Sex hormones differentially influence voluntary running activity, food intake and body weight in aging female and male rats

Abstract

The aim of this study was to examine the longer-term effects of reduced gonadal hormones on food intake, food efficiency, voluntary running activity and body weight in mature male and female rats, compared to age-matched controls. We hypothesized that hormonal effects would differ for rats that were not rapidly growing and our results are consistent with this hypothesis. 6-8 month male and female rats were divided into four groups: Female and male control groups and a female and male experimental group. Control groups were intact for 46 weeks. Experimental groups were intact during Phase I (16 weeks), ovariectomized or orchidectomized during Phase II (20 weeks), and received estrogen or testosterone hormone replacement therapy (HRT) during the final Phase III (10 weeks). Food intake and running distance were monitored daily and body weight was recorded weekly for 46 weeks. Contrary to findings for young and growing animals, we did not observe a (1) stabilization of food intake in female rats following OVX, (2) loss of body weight with ORX in males, or (3) complete restoration of running activity in ORX males given testosterone, compared to females given estrogen. Feeding efficiency was not affected by aging in females or males. Loss of estrogen increased energy intake whereas reduced testosterone in males resulted in a negative energy balance. Findings suggest variable hormonal effects for aging male/female rats.

Gonad-related factors promote muscle performance gain during postnatal development in male and female mice

“…A 534 possibility is that androgen effect on muscle growth can be mediated via AR localized in the 535 brain. This hypothesis is supported by the facts that: (i) the level of voluntary exercise in 536 male animals is negatively and positively modulated by castration and androgen 537 administration, respectively (14,35) and (ii) reduced activity alters muscle performance and 538 size (31). 539…”

“…There is a possibility that estrogen effects can be 597 mediated by brain ER since estrogens increase the level of voluntary exercise (14,21) which 598 is known to modulate muscle performance and growth. In agreement, a recent study 599…”

Efeitos do exercício físico associado à suplementação de creatina na massa óssea de ratas ovariectomizadas

“…Sabe-se que em animais, o aumento do peso corporal observado após a ovariectomia está primordialmente relacionado ao surgimento da hiperfagia, uma vez que o estradiol está fortemente associado à regulação do consumo alimentar por meio de vias anorexígenas no sistema nervoso central, as quais são mediadas a partir da ativação dos receptores de estrógeno (Fisher et al, 2000;Jiang et al, 2008;Eckel, 2011;Ferreira et al, 2012 (Kalu, 1991;Li et al, 1997).…”

“…Dentre as alterações fisiológicas encontradas em modelo experimental de pós-menopausa, a deficiência de estrógeno foi relacionada ao aumento do consumo alimentar (hiperfagia) (Fisher et al, 2000;Jiang et al, 2008;Eckel, 2011;Ferreira et al, 2012) tornando-se relevante, portanto, o controle dessa variável a fim de eliminar possíveis vieses. O protocolo pair-feeding utilizado foi adaptado de um estudo prévio que utilizou suplementação de creatina em animais tratados com dexametasona (Nicastro et al, 2012).…”

Influência do Treinamento Físico em parâmetros cardíacos, vasculares, inflamatórios e de estresse oxidativo em um modelo de menopausa e síndrome metabólica no envelhecimento

“…A interação entre os hormônios sexuais e o ganho de peso ponderal vem sendo avaliada constantemente (FERREIRA; FOLEY; BROWN, 2012;FISHER et al, 2000;TEZINI et al, 2013). No presente trabalho, o grupo de ratas jovens ooforectomizadas (JOS) apresentou maior ganho de peso corporal quando comparadas às ratas jovens controle (JCS).…”