A non-invasive method for detecting the metabolic stress response in rodents: characterization and disruption of the circadian corticosterone rhythm.

Plasma corticosterone (CORT) measures are a common procedure to detect stress responses in rodents. However, the procedure is invasive and can influence CORT levels, making it less than ideal for monitoring CORT circadian rhythms. In the current paper, we examined the applicability of a non-invasive fecal CORT metabolite measure to assess the circadian rhythm. We compared fecal CORT metabolite levels to circulating CORT levels, and analyzed change in the fecal circadian rhythm following an acute stressor (i.e. blood sampling by tail veil catheter). Fecal and blood samples were collected from male adolescent rats and analyzed for CORT metabolites and circulating CORT respectively. Fecal samples were collected hourly for 24 h before and after blood draw. On average, peak fecal CORT metabolite values occurred 7-9 h after the plasma CORT peak and time-matched fecal CORT values were well correlated with plasma CORT. As a result of the rapid blood draw, fecal production and CORT levels were altered the next day. These results indicate fecal CORT metabolite measures can be used to assess conditions that disrupt the circadian CORT rhythm, and provide a method to measure long-term changes in CORT production. This can benefit research that requires long-term glucocorticoid assessment (e.g. stress mechanisms underlying health).

Understanding the Scientific Basis of Post-traumatic Stress Disorder (PTSD): Precision Behavioral Management Overrides Stigmatization.

Post-traumatic stress disorder (PTSD) is a severe polygenic disorder triggered by environmental factors. Many polymorphic genes, particularly the genetic determinants of hypodopaminergia (low dopamine function), associate with a predisposition to PTSD as well as substance use disorder. Support from the National Institutes of Health for neuroimaging research and molecular, genetic applied technologies has improved understanding of brain reward circuitry functions that have inspired the development of new innovative approaches to their early diagnosis and treatment of some PTSD symptomatology and addiction. This review presents psychosocial and genetic evidence that vulnerability or resilience to PTSD can theoretically be impacted by dopamine regulation. From a neuroscience perspective, dopamine is widely accepted as a major neurotransmitter. Questions about how to modulate dopamine clinically in order to treat and prevent PTSD and other types of reward deficiency disorders remain. Identification of genetic variations associated with the relevant genotype-phenotype relationships can be characterized using the Genetic Addiction Risk Score (GARS®) and psychosocial tools. Development of an advanced genetic panel is under study and will be based on a new array of genes linked to PTSD. However, for now, the recommendation is that enlistees for military duty be given the opportunity to voluntarily pre-test for risk of PTSD with GARS, before exposure to environmental triggers or upon return from deployment as part of PTSD management. Dopamine homeostasis may be achieved via customization of neuronutrient supplementation "Precision Behavioral Management" (PBM™) based on GARS test values and other pro-dopamine regulation interventions like exercise, mindfulness, biosensor tracking, and meditation.

Differences in response to food stimuli in a rat model of obesity: in-vivo assessment of brain glucose metabolism.

OBJECTIVE: Food intake is regulated by factors that modulate caloric requirements as well as food's reinforcing properties. In this study, we measured brain glucose utilization to an olfactory stimulus (bacon scent), and we examined the role of food restriction and genetic predisposition to obesity on such brain metabolic activity. METHODS: Zucker obese (Ob) and lean (Le) rats were divided into four groups: (1) Ob ad-libitum fed, (2) Ob food restricted (70% of ad libitum), (3) Le ad-libitum fed and (4) Le food restricted. Rats were scanned using micro-positron emission tomography and 2-[(18)F]-fluoro-2-deoxy-D-glucose under two conditions: (1) baseline scan (no stimulation) and (2) challenge scan (food stimulation, FS). RESULTS: FS resulted in deactivation of the right and left hippocampus. Ob rats showed greater changes with FS than Le rats (deactivation of hippocampus and activation of the medial thalamus) and Ob but not Le animals deactivated the frontal cortex and activated the superior colliculus. Access to food resulted in an opposite pattern of metabolic changes to the food stimuli in olfactory nucleus (deactivated in unrestricted and activated in restricted) and in right insular/parietal cortex (activated in unrestricted and deactivated in restricted). In addition, restricted but not unrestricted animals activated the medial thalamus. CONCLUSIONS: The greater changes in the Ob rats suggest that leptin modulates the regional brain responses to a familiar food stimulus. Similarly, the differences in the pattern of responses with food restriction suggest that FS is influenced by access to food conditions. The main changes with FS occurred in the hippocampus, a region involved in memory, the insular cortex, a region involved with interoception (perception of internal sensations), the medial thalamus (region involved in alertness) and in regions involved with sensory perception (olfactory bulb, olfactory nucleus, occipital cortex, superior colliculus and parietal cortex), which corroborates their relevance in the perception of food.

Insurance Companies Fighting the Peer Review Empire without any Validity: the Case for Addiction and Pain Modalities in the face of an American Drug Epidemic.

The United States are amid an opioid overdose epidemic; we are challenged to provide non-addicting/non-pharmacological alternatives to assist in pain attenuation. There are proven strategies available to manage chronic pain effectively without opioids. Utilization review providers for insurance companies often ignore medicine based scientific peer-reviewed studies that warn against the chronic use of opioid medications, as well as the lack of evidence to support long-term use of opioids for pain. This paradigm must change if we are to indeed change the drug-embracing culture in American chronic pain management. A barrier to treatment is pushback on the part of insurance companies especially as it relates to fighting against pain relief alternatives compared to classical analgesic agents. Pain specialists in the U.S., are compelled to find alternative solutions to help pain victims without promoting unwanted tolerance to analgesics and subsequent biological induction of the "addictive brain." It is noteworthy that reward center of the brain plays a crucial role in the modulation of nociception, and that adaptations in dopaminergic circuitry may affect several sensory and affective components of chronic pain syndromes. Possibly knowing a patient's genetic addiction risk score (GARS™) could eliminate guessing as it relates to becoming addicted.

Caffeine increases striatal dopamine D2/D3 receptor availability in the human brain.

Caffeine, the most widely consumed psychoactive substance in the world, is used to promote wakefulness and enhance alertness. Like other wake-promoting drugs (stimulants and modafinil), caffeine enhances dopamine (DA) signaling in the brain, which it does predominantly by antagonizing adenosine A2A receptors (A2AR). However, it is unclear if caffeine, at the doses consumed by humans, increases DA release or whether it modulates the functions of postsynaptic DA receptors through its interaction with adenosine receptors, which modulate them. We used positron emission tomography and [(11)C]raclopride (DA D2/D3 receptor radioligand sensitive to endogenous DA) to assess if caffeine increased DA release in striatum in 20 healthy controls. Caffeine (300 mg p.o.) significantly increased the availability of D2/D3 receptors in putamen and ventral striatum, but not in caudate, when compared with placebo. In addition, caffeine-induced increases in D2/D3 receptor availability in the ventral striatum were associated with caffeine-induced increases in alertness. Our findings indicate that in the human brain, caffeine, at doses typically consumed, increases the availability of DA D2/D3 receptors, which indicates that caffeine does not increase DA in the striatum for this would have decreased D2/D3 receptor availability. Instead, we interpret our findings to reflect an increase in D2/D3 receptor levels in striatum with caffeine (or changes in affinity). The association between increases in D2/D3 receptor availability in ventral striatum and alertness suggests that caffeine might enhance arousal, in part, by upregulating D2/D3 receptors.

N-methyl-D-aspartate unilaterally injected into the dorsal striatum of rats produces contralateral circling: antagonism by 2-amino-7-phosphonoheptanoic acid and cis-flupenthixol.

To evaluate the possible contribution of dorsal striatal glutamate receptors to motor behavior, circling responses were observed in rats following unilateral intrastriatal microinjections of the agonist, N-methyl-D-aspartate (NMDA) or the antagonist, 2-amino-7-phosphonoheptanoic acid (APH). The role of dopamine (DA) in NMDA-produced circling also was evaluated. In experiment 1, an NMDA dose of 5.0 micrograms (in 0.5 microliter), but not 0.5 or 0.05 microgram produced significant contraversive circling. In experiment 2, an APH dose of 10.0 micrograms but not 1.0 or 0.1 microgram produced significant ipsiversive circling. In experiment 3, microinjection of the ineffective 0.1 microgram dose of APH or a dose (20 micrograms) of the DA antagonist, cis-flupenthixol, that did not produce circling when administered alone, significantly reduced the circling response produced by the 5.0 micrograms dose of NMDA. As NMDA produced circling in the same direction as that seen following similar unilateral injections of locomotion-stimulating DA agonists, the present results suggest that glutamate, acting via NMDA receptors in the dorsal striatum, may exert an excitatory influence on motor systems. The observation that a DA receptor blocker antagonized the NMDA response further suggests that the observed motor excitatory effect of glutamate at NMDA receptors requires concurrent stimulation of DA receptors in the same region of the striatum.

Cocaine abusers show a blunted response to alcohol intoxication in limbic brain regions.

UNLABELLED: Cocaine and alcohol are frequently used simultaneously and this combination is associated with enhanced toxicity. We recently showed that active cocaine abusers have a markedly enhanced sensitivity to benzodiazepines. Because both benzodiazepines and alcohol facilitate GABAergic neurotransmission we questioned whether cocaine abusers would also have an enhanced sensitivity to alcohol that could contribute to the toxicity. In this study we compared the effects of alcohol (0.75 g/kg) on regional brain glucose metabolism between cocaine abusers (n = 9) and controls (n = 10) using PET and FDG. Alcohol significantly decreased whole brain metabolism and this effect was greater in controls (26+/-6%) than in abusers (17+/-10%) even though they had equivalent levels of alcohol in plasma. Analysis of the regional measures showed that cocaine abusers had a blunted response to alcohol in limbic regions, cingulate gyrus, medial frontal and orbitofrontal cortices. CONCLUSIONS: The blunted response to alcohol in cocaine abusers contrasts with their enhanced sensitivity to benzodiazepines suggesting that targets other than GABA-benzodiazepine receptors are involved in the blunted sensitivity to alcohol and that the toxicity from combined cocaine-alcohol use is not due to an enhanced sensitivity to alcohol in cocaine abusers. The blunted response to alcohol in limbic regions and in cortical regions connected to limbic areas could result from a decreased sensitivity of reward circuits in cocaine abusers.

Short-term odor memory: effects of posterior transection of the lateral olfactory tract in the rat.

Rats were trained on a series of novel 2-odor discrimination problems before and after combined unilateral bulbectomy and posterior transection of the contralateral lateral olfactory tract. In postoperative tests, experimental rats performed as well as controls when a short intertrial interval (30 seconds) was used but, in contrast to controls, failed to learn a 2-odor discrimination when the intertrial interval was 10 minutes. When tested on a reversal task, controls showed memory for original learning by making many errors while experimental rats quickly acquired the task. The results suggest that lateral olfactory tract afferents to posterior olfactory cortex may play a significant role in short-term memory for odors.

Chronic co-administration of nicotine and methamphetamine causes differential expression of immediate early genes in the dorsal striatum and nucleus accumbens of rats.

Nicotine and methamphetamine (METH) cause addiction by triggering neuroplastic changes in brain reward pathways though they each engage distinct molecular targets (nicotine receptors and dopamine transporters respectively). Addiction to both drugs is very prevalent, with the vast majority of METH users also being smokers of cigarettes. This co-morbid occurrence thus raised questions about potential synergistic rewarding effects of the drugs. However, few studies have investigated the chronic neurobiological changes associated with co-morbid nicotine and METH addiction. Here we investigated the effects of these two drugs alone and in combination on the expression of several immediate early genes (IEGs) that are sensitive to drug exposures. Chronic exposure to either nicotine or METH caused significant decreases in the expression of fosb, fra1, and fra2 in the nucleus accumbens (NAc) but not in the dorsal striatum whereas the drug combination increased fra2 expression in both structures. Except for junB mRNA levels that were decreased by the three drug treatments in the NAc, there were no significant changes in the Jun family members. Of the Egr family members, NAc egr2 expression was decreased after nicotine and the drug combination whereas NAc egr3 was decreased after METH and the drug combination. The drug combination also increased striatal egr3 expression. The Nr4a family member, nr4a2/nurr1, showed increased striatal expression after all three drug treatments, while striatal nr4a3/nor-1 expression was increased by the drug combination whereas NAc nr4a1/nurr77 was decreased by nicotine and the drug combination. These observations suggest that, when given in combination, the two drugs exert distinct effects on the expression of IEGs in dopaminergic projection areas from those elicited by each drug alone. The significance of these changes in IEG expression and in other molecular markers in fostering co-morbid METH and nicotine abuse needs to be further evaluated.

Conditioned place preference and locomotor activity in response to methylphenidate, amphetamine and cocaine in mice lacking dopamine D4 receptors.

Methylphenidate (MP) and amphetamine (AMPH) are the most frequently prescribed medications for the treatment of attention-deficit/hyperactivity disorder (ADHD). Both drugs are believed to derive their therapeutic benefit by virtue of their dopamine (DA)-enhancing effects, yet an explanation for the observation that some patients with ADHD respond well to one medication but not to the other remains elusive. The dopaminergic effects of MP and AMPH are also thought to underlie their reinforcing properties and ultimately their abuse. Polymorphisms in the human gene that codes for the DA D4 receptor (D4R) have been repeatedly associated with ADHD and may correlate with the therapeutic as well as the reinforcing effects of responses to these psychostimulant medications. Conditioned place preference (CPP) for MP, AMPH and cocaine were evaluated in wild-type (WT) mice and their genetically engineered littermates, congenic on the C57Bl/6J background, that completely lack D4Rs (knockout or KO). In addition, the locomotor activity in these mice during the conditioning phase of CPP was tested in the CPP chambers. D4 receptor KO and WT mice showed CPP and increased locomotor activity in response to each of the three psychostimulants tested. D4R differentially modulates the CPP responses to MP, AMPH and cocaine. While the D4R genotype affected CPP responses to MP (high dose only) and AMPH (low dose only) it had no effects on cocaine. Inasmuch as CPP is considered an indicator of sensitivity to reinforcing responses to drugs these data suggest a significant but limited role of D4Rs in modulating conditioning responses to MP and AMPH. In the locomotor test, D4 receptor KO mice displayed attenuated increases in AMPH-induced locomotor activity whereas responses to cocaine and MP did not differ. These results suggest distinct mechanisms for D4 receptor modulation of the reinforcing (perhaps via attenuating dopaminergic signalling) and locomotor properties of these stimulant drugs. Thus, individuals with D4 receptor polymorphisms might show enhanced reinforcing responses to MP and AMPH and attenuated locomotor response to AMPH.

Motor endplate analysis of the denervated and reinnervated orbicularis oculi muscle in the rat.

The present study examined the histochemical characteristics of the orbicularis oculi muscle (OOM) in the rat, in order to better understand the target muscle of the blink reflex-specifically, the motor endplate distribution and number in the normal, denervated, and reinnervated OOM. Assessment of the number of endplates needed to accomplish eye closure would provide critical information in the microsurgical restoration of the blink reflex in facial paralysis. Results demonstrated a 50% increase in the number of endplates of reinnervated rats, compared to denervated animals.

A histomorphometric analysis of the cross-facial nerve graft in the treatment of facial paralysis.

One of the most unsettling sequela of facial paralysis (FP) is the loss of the blink reflex, leading to both a functional and aesthetic deformity. A successful method of treating FP and, in particular, loss of eye-sphincter function, is the use of the cross-facial nerve graft (CFNG) to reinnervate the previously denervated orbicularis oculi muscle. The present study examined the histomorphometric aspects of the entire CFNG, with respect to axon diameter and myelin area. The axon profile of the CFNG had a positive correlation with motor end-plate counts and electrophysiologic recordings. These results should help in further understanding the number of motor axons needed to restore adequate function to the paralyzed eye sphincter, and establish more rational reconstructive procedures.

Ultrastructure and cellular biology of nerve regeneration.

Hippocrates provided the first written description of the peripheral nervous system (PNS), as early as the 4th century B.C., and later Herophilus identified nerves as such, distinguished them from tendons; he also traced nerves to the spinal cord. The traditional Hippocratic teaching of the time, however, doubted that nerve healing occurred. Through the subsequent centuries, several papers were written about the PNS but, without sufficient understanding of anatomy, physiology, and the regenerative capacity of the PNS, it is not difficult to comprehend the frustration that might have been encountered by surgeons in dealing with nerve injuries and their subsequent repair. This was probably the reason why nerve repair was rarely actually undertaken prior to the 19th century. A plethora of studies on the PNS and its regeneration has been reported over the last 150 years and has provided us with current knowledge. It is important, before describing the most recent developments in the area of peripheral nerve regeneration, to briefly outline the major advances over the last century. Currently, the therapeutic approaches taken toward the patient with peripheral nerve injury change continuously. Sophisticated advances in technology, cellular and molecular neurobiology, and electron microscopy will doubtless optimize reconstructive strategies in treating nerve injury. A greater awareness and understanding of the nerve ultrastructure, as well as the underlying mechanisms of the regenerative process and those factors detrimental to nerve regeneration, will assist in the successful repair of nerve injury. This paper reviews the cellular, biochemical, and ultrastructural elements of nerve injury and repair, and the rationale for current reconstructive strategies and techniques.

Enhanced reinnervation of the paralyzed orbicularis oculi muscle after insulin-like growth factor-I (IGF-I) delivery to a nerve graft.

Facial paralysis (FP) remains today one of the most disturbing cranial nerve disorders. The present study utilized the rat model of FP and examined a dual approach of combining the current microsurgical treatment of cross-facial nerve graft (CFNG) with local administration of insulin-like growth factor-I (IGF-I). The efficacy of this combined treatment approach was assessed by motor end-plate analysis of the reinnervated orbicularis oculi muscle (OOM). Local administration of IGF-I (50 microg/ml) to the CFNG demonstrated a 61 percent increase in the number of end-plates in the reinnervated OOMs, compared to the OOMs reinnervated with CFNG plus vehicle. These results indicate that the local therapeutic augmentation of IGF-I levels at the coaptation site(s) of the CFNG may, in fact, enhance reinnervation of muscle and recovery of function in general.

Overexpression of dopamine D2 receptors reduces alcohol self-administration.

The mechanism(s) underlying predisposition to alcohol abuse are poorly understood but may involve brain dopamine system(s). Here we used an adenoviral vector to deliver the dopamine D2 receptor (DRD2) gene into the nucleus accumbens of rats, previously trained to self-administer alcohol, and to assess if DRD2 levels regulated alcohol preference and intake. We show that increases in DRD2 (52%) were associated with marked reductions in alcohol preference (43%), and alcohol intake (64%) of ethanol preferring rats, which recovered as the DRD2, returned to baseline levels. In addition, this DRD2 overexpression similarly produced significant reductions in ethanol non-preferring rats, in both alcohol preference (16%) and alcohol intake (75%). This is the first evidence that overexpression of DRD2 reduces alcohol intake and suggests that high levels of DRD2 may be protective against alcohol abuse.

Regional brain metabolism during alcohol intoxication.

BACKGROUND: Ethanol has a broad range of actions on many neurotransmitter systems. The depressant actions of ethanol in the brain are related in part to facilitation of gamma-aminobutyric acid (GABA) neurotransmission via its interaction with the benzodiazepine/GABA receptor complex. The purpose of this study was to evaluate the effects of ethanol on regional brain metabolism in 10 healthy right-handed men. The results were compared with those we previously published in a different group of 16 normal male subjects who received intravenous lorazepam, a benzodiazepine drug that also enhances GABA neurotransmission. METHODS: The subjects were scanned with positron emission tomography and [F-18] fluorodeoxyglucose twice: 40 min after the end of placebo (diet soda) or ethanol (0.75 g/kg) oral administration. Image data sets were analyzed by using both the region of interest and the statistical parametric mapping (SPM) approach. SPM was used to generate a difference image between baseline and ethanol, which we compared to the difference image between baseline and lorazepam (30 microg/kg). RESULTS: Ethanol significantly increased self-reports of "high" (p < or = 0.0001), dizziness (p < or = 0.004), and intoxication (p < or = 0.0001). Ethanol significantly decreased whole brain (-25 +/- 6%, p < or = 0.0001) and regional metabolism. Normalization of the regional measures by whole brain metabolism (relative measures) showed that ethanol decreased relative metabolic activity in occipital cortex (-4.9 +/- 4.1%, p < or = 0.006), whereas it increased relative metabolic act in left temporal cortex (+3.5 +/- 2.9%, p < or = 0.006) and left basal ganglia (+9 +/- 6.3%, p < or = 0.0009). SPM analyses revealed the same pattern of responses as the relative measures, showing decreases in occipital cortex and increases in left temporal cortex. Comparison of the relative measures and the SPM analyses obtained with lorazepam data revealed a similar pattern of effects, with relative decreases in occipital cortex (-7.8 +/- 4.8%) and relative increases in left temporal cortex (+3.8 +/- 5.7%). Lorazepam, but not ethanol, also decreased thalamic metabolism (-11.2 +/- 7.2%). CONCLUSIONS: These results support similar though not identical mechanisms for the effects of alcohol and benzodiazepines on brain glucose metabolism. The fact that lorazepam, but not alcohol, reduced thalamic metabolism, an effect associated with sleepiness, could explain the higher sedative effects of lorazepam than of alcohol.