Abstract This study investigated whether increased food intake after 15 days of low-protein, high-carbohydrate (LPHC) and its normalization in the later period of development change the content of key proteins related to leptin or adiponectin signaling in the hypothalamus. Male rats were divided into five groups: Control groups received a control diet (17% protein, 63% carbohydrate) for 15 (C15) or 45 (C45) days; LPHC groups received an LPHC diet (6% protein, 74% carbohydrate) for 15 (LPHC15) or 45 (LPHC45) days; and Reverse group (R): received LPHC diet for 15 days followed by control diet for another 30 days. The LPHC15 group showed increased adiposity index, leptin level, and adiponectin level, as well as decreased the leptin receptor (ObRb) and pro-opiomelanocortin (POMC) content in the hypothalamus compared with the C15 group. LPHC diet for 45 days or diet reversion (R group) rescued these alterations, except the adiponectin level in LPHC45 rats, which was higher. In summary, LPHC diet reduced hypothalamic leptin action by diminishing ObRb and POMC levels, leading to hyperphagia and adiposity body. Medium-term administration of LPHC diet or reverting to control diet restored the levels of these proteins, thereby improving body lipid mass rearrangement in adulthood.

ResumoO estudo foi realizado para avaliar se a restrição calórica ou proteica em fêmeas lactantes influencia o início da puberdade de seus cordeiros. Foram utilizados 21 cordeiros, sendo duas fêmeas e cinco machos por tratamento. Durante sessenta dias as mães receberam o tratamento aleatoriamente escolhido para o seu cordeiro: controle (TC, mantença), restrição calórica (TRC, ½ da energia do TC) e restrição proteica (TRP, 1/3 da proteína do TC). Após o desmame, os cordeiros receberam uma dieta composta por silagem de milho e concentrado, sendo pesados e avaliados quinzenalmente. Nos machos, coletava-se o ejaculado, mensurava-se circunferência escrotal e as dimensões testiculares. Nas fêmeas, realizava-se ultrassonografia para medir os ovários e verificar presença de corpo lúteo. Os machos eram considerados púberes se apresentassem ejaculado com, no mínimo: motilidade de 50%, concentração do ejaculado de 50 x 106espermatozóides/mL e, no máximo, 50% de anormalidades espermáticas totais, e as fêmeas, se apresentassem corpo lúteo. Foi encontrada interação entre período de avaliação e tratamento para circunferência escrotal (p=0,0019), volume testicular médio (p=0,0025), motilidade (p<0,0001) e concentração espermática (p=0,027), sendo o TRP, mais tardio do que TRC e TC em todas variáveis. Nas borregas não houve diferença (p>0,05) entre os tratamentos quanto às características foliculares, porém houve quanto ao corpo lúteo (p=0,0179). Notou-se que as fêmeas do TC apresentaram corpo lúteo a partir da 10a semana, TRC da 11a e o TRP da 13a. Concluiu-se que a restrição proteica materna durante a lactação atrasa o início da puberdade de seus cordeiros.

AbstractThis study was carried out to evaluate if caloric or protein restriction in lactation ewe affect puberty beginning of its lambs. Had been used 21 lambs, two females and five males per type of treatment. During 60 days the mothers received the treatment for which its lamb was sort out: Control Treatment (TC, maintenance), Energy Restriction Treatment (TRC, ½ of the energy of the TC) and Protein Restriction Treatment (TRP, 1/3 of the protein of the TC). The lambs were weaned and received a diet composed by corn silage and concentrate, weighed and evaluated fortnightly. In males, the ejaculate was collected, scrotal circumference and testicular size measured. In females, it was realized ultrasound to measure the ovaries and verify the corpus luteum presence. For males was considered in puberty if produced ejaculation with at least: motility of 50%, sperm concentration of 50 x 106espermatozoa/mL and maximum of 50% total sperm abnormalities, and females if exhibit corpus luteum. An interaction was found between evaluation period and treatment for scrotum circumference (p=0.0019), testicular volume (p=0.0025) sperm motility (p<0.0001) and concentration (p=0.027), TRP was later than TRC and TC in all variable. In female no treatment effect (p>0.05) were found about follicles characteristics, however that was difference in the presence of corpous luteum (p=0.0179). The TC females showed corpus luteum from the 10th week, TRC 11th and 13th for TRP. It was concluded that mother protein restriction during the lactation delays the beginning of the puberty of its lambs.