Ester Fride

2-Arachidonyl glyceryl ether, an endogenous agonist of the cannabinoid CB1 receptor

Two types of endogenous cannabinoid-receptor agonists have been identified thus far. They are the ethanolamides of polyunsaturated fatty acids—arachidonoyl ethanolamide (anandamide) is the best known compound in the amide series—and 2-arachidonoyl glycerol, the only known endocannabinoid in the ester series. We report now an example of a third, ether-type endocannabinoid, 2-arachidonyl glyceryl ether (noladin ether), isolated from porcine brain. The structure of noladin ether was determined by mass spectrometry and nuclear magnetic resonance spectroscopy and was confirmed by comparison with a synthetic sample. It binds to the CB1 cannabinoid receptor (Ki = 21.2 ± 0.5 nM) and causes sedation, hypothermia, intestinal immobility, and mild antinociception in mice. It binds weakly to the CB2 receptor (Ki > 3 μM).

Pharmacological activity of the cannabinoid receptor agonist, anandamide, a brain constituent

Anandamide (arachidonylethanolamide) is a brain constituent which binds to the cannabinoid receptor. We now report the first in vivo examination of this ligand. Anandamide administered i.p. in mice, caused lowering of activity in an immobility and in an open field test, and produced hypothermia and analgesia. These effects parallel those caused by psychotropic cannabinoids.

Effects of prenatal stress on vulnerability to stress in prepubertal and adult rats

This study investigated the hypotheses that unpredictable prenatal stress has effects on the offspring, similar to those induced by perinatal administration of glucocorticoids and increases the vulnerability to stressful situations at adulthood. Rats were exposed to random noise and light stress throughout pregnancy. Offspring were tested for the development of spontaneous alternation behavior (SA) and at adulthood, their response to novel or aversive situations, open field, extinction and punishment following acquisition of an appetitive response and two-way active avoidance, were assessed. In prenatally stressed rats, the development of SA was significantly delayed. On repeated exposure to an open field they were less active; control rats had elevated plasma corticosterone (CCS) on days 2 and 4 of open field exposure, while prenatally stressed rats had significantly raised plasma CCS after each exposure (days 1-8). Furthermore, punishment-induced suppression of an appetitive response was enhanced. Acquisition of active avoidance was faciliated in female but reduced in male prenatally stressed offspring. It is suggested that random prenatal noise and light stress may cause impairment of development of hippocampal function which lasts into adulthood. This impairment is manifested as an increase in vulnerability and a decrease in habituation to stressful stimuli.

Biphasic Effects of Anandamide

Effects of the endogenous cannabimimetic anandamide were assessed over a wide dose range in a series of physiological and behavioral assays. These included the tetrad of tests in mice commonly used to assess cannabinoid-induced effects (motor activity, ring catalepsy, hypothermia, and analgesia tests), as well as a model for agonistic behavior on dyadic interactions of singly housed males with nonaggressive group-housed partners. Anandamide-induced effects on leukocyte phagocytosis were measured in a chemiluminescence assay. Results indicated that the higher doses tested (10-100 mg/kg) produced the well-known inhibitory effects in all of the above parameters as well as inhibition of phagocytosis. The lowest dose of anandamide tested (0.01 mg/kg) stimulated behavioral activities in the open field, on the ring and aggressive behavior in timid singly housed mice. This dose of 0.01 mg/kg, also stimulated phagocytosis. We suggest several possible mechanisms to explain these findings such as a differential involvement of a Gs and a Gi protein activated at low and high doses, respectively, allosteric modulation of the cannabinoid, and activation of presynaptic cannabinoid receptors by low doses of anandamide.

Prenatal stress effects on functional development of the offspring

Publisher Summary This chapter reveals prenatal stress effects on functional development of the off spring. The term “psychological stress” is used to denote situations that, although not physically harmful in terms of causing direct tissue damage, evoke behavioral and physiological responses that are characteristic of the “stress” response. Early reports that prenatal psychological stress in human subjects may influence the behavior of the offspring prompted a large number of studies in experimental animals in an attempt to provide more precise information about the nature of the changes induced by such stress and their underlying mechanisms. In the absence of any direct neural connections between the mother and foetus, it has been postulated that hormones (e.g., glucocorticoids, adrenaline) transported from the maternal blood to the placenta are the most likely mediators. The nature of the effect of prenatal stress on early physical development and later behavior appears to depend upon genetic factors, the severity of the stress, and its timing. These in turn determine whether abnormal maternal and foetal hormonal and neuronal activity occurs at a critical period of foetal development.

Critical role of the endogenous cannabinoid system in mouse pup suckling and growth

Delta9-tetrahydrocannabinol, the active principle in marijuana, is a cannabinoid receptor agonist. Both the crude drug and delta9-tetrahydrocannabinol have been used as appetite promoters. The endogenous cannabinoid, arachidonoyl ethanolamide (anandamide), likewise a cannabinoid receptor agonist, has been shown to have the same effect. In contrast, the cannabinoid CB1 receptor antagonist N-(piperidin-1-yl)-5(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1-H-pyrazole-3-carboxamide (SR141716A) reduces food intake. Here, we report that administration of SR141716A to newly born mouse pups (either a single administration on postnatal day 1, or daily for a week as of postnatal day 2) had a devastating effect on milk ingestion and growth. The first 24 h after birth appeared the most critical for the growth stunting effect of SR141716A. Death followed within 4-8 days. Co-administration of delta9-tetrahydrocannabinol almost fully reversed the effect of the antagonist in the week-long regimen. Co-administration of 2-arachidonoyl glycerol, an endocannabinoid, with 2-palmitoyl glycerol and 2-linoleoyl glycerol, which enhance 2-arachidonoyl glycerol potency, resulted in a significant delay in mortality rates caused by the antagonist. We conclude that the endocannabinoid system plays a vital role in milk suckling, and hence in growth and development during the early stages of mouse life.

Involvement of neuronal cannabinoid receptor CB1 in regulation of bone mass and bone remodeling.

The CB1 cannabinoid receptor has been implicated in the regulation of bone remodeling and bone mass. A high bone mass (HBM) phenotype was reported in CB1-null mice generated on a CD1 background (CD1CB1-/- mice). By contrast, our preliminary studies in cb1-/- mice, backcrossed to C57BL/6J mice (C57CB1-/- mice), revealed low bone mass (LBM). We therefore analyzed CB1 expression in bone and compared the skeletons of sexually mature C57CB1-/- and CD1CB1-/- mice in the same experimental setting. CB1 mRNA is weakly expressed in osteoclasts and immunoreactive CB1 is present in sympathetic neurons, close to osteoblasts. In addition to their LBM, male and female C57CB1-/- mice exhibit decreased bone formation rate and increased osteoclast number. The skeletal phenotype of the CD1CB1-/- mice shows a gender disparity. Female mice have normal trabecular bone with a slight cortical expansion, whereas male CD1CB1-/- animals display an HBM phenotype. We were surprised to find that bone formation and resorption are within normal limits. These findings, at least the consistent set of data obtained in the C57CB1-/- line, suggest an important role for CB1 signaling in the regulation of bone remodeling and bone mass. Because sympathetic CB1 signaling inhibits norepinephrine (NE) release in peripheral tissues, part of the endocannabinoid activity in bone may be attributed to the regulation of NE release from sympathetic nerve fibers. Several phenotypic discrepancies have been reported between C57CB1-/- and CD1CB1-/- mice that could result from genetic differences between the background strains. Unraveling these differences can provide useful information on the physiologic functional milieu of CB1 in bone.

Carbachol, an acetylcholine receptor agonist, enhances production in rat aorta of 2-arachidonoyl glycerol, a hypotensive endocannabinoid

The production of 2-arachidonoyl glycerol, an endogenous cannabinoid, is enhanced in normal, but not in endothelium-denuded rat aorta on stimulation with carbachol, an acetylcholine receptor agonist. 2-Arachidonoyl glycerol potently reduces blood pressure in rats and may represent an endothelium-derived hypotensive factor.

Alterations in behavioral and striatal dopamine asymmetries induced by prenatal stress

We investigated the effects of maternal noise and light stress, randomly applied throughout pregnancy, on the development of behavioral and neurochemical asymmetries in the rat offspring. This form of maternal stress resulted in a rightward positioning of the tail of both sexes soon after birth as opposed to the leftward bias in controls. At adulthood, prenatally stressed offspring showed a change in directional bias compared to controls with a preponderance of left turns after amphetamine. In the males, this was expressed as a reduction in directional preference, while in females a reversal occurred of their dominant turning direction from right (controls) to left. We also observed a reduction in dopamine turnover rates in the left corpora striata of stressed offspring of both sexes. Again, in the females, this change was particularly marked and resulted in a reversal towards the right hemisphere. The findings from this study are consistent with the possibility that the alterations in cerebral asymmetries induced by prenatal stress may underly the decrease in the ability of the offspring to cope with anxiety provoking situations.

Trick or treat from food endocannabinoids

The discovery of the endogenous cannabinoid N-arachidonoylethanolamine (anandamide) and other N-acylethanolamines (NAEs) in chocolate has led to speculation that the purported rewarding properties of cocoa are due to the presence of compounds “that could act as cannabinoid mimics”. This observation raises some important questions. First, are NAEs and anandamide, or the ‘endocannabinoid’ 2-arachidonoylglycerol (2-AG), present in widely consumed foods (such as milk) that are less ‘rewarding’ than chocolate? And second, to what extent do these compounds reach the bloodstream and exert pharmacological effects when consumed orally? We believe that the content of endocannabinoids in foods, and in cocoa in particular, is not sufficient to produce cannabis-like effects in mammals.