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Year : 2015  |  Volume : 3  |  Issue : 1  |  Page : 29-32

Histomorphologic effects of Cannabis sativa on the brains of adult Wistar rats

Department of Human Anatomy and Cell Biology, College of Health Sciences, Delta State University, Abraka, Nigeria

Date of Web Publication13-Jul-2015

Correspondence Address:
Emmanuel Igho Odokuma
Department of Human Anatomy and Cell Biology, Faculty of Basic Medical Sciences, College of Health Sciences, Delta State University, PMB - 1, Abraka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2315-7992.160747

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Introduction: Cannabis sativa is one of the species of cannabis plant. The objective of this study was to determine the short- and long-term effects of Cannabis sativa on the brains of adult Wistar rats. Materials and Methods: Thirty (30) healthy adult Wistar rats of both sexes were used as experimental animals. The Cannabis sativa leaves obtained were extracted at the Laboratory Facility of the Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Delta State University, Abraka, Nigeria. The animals were grouped as follows: Positive control (one: Group I), negative control (one: Group II), and experimental groups (three: Groups III-V); different doses of the drug in volume were calculated (0.10 mL for acute study, 0.23 mL for subacute study, and 0.50 mL for subchronic study) and administered orally with the use of an improvised orogastric cannula. The animals were sacrificed and the organs harvested for manual tissue processing and hematoxylin-eosin (H&E) staining. The stained slides were interpreted with the aid of a light microscope and analyzed for histomorphological changes across the groups. Results: The results showed that the histomorphologic changes induced by Cannabis sativa in short- and long-term studies caused extensive cerebral gliosis in the brains of adult Wistar rats. Conclusion: It could, therefore, be deduced that there were both dose- and time-dependent toxic effects of Cannabis sativa on the experimental animals. Cannabis sativa was shown to cause marked neuronal changes in the brains of adult Wistar rats.

Keywords: Cannabis sativa , cerebrum, gliosis, histology

How to cite this article:
Odokuma EI, Ogbor-Omorie E. Histomorphologic effects of Cannabis sativa on the brains of adult Wistar rats. Ann Bioanthropol 2015;3:29-32

How to cite this URL:
Odokuma EI, Ogbor-Omorie E. Histomorphologic effects of Cannabis sativa on the brains of adult Wistar rats. Ann Bioanthropol [serial online] 2015 [cited 2018 Mar 6];3:29-32. Available from: http://www.bioanthrojournal.org/text.asp?2015/3/1/29/160747

  Introduction Top

Cannabis could be described as a dry, shredded mixture of the flowers, stems, leaves, and seeds of the cannabis plant. The plant has three different species including: Cannabis sativa, Cannabis indica, and Cannabis ruderalis. Cannabis sativa leaf is typically green, but brown if dried. All forms of cannabis contain delta-9- tetrahydrocannabinol (Δ9-THC) as the main psychoactive ingredient.[1]

Previous research has shown that the brain is one of the sites of action of Cannabis sativa. [2] Cannabinoid type 1 (CB1) receptors are distributed widely throughout the central, peripheral, and enteric nervous systems. [3] Cannabinoid type 2 (CB2) receptors are closely linked within the immune tissue, predominantly the spleen and macrophages. [4]

In another report, [5] it was shown that long-term, heavy C. sativa use was associated with gross anatomical abnormalities in two cannabinoid receptor-rich regions (the hippocampus and the amygdala) of the brain. Similar studies have shown that heavy, daily C. sativa use across protracted periods exerted harmful effects on brain tissue and mental health. [6],[7],[8],[9]

The report of another study showed that an acute dose of oral THC was associated with a decrease in threat-related amygdala reactivity, which suggests that cannabinoids have an inhibitory effect on threat-related amygdala reactivity. [10]

The literatures suggest in general that long-term C. sativa use is associated with a wide range of adverse health consequences, especially on the brain.

This study was therefore aimed at determining the acute and chronic effects of C. sativa on the brains of adult Wistar rats.

  Materials and methods Top

Experimental design

Thirty (30) healthy, adult Wistar rats of both sexes were used as experimental animals. [11]

Ethical considerations

Approval was obtained from the Research and Bioethics Committee of the Faculty of Basic Medical Sciences, Delta State University, Abraka, Nigeria, and the study was carried out in strict accordance with the guidelines for the care and use of animals for research. [12]

Procurement of plant material and authentication

Permission was sought from the National Drug Law Enforcement Agency (NDLEA) at their head office at Ogwashi-Uku, Delta State. The leaves were also obtained from the NDLEA office and were authenticated at the Department of Botany, Delta State University, Abraka.

Method of C. sativa extraction

The agent C. sativa was extracted using standard methods [13] at the Laboratory Facility of the Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Delta State University, Abraka.

Animal grouping and administration of plant extract

On transfer to the work area, the animals were allowed 14 days for acclimatization. The Wistar rats weighed 150-195 g and were divided at random into five groups of 6 animals each of both sexes, as follows: Group I (positive control), Group II (negative control), Group III (experimental group 1), Group IV (experimental group 2), and Group V (experimental group 3). The drug was administered to the groups via oral route using improvised orogastric cannula as follows: Rats in group I received normal saline for 42 days; group II 0.10 mL (acute), 0.23 mL (subacute), and 0.50 mL (subchronic) 5% ethanol for 7 days, 21 days, and 42 days respectively; group III 0.10 mL/day of 5% ethanol extract of C. sativa for 7 days (63.5 mg/kg/day) for acute study; group IV 0.23 mL/day (127 mg/kg/day) of 5% ethanol extract of C. sativa for 21 days for subacute study; and group V 0.50 mL/day (254 mg/kg/day) of 5% ethanol extract of C. sativa for 42 days for subchronic study. The animals were housed within the facility and maintained on standard rodent pellets and water ad libitum.

Animal sacrifice and harvest of selected organs

After the experimental periods, rats in each of the groups were weighed and then sacrificed by cervical dislocation. Harvest of the organs was made on the same day; the harvested organs were placed in universal bottles that were labeled accordingly and preserved with 10% formal saline for 48 h. The tissues were then grossed and placed into tissue cassettes that had been labeled, and thereafter the tissues were processed manually as prescribed previously. [14]

The stained tissue images were captured using the digital camera and microscope ScopeTek DCM500 connected to the universal serial bus (USB) port of a computer. The stained slides were interpreted with the aid of a light microscope and analyzed for histomorphological changes across the groups.

Inclusion/exclusion criteria

The experimental animals were randomly chosen based on the following criteria during and after the period of acclimatization: Rats that weighed 150-195 g and had normal feeding patterns were included, while rats that had physical sign of sickness or weakness were excluded.

  Results Top

In [Plate 1 [Additional file 1]] and [Plate 2 [Additional file 2]], sections through the cerebrum for the positive and negative control groups are shown. Extensive gliosis is seen in all the experimental groups [Plate 3 [Additional file 3]],[Plate 4 [Additional file 4]] and [Plate 5 [Additional file 5]].

  Discussion Top

The results of the study as seen in the experimental groups were both dose- and time-dependent. Factoring in normal body adaptations, it was imperative to increase the dosage with time. An oligodendrocyte can be described as a type of glial cell that generates and maintains the formation of myelin around the axons of large neurons in the central nervous system (CNS), allowing for rapid transmission of neural signals. [15] The presence of oligodendrogliosis indicated a proliferation of oligodendrocytes, which suggested damage of or injury to the CNS; this was in agreement with previous findings. [5] It is noteworthy that several different patterns of oligodendrocyte injury/reaction may occur depending on the mechanism of insult, though some oligodendrocytes could be lost through necrosis or apoptosis, while others may survive and form part of the glial scar along with myelin debris. [16] Oligodendrocyte precursor cells could also be affected by CNS insult and therefore be recruited to demyelinated areas within 1 week following traumatic injury. This may further suggest that the degeneration of axons due to trauma (such as the effect of C. sativa on the CNS) could result in the degeneration of the myelin sheath.

Moreover, cannabinoids have been known to act on specific neurotransmitters in certain memory regions of the brain, thereby causing memory loss. [17],[18] Glutamate, dopamine, and acetylcholine are three neurotransmitter systems that are thought to play a role in meditating the memory effects of cannabis. Consequently, C. sativa acts by reducing the glutamate levels by possibly using presynaptic mechanisms, activating dopamine receptor (D1) in the prefrontal cortex, and selectively modulating the activation of the cholinergic neurons in the septal-hippocampal pathway. [19] C. sativa resulted in severe brain injury in the index study, especially in the cerebral region, resulting in gliosis, which is known to involve alterations in cellular activity, potentially creating widespread effects on neurons as well as other nonneural cells and resulting in impairment of several functions. [20],[21]

  Conclusion Top

This study has clearly demonstrated that acute and chronic exposure of experimental rats to orally administered Cannabis sativa may result in marked neuronal damage.


More studies should be conducted to identify the molecular target of gliosis, knowing which could improve healing in all types of injury.

  References Top

Ashton CH. Adverse effects of Cannabis sativa and cannabinoids. Br J Anaesth 1999;83:637-49.   Back to cited text no. 1
Karen S, Thomas V. The medical effects of marijuana on the brain. Winter 1998;59-69.   Back to cited text no. 2
Kumar RN, Chambers WA, Pertwee RG. Pharmacological actions and therapeutic uses of Cannabis sativa and cannabinoids. Anaesthesia 2001;56:1059-68.  Back to cited text no. 3
Pertwee RG. Pharmacology of cannabinoid CB1 and CB2 receptors. Pharmacol Ther 1997;74:129-80.   Back to cited text no. 4
Yücel M, Solowij N, Respondek C, Whittle S, Fornito A, Pantelis C, et al. Regional brain abnormalities associated with long-term heavy cannabis use. Arch Gen Psychiatry 2008;65:694-701.  Back to cited text no. 5
Chan GC, Hinds TR, Impey S, Storm DR. Hippocampal neurotoxicity of Delta9-tetrahydrocannabinol. J Neurosci 1998;18:5322-32.   Back to cited text no. 6
Landfield PW, Cadwallader LB, Vinsant S. Quantitative changes in hippocampal structure following long-term exposure to delta 9-tetrahydrocannabinol: Possible mediation by glucocorticoid systems. Brain Res 1988;443:47-62.  Back to cited text no. 7
Lawston J, Borella A, Robinson JK, Whitaker-Azmitia PM. Changes in hippocampal morphology following chronic treatment with the synthetic cannabinoid WIN 55,212-2. Brain Res 2000;877:407-10.  Back to cited text no. 8
Scallet AC, Uemura E, Andrews A, Ali SF, McMillan DE, Paule MG, et al. Morphometric studies of the rat hippocampus following chronic delta-9-tetrahydrocannabinol (THC). Brain Res 1987;436:193-8.   Back to cited text no. 9
Phan KL, Angstadt M, Golden J, Onyewuenyi I, Popovska A, de Wi H. Cannabinoid modulation of amygdala reactivity to social signals of threat in humans. J Neurosci 2008;28:2313-9.  Back to cited text no. 10
Mukhtar AH, Elbagir NM. Effect of Cannabis sativa on hematological indices in rats and men. Pak J Nutr 2011;10:313-6.   Back to cited text no. 11
Flecknell P. Small mammals. Ch. 16 In: Anderson RS, Edney ATB, editors. Practical Animal Handling. Pergamon: Oxford; 1991. p. 177-87.  Back to cited text no. 12
Soxhlet F. Die gewichtsanalytische Bestimmung des Milchfettes. Dingler′s Polytech J 1879;232:461-5.   Back to cited text no. 13
Carleton HM. Carlton′s Histological Techniques. Toronto, New York: Oxford University Press; 1967. p. 144-9.  Back to cited text no. 14
Rivera-Zengotita M, Yachnis AT. Gliosis versus glioma: Don′t grade until you know. Adv Anat Pathol 2012;19:239-49.  Back to cited text no. 15
Fawce JW, Asher RA. The glial scar and central nervous system repair. Brain Res Bull 1999;49:377-91.   Back to cited text no. 16
Ranganathan M, D′Souza DC. The acute effects of Cannabiniods on memory in humans: A review. Psychopharmacology (Berl) 2006;188:425-44.   Back to cited text no. 17
Iversen L. Cannabis and the brain. Brain 2003;126:1252-70.   Back to cited text no. 18
Misner DL, Sullivan JM. Mechanism of Cannabinoid effects on long-term potentiation and depression in hippocampal CA1 neurons. J Neurosci 1999;19:6795-805.   Back to cited text no. 19
Sofroniew MV, Vinters HV. Astrocytes: Biology and pathology. Acta Neuropathol 2010;119:7-35.   Back to cited text no. 20
Hamby ME, Sofroniew MV. Reactive astrocytes as therapeutic targets for CNS disorders. Neurotherapeutics 2010;7:494-506.  Back to cited text no. 21


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