Serotonin depletion and barrel cortex development: impact of growth impairment vs. serotonin effects on thalamocortical endings.
Converging evidence supports a role of serotonin (5-hydroxytryptamine; 5-HT) in barrel cortex development. Systemic administration of 5-HT-depleting drugs reduces cross-sectional whisker barrel areas in the somatosensory cortex (SSC) of neonatal rats. Here we assess the relative impact on barrel pattern formation of (i) 5-HT depletion and (ii) decreased brain growth, which is often associated with pharmacological 5-HT depletion, by comparing the effects of 5-HT-depleting drugs with those of reduced protein intake. Left hemisphere 5-HT levels in the SSC and right hemisphere whisker barrel areas were assessed at postnatal day 6 (P6) in the same animal following injection of p-chloroamphetamine (PCA) or p-chlorophenylalanine (PCPA) at P0. Both drugs significantly reduced cortical 5-HT content and mean barrel areas at P6, but also body and brain growth. Differences in brain weight accounted for 84.4% of the variance in barrel size, with negligible contributions by cortical 5-HT content. PCPA-treated animals sacrificed at P14 yielded similar trends, albeit less pronounced. Finally, reduced protein intake resulted in lower body weight and cortical 5-HT levels at P6, but yielded no change in brain weight or mean barrel area. Barrel formation therefore appears markedly less sensitive to 5-HT depletion per se than to drug-induced growth impairment.
Persico
A M
AM
Laboratory of Neuroscience, Department of Physiology, Libera Università 'Campus Bio-Medico', Rome, Italy.
Altamura
C
C
Calia
E
E
Puglisi-Allegra
S
S
Ventura
R
R
Lucchese
F
F
Keller
F
F
D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000033:anatomy & histology; D010134:Fenclonine / Q000494:pharmacology*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011917:Rats, Inbred Lew; D012701:Serotonin / Q000378:metabolism*; D013003:Somatosensory Cortex / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D014738:Vibrissae / Q000294:innervation; D010133:p-Chloroamphetamine / Q000494:pharmacology*
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D010133:p-Chloroamphetamine; D010134:Fenclonine