Tag Archives: Cannabinoids

Possible endocannabinoid control of colorectal cancer growth.

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Abstract

“BACKGROUND & AIMS:

The endocannabinoids anandamide and 2-arachidonoylglycerol (2-AG) inhibit cancer cell proliferation by acting at cannabinoid receptors (CBRs). We studied (1). the levels of endocannabinoids, cannabinoid CB(1) and CB(2) receptors, and fatty acid amide hydrolase (FAAH, which catalyzes endocannabinoid hydrolysis) in colorectal carcinomas (CRC), adenomatous polyps, and neighboring healthy mucosa; and (2). the effects of endocannabinoids, and of inhibitors of their inactivation, on human CRC cell proliferation.

METHODS:

Tissues were obtained from 21 patients by biopsy during colonoscopy. Endocannabinoids were measured by liquid chromatography-mass spectrometry (LC-MS). CB(1), CB(2), and FAAH expression were analyzed by RT-PCR and Western immunoblotting. CRC cell lines (CaCo-2 and DLD-1) were used to test antiproliferative effects.

RESULTS:

All tissues and cells analyzed contain anandamide, 2-AG, CBRs, and FAAH. The levels of the endocannabinoids are 3- and 2-fold higher in adenomas and CRCs than normal mucosa. Anandamide, 2-AG, and the CBR agonist HU-210 potently inhibit CaCo-2 cell proliferation. This effect is blocked by the CB(1) antagonist SR141716A, but not by the CB(2) antagonist SR144528, and is mimicked by CB(1)-selective, but not CB(2)-selective, agonists. In DLD-1 cells, both CB(1) and CB(2) receptors mediate inhibition of proliferation. Inhibitors of endocannabinoid inactivation enhance CaCo-2 cell endocannabinoid levels and block cell proliferation, this effect being antagonized by SR141716A. CaCo-2 cell differentiation into noninvasive cells results in increased FAAH expression, lower endocannabinoid levels, and no responsiveness to cannabinoids.

CONCLUSIONS:

Endocannabinoid levels are enhanced in transformed colon mucosa cells possibly to counteract proliferation via CBRs. Inhibitors of endocannabinoid inactivation may prove useful anticancer agents.”

http://www.ncbi.nlm.nih.gov/pubmed/12949714

Increased endocannabinoid levels reduce the development of precancerous lesions in the mouse colon

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Abstract

“Colorectal cancer is an increasingly important cause of death in Western countries. Endocannabinoids inhibit colorectal carcinoma cell proliferation in vitro. In this paper, we investigated the involvement of endocannabinoids on the formation of aberrant crypt foci (ACF, earliest preneoplastic lesions) in the colon mouse in vivo. ACF were induced by azoxymethane (AOM); fatty acid amide hydrolase (FAAH) and cannabinoid receptor messenger ribonucleic acid (mRNA) levels were analyzed by the quantitative reverse transcription polymerase chain reaction (RT-PCR); endocannabinoid levels were measured by liquid chromatography-mass spectrometry; caspase-3 and caspase-9 expressions were measured by Western blot analysis. Colonic ACF formation after AOM administration was associated with increased levels of 2-arachidonoylglycerol (with no changes in FAAH and cannabinoid receptor mRNA levels) and reduction in cleaved caspase-3 and caspase-9 expression. The FAAH inhibitor N-arachidonoylserotonin increased colon endocannabinoid levels, reduced ACF formation, and partially normalized cleaved caspase-3 (but not caspase-9) expression. Notably, N-arachidonoylserotonin completely prevented the formation of ACF with four or more crypts, which have been show to be best correlated with final tumor incidence. The effect of N-arachidonoylserotonin on ACF formation was mimicked by the cannabinoid receptor agonist HU-210. No differences in ACF formation were observed between CB(1) receptor-deficient and wild-type mice. It is concluded that pharmacological enhancement of endocannabinoid levels (through inhibition of endocannabinoid hydrolysis) reduces the development of precancerous lesions in the mouse colon. The protective effect appears to involve caspase-3 (but not caspase-9) activation.

Cannabinoids have been licensed for clinical use as palliative treatment of chemotherapy, but increasing evidence shows antitumor actions of cannabinoid agonists on several tumor cells in vitro and in animal models [4, 5]. The main psychotropic cannabinoid is Δ9-tetrahydrocannabinol, which exerts its biological effects mainly by activating two G protein-coupled cannabinoid receptors, named CB1 and CB2 receptors [5]. Endogenous ligands for the cannabinoid receptors have been identified; the best known are arachidonylethanolamide (anandamide) and 2-arachidonoylglycerol (2-AG) [4–6]. When released, anandamide and 2-AG are removed from extracellular compartments by a carrier-mediated reuptake process, and once within the cell, both endocannabinoids are hydrolyzed by intracellular hydrolytic enzymes of which the enzyme fatty acid amide hydrolase (FAAH) is capable of recognizing both compounds as substrates [5, 6].

The proposed mechanisms of the antitumoral effect of cannabinoids are complex and may involve induction of apoptosis in tumor cells, antiproliferative actions, and an antimetastatic effects through inhibition of angiogenesis and tumor cell migration [6]. Concerning the gastrointestinal tract, it has been shown that cannabinoid receptor agonists, mostly via CB1 activation, potently inhibit the cell proliferation of colorectal carcinoma cell lines [7]. Furthermore, compounds capable of inhibiting endocannabinoid degradation and hence of prolonging the lifespan of endocannabinoids only when and where these compounds are produced to exert physiological or pathophysiological functions also inhibit colorectal carcinoma growth in vitro [7].

In summary, the present study provides strong evidence that enhancement of colon endocannabinoid levels through pharmacological inhibition of their enzymatic hydrolysis may be protective against preneoplastic lesions in the mouse colon; a condition that, like humans adenomatous polyps and colorectal carcinoma [7], is accompanied by an elevated endocannabinoid tone. This protective effect could be due to indirect activation of one or more of the several targets proposed to date for the endocannabinoids and appears to involve caspase-3 activation and subsequent apoptosis of colon preneoplastic cells. Further studies will be required to investigate if cannabinoid CB2 receptors are involved in the protective effects of AA-5-HT and HU210 and if these effects have any therapeutic relevance for the treatment of human colon carcinoma.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2755791/

Cluster attacks responsive to recreational cannabis and dronabinol.

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Abstract

“Pharmacological preparations of cannabinoid compounds have a variety of therapeutic uses in medicine, including different pain syndromes, but have not been previously reported as beneficial for cluster headache. We present a patient with cluster headache who was refractory to multiple acute and preventive medications but successfully aborted his attacks with recreational marijuana use; subsequent use of dronabinol provided equally effective pain relief. The beneficial effect may be related to the high concentration of cannabinoid receptors in the hypothalamus, which has been implicated as a site of dysfunction in neuroimaging studies of patients with cluster headache.”

http://www.ncbi.nlm.nih.gov/pubmed/19220500

Biochemical changes in endocannabinoid system are expressed in platelets of female but not male migraineurs.

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Abstract

“The endogenous cannabinoid anandamide (AEA) plays important roles in modulating pain. Head pain is an almost universal human experience, yet primary headache disorders, such as migraine without aura (MoA) or episodic tension-type headache (ETTH), can represent a serious threat to well-being when frequent and disabling. We assessed the discriminating role of endocannabinoids among patients with ETTH or MoA, and control subjects. We measured the activity of AEA hydrolase and AEA transporter, and the level of cannabinoid receptors in peripheral platelets from MoA, ETTH and healthy controls. Sixty-nine headache patients and 36 controls were selected. Diagnosis of headache type was made according to the International Headache Society criteria. We observed significant sex differences concerning AEA membrane transporter and fatty acid amide hydrolase activity in all groups. An increase in the activity of AEA hydrolase and AEA transporter was found in female but not male migraineurs. Cannabinoid receptors were the same in all groups. Here we show that the endocannabinoid system in human platelets is altered in female but not male migraneurs. Our results suggest that in migraineur women an increased AEA degradation by platelets, and hence a reduced concentration of AEA in blood, might reduce the pain threshold and possibly explain the prevalence of migraine in women. The involvement of the endocannabinoid system in migraine is new and broadens our knowledge of this widespread and multifactorial disease.”

http://www.ncbi.nlm.nih.gov/pubmed/16472333

Anandamide Is Able to Inhibit Trigeminal Neurons Using an in Vivo Model of Trigeminovascular-Mediated Nociception

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Abstract

“Arachidonylethanolamide (anandamide, AEA) is believed to be the endogenous ligand of the cannabinoid CB(1) and CB(2) receptors. CB(1) receptors have been found localized on fibers in the spinal trigeminal tract and spinal trigeminal nucleus caudalis. Known behavioral effects of anandamide are antinociception, catalepsy, hypothermia, and depression of motor activity, similar to Delta(9)-tetrahydocannanbinol, the psychoactive constituent of cannabis. It may be a possible therapeutic target for migraine. In this study, we looked at the possible role of the CB(1) receptor in the trigeminovascular system, using intravital microscopy to study the effects of anandamide against various vasodilator agents. Anandamide was able to inhibit dural blood vessel dilation brought about by electrical stimulation by 50%, calcitonin gene-related peptide (CGRP) by 30%, capsaicin by 45%, and nitric oxide by 40%. CGRP(8-37) was also able to attenuate nitric oxide (NO)-induced dilation by 50%. The anandamide inhibition was reversed by the CB(1) receptor antagonist AM251. Anandamide also reduced the blood pressure changes caused by CGRP injection, this effect was not reversed by AM251. It would seem that anandamide acts both presynaptically, to prevent CGRP release from trigeminal sensory fibers, and postsynaptically to inhibit the CGRP-induced NO release in the smooth muscle of dural arteries. CB(1) receptors seem to be involved in the NO/CGRP relationship that exists in causing headache and dural blood vessel dilation. It also seems that some of the blood pressure changes caused by anandamide are mediated by a noncannabinoid receptor, as AM251 was unable to reverse these effects. It can be suggested that anandamide is tonically released to play some form of modulatory role in the trigeminovascular system.

The known behavioral effects of anandamide are similar to that of Δ9-tetrahydrocannabinol, the psychoactive constituent of cannabis, being antinociception, catalepsy, hypothermia, and depression of motor activity (Dewey, 1986; Adams et al., 1998). Although there is a history of anecdotal evidence suggesting the use of cannabinoids is effective at reducing headache and providing other pain relief, its potential as an acute migraine treatment and even preventive has never been scientifically studied in animal studies or clinical trial (Russo, 1998). However, one anonymous standardized survey found that of those using cannabis medicinally, over 10% were using it to relieve headache or migraine (Schnelle et al., 1999). Although many aspects of the study are open to debate, such as the highly selected nature of patient group, it is nevertheless an interesting observation.”

http://jpet.aspetjournals.org/content/309/1/56.long

Cannabinoid (CB1) Receptor Activation Inhibits Trigeminovascular Neurons

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Abstract

“Migraine is a common and disabling neurological disorder that involves activation or the perception of activation of the trigeminovascular system. Cannabinoid (CB) receptors are present in brain and have been suggested to be antinociceptive. Here we determined the effect of cannabinoid receptor activation on neurons with trigeminovascular nociceptive input in the rat. Neurons in the trigeminocervical complex (TCC) were studied using extracellular electrophysiological techniques. Responses to both dural electrical stimulation and cutaneous facial receptive field activation of the ophthalmic division of the trigeminal nerve and the effect of cannabinoid agonists and antagonists were studied. Nonselective CB receptor activation with R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2, 3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl) (WIN55,212; 1 mg kg(-1)) inhibited neuronal responses to A-(by 52%) and C-fiber (by 44%) afferents, an effect blocked by the CB(1) receptor antagonist SR141716 [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide; 3 mg kg(-1)] but not the CB2 receptor antagonist AM630 (6-iodopravadoline; 3 mg kg(-1)). Anandamide (10 mg kg(-1)) was able to inhibit both A- and C-fiber-elicited TCC firing, only after transient receptor potential vanilloid 1 receptor inhibition. Activation of cannabinoid receptors had no effect on cutaneous receptive fields when recorded from TCC neurons. The data show that manipulation of CB1 receptors can affect the responses of trigeminal neurons with A- and C-fiber inputs from the dura mater. This may be a direct effect on neurons in the TCC itself or an effect in discrete areas of the brain that innervate these neurons. The data suggest that CB receptors may have therapeutic potential in migraine, cluster headache, or other primary headaches, although the potential hazards of psychoactive side effects that accompany cannabinoid treatments may be complex to overcome.”

“In conclusion, activation of CB1 receptors is able to inhibit trigeminal neurons with A-fiber and C-fiber input in the TCC in response to activation of the ophthalmic division of the trigeminal nerve. Anandamide was only able to inhibit neurons with A-fiber inputs after inhibition of the TRPV1 receptor, highlighting the dual agonist properties of anandamide in the brain. These results support an involvement of the cannabinoid CB1 receptor and TRPV1 receptors in trigeminal neuronal firing, helping to further understand the pathophysiology of the trigeminovascular system and indicate potential directions for the development of new therapeutic agents, notwithstanding the potential difficulties of the psychoactive side effects accompanying cannabinoid treatments.”

http://jpet.aspetjournals.org/content/320/1/64.long

Effects of anandamide in migraine: data from an animal model.

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Abstract

“Systemic nitroglycerin (NTG) produces spontaneous-like migraine attacks in migraine sufferers and induces a condition of hyperalgesia in the rat 4 h after its administration. Endocannabinoid system seems to be involved in the modulation of NTG-induced hyperalgesia, and probably, in the pathophysiological mechanisms of migraine. In this study, the analgesic effect of anandamide (AEA) was evaluated by means of the formalin test, performed in baseline conditions and following NTG-induced hyperalgesia in male Sprague-Dawley rats. AEA was administered 30 min before the formalin injection. In addition, the effect of AEA (administered 30 min before NTG injection) was investigated on NTG-induced Fos expression and evaluated 4 h following NTG injection. AEA induced a significant decrease in the nociceptive behavior during both phases of the formalin test in the animals treated with vehicle, while it abolished NTG-induced hyperalgesia during the phase II. Pre-treatment with AEA significantly reduced the NTG-induced neuronal activation in nucleus trigeminalis caudalis, confirming the results obtained in our previous study, and in area postrema, while the same treatment induced an increase of Fos expression in paraventricular and supraoptic nuclei of the hypothalamus, parabrachial nucleus, and periaqueductal grey. The study confirms that a dysfunction of the endocannabinoid system may contribute to the development of migraine attacks and that a pharmacological modulation of CB receptors can be useful for the treatment of migraine pain.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3072518/

Endocannabinoids in Chronic Migraine: CSF Findings Suggest a System Failure

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Abstract

“Based on experimental evidence of the antinociceptive action of endocannabinoids and their role in the modulation of trigeminovascular system activation, we hypothesized that the endocannabinoid system may be dysfunctional in chronic migraine (CM). We examined whether the concentrations of N-arachidonoylethanolamide (anandamide, AEA), palmitoylethanolamide (PEA), and 2-arachidonoylglycerol (2-AG) in the CSF of patients with CM and with probable CM and probable analgesic-overuse headache (PCM+PAOH) are altered compared with control subjects. The above endocannabinoids were measured by high-performance liquid chromatography (HPLC), and quantified by isotope dilution gas-chromatography/mass-spectrometry. Calcitonin gene-related peptide (CGRP) levels were also determined by RIA method and the end products of nitric oxide (NO), the nitrites, by HPLC. CSF concentrations of AEA were significantly lower and those of PEA slightly but significantly higher both in patients with CM and PCM+PAOH than in nonmigraineur controls (p<0.01 and p<0.02, respectively). A negative correlation was found between AEA and CGRP levels in CM and PCM+PAOH patients (r=0.59, p<0.01 and r=-0.65, p<0.007; respectively). A similar trend was observed between this endocannabinoid and nitrite levels. Reduced levels of AEA in the CSF of CM and PCM+PAOH patients may reflect an impairment of the endocannabinoid system in these patients, which may contribute to chronic head pain and seem to be related to increased CGRP and NO production. These findings support the potential role of the cannabinoid (CB)1 receptor as a possible therapeutic target in CM.

A clinical endocannabinoid deficiency (CECD) has been hypothesized to underlie the pathophysiology of migraine, fibromyalgia, irritable bowel syndrome (IBS), and other functional conditions alleviated by clinical cannabis but no clear evidence to support this deficiency has been reported until now in this regard (Russo, 2004).”

http://www.nature.com/npp/journal/v32/n6/full/1301246a.html

The periaqueductal gray contributes to bidirectional enhancement of antinociception between morphine and cannabinoids.

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“Co-administration of opioids and cannabinoids can enhance pain relief even when administered on different days. Repeated systemic administration of morphine has been shown to enhance the antinociceptive effect of tetrahydrocannbinol (THC) administered 12hours later, and repeated microinjection of the cannabinoid receptor agonist HU-210 into the ventrolateral periaqueductal gray (PAG) has been shown to enhance the antinociceptive effect of morphine administered one day later. The primary objective of the present study was to test the hypotheses that this cannabinoid/opioid interaction is bidirectional. Experiment 1 showed that microinjection of morphine into the ventrolateral PAG of male Sprague-Dawley rats twice daily for 2days enhanced the antinociceptive effect of HU-210 measured one day later. In Experiment 2, twice daily systemic injections of THC enhanced the antinociceptive effect of morphine administered one day later. These results complement the previously mentioned studies by showing that morphine and cannabinoid interactions are bidirectional and that the ventrolateral PAG plays an important role in this effect. In contrast to the PAG, repeated administration of HU-210 or the cannabinoid receptor agonist, WIN 55,212-2, into the RVM had a neurotoxic effect. Rats became ill following repeated cannabinoid administration whether given alone or with morphine. Presumably, this neurotoxic effect was caused by the high cannabinoid concentration following RVM microinjection because rats did not become ill following repeated systemic THC administration. These findings indicate that alternating opioid and cannabinoid treatment could produce a longer lasting and more potent analgesia than either compound given alone.”

http://www.ncbi.nlm.nih.gov/pubmed/23063785

Hallucinogens and cannabinoids for headache.

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“Most hallucinogens and cannabinoids fall into Federal Controlled Substances schedule 1, meaning they cannot be prescribed by practitioners, allegedly have no accepted medical use, and have a high abuse potential. The legal and regulatory status has inhibited clinical research on these substances such that there are no blinded studies from which to assess true efficacy. Despite such classification, hallucinogens and cannabinoids are used by patients with headache on occasion.

 Cannabinoids in particular have a long history of use for headache and migraine before prohibition and are still used by patients as a migraine abortive.

 Hallucinogens are being increasing used by cluster headache patients outside of physician recommendation mainly to abort a cluster period and to maintain quiescence for which there is considerable anecdotal success.”

http://www.ncbi.nlm.nih.gov/pubmed/23030539