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-Serotonin influences the growth and development of the nervous system, as well as its behavioral manifestations. The possibility exists that increased brain serotonin availability in young animals modulates their neuro-behavioral responses. This study investigated the body weight gain and reflex ontogeny of neonatal rats treated during the suckling period with two doses of citalopram (5 mg, or 10 mg/kg, sc, daily). The time of the appearance of reflexes (palm grasp righting, free-fall righting, vibrissa placing, auditory startle response, negative geotaxis and cliff avoidance) as well as the body weight evolution were recorded. In general, a delay in the time of reflex development and a reduced weight gain were observed in drug-treated animals. These findings suggest that serotoninergic mechanisms play a role in modulating body weight gain and the maturation of most reflex responses during the perinatal period in rats.Key wordS: serotonin, programming, SSrI, citalopram, reflex development. Exposição neonatal ao citalopram, um inibidor seletivo da recaptação de serotonina, programa retardo na ontogênese reflexa em ratosResumo -A serotonina influencia o crescimento e o desenvolvimento do sistema nervoso e sua expressão comportamental. o aumento da disponibilidade de serotonina no cérebro de ratos jovens parece modular as respostas neurocomportamentais. Neste estudo, foram investigados o ganho de peso corporal e a ontogênese dos reflexos em ratos neonatos, tratados diariamente, durante o período de aleitamento, com duas doses de citalopram (5 ou 10 mg/Kg de peso corporal, via subcutânea). Foram avaliados, o tempo de aparecimento dos reflexos (preensão palmar, endireitamento, colocação pelas vibrissas, resposta ao susto, geotáxico negativo e aversão ao precipício), e a evolução do peso corporal. Foi observado atraso no tempo de desenvolvimento de alguns reflexos e redução no ganho de peso corporal. os achados em ratos sugerem que as alterações no ganho de peso corporal e na maturação dos reflexos são programadas, durante o período perinatal, com participação de mecanismos serotoninérgicos de modulação.

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Little is known about the effects of undernutrition on the specific muscles and neuronal circuits involved in mastication. The aim of this study was to document the effects of neonatal low-protein diet on masticatory efficiency. Newborn rats whose mothers were fed 17 % (nourished (N), n 60) or 8 % (undernourished (U), n 56) protein were compared. Their weight was monitored and their masticatory jaw movements were video-recorded. Whole-cell patch-clamp recordings were performed in brainstem slice preparations to investigate the intrinsic membrane properties and N-methyl-Daspartate-induced bursting characteristics of the rhythmogenic neurons (N, n 43; U, n 39) within the trigeminal main sensory nucleus (NVsnpr). Morphometric analysis (N, n 4; U, n 5) were conducted on masseteric muscles serial cross-sections. Our results showed that undernourished animals had lower numbers of masticatory sequences (P = 0·049) and cycles (P = 0·045) and slower chewing frequencies (P = 0·004) (N, n 32; U, n 28). Undernutrition reduced body weight but had little effect on many basic NVsnpr neuronal electrophysiological parameters. It did, however, affect sag potentials (P < 0·001) and rebound firing (P = 0·005) that influence firing pattern. Undernutrition delayed the appearance of bursting and reduced the propensity to burst (P = 0·002), as well as the bursting frequency (P = 0·032). Undernourished animals showed increased and reduced proportions of fibre type IIA (P < 0·0001) and IIB (P < 0·0001), respectively. In addition, their fibre areas (IIA, P < 0·001; IIB, P < 0·001) and perimeters (IIA, P < 0·001; IIB, P < 0·001) were smaller. The changes observed at the behavioural, neuronal and muscular levels suggest that undernutrition reduces chewing efficiency by slowing, weakening and delaying maturation of the masticatory muscles and the associated neuronal circuitry.

Purpose Children with cerebral palsy (CP) often exhibit difficulties in feeding resulting from deficits in chewing. This study investigates the therapeutic potential of Ltryptophan (TRI) to reduce deficits in chewing in rats subjected to an experimental model of CP. Methods A total of 80 Wistar albino rats were used. Pups were randomly assigned to 4 experimental groups: Control Saline, Control TRI, CP Saline, and CP TRI groups. The experimental model of CP was based on the combination of perinatal anoxia associated with postnatal sensorimotor restriction of the hind limbs. TRI was administered subcutaneously during the lactation period. Anatomical and behavioral parameters were evaluated during maturation, including body weight gain, food intake, chewing movements, relative weight and the distribution of the types of masseter muscle fibers. Results The induction of CP limited body weight gain, decreased food intake and led to impairment in the morphological and functional parameters of chewing. Moreover, for a comparable amount of food ingested, CP TRI animals grew the most. In addition, supplementation with TRI improved the number of chewing movements, and increased the weight and proportion of type IIB fibers of the masseter in rats subjected to CP. Conclusion These results demonstrate that experimental CP impaired the development of mastication and that TRI supplementation increased masticatory Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation maturation in animals subjected to CP.