opiates are an extremely powerful anti-depressant, yes. That is also why the government is scared of them. Some degree of anxiety and even fear make workers more productive, students more studious and achieving higher grades, etc. The idea of everybody essentially lounging around and feeling good all the time takes away goals and natural drives; it is in a sense, completely against nature. If it were in our best interests (ie. Help us survive) to have massive amounts of opiates flooding our brains at all times, that would be selected for extremely quickly. Our reward circuitry in our brains is very complex, the product of millions upon millions of years of natural selection, and plays a critical role determining who we are and why we do the things we do.
As you know, small amounts of natural opiates are constantly being released into the brain. They are what make you feel good after intense exercise, because exercise aids the body by keeping you healthy and free of disease in general. This healthy state strongly outcompetes any organism that does not maintain their physical body, and so the former will always be selected for. Fattening and sugary foods are extremely rich in calories - foods that have only become available to us easily in the last couple hundred years. For the rest of our 7 million year evolutionary journey from our ape ancestors, food had to be hunted, fruits gathered, all among mortal peril and a necessity to do so for survival. Fat tastes good because it benefits whoever eats it by large caloric (energy) increases. Those who manage to eat these foods will then be far more likely to survive during the next famine.
Sex - pretty self explanatory. Obviously, sex feels good for a reason. It is the single most important biological drive we have (from the viewpoint of our dna anyway) as it is the only mechanism to keep our species alive. The process of maturing our sex cells and finding a mate is so incredibly important, it dwarfs all other worldy pleasures such as eating, urinating and sleeping. Nature needs us to procreate as much as we possibly can. Once again, most of our evolutionary history consisted of humans afflicted with dreadful and fatal diseases: Cholera. Typhus. Polio. Smallpox. Fever. Bacterisl infections and their toxins. I could go on forever. Did you know that viruses are by far the most abundant "living" organisms in the ocean, and also on land? My point is that there has always been enormous selection pressure to have as many children as possible. Very recently, most births were either stillborn or else babies had a much lower chance of surviving. To compensate, we needed to make as many humans as possible; for that, we needed a very strong reward. Enter - sex. There's no need to describe the mechanics that we all know and love in great detail. Suffice to dsay that any sexual encounter (including solo) positively floods our brains with endorphins, dopamine and many other feel-good chemicals - all so we do it more. What i have always found fascinating is that mother nature has also built in a generally fail-safe mechanism to avoid us humans do nothing but have sex all the time. Prolactin is the cause of refractory periods in both sexes. It and other neurotransmitters are extremely complex in their normal functions, and they are what produce the feeling we interpret to be satiety.
Endorphins then are critical to all of us and our well-being. They are what make us enjoy life - and indeed, our desire to live at all. Without them...well, any opiate addict can tell you exactly how they feel while in withdrawal and their endorphins are lower than usual (that's right; never outright gone, just reduced. So imagine what it must be like to have absolutely zero intrinsic opioid activity. There is no reason to live.)
depression is a much more complex phenomenon than most people realize. Pharmaceutical companies and the media have done a very good job in convincing the general public that depression is caused by a simple lack of serotonin, and that it is a disorder requiring immediate treatment with a pill that increases serotonin. While partly true, this is soooo far from reality that it is actually laughable. There are likely many hundreds if not thousands of different neurotransmitters in our systems, many which carry out extremely specific tasks. The vast machinery and biological network of our neurons can never be summed up so cleanly as to be able to declare that any one disease is caused by any one factor - and by extension, that any one drug can eliminate or reduce this said affliction. The reality is, nearly all antidepressants on the market show weak efficacy compared to placebo - at best. Yes, there certainly are individuals who do have severe depression that has primarily been caused by serotonin dysregulation. In this case, an ssri can be a lifesaver. However, most people can never alter their internal biochemistry to such a degree simply by changing the dynamics of one single chemical.
However, this is where opiates come in to play. There are opiate receptors all throughout the brain and spinal cord in the central nervous system. There are also a great deal of them in the digestive tract (which do not contribute to the high or depression in any way, but simply alter longitudinal muscle contractions of the gut to slow movement). But in the brain, there is a very small but very powerful locus located deep into the brain and quite close to the brainstem. This is the master of the limbic system, or the pleasure pathway if you will. Although just about the size of a small nut, activation of this tiny locus creates intense pleasure. Normally it is stimulated indirectly by endogenous neurotransmitters. This may be in response to a very pleasant surprise, your favorite song coming up on the radio, naturally sexual situations, and so on. It was discovered accidentally several decades ago when scientists hooked up electrodes to a rat's brain in different areas. A mild electric current would be administered when the rat pressed a tiny lever, and this would artificially activate the part of the brain to which the electrodes were connected. To their surprise, they found that when connected to the tiny locus described above, the rat displayed unmistakeable signs of extreme pleasure. Another lever in the same cage would provide the rat with food if it pressed that lever. Yet not only did the rat not press the lever providing food (and thus ensuring its survival), it chose every time to activate its brain via the electrode lever - several thousand times in a span of an hour or less. With this connection available, rats will always choose to push this lever over obtaining food until they eventually starve to death.
Years later after much research had been conducted, this phenomenon was finally explained; the scientists had indeed activated the most important and "acute" pleasure center of the brain, which among other functions, is responsible for regulating reward and desire. It is critical for the process of reinforcement and learning to take place. It is now known as the xxx and perhaps not surprisingly, it contains mu-opioid receptors in vast concentrations found nowhere else in the body. There is also what amounts to an extension of the brain ( ie the spinal cord) which of course is made up of neurons and myelin like the brain (but in the opposite layers). One small part of this area formed by many millions of neurons is called the substantia gelatinosa - so named because it lacks connective tissue and myelin, and so resembles and feels like soft, fragile gelatin. This is where opioid receptors are found to be in the greatest numbers,and agaun unsurprisignly, this pathwat regulates pain, pleasure, bonding and love among others and in association with other brain structures such as the amygdala.
Evolution has primed not only us humans, but most other animals as far as we can tell, to utilize endorphins for many purposes. It is thought that it was only relatively recently (in evolutionary terms) that it had begun to be used to facilitate bonding between parents and children, siblings, lovers and other kin. However, as a natural painkiller and integral component of the pleasure center of the brain for many eons, endorphins, other natural opiods produced in the body, and as a result, the great number of chemicals found naturally or made synthetically which are similar enough to these natural neurotransmitters to result in very similar to identical effects, have been consumed by humans since the dawn of their creation. Many scientists now believe that humans and poppies actual evolved in tandem in a form of co-evolution. Morphine and other alkaloids from p somniferum (the opium poppy) were very likely first produced by the poppy plant as a chemical way to deter predators from eating it. It is thought that the morphine, codeine and other natural alkaloids being so similar to our endorphins and thereby causing pleasure - is no accident. It may be a mutualistic relationship. Latex is harvested from freshly-grown pods and converted into most of the narcotic drugs we know of today. Morphine and codeine are found naturally in opium. Oxycodone, hydromorphone, oxymorphone, dihydrocodeine, heroin and many others are termed semi-synthetic opioids; that is, they are not found naturally in opium (or else in exceedingly tiny amounts) but can be synthesized by using molecules that are produced - particularly thebaine.
Such a close and personal history of these plants, our own history of evolution and the necessities we must bear, and many other factors have resulted in both natural and artificial chemicals that bind to the pleasure centers of our brains being an extremely potent antidepressant for humans. Rather than being synthesized or discovered by accident, they cause many profoundly significant and pleasant effects in the human brain that they themselves - along with certain downstream regulators and chemical cascades - are very potent at relieving depression. With tthe right dosage and treated as medicine, they can do wonders helping people escape such horrible lifestyles and make them feel good again. Often, people who have lost their purpose (or never had one) or have not experienced enough of the pleasures of the natural world, get their fix when under the influence of these amazing substances. They may suddenly - or over time - feel things they have never felt before; tragically not realizing that this lack of well-being is in fact not the norm for humans. This can open up a new world with new opportunities and a fresh outlook on life. Because of all these factors, opioids in general often are the most effective anti-depressants on the planet.
Note: I felt that this post is aimed toward understanding and explaining parts of the disease of depression and why opiates do what they do and are often so effective while many other synthetic drugs such as ssri's are not. Needless to say, it is the very pleasant and efficacious nature of these natural miracles that can suddenly turn on you with a vengeance - leading a previously healthy person into the abyss of addiction; a living hell which may result in the utter destruction of happiness, friendship, family and even life itself. I didn't want to focus on that here, of course. However as a harm reduction website first and foremost, i did not want to come across as though i am praising opiates in a way that convinced others to begin using them. They are unquestionably double-edged swords, and addiction is all too likely. Not all people are able to use these drugs only once in awhile - prescribed or not. I wanted to thoroughly explain why they make good antidepressants as that was the point of this topic, but it must also be emphasized that there is a yang for every yin.
This is a yang that you don't want to ever become.
