Addiction and Evolutionary Process, Common Aspects in Physio-Pathologic Pathways Useful in Pharmaco-Toxicological Approach

Observing vertebrates evolutionary in mammalian are present characteristic pathways involved in progeny take care in first period after birth. In this behavior and instinct, learning neuronal circuits are evolved and reward mechanism the same. In addiction is possible to observe that definite neuronal circuits plays a crucial role. In this work are showed this similarity to better understand the addiction condition. Reward mechanism (primary, intrinsic or extrinsic) are involved in food, reproductive- sexual activity but also in other human condition. Conditioning, reinforce, reward, learning behavior, depression status, level of motivations is common concept involved also in addiction.


Introduction
Starting from the evolutionary of vertebrates is possible to verify that mammalians vs reptile in example show a great characteristic in cooperative behavior, maternal instinct, high mother depending of progeny and other relevant aspects. So is clear that this kind of vertebrates show a great depending relationship between mother-progeny and we can say that this kind of "animals Human imaging studies have shown a reduction of dopamine receptors accompanied by a lesser release of endogenous DA in the ventral striatum of cocaine, heroin, and alcohol-dependent subjects, thereby offering visual proof of the "dopamine-impoverished" addicted human brain. The lasting reduction in physiological activity of the DA system leads to the idea that an increment in its activity, to restore pre-drug levels, may yield significant clinical improvements (reduction of craving, relapse, and drug-seeking/ taking). In theory, it may be achieved pharmacologically and/or with novel interventions such as transcranial magnetic stimulation.
Its anatomo-physiological rationale as a possible therapeutic aid in alcoholics and other addicts will be described and proposed as a theoretical framework to be subjected to experimental testing in human addicts [2].

Andrew B Barron et al. [3]: Motile animals actively seek out
and gather resources they find rewarding, and this is an extremely powerful organizer and motivator of the animal behavior.
Mammalian research studies have revealed interconnected neurobiological systems for reward learning, reward assessment, reinforcement and reward-seeking; all involving the biogenic amine dopamine. The neuro-biology of reward-seeking behavioral systems is less well understood in the invertebrates, but in many diverse invertebrate groups, reward learning and responses to food rewards also involve dopamine. The obvious exceptions are the arthropods in which the chemically related biogenic amine octopamine has a greater effect on reward learning and reinforcement than dopamine. We review the functions of these biogenic amines in behavioral responses to rewards in different animal groups and discuss these findings in an evolutionary contex [3].
Tonse NK Raju [4]: "Sometimes, even the most obvious facts need to be reiterated. An infant suckling at his or her mother's breast is not simply receiving a meal, but is intensely engaged in a dynamic, bidirectional, biological dialogue. It is a process in which physical, biochemical, hormonal, and psychosocial exchange takes place, designed for the transfer of much needed nutrients, for building a lasting psychosocial bond between the mother and her infant. Among mammals, breastfeeding has evolved over millions of years as a multitiered interaction to meet the biological and psychosocial needs of the progeny, enhancing its well-being and survival chances, as well as complementing the nurturing role of the mother. this unique, dynamic process benefits both the mother and her infant. Breastfeeding needs to be considered quintessentially as a continuation of the more intense, intrauterine dialogue, mediated through the placenta and the umbilical cord between the mother and her fetus.
Whether feeding at the breast is complementary to the nutritional value of human milk, which might explain the diverse range of benefits to the mother and her infant, remains to be studied.
innovative methods from different scientific disciplines, such as behavioral, cognitive, and developmental neurosciences, and social anthropology may be useful to study this unexplored territory.
Among the many benefits from breastfeeding during the first year of an infant's life, the effects on long-term cognitive development and IQ have been most controversial. Some researcher contend that breastfeeding should be considered the social norm, and lower cognitive scores in infants fed formula should be considered abnormal. Sullivan asked, "Is it possible that some property in the infant formula may not be conducive to full cognitive development?" It is an interesting question that needs to be elucidated in future studies. Be that as it may, the above arguments require one to critically consider the cause-and-effect relationships between breast-feeding and cognitive outcomes. 2  It includes a strong desire to take the drug, difficulties in controlling its use, persisting in its use despite harmful consequences, a higher priority given to drug use than to other activities and obligations, increased tolerance and sometimes a physical withdrawal state (International Classification of Diseases (ICD).
Drug addiction has been conceptualized as a complex and chronic disease process occurring in the brain, which is modulated by genetic, developmental and environmental factors. The most consistent and reproducible finding in drug addiction is that abused substances activate the mesolimbic dopamine system, which reinforces both pharmacological and natural rewards. The   Evolutionarily speaking, children that receive care that is more erratic may focus more so on short-term risks that may have proved to be an adaptive quality for survival in ancient environments.
Compounding that attachment, the pharmacological mechanism describes the concept of biological adaptation of the mesolimbic dopamine system to endogenous substance intake. Problematic use of drugs develops into addiction as the brain becomes dependent on the chemical neural homeostatic circuitry altered by the drug. No matter the theory of drug addiction, there remains one constant: withdrawal is inevitable. As a drug is administered continuously and an individual becomes addicted, the brain becomes dependent on the presence of the drug. With an absence of the drug, withdrawal symptoms are experienced as the brain attempts to deal with the chemical changes. There are believed to be evolutionary origins of drug addiction, which will be discussed further, as well as a link between physiological addiction and the evolution of emotion [10]. in the Morris water maze at 22-24 days of age. Alcohol-exposed subjects who were weaned early were more impaired in spatial navigation ability than any other group. the combination of early weaning and prenatal alcohol exposure caused the slowest growth. All subjects exposed to alcohol, regardless of weaning condition, had greater latencies to find the platform than those from the two control groups. There was no synergistic effect of alcohol and stress on activity levels, but all early-weaned females were more active than normally weaned females; males did not show this effect. Thus, environmental stressors such as early weaning can compound detrimental symptoms of prenatal alcohol exposure.
These results have implications for the understanding of the effects of the environment on neuronal plasticity [11]. This change occurred around the time that our ancestors adopted a terrestrial lifestyle. Because fruit collected from the forest floor contains higher concentrations of fermenting yeast and alcohol than similar fruits hanging from trees, this transition may also be the first time our ancestors were exposed to and adapted to substantial amounts of alcohol. These discoveries favor the idea that from an evolutionary perspective, alcohol and drug-intake behavior has been shaped over millions of years and should be considered a part of our normal behavioral repertoire. These evolutionary roots of alcohol-and drug-taking behavior in mammals support the real face validity of animal models of drug self-administration [14].

Adam T Shipley et al. [15]:
The idea that addiction occurs when the brain is not able to differentiate whether specific to an organism, which is distinct from hedonia. The "wanting" mechanism may be modulated by dopamine systems via perceived attractiveness, rather than the traditional view of receiving pleasure, or "liking" a stimulus.
The distinction between "wanting" and "liking" is important as it appears that drug-mediated dopamine responses progress by "wanting" something more but "liking" it less; Drugs can be associated with certain contextual cues, such as a novel environment. In example, when an organism is conditioned to receive a psychoactive drug paired with a sensory cue, associated neural functions are activated in response to the environmental cue. In the absence of the drug itself, the effect goes so far to reactivate and sustain drug seeking behavior.   Oxytocin appears to be of crucial importance for understanding mother-infant relationships. The findings of this review suggest that the pioneering, but preliminary, research undertaken to date is promising and that replication with larger samples is needed.
Research that draws on more robust measures of attachment and bonding, as well as improved measures of oxytocin that include both central and peripheral levels, will elucidate the role of oxytocin in human mother-infant relationships. As the production of oxytocin is by no means restricted to mothers, the extension of the oxytocin studies to fathering, as well as to alloparental caregiving, would be an intriguing next step [19].

Conclusion
In many addiction behavior is possible to verify that the subject involved present family or social problems. And a lack of this link (between single individual and his "caregiver") can produce this kind of disorder whit un psychological unbalance. Is possible to contextualize this fact with the vertebrate " mammalian "evolutionary pattern?. Mammalians are vertebrates that make dependent behavior a crucial aspect of their evolution and this present similarity in the pathways of addiction. Is possible to verify that some same neuronal circuits and related neuro-trasmitters or hormone are involved in physiology of breast-feed or reward mechanism in mammalian and also in addiction physio pathology.
(dependency-addiction, reinforce, reward circuits compulsive behavior). But breast feed period of progeny is a limited time and determinate endogenous factors contribute in this Fact. (a sort of dependence is stopped): the weaning phases and related motor neuron maturation). This aspect must be adequately investigated to better understand also addiction pathology, drugs weaning mechanism and the pharmaco-toxicology implications. In some situation the border between physiology and pathology is very thin.

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