Characterization of the kinetics and distribution of N-arachidonylethanolamine (anandamide) hydrolysis by rat brain.

Arachidonoylethanolamide or 'anandamide' is a naturally occurring derivative of arachidonic acid that has been shown to activate cannabinoid receptors in the brain. Its metabolic inactivation by brain tissue has been investigated. Anandamide is hydrolyzed by the membrane fraction of rat brain homogenate to arachidonic acid and ethanolamine.

Effects of intraocular mescaline and LSD on visual-evoked responses in the rat.

The effects of mescaline and LSD on the flash-evoked cortical potential (FEP) were determined in unrestrained rats with chronically-implanted electrodes. Systemic administration of mescaline or LSD significantly attenuated the primary component of the FEP at three stimulus intensities with the greatest effect observed 60-90 minutes following drug administration. The magnitude and specificity of the effects of these agents on the primary response suggest that they produce deficits in conduction through the retino-geniculato-cortical system.

Inhibition of heterosensory thalamocortical evoked potentials by delta-9-tetrahydrocannabinol.

The effects of delta-9-tetrahydrocannabinol on sensory activity in the thalamic intralaminar nuclei, centralis lateralis and the mesencephalic reticular formation were compared with the effects on cortical association or heterosensory systems in alpha-chloralose-anesthetized cats. The drug depressed the anterior marginal responses to multiple-modality sensory stimulation 30 min after administration of 2 mg/kg. Posterior suprasylvian responses were not significantly depressed except during 15 min postadministration.

The actions of THC on the intact hippocampus: a comparison of dentate and CA1 responses.

The effects of delta-9-tetrahydrocannabinol were compared on two afferent pathways of the rat hippocampal formation in urethane-anesthetized and chronically implanted awake animals. In urethane-anesthetized rats, THC produced a shift to the right in the input/output relationship without altering the relation between the measures of synaptic wave and the population spike of the CA1 response to contralateral CA3 stimulation. In contrast, the dentate response to perforant path stimulation was not altered by THC.

Separation of components of hippocampal field potentials by digital filtering on a PC-based microcomputer.

A versatile digital filtering system is described which enables separation of wave components of evoked potentials based on their frequencies. The utility of this technique is exemplified by application of digital filtering to hippocampal field potentials. Separation of population spikes from lower frequency synaptic potentials provides less ambiguous interpretation of the compound slope of the field potential during the first 5 milliseconds of the response.

Alteration of electrical correlates of sensory processing by tetrahydrocannabinol.

The action of tetrahydrocannabinol on the function of four multimodality responsive neocortical areas was assessed in the cat. Cats, anesthetized with alpha-chloralose, were subjected to auditory, somatosensory, and two types of visual stimulation. Simultaneous evoked field potentials and multiple-unit activity were recorded.

A microcomputer-based package for determination of regional and global cardiac function and coronary hemodynamics.

A multichannel data acquisition package for reduction of systemic and coronary hemodynamic data that utilizes a personal microcomputer is described. The system provides a printout of heart rate, maximal rate of left ventricular pressure development (+dP/dt), maximal rate of ventricular relaxation (-dP/dt), absolute and normalized myocardial segment lengths, the degree of shortening of the segment over the cardiac cycle, systolic, diastolic, and mean coronary blood flow velocities, left ventricular systolic and end diastolic pressures, and systolic, diastolic, and mean aortic blood pressure from six channels of input data. Obtained values are precisely linked to the cardiac cycle.

Differential effects of lysergic acid diethylamide, methysergide, and cyproheptadine on modality-specific and nonspecific sensory evoked potentials.

The effects of lysergic acid diethylamide (LSD), methysergide, and cyproheptadine on activity in classical primary pathways of the visual and somatosensory systems were compared with their effects on activity in sensory convergent (association) regions in alpha-chloralose-anesthetized cats. Those effects were blocked by cyproheptadine whereas methysergide potentiated the actions of LSD on visual primary activity. In contrast, LSD depressed the primary somatic pathway, at small doses (25 to 50 micrograms/kg) and facilitated the response at larger doses (200 micrograms/kg).

Estimation of thresholds for evoked potentials using a laboratory computer.

To study drug effects on bioelectric activity evoked by near-threshold stimulation, we have developed a computerized threshold estimation technique. The procedure utilizes a laboratory computer (PDP 11/34) equipped with a standard laboratory interface with A/D and D/A capabilities. Program-controlled voltage pulses, delivered via D/A, are interfaced through a constant current stimulus isolation unit for electrical stimulation.

Slowing of cortical somatosensory evoked activity by delta 9-tetrahydrocannabinol and dimethylheptylpyran in alpha-chloralose-anesthetized cats.

Somatosensory and visual evoked potentials in the classical afferent primary pathways in cats anesthetized with alpha-chloralose were studied in order to characterize the effects of delta 9-tetrahydrocannabinol (THC) and the synthetic analog, dimethylheptylpyran (DMHP) on central sensory processing. THC and DMHP slowed primary cortical responses to radial nerve or ventralis posterolateralis (VPL) stimulation in a dose dependent manner. THC did not alter VPL activity evoked by radial nerve stimulation.