If the main action of uridine is mostly to increase dopamine neurotransmitters, then why wouldn't one just try MP as it contains dopamine as well. I still thought uridine was mostly considered for its effects on dopa receptors?
And for an ideal dopamine system, is it better to have more receptors and less neurotransmitters?
On uridine: the only two studies are the ones I listed, and they say opposite things (one says increased dopamine release, the other says decreased). The question is who will you choose to believe?
Well, just found a third study (1989, found via the book in my first post) is the only other I could find... so basically it's two studies against one. 66.7% chance you are right, it increases receptors, deceases transmitter.
Effects of chronic treatment with uridine on striatal dopamine release and dopamine related behaviours in the absence or the presence of chronic treatment with haloperidol.
Uridine (15mg/kg/day, i.p.), haloperidol (1mg/kg/day, i.p.), uridine (15mg/kg/day, i.p.) plus haloperidol (1mg/kg/day, i.p.) or saline have been chronically administered to Sprague-Dawley male rats. Following 1 week of wash-out, the effects of these treatments on basal striatal dopamine (DA) release as well as on the DA release induced by an acute haloperidol challenge (2mg/kg, i.p.) were studied by means of intracerebral microdialysis. Behavioural tests such as haloperidol-induced catalepsy or apomorphine-induced stereotypics were also performed 4-7 days after drug withdrawal. The chronic treatment with uridine alone or associated with haloperidol markedly reduced DA release induced by an acute haloperidol challenge. The behavioural studies also indicated a change in DA-related behaviours in these conditions. The animals chronically treated with uridine showed significant increases in the stereotypy scores and in the catalepsy induced by an acute haloperidol challenge with respect to saline treated rats. The present results indicate that a chronic uridine treatment is able to potentiate the reduction of the striatal DA transmission induced by acute and chronic haloperidol treatment. This finding suggests the possibility to reduce the neuroleptic dose in the treatment of schizophrenia by combining neuroleptic and uridine treatments, thus making it possible to relieve some of the side effects of neuroleptic therapy.
methylphenidate, i must assume? and forgive my impatience, but just send Flex a PM asking why it is bad, tell him I sent you and he can thank me later. ok nvm you can spare him the annoyance, although he would also be amused
long story short, it's nearly as bad as amphetamine
and not to be overly pedantic or a science Nazi, but it doesn't contain dopamine, it reduces dopamine uptake, thereby increasing synaptic levels.
Methylphenidate Administration to Adolescent Rats Determines Plastic Changes on Reward-Related Behavior and Striatal Gene Expression
Administration of methylphenidate (MPH, Ritalin®) to children with attention deficit hyperactivity disorder (ADHD) is an elective therapy, but raises concerns for public health, due to possible persistent neurobehavioral alterations. Wistar adolescent rats (30 to 46 day old) were administered MPH or saline (SAL) for 16 days, and tested for reward-related and motivational-choice behaviors. When tested in adulthood in a drug-free state, MPH-pretreated animals showed increased choice flexibility and economical efficiency, as well as a dissociation between dampened place conditioning and more marked locomotor sensitization induced by cocaine, compared to SAL-pretreated controls. The striatal complex, a core component of the natural reward system, was collected both at the end of the MPH treatment and in adulthood. Genome-wide expression profiling, followed by RT-PCR validation on independent samples, showed that three members of the postsynaptic-density family and five neurotransmitter receptors were upregulated in the adolescent striatum after subchronic MPH administration. Interestingly, only genes for the kainate 2 subunit of ionotropic glutamate receptor (Grik2, also known as KA2) and the 5-hydroxytryptamine (serotonin) receptor 7 (Htr7) (but not GABAA subunits and adrenergic receptor alpha1b) were still upregulated in adulthood. cAMP responsive element-binding protein and Homer 1a transcripts were modulated only as a long-term effect. In summary, our data indicate short-term changes in neural plasticity, suggested by modulation of expression of key genes, and functional changes in striatal circuits. These modifications might in turn trigger enduring changes responsible for the adult neurobehavioral profile, that is, altered processing of incentive values and a modified flexibility/habit balance.
Methylphenidate (Ritalin) induces Homer 1a and zif 268 expression in specific corticostriatal circuits.
Corticostriatal circuits participate in limbic, attentional, motor and other networks, and are implicated in psychostimulant addiction. The psychostimulant methylphenidate is used in the treatment of attention-deficit hyperactivity disorder and for recreational purposes. Recent studies indicate that methylphenidate alters gene expression in striatal neurons. We investigated whether methylphenidate affects gene regulation in specific corticostriatal circuits, by comparing drug-induced molecular changes in different functional domains of the striatum with changes in their cortical input regions. In order to assess the potential functional significance of methylphenidate-induced molecular changes, we examined members of two different classes of plasticity-related molecules, the transcription factor zif 268 and the synaptic plasticity factor Homer 1a. Acute methylphenidate administration in adult rats increased the expression of Homer 1a and zif 268 in both cortex and striatum in a dose-dependent and regionally selective manner. These changes in gene expression occurred after doses of 2 mg/kg (i.p.) and higher, and were highly correlated between cortical regions and their striatal targets. In the cortex, increases were maximal in the medial agranular (premotor) and cingulate cortex, followed by motor and somatosensory cortex, and were minimal in the insular cortex. Correspondingly, in the striatum, increases were most robust in sensorimotor sectors that receive medial agranular input, and were weaker or absent in ventral sectors. The methylphenidate-induced increases in cortical Homer 1a and zif 268 expression were also correlated with increases in striatal substance P and dynorphin expression (direct pathway). Overall, the regional distribution of methylphenidate-induced molecular changes in the striatum was similar to that of changes induced by psychostimulants such as cocaine. These findings demonstrate that methylphenidate affects transcription and synaptic plasticity regulatory proteins in specific corticostriatal circuits, including those implicated in attentional functions and psychostimulant addiction. Such methylphenidate-induced gene regulation may contribute to the therapeutic effects and/or abuse liability of this psychostimulant.
Prefrontal cortical and striatal transcriptional responses to the reinforcing effect of repeated methylphenidate treatment in the spontaneously hypertensive rat, animal model of attention-deficit/hyperactivity disorder (ADHD)
Background
Methylphenidate is the most commonly used stimulant drug for the treatment of attention-deficit/hyperactivity disorder (ADHD). Research has found that methylphenidate is a “reinforcer” and that individuals with ADHD also abuse this medication. Nevertheless, the molecular consequences of long-term recreational methylphenidate use or abuse in individuals with ADHD are not yet fully known.
Methods
Spontaneously hypertensive rats (SHR), the most validated and widely used ADHD animal model, were pretreated with methylphenidate (5 mg/kg, i.p.) during their adolescence (post-natal day [PND] 42–48) and tested for subsequent methylphenidate-induced conditioned place preference (CPP) and self-administration. Thereafter, the differentially expressed genes in the prefrontal cortex (PFC) and striatum of representative methylphenidate-treated SHRs, which showed CPP to and self-administration of methylphenidate, were analyzed.
Results
Genome-wide transcriptome profiling analyses revealed 30 differentially expressed genes in the PFC, which include transcripts involved in apoptosis (e.g. S100a9, Angptl4, Nfkbia), transcription (Cebpb, Per3), and neuronal plasticity (Homer1, Jam2, Asap1). In contrast, 306 genes were differentially expressed in the striatum and among them, 252 were downregulated. The main functional categories overrepresented among the downregulated genes include those involved in cell adhesion (e.g. Pcdh10, Ctbbd1, Itgb6), positive regulation of apoptosis (Perp, Taf1, Api5), (Notch3, Nsbp1, Sik1), mitochondrion organization (Prps18c, Letm1, Uqcrc2), and ubiquitin-mediated proteolysis (Nedd4, Usp27x, Ube2d2).
Conclusion
Together, these changes indicate methylphenidate-induced neurotoxicity, altered synaptic and neuronal plasticity, energy metabolism and ubiquitin-dependent protein degradation in the brains of methylphenidate-treated SHRs, which showed methylphenidate CPP and self-administration. In addition, these findings may also reflect cognitive impairment associated with chronic methylphenidate use as demonstrated in preclinical studies. Future studies are warranted to determine the clinical significance of the present findings with regard to long-term recreational methylphenidate use or abuse in individuals with ADHD.
A Study on the Effect of Methylphenidate on Creativity of Healthy Adults
(above study has yet to be completed, or rather they're taking their sweet time processing the data, my guess is a negative result)
Roughly an equal ratio of receptor to transmitter, neither hyperdopamine nor hypo, but a happy middle, or perfect harmony. That's what nature intended: not for us to disrupt her homeostasis.