol and cannabidiol had only a slight effect while cannabigerol had a moderate effect. The activity was measured 3 hr after a 10 mg/kg s.c. dose. The duration of effect was tested with Δ⁹-THC. It was significant after 1 hr, maximally developed after 3 hr, and almost completely diminished after 6 hr.     

Retrograde filling of pyramidal neurons in postmortem human cerebral cortex using horseradish peroxidase

A method for retrograde filling of neurons in the postmortem human brain is described. Fresh human brains with minimal postmortem delay (3-11 h) were used. Horseradish peroxidase (HRP) crystals were applied directly to white matter underlying the cerebral cortex. After 5 min, the HRP was washed off and the tissue incubated in the cold for 24-48 h prior to frozen sectioning and development with 3,3'-diaminobenzidine. Reaction product filled pyramidal neurons and fibers in laminae V and VI. The method appears to be useful for labelling cortical projection neurons and cortical afferent fibers and should be applicable to other brain areas.     

THA increases action potential duration of central histamine neurons in vitro

Long-term administration of 9-amino-1,2,3,4-tetrahydroacridine (THA) has been reported to produce marked clinical improvement in patients suffering from Alzheimer's disease. The dramatic enhancement of cognitive function seen with THA contrasts sharply with the modest improvements seen with other forms of anticholinesterase therapy, suggesting that additional mechanisms might play a role in its therapeutic efficacy. When applied to hypothalamic histamine neurons maintained in vitro, THA produced a dose-dependent increase in action potential duration. By its effect upon action potential duration, THA may increase release of transmitter from the axon terminals of cortically projecting aminergic neurons which have been shown to degenerate in Alzheimer's disease. Thus, the therapeutic efficacy of THA may derive from a combination of its anticholinesterase activity and its effects upon the duration of action potentials of aminergic neurons.     

Retrograde HRP tracing combined with a pharmacohistochemical method for GABA transaminase for the identification of presumptive GABAergic projections to the habenula

A pharmacohistochemical method for GABA-transminase (GABA-T), the key enzyme for GABA metabolism, has been combined with retrograde tracing by horseradish peroxidase, to a study of projections to the lateral habenualla. The results indicate that projections to the lateral habenula arise from both GABA-T intensive and non-GABA-T staining cells in the rostral entopeduncular nucleus and the lateral hypothalamus suggesting that these projections contain GABAergic elements, as indicated by previous work, but also involve other neurotransmitters. A few GABA-T intensive cells in the lateral preoptic area were also found to project to the lateral habenula by this double staining technique.