Leptin and leptin receptor are expressed only in clear cells of rat epididymis epithelia / La leptina y el receptor de leptina se expresan solamente en células claras del epitelio epidídimario de rata

SUMMARY: Leptin is a 16 kilodaltons hormone secreted by adipose tissue and in the past few years it has been related to the reproductive system regulation. Leptin and its receptor (OBR) have been described in several reproductive organs and in different species but, in epididymis, there is still a lack of information. The aim of this work is to establish if leptin and its receptor are present on epididymis and where the production is occurring. At mRNA level the cauda portion showed a high expression of leptin (p<0.025) and OBRa (p<0.002) while at protein level the OBR expression was lower in cauda region (p<0.025) and leptin was not detected. The ratio between OBRa and OBRb was higher in both regions despite its total amount. By immunohistochemistry leptin and OBR were detected on epididymis epithelia, restricted to clear cells (CC). After efferent duct ligation (EDL) a decrease on leptin staining on CC was observed, suggesting that despite of epididymis production, most of leptin source may probably come from testis. Our results show that leptin and OBR, both mRNA and protein, are present on epididymis and exclusively in CC, suggesting that this tissue is responsive to the hormone and may have an important role on CC regulation.

RESUMEN: La leptina es una hormona de 16 kilodaltons secretada por el tejido adiposo y se ha relacionado en los últimos años con la regulación del sistema reproductivo. La leptina y su receptor (OBR) se han reportado en varios órganos reproductores y en diferentes especies sin embargo, en el epidídimo aún falta información. El objetivo de este trabajo fue establecer si la leptina y su receptor están presentes en el epidídimo y donde se produce. A nivel de ARNm la porción de cauda mostró una alta expresión de leptina (p <0,025) y OBRa (p <0,002) mientras que a nivel de proteína la expresión de OBR fue menor en la región de la cauda epididimaria (p <0,025) y no se detectó leptina. La relación entre OBRa y OBRb fue mayor en ambas regiones a pesar de su cantidad total. Por inmunohistoquímica se detectaron leptina y OBR en el epitelio del epidídimo restringido a células claras (CC). Después de la ligadura del conducto deferente (EDL) se observó una disminución en la tinción de leptina en CC, lo que sugiere que a pesar de la producción del epidídimo, la mayor parte de la fuente de leptina puede provenir probablemente del testículo. Nuestros resultados mostraron que la leptina y OBR, mRNA y proteína, están presentes en el epidídimo y exclusivamente en CC, lo que sugiere que este tejido es sensible a la hormona y puede tener un papel importante en la regulación CC.

Metabolic programming of lipid profile and reproductive organs weight by leptin treatment on early life / Programação metabólica do perfil lipídico e peso dos órgãos do sistema reprodutor pelo tratamento com leptina nos primeiros dias de vida

PURPOSE: To evaluate whether the neonatal leptin treatment during the first days of life can program the male reproductive organs weight and the lipid profile. METHODS: At birth 6 dams were divided into 2 groups: Leptin - each pup was injected with 50μL of recombinant rat leptin (80ng/g BW, sc), for the first 10 d of lactation; Control - each pup received the same volume of saline. After weaning, all pups received unlimited access to food until 190 days of age when they were killed. Values are given as mean ± SEM of 6 animals and Test t Student was used to analyze the results. RESULTS: The leptin treatment resulted in a significant increase in body weight (Control= 411.8±16.31; Leptin= 481.8±11.29, p=0.005) and food consumption (Control= 25.32±0.09; Leptin= 32.42±0.15, p=0.0001) and a significant reduction in triglycerides levels (Control= 540.0±117.9; Leptin= 93.25±15.21, p=0.006) and in the weight of hypothalamus (Control= 0.234±0.016; Leptin= 0.154±0.015, p=0.007), pituitary (Control= 0.104±0.0120; Leptin= 0.033±0.012, p=0.003), testis (Control= 3.75±0.055; Leptin= 3.19±0.10, p=0.002) and prostate (Control=1.641±0.1389; Leptin= 0.91±0.07, p=0.001). CONCLUSION: Leptin treatment on the first days of life can program the reproductive organs weight and the lipid profile of the progeny.

OBJETIVO: Avaliar se o tratamento neonatal com leptina durante os primeiros dias de vida poderia programar o peso dos orgãos do sistema reprodutor masculino e o perfil lipídico. MÉTODOS: Ao nascimento seis ratas-mãe foram distribuídas em dois grupos: Leptina - cada filhote recebeu 50μL de leptina recombinante (80ng/gPC, SC) nos primeiros 10 dias de lactação; Controle - cada filhote recebeu o mesmo volume de salina. Após o desmame, todos os filhotes tiveram acesso ilimitado a ração até 190 dias de idade quando foram mortos. Os dados são expressos como média ± erro padrão e foram analisados pelo teste t Student. RESULTADOS: O tratamento com leptina resultou em aumento significativo no peso corporal (Control= 411.8±16.31; Leptin= 481.8±11.29, p=0.005) e consumo alimentar (Control= 25.32±0.09; Leptin= 32.42±0.15, p=0.0001) e redução significativa nos níveis séricos de triglicerídeos (Control= 540.0±117.9; Leptin= 93.25±15.21, p=0.006), no peso do hipotálamo (Control= 0.234±0.016; Leptin= 0.154±0.015, p=0.007), hipófise (Control= 0.104±0.0120; Leptin= 0.033±0.012, p=0.003), testículo (Control= 3.75±0.055; Leptin= 3.19±0.10, p=0.002) e próstata (Control=1.641±0.1389; Leptin= 0.91±0.07, p=0.001). CONCLUSÃO: O tratamento com leptina nos primeiros dias de vida pode programar o peso dos órgãos do sistema reprodutor e o perfil lipídico da prole.