Contents lists available at ScienceDirect General and Comparative Endocrinology journal homepage: www.elsevier.com/locate/ygcen Review article The volcano mouse Neotomodon alstoni of central Mexico, a biological model in the study of breeding, obesity and circadian rhythms M. Miranda-Anaya ⁎ , M. Pérez-Mendoza, C.R. Juárez-Tapia, A. Carmona-Castro Unidad Multidisciplinaria de Docencia e Investigación, Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), Juriquilla, Querétaro 76230 Mexico ARTICLE INFO Keywords: Neotomodon alstoni Reproduction Metabolism Circadian rhythms Obesity ABSTRACT The “Mexican volcano mouse” Neotomodon alstoni, is endemic of the Transverse Neovolcanic Ridge in central Mexico. It is considered as least concern species and has been studied as a potential laboratory model from different perspectives. Two lines of research in neuroendocrinology have been addressed: reproduction and parental care, particularly focused on paternal attention and the influence of testosterone, and studies on physiology and behavior of circadian rhythms, focused on the circadian biology of the species, its circadian locomotor activity and daily neuroendocrine regulation of metabolic parameters related to energy balance. Some mice, when captive, spontaneously develop obesity, which allows for comparisons between lean and obese mice of daily changes in neuronal and metabolic parameters associated with changes in food intake and locomotor activity. This review includes studies that consider this species an attractive animal model where the alteration of circadian rhythms influences the pathogenesis of obesity, specifically with the basic regulation of food intake and metabolism and differences related to sex. This study can be considered as a reference to the comparative animal physiology among rodents. 1. Introduction The mouse Neotomodon alstoni Merriam, 1898, is an endemic noc- turnal murid rodent of the Neotominae subfamily restricted to the Transverse Neovolcanic Ridge of the central zone of Mexico, hence its name of “Mexican volcano mouse.” N. alstoni inhabits pine forests, especially in areas covered with grass. Its altitudinal distribution is between 2600 and 4600 m and can be located in the States of Morelos, Michoacán, Veracruz and Estado de México (García-Becerra et al., 2012). Nowadays, Neotomodon alstoni is listed as Least Concern given its wide distribution, according to the red list of the International Union for Conservation of Nature (IUCN) (Álvarez-Castañeda and Castro- Arellano, 2016). N. alstoni cohabits with other rodents such as Per- omyscus maniculatus, Reithrodontomys megalotis and Microtus mexicanus (Castillo-Guevara et al., 2012; Sánchez-Cordero and Canela-Rojo, 1991; Sánchez-Cordero and Méndez, 2014). N. alstoni lives in burrows and has an omnivorous diet based on grains and insects, which does not seem to vary according to the time of year (Alvarez and Mayo, 1993). In adults, the nasoanal length is 100–130 mm, and the tail ranges from 80 to 105 mm. Ears are almost bare; hair of the dorsal region is dense and gray while the ventral fur is whitish. Adults usually weigh from 40 to 50 g (Nowak, 1999). A cytogenetic analysis shows that its chromosome number is 2n = 48 with a fundamental number NF = 66, like Peromyscus (Uribe et al., 1974). Diverse studies on its reproductive biology show that N. alstoni may adapt favorably to captive conditions (Granados and Hoth, 1989; Luis and Granados, 1990) and, in captivity, it can live up to five years (Ayala-Guerrero et al., 1998). 2. Reproduction and paternal care N. alstoni is reproductive throughout the year but mainly during the dry season of spring, with a higher birth rate from April to May, de- caying during the summer rainy season (Sánchez-Cordero and Canela- Rojo, 1991). N. alstoni can reach sexual maturity in both sexes at three months of age. The estrous cycle lasts between 4 and 5 days, and it is characterized by typical variations of vaginal histology in mice, ac- companied by fluctuations in estradiol, that in females may influence the amplitude of activity, also referred to as “scalloping” (Juárez-Tapia and Miranda-Anaya, 2017). Ultrastructural studies of follicular devel- opment indicate that the first preovulatory follicles, as well as Corpus luteum, are observed after 40 days of age, and the ovulation is spon- taneous (Luis et al., 2008). In males, spermatozoa show an asymmetric head and a recurved hook. They also present long flagella composed of a medium piece and a thin end region, and asymmetric development of microfiber 1,5 and 6 of the axoneme, possibly related to its mobility, which increases in bicarbonate solutions (Villalpando et al., 2000). https://doi.org/10.1016/j.ygcen.2018.04.024 Received 10 February 2018; Received in revised form 6 April 2018; Accepted 23 April 2018 ⁎ Corresponding author. E-mail address: miranmanuel@ciencias.unam.mx (M. Miranda-Anaya). General and Comparative Endocrinology xxx (xxxx) xxx–xxx 0016-6480/ © 2018 Published by Elsevier Inc. Please cite this article as: Miranda-Anaya, M., General and Comparative Endocrinology (2018), https://doi.org/10.1016/j.ygcen.2018.04.024