Estrus induction in four species of voles (Microtus).

Abstract

Male-induced estrus was examined in montane (Microtus montanus), meadow (M. pennsylvanicus), prairie (M. ochrogaster), and pine (M. pinetorum) voles. Duration of male contact needed for receptivity, effects of parity, and vaginal cytology were assessed. Among nulliparous females, montane voles attained receptivity with less male contact than prairie voles. Meadow and pine voles showed very low receptivity rates. Among parous females, montane and meadow voles did not differ in duration of male contact needed for receptivity and required less than prairie voles. Overall, parous females had higher receptivity rates than nulliparous females. When isolated from males, prairie and pine voles had more leukocytes and fewer cornified cells in vaginal smears than montane or meadow voles. Species differences in estrus induction are discussed in relation to species differences in social organization.

Parental Responsiveness Is Feminized after Neonatal Castration in Virgin Male Prairie Voles, but Is Not Masculinized by Perinatal Testosterone in Virgin Females

“…However, this apparently cannot be generalized across all induced ovulators, or even across the genus Microtus, because sexual behavior in the biparental, monogamous, and induced-ovulating pine vole (Microtus pinetorum) (Fitzgerald and Madison, 1983;Oliveras and Novak, 1986;Sawrey and Dewsbury, 1985;Taylor, Salo, and Dewsbury, 1992) can be both masculinized and defeminized by even a brief neonatal testosterone treatment (a single 0.5-mg TP injection on day of birth) (Wekesa and Vandenbergh, 1996). Therefore, even within closely related species of Microtus there is a diverse array of hormonal mechanisms affecting sexual differentiation of reproductive behaviors, emphasizing the value of using Microtine rodents as a model for studying the effects of hormones on behavioral development in mammals.…”

Chemical Cues are Necessary but Insufficient for Reproductive Activation of Female Pine Voles (Microtus pinetorum)1

“…The nature of the stimuli controlling these changes has received considerable attention. Chemical cues were once thought to be sufficient for reproductive activation in arvicoline rodents, but more recently this finding has been reexamined [16][17][18]. It has been hypothesized that there may be a relationship between the type of mating system displayed by a rodent species and the type of cues sufficient to induce estrus [16][17][18].…”

“…Chemical cues were once thought to be sufficient for reproductive activation in arvicoline rodents, but more recently this finding has been reexamined [16][17][18]. It has been hypothesized that there may be a relationship between the type of mating system displayed by a rodent species and the type of cues sufficient to induce estrus [16][17][18]. In socially monogamous prairie voles (Microtus ochrogaster), initial changes are induced by contact with chemical cues in male urine, but extended cohabitation with a male is necessary for behavioral receptivity [19].…”

“…In other mammals, estrus and ovulation do not occur spontaneously. Male-related stimuli appear to be essential for induction of estrus in a number of arvicoline rodents (voles and lemmings) [15][16][17]. Stimuli from males induce rapid changes in neuroendocrine and endocrine functions.…”

Estrogen regulation of cell proliferation and distribution of estrogen receptor‐α in the brains of adult female prairie and meadow voles

“…For example, in comparison with monogamous voles, promiscuous voles develop more rapidly in their overall brain growth (Gutierrez et al, 1989) and in the development of specific central systems, such as brain-derived neurotrophic factor (Liu et al, 2001b). Female meadow voles are induced to undergo behavioral estrus more rapidly after exposure to a conspecific male (Taylor et al, 1992) and appear to perform better in navigational mazes (Gaulin et al, 1990) compared with female prairie voles. Monogamous and promiscuous voles also differ in their neuropeptide systems, such as vasopressin and oxytocin (Insel and Shapiro, 1992;Wang et al, 1997b), and such differences appear to underlie their ability to form and express pair bonding behavior (Insel and Hulihan, 1995;Liu et al, 2001a).…”