5-Hydroxy-l-tryptophan suppresses food intake in food-deprived and stressed rats

Amer, Ahmed; Breu, Jeff; McDermott, Josh H.; Wurtman, Richard J.; Maher, Timothy J.

doi:10.1016/j.pbb.2003.10.011

Cited by 36 publications

(25 citation statements)

References 24 publications

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“…In the present study, acute mild tail pinch robustly increases food intake with an immediate onset of action in freely fed rats consistent with previous reports in rats showing facilitation of behavior related to the incentive present in the environment (2,4,21,46,51). NPY neurons located in the arcuate nucleus are a major hypothalamic component mediating the signals of orexigenic peptides (47).…”

Section: Discussionsupporting

confidence: 92%

Orexigenic response to tail pinch: role of brain NPY₁ and corticotropin releasing factor receptors

Goebel-Stengel

Stengel

Wang

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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Tail pinch stimulates food intake in rats. We investigated brain mechanisms of this response and the influence of repeated exposure. Sprague-Dawley rats received acute (5 min) or repeated (5 min/day for 14 days) tail pinch using a padded clip. Acute tail pinch increased 5-min food intake compared with control (0.92 ± 0.2 vs. 0.03 ± 0.01 g, P < 0.01). This response was inhibited by 76% by intracerebroventricular injection of BIBP-3226, a neuropeptide Y1 (NPY1) receptor antagonist, increased by 48% by astressin-B, a corticotropin-releasing factor (CRF) receptor antagonist, and not modified by S-406-028, a somatostatin subtype 2 antagonist. After the 5-min tail pinch without food, blood glucose rose by 21% (P < 0.01) while changes in plasma acyl ghrelin (+41%) and adrenocorticotropic hormone (+37%) were not significant. Two tail pinches (45 min apart) activate pontine and hindbrain catecholaminergic and hypothalamic paraventricular CRF neurons. After 14 days of repeated tail pinch, the 5-min orexigenic response was not significantly different from days 2 to 11 but reduced by 50% thereafter (P < 0.001). Simultaneously, the 5-min fecal pellet output increased during the last 5 days compared with the first 5 days (+58%, P < 0.05). At day 14, the body weight gain was reduced by 22%, with a 99% inhibition of fat gain and a 25% reduction in lean mass (P < 0.05). The orexigenic response to acute 5-min tail pinch is likely to involve the activation of brain NPY1 signaling, whereas that of CRF tends to dampen the acute response and may contribute to increased defecation and decreased body weight gain induced by repeated tail pinch.

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Section: Discussionsupporting

confidence: 92%

Orexigenic response to tail pinch: role of brain NPY₁ and corticotropin releasing factor receptors

Goebel-Stengel

Stengel

Wang

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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“…As noted in the Introduction, (+)-amphetamine has shown promise as a medication for treating stimulant addiction and has been administered safely in this patient population (Grabowski et al, 2004). 5-HTP is available for human use as an over-the-counter supplement and has been administered with and without carbidopa for the treatment of depression, obesity and insomnia (Amer et al, 2004; Cangiano et al, 1992; Cangiano et al, 1998; Turner et al, 2006; Zmilacher et al, 1988). Carbidopa, like benserazide, selectively blocks the conversion of 5-HTP to 5-HT in the periphery, but not in the brain.…”

Section: Discussionmentioning

confidence: 99%

Serotonin (5-HT) precursor loading with 5-hydroxy-l-tryptophan (5-HTP) reduces locomotor activation produced by (+)-amphetamine in the rat

Baumann

Williams

Żółkowska

et al. 2010

Drug and Alcohol Dependence

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Background-Evidence suggests that increases in synaptic serotonin (5-HT) can reduce the stimulant properties of amphetamine-type drugs. Here we tested the hypothesis that administration of the 5-HT precursor 5-hydroxy-L-tryptophan (5-HTP), along with the peripheral decarboxylase inhibitor benserazide, would decrease locomotor effects of (+)-amphetamine.Methods-Drug treatments were administered to conscious male rats undergoing in vivo microdialysis in nucleus accumbens. During dialysis sampling, rats were housed in chambers equipped with photobeams to detect forward locomotion (i.e., ambulation) and repetitive movements (i.e., stereotypy). Extracellular concentrations of dopamine (DA) and 5-HT were measured by high-pressure liquid chromatography with electrochemical detection. Conclusions-Our results confirm that 5-HTP can decrease hyperactivity produced by (+)-amphetamine, even in the presence of elevations in dialysate DA. The data suggest that 5-HTP and (+)-amphetamine may be useful to broadly enhance monoamine function in the clinical setting, while reducing undesirable effects of (+)-amphetamine. Results-5-HTP

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“…For large neutral amino acids (LNAA: tryptophan, tyrosine, phenylalanine, valine, isoleucine, and leucine), the barrier across cell membranes, including the blood-brain barrier, comprises the sodium-independent L system (Pardridge and Oldendorf, 1977). The entry of plasma HTP into the brain is competitive with L-valine and thus presumably with other large neutral amino acids (Amer et al, 2004). Estimates of the Michaelis-Menten constants for blood-brain barrier transport of labelled AMT have been shown to agree reasonably with those previously measured for tryptophan (Diksic et al, 1991).…”

Section: Discussionmentioning

confidence: 99%

5-Hydroxy-l-[β-¹¹C]tryptophan versus α-[¹¹C]Methyl-l-tryptophan for Positron Emission Tomography Imaging of Serotonin Synthesis Capacity in the Rhesus Monkey Brain

Lundquist

Hartvig

Blomquist

et al. 2006

J Cereb Blood Flow Metab

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The purpose of this study was to compare two positron emission tomography (PET) tracers that were developed to follow serotonin (5HT) synthesis by performing sequential PET scanning of the same rhesus monkey (n = 4) on the same day. a-[ 11 C]Methyl-L-tryptophan ([ 11 C]AMT) and 5-Hydroxy-L-[b-11 C]tryptophan ([ 11 C]HTP) are substrates in the first and second enzymatic steps, respectively, in the biosynthesis of 5HT. Regional net accumulation rate constants were derived from kinetic (two-tissue compartment model with irreversible tracer trapping) and graphic (Patlak) analyses, using the arterial plasma concentrations as input. The kinetic data analysis showed that the rate constant for the transfer of [ 11 C]HTP into the brain (K 1) was higher than that for [ 11 C]AMT in the striatum and thalamus but was similar in other brain regions. The rate constant for tracer trapping (k 3) was also higher for [ 11 C]HTP than for [ 11 C]AMT in the striatum (0.04660.024 versus 0.01960.006 min À1) and thalamus (0.03960.013 versus 0.01660.007 min À1). In agreement with previously reported regional HTP accumulation rates, the net accumulation rate constant (K acc) for [ 11 C]HTP was also higher in these regions than in other brain regions; this is in contrast to the uniform distribution of [ 11 C]AMT K acc values. This suggests that the regional net accumulation rates obtained with these two PET tracers will be of different magnitude, which might be related to the activity of each targeted enzyme.

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5-Hydroxy-l-tryptophan suppresses food intake in food-deprived and stressed rats

Cited by 36 publications

References 24 publications

Orexigenic response to tail pinch: role of brain NPY₁ and corticotropin releasing factor receptors

Orexigenic response to tail pinch: role of brain NPY₁ and corticotropin releasing factor receptors

Serotonin (5-HT) precursor loading with 5-hydroxy-l-tryptophan (5-HTP) reduces locomotor activation produced by (+)-amphetamine in the rat

5-Hydroxy-l-[β-¹¹C]tryptophan versus α-[¹¹C]Methyl-l-tryptophan for Positron Emission Tomography Imaging of Serotonin Synthesis Capacity in the Rhesus Monkey Brain

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5-Hydroxy-l-tryptophan suppresses food intake in food-deprived and stressed rats

Cited by 36 publications

References 24 publications

Orexigenic response to tail pinch: role of brain NPY1 and corticotropin releasing factor receptors

Orexigenic response to tail pinch: role of brain NPY1 and corticotropin releasing factor receptors

Serotonin (5-HT) precursor loading with 5-hydroxy-l-tryptophan (5-HTP) reduces locomotor activation produced by (+)-amphetamine in the rat

5-Hydroxy-l-[β-11C]tryptophan versus α-[11C]Methyl-l-tryptophan for Positron Emission Tomography Imaging of Serotonin Synthesis Capacity in the Rhesus Monkey Brain

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Orexigenic response to tail pinch: role of brain NPY₁ and corticotropin releasing factor receptors

Orexigenic response to tail pinch: role of brain NPY₁ and corticotropin releasing factor receptors

5-Hydroxy-l-[β-¹¹C]tryptophan versus α-[¹¹C]Methyl-l-tryptophan for Positron Emission Tomography Imaging of Serotonin Synthesis Capacity in the Rhesus Monkey Brain