The Serotonergic Agonists Quipazine, CGS-12066A, and α-Methylserotonin Alter Motor Activity and Induce Hindlimb Stepping in the Intact and Spinal Rat Fetus.

The effects of serotonergic agonists were examined in intact and spinal fetuses, using an in vivo fetal rat preparation. On Gestational Day 20, fetuses were prepared with a midthoracic or sham spinal transection. Dose-response curves were obtained for quipazine (nonselective 5-hydroxytryptamine [5-HT] agonist; 1.0-10.0 mg/kg), CGS-12066A (5-HT1B agonist; 1.0-30.0 mg/kg), and α-methylserotonin (α-Me-5-HT; 5-HT? agonist; 0.2-15.0 mg/kg). During a 10-min test, each of the agonists (delivered via intraperitoneal injection) influenced fetal behavior: They increased the occurrence of head movements, mouthing, and hindlimb stepping. Quipazine and α-Me-5-HT also promoted hindlimb activity in spinal fetuses. Thus, stimulation of the fetal 5-HT system modulates motor activity at multiple levels of the developing central nervous system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

m-Chlorophenylpiperazine (mCPP) Modulates the Discriminative Stimulus Effects of Cocaine Through Actions at the 5-HT?C Receptor.

Agonists acting at the serotonin-1B receptor (5-HT?BR) and 5-HT?CR have been reported to potentiate and block, respectively, the discriminative stimulus effects of cocaine. The present investigation reassessed the antagonistic effects of the mixed 5-HT?C/?BR agonist m-chlorophenylpiperazine (mCPP) on the discriminative stimulus effects of cocaine in the presence or absence of selective antagonism of the 5-HT?BR or 5-HT?CR. The stimulus effects of cocaine were attenuated by mCPP at doses that reduced response rates. The selective 5-HT?CR antagonist SB 242084, but not the selective 5-HT?BR antagonist GR 127935, reversed the mCPP-evoked attenuation of the cocaine cue and the suppression of response rates. These results demonstrate that the suppressive effects of mCPP on cocaine discrimination are related to stimulation of the HT?CR. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How important is tryptophan in human health?

Tryptophan (Trp) is an amino acid and an essential component of the human diet. It plays a crucial role in many metabolic functions. Clinicians can use Trp levels in the course of diagnosing various metabolic disorders and the symptoms associated with those diseases. Furthermore, supplementation with this amino acid is considered in the treatment of depression and sleep disorders, mainly due to the Trp relationship with the synthesis of serotonin (5-HT) and melatonin. It is also used in helping to resolve cognitive disorders, anxiety, or neurodegenerative diseases. Reduced secretion of serotonin is associated with autism spectrum disorder, obesity, anorexia and bulimia nervosa, and other diseases presenting peripherals symptoms. The literature strongly suggests that Trp has a significant role in the correct functionality of the brain-gut axis and immunology. This information leads to the consideration of Trp as an essential dietary component due to its role in the serotonin pathway. A reduced availability of Trp in diet and nutraceutical supplementation should be considered with greater concern than one might expect. This paper constitutes a review of the more salient aspects gleaned from the current knowledge base about the role of Trp in diseases, associated nutritional disorders, and food science, in general.     

Association of the serotonin transporter gene promoter region (5-HTTLPR) polymorphism with biased attention for emotional stimuli.

A deletion polymorphism in the serotonin transporter-linked polymorphic region (5-HTTLPR) has been associated with vulnerability to affective disorders, yet the mechanism by which this gene confers vulnerability remains unclear. Two studies examined associations between the 5-HTTLPR polymorphism and attentional bias for emotional stimuli among nondepressed adults. Biased attention, attention engagement, and difficulty with attention disengagement were assessed with a spatial cuing task using emotional stimuli. Results from Study 1 (N = 38) indicated that short 5-HTTLPR allele carriers experienced greater difficulty disengaging their attention from sad and happy stimuli compared with long allele homozygotes. Study 2 participants (N = 144) were genotyped for the 5-HTTLPR polymorphism, including single nucleotide polymorphism rs25531 in the long allele of the 5-HTTLPR. Consistent with Study 1, individuals homozygous for the low-expressing 5-HTTLPR alleles (i.e., S and LG) experienced greater difficulty disengaging attention from sad, happy, and fear stimuli than high-expressing 5-HTTLPR homozygotes. Because this association exists in healthy adults, it may represent a susceptibility factor for affective disorders that becomes problematic during stressful life experiences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effective components of TORDIA cognitive–behavioral therapy for adolescent depression: Preliminary findings.

In this report, we conducted a secondary analysis of the Treatment of SSRI-Resistant Depression in Adolescents (TORDIA) study to explore the impact of specific cognitive–behavioral therapy (CBT) treatment components on outcome. In TORDIA, 334 youths (ages 12 to 18 years) with major depressive disorder who had failed to respond to an adequate course of selective serotonin reuptake inhibitor (SSRI) medication were randomized to a medication switch (either to an alternative SSRI or venlafaxine) with or without 12 weeks of adjunctive CBT. Participants who had more than 9 CBT sessions were 2.5 times more likely to have adequate treatment response than those who had 9 or fewer sessions. CBT participants who received problem-solving and social skills treatment components, controlling for number of sessions and other confounding variables, were 2.3 and 2.6 times, respectively, more likely to have a positive response. These preliminary findings underscore the importance of receiving an adequate number of sessions to attain an adequate clinical response. Finally, social skills and problem solving may be active elements in CBT for adolescent depression and should be considered in treatment by those working with seriously depressed youths. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Plant Neurobiology,a Fascinating Perspective in the Field of Research on Plant Secondary Metabolites

In this Editorial, I comment on the exciting and original topic of plant neurobiology, focusing on natural products whose biosynthesis is shared by animal and plant organisms, i.e., indoleamines (melatonin and serotonin) and catecholamines (dopamine, norepinephrine and epinephrine).     

Alterations in anterior hypothalamic vasopressin, but not serotonin, correlate with the temporal onset of aggressive behavior during adolescent anabolic-androgenic steroid exposure in hamsters (Mesocricetus auratus).

In hamsters (Mesocricetus auratus), anabolic-androgenic steroid (AAS) exposure during adolescence facilitates offensive aggression that is correlated with the enhanced development of the arginine vasopressin (AVP) neural system and reduced development of the serotonin (5-HT) neural system in the anterior hypothalamus (AH). This study examined the temporal onset of these effects by measuring aggression and AH AVP and 5-HT during progressively shorter periods of AAS exposure during adolescent development. The authors tested adolescent hamsters that received AAS for 3, 7, 14, or 28 days for offensive aggression and then examined the hamsters for AVP/5-HT afferent innervation to the AH using immunohistochemistry. While reductions in AH 5-HT afferent innervation were detectable by 7 days of AAS exposure, no concomitant increases in offensive aggression were observed compared to oil-treated littermates. In contrast, by Day 14 of AAS treatment, AH AVP and offensive aggression were significantly higher than oil-treated controls. These data indicate that relatively short-term adolescent AAS exposure alters aggression and AH 5-HT and AVP development, yet only alterations in AH AVP development correlate with temporal onset of the aggressive behavioral phenotype during adolescent AAS exposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive and serotonergic vulnerability to depression: Convergent findings.

Cognitive reactivity (CR) is a psychological vulnerability marker of depression, whereas response to acute tryptophan depletion (ATD; a serotonergic challenge procedure) is a biological vulnerability marker. The aim of this study was to investigate the relationship between these markers. Thirty-nine remitted depressed patients participated in 2 ATD sessions in a double-blind crossover design. CR, assessed prior to the ATD sessions, predicted depressive response to high-dose ATD. CR also diminished the effects of 2 known predictors of ATD response: gender and residual symptoms. Neuroticism and behavioral inhibition were unrelated to ATD response. CR is associated with an increased sensitivity to reductions of serotonin concentrations. These findings present a small step toward unifying cognitive and neurobiological theories of depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fluorescence histochemical techniques for catecholamines as tools in neurobiology

Formaldehyde-induced and glyoxylic-acid-induced fluorescence histochemistry permits the tissue localization of catecholamines in the central nervous system (CNS) and peripheral nervous system (PNS), and in culture. Counterstains such as ethidium bromide provide excellent background identification of specific innervated regions in both the CNS and the periphery. Use of fluorescence histochemistry with immunocytochemistry can elucidate catecholamine-peptide relationships. Gelatin-ink perfusion used with fluorescence histochemistry permits the investigation of neuro-vascular relationships and documentation of vascular and parenchymal compartmentation of innervation. Combined use of fluorescence histochemistry and retrograde tracing methods demonstrates the specific cellular sources of innervation of target regions. Micropunch neurochemical analysis provides quantitative data for correlation with fluorescence histochemistry within a target region of innervation, and micro-spectrofluorometric analysis provides a semi-quantitative evaluation of the amount of fluorophore within a target region or within specific subcellular compartments such as the cell body or terminals.