Impact of Morphine on Central Nervous System (CNS)

Increased usage of opioids is a potential threat worldwide which often leads to an opioid overdose crisis. The reinforcing impact of opioid makes the people vulnerable to illicit use^1,2. In 2018, according to the Centers for Disease Control and Prevention (CDC), 128 people died in the United States after overdosing on opioids³.

Opioid such as morphine helps to alleviate moderate or severe pain before or after the surgery, if prescribed properly⁴. It is reported that morphine derives from the poppy plant, scientifically known as Papaver somniferum⁵ and this opioid acts by attaching with opioid receptors (specific protein) which is present in the brain, spinal cord and gastrointestinal tract in order to help the person to relieve the pain⁶.

Astrocytes are star-shaped glial cells that are present in the brain as well as the spinal cord. These cells are in charge of homeostasis of the Central Nervous System.

The traditional perception of opioid actions are that they are neurally-mediated, however, the current research has exhibited a significant modulatory role in the areas of tolerance, analgesia and dependence⁷.

Accordingly, new research was carried out in order to determine the effect of morphine and conditioning place preference on number of Astrocytes in rat hippocampus by using immunohistochemical methods⁸.

For this purpose, the research team selected forty-eight male Wistar rats with an average weight of 220-250 g, afterward rats were categorized into 8 groups for behavioral tests. Experimental groups were subjected to morphine at different doses (2.5, 5, 7.5 mg kg^-1) by subcutaneous injection. On the other hand, sham groups were given saline dose (1 mL kg^-1)⁴.

At the end of this experiment, significant responses of morphine were noticed in 7.5 mg kg^-1. In a nutshell, morphine-based conditioned place preference showed a significant increase in the number of Astrocytes in experimental groups as compared to controls.

REFERENCES

1. Spanagel, R. and F. Weiss, 1999. The dopamine hypothesis of reward: Past and current status. Trends Neurosci., 22: 521-527.
2. Compton, W.M. and N.D. Volkow, 2006. Major increases in opioid analgesic abuse in the United States: Concerns and strategies. Drug Alcohol Depend., 81: 103-107.
3. CDC/NCHS., 2018. National vital statistics system, mortality. CDC WONDER, US Department of Health and Human Services, CDC., Atlanta, GA.
4. WHO., 1990. Cancer pain relief and palliative care. Report of the WHO Expert Committee. Technical Report Series, No. 804, World Health Organization, Geneva.
5. DEA., 2017. Drugs of abuse: A DEA resource guide. 2017 Edition. Morphine. Drug Enforcement Agency, USA.
6. MedlinePlus, 2018. Morphine. US National Library of Medicine, March 15, 2018.
7. Hutchinson, M.R., S.T. Bland, K.W. Johnson, K.C. Rice, S.F. Maier and L.R. Watkins, 2007. Opioid-induced glial activation: Mechanisms of activation and implications for opioid analgesia, dependence and reward. Scient. World J., 7: 98-111.
8. Shaabani, R., M. Jahanshahi, M. Nowrouzian, Y. Sadeghi and N.S. Azami, 2011. Effect of morphine based cpp on the hippocampal astrocytes of male wistar rats. Asian J. Cell Biol., 6: 89-96.