Hypothyroidism affects lipid and glycogen content and peroxisome proliferator-activated receptor d expression in the ovary of the rabbit Julia Rodrı ´guez-Castela ´n A , Maribel Me ´ndez-Tepepa A , Jorge Rodrı ´guez- Antolı ´n B , Francisco Castela ´n B,C,D and Estela Cuevas-Romero B,D A Doctorado en Ciencias Biolo ´ gicas, Centro Tlaxcala de Biologı ´a de la Conducta, Universidad Auto ´ noma de Tlaxcala, Tlaxcala, 90070, Me ´xico. B Centro Tlaxcala de Biologı ´a de la Conducta, Universidad Auto ´ noma de Tlaxcala, Tlaxcala, Me ´xico, 90070. C Departamento de Biologı ´a Celular y Fisiologı ´a, Instituto de Investigaciones Biome ´ dicas, Unidad Fora ´nea Tlaxcala, Universidad Nacional Auto ´ noma de Me ´xico, Tlaxcala, 90070, Me ´xico. D Corresponding authors. Emails: ecuevas@uatx.mx; fcocastelan@iibiomedicas.unam.mx Abstract. Dyslipidaemia and hyperglycaemia are associated with ovarian failure and both have been related to hypothyroidism. Hypothyroidism promotes anovulation and ovarian cysts in women and reduces the size of follicles and the expression of aromatase in the ovary of rabbits. Considering that ovarian steroidogenesis and ovulation depend on lipid metabolism and signalling, the aim of the present study was to analyse the effect of hypothyroidism on the lipid content and expression of peroxisome proliferator-activated receptor (PPAR) d in the ovary. Ovaries from female rabbits belonging to the control (n ¼ 7) and hypothyroid (n ¼ 7) groups were processed to measure total cholesterol (TC), triacylglycerol (TAG) and glycogen content, as well as to determine the presence of granules containing oxidized lipids (oxysterols and lipofuscin) and the relative expression of perilipin A (PLIN-A) and PPARd. Hypothyroidism increased TC and glycogen content, but reduced TAG content in the ovary. This was accompanied by a reduction in the expression of PLIN-A in total and cytosolic extracts, changes in the presence of granules containing oxidative lipids and low PPARd expression. The results of the present study suggest that hypothyroidism modifies the content and signalling of lipids in the ovary, possibly affecting follicle maturation. These results could improve our understanding of the association between hypothyroidism and infertility in females. Additional keywords: oogenesis, ovary metabolism, ovulation, reproduction. Received 12 October 2017, accepted 27 March 2018, published online 3 May 2018 Introduction Dyslipidaemias are related to polycystic ovary syndrome (PCOS; Altintas et al. 2017), premature ovarian dysfunction (Knauff et al. 2008; Therani et al. 2014) and difficulties getting pregnant (Schisterman et al. 2014). The presence of ovarian cysts in sows is linked with high serum concentrations of total cholesterol (TC) and triacylglycerol (TAG; Stankiewicz 2015). This could be associated with ovarian metabolism. In this regard, ovarian follicles contain lipid droplets, such as TAG, TC and free fatty acids (FFA; i.e. oleic and linolenic acids), as well as hormone-sensitive lipase and perilipin A (PLIN-A; Sztalryd et al. 2003). All these determine the quality and competence of follicles (Dunning et al. 2014; Dadarwal et al. 2015). In addi- tion, an excess of lipid peroxidation affects LH signalling and apoptosis in theca and granulose cells (Brannian and Rickert 2000; Lo ¨hrke et al. 2005), and affects the fertilisation rate of oocytes and subsequent blastocyst development (Otsuki et al. 2007). Furthermore, ovarian follicles and stroma express per- oxisome proliferator-activated receptor (PPAR) d (Komar 2005), the activation of which regulates the secretion of pros- taglandin (PG) F 2a (Kurzynska et al. 2016) and steroidogenesis in the ovary (Kurzynska et al. 2014). Hypothyroidism promotes dyslipidaemias in women (Jaya- singh and Puthuran 2016), mares (Frank et al. 1999) and female rabbits (Rodrı ´guez-Castela ´n et al. 2017a). Moreover, hypothy- roidism has been associated with the formation of cysts (Shu et al. 2011; Mutinati et al. 2013) and disruptions in follicle growth and ovulatory rate (Meng et al. 2016; Rodrı ´guez- Castela ´n et al. 2017a). Hypothyroid rats show alterations in proliferation, angiogenesis and apoptosis of the corpus luteum (Silva et al. 2013). These findings could be related to the effects of hypothyroidism on ovarian lipid metabolism or signalling. CSIRO PUBLISHING Reproduction, Fertility and Development https://doi.org/10.1071/RD17502 Journal compilation Ó CSIRO 2018 www.publish.csiro.au/journals/rfd