[lyka_candelario]

The above case was led by the team of Renyu Liu who is an assistant professor in the Department of Anesthesiology and Critical Care at Perelman School of Medicine, Pennsylvania. Together with him was Jeffery Saven, also an associate professor in a Department of Chemistry in the School of Arts and Sciences. Their study was published online in the journal PLOS ONE.

Opioid receptors are a set of G protein-coupled receptors which are bound by opioids. They are found in the brain, spinal cord, and even in the digestive tract.

There are actually four subtypes of these receptors:
1. Delta – found in the brain and peripheral sensory neurons. They have analgesic, antidepressant, and convulsant effects. The name of this receptor was coined after the tissue of a mouse vas deferens in which it was first characterized.
2. Kappa – found in the brain, spinal cord, and peripheral sensory neurons. They produce analgesic, anticonvulsant, dissociative, deliriant, sedative, and diuretic effects, among others. Ketocyclazocine is the first drug known to attach to them.
3. Mu – found in the brain, spinal cord, peripheral sensory neurons, and intestinal tract. They produce effects from its three classifications. These are analgesia and physical dependence; miosis, reduced GI motility, respiratory depression, euphoria, and physical dependence; and vasodilation. Morphine is the first chemical discovered to bind to these receptors.
4. Nociceptin – found in the brain and spinal cord. They generate depression and anxiety, among others. It is an opiate-like receptor and was cloned basing on the homology of cDNA.

Mu opioid receptors have a high affinity for beta-endorphin and enkephalins but do the opposite for dynorphins. They are also known as mu opioid peptide (MOP) receptors.

Since the above article discussed about opioid drugs, let us review the details about morphine. The common side effects of morphine are as follows:
Low blood pressure
Constipation
Drowsiness
Lightheadedness
Dizziness
Hyperhidrosis
Nausea
Vomiting

The less common side effects of morphine are the following:
Blurred vision
Diplopia
Dry mouth
Headache
Loss of appetite
Oliguria
Rashes
Respiratory problems

The rare side effects of morphine are:
Restlessness
Depression
Anemia
Delirium
Amnesia
Polydipsia
Seizures
Hallucination
Shock
Coma

Here is the link to the study: http://www.plosone.org/article/info%3Ado...ne.0066009