Neuroscience 169 (2010) 1094–1104 BRIEF PUP EXPOSURE INDUCES Fos EXPRESSION IN THE LATERAL HABENULA AND SEROTONERGIC CAUDAL DORSAL RAPHE NUCLEUS OF PATERNALLY EXPERIENCED MALE CALIFORNIA MICE (PEROMYSCUS CALIFORNICUS) T. R. DE JONG,a* K. R. MEASOR,b M. CHAUKE,a,b In a majority of mammalian species, mothers play the largest B. N. HARRISa,c AND W. SALTZMANa,b,c or only role in providing food, warmth and protection to off- aDepartment of Biology, University of California, Riverside, CA 92521, spring. However, fathers are significantly involved in parental USA care in approximately 5–6% of mammalian species, includ- bNeuroscience Graduate Program, University of California, Riverside, ing humans (Kleiman and Malcolm, 1981). Despite the strong CA 92521, USA impact of both adequate and inadequate human paternal cEvolution, Ecology and Organismal Biology Graduate Program, Uni- care on child development, mammalian paternal care is versity of California, Riverside, CA 92521, USA much less studied and understood than its maternal counter- part (Sarkadi et al., 2008; Kentner et al., 2009). Abstract—Fathers play a substantial role in infant care in a The California mouse (Peromyscus californicus), a ro- small but significant number of mammalian species, includ- dent species that is highly monogamous and biparental, ing humans. However, the neural circuitry controlling pater- both in the wild (Ribble and Salvioni, 1990; Ribble, 1991; nal behavior is much less understood than its female coun- Gubernick and Teferi, 2000) and in the laboratory (Dudley, terpart. In order to characterize brain areas activated by pa- 1974; Gubernick and Alberts, 1987), is often used to study ternal care, male California mice were separated from their causes and consequences of paternal care. Similar to female mate and litter for 3 h and then exposed to a pup or a control object (a glass pebble with the approximate size and most female mammals, sexually and parentally experi- oblong shape of a newborn pup) for 10 min. All males receiv- enced male California mice are more likely to respond ing a pup showed a strong paternal response towards it, paternally to a stimulus pup (grooming, huddling and even whereas males receiving a pebble interacted with it only performing the kyphotic nursing posture) than virgin males occasionally. Despite the clear behavioral differences, expo- (Gubernick and Nelson, 1989; Gubernick et al., 1994; de sure to a pup did not increase Fos-like immunoreactivity Jong et al., 2009). In females, this phenomenon is thought (Fos-LIR) compared to a pebble in brain areas previously to be caused by a shift in perception of distal sensory cues found to be associated with parental care, including the me- dial preoptic nucleus and medial bed nucleus of the stria (mostly olfactory and auditory) from pups, from threatening terminalis. Pup exposure did, however, significantly increase and aversive to non-threatening and rewarding (Numan, Fos-LIR in the lateral habenula (LHb) and in predominantly 2007; Numan and Stolzenberg, 2008). It is likely that a serotonergic neurons in the caudal dorsal raphe nucleus similar shift occurs in males. In females, however, peripar- (DRC), as compared to pebble exposure. Both the LHb and tum release of estrogen, progesterone, oxytocin, and pro- DRC are known to be involved in the behavioral responses to lactin plays an important and well-described role in the strong emotional stimuli; therefore, these areas might play a role in controlling parental behavior in male California mice. onset of maternal behavior (Grattan, 2001; Mann and © 2010 IBRO. Published by Elsevier Ltd. All rights reserved. Bridges, 2001; Russell et al., 2001; Numan and Insel, 2003; Numan, 2006; Bosch and Neumann, 2008; Brunton et al., Key words: paternal care, Fos, lateral habenula, caudal dor- 2008), whereas these hormones seem to play a smaller and sal raphe, serotonin (5-HT). less understood role in the onset of paternal care (Wynne- *Corresponding author. Tel: ϩ1-951-827-5929; fax: ϩ1-951-827- Edwards and Timonin, 2007; Kentner et al., 2009). 4286. Maternal responses to pups are controlled by an exten- E-mail address: [email protected] (T. R. de Jong). Abbreviations: 5-HT-LIR, serotonin-like immunoreactiv(e)(ity); AcbC, sive neural network, of which many components have been nucleus accumbens core; AcbSh, nucleus accumbens shell; BLA, identified using immunohistochemical staining of the peptide basolateral amygdaloid nucleus; CeL, lateral division of the central Fos, a widely used marker for neuronal activation (Hoffman amygdaloid nucleus; DRC, caudal dorsal raphe nucleus; DRI, inter- fascicular dorsal raphe nucleus; Fos-LIR, Fos-like immunoreactiv(e- and Lyo, 2002). In maternal females, full or partial access to )(ity); LC, locus coeruleus; LHb, lateral habenula; LSV, ventral lateral a pup consistently activates the medial preoptic area and the septal nucleus; MePD, posterodorsal medial amygdaloid nucleus; ventromedial bed nucleus of the stria terminalis, and (less MPN, medial preoptic nucleus; MPO, medial preoptic nucleus; PaL, lateral paraventricular hypothalamic nucleus; STLD, dorsal lateral di- consistently) the nucleus accumbens, lateral septum, central vision of the bed nucleus of the stria terminalis; STMPM, medial and medial amygdala, lateral habenula and ventrolateral peri- posteromedial division of the bed nucleus of the stria terminalis; aqueductal grey (Calamandrei and Keverne, 1994; Fleming STMV, ventromedial division of the bed nucleus of the stria terminalis; VLPAG, ventrolateral periaqueductal gray; VLPO, ventrolateral preop- et al., 1994; Fleming and Walsh, 1994; Numan and Numan, tic area. 1994; Walsh et al., 1996; Lonstein et al., 1998, 2000; 0306-4522/10 $ - see front matter © 2010 IBRO. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.neuroscience.2010.06.012 1094 T. R. de Jong et al. / Neuroscience 169 (2010) 1094–1104 1095 Kalinichev et al., 2000; Lonstein and De Vries, 2000; Shee- 44ϫ24ϫ20 cm3) containing wood chip bedding and cotton for nest han et al., 2000; Stack and Numan, 2000). building. Mice were maintained on a 14:10-h day/night cycle To date, only a few researchers have attempted to (lights on at 0500 h.), in an ambient temperature of approximately study pup-induced Fos expression in male rodents. In 23 °C and approximately 65% humidity. They had ad libitum virgin male prairie voles (Microtus ochrogaster), Fos ex- access to chow (Purina 5001 Rodent Diet) and water. All mice were descendants of mice purchased from the Pero- pression was increased following3hofpaternal interac- myscus Genetic Stock Center (University of South Carolina, Colum- tion with pups (compared with exposure to a piece of bia, SC, USA). They were born and raised in our laboratory colony, chocolate) in the lateral septum, medial preoptic area, weaned at 27–33 days of age (prior to the birth of the next litter of medial bed nucleus of the stria terminalis, posterodorsal siblings to prevent non-experimental pup exposure) and housed in medial amygdala, nucleus reuniens, and paraventricular same-sex groups of 2–4 animals (littermates or unrelated, age- nucleus of the thalamus (Kirkpatrick et al., 1994). Previous matched mice) until the start of the experiment. The male and female work in our laboratory showed that distal pup cues in- in each breeding pair were never siblings or first-cousins. creased Fos expression in the medial preoptic nucleus All experimental procedures were carried out in accordance (MPN) of paternally experienced, but not virgin male Cal- with the National Institutes of Health Guide for the Care and Use of Laboratory Animals, and were approved by the University of ifornia mice, and paternally experienced California mice California, Riverside, Institutional Animal Care and Use Commit- showed increased Fos expression in the medial postero- tee. All efforts were made to minimize the number of animals used medial and medioventral bed nucleus of the stria terminalis and their suffering. The University of California, Riverside is fully (STMV and STMPM) compared to virgin males, even after accredited by the Association for Assessment and Accreditation of 3 h of isolation (de Jong et al., 2009). Interestingly, pater- Laboratory Animal Care (AAALAC). nally experienced California mice also showed increased Fos expression in the caudal dorsal raphe nucleus Experimental design (DRC) compared to virgin males. The dorsal raphe nu- Breeding pairs were weighed twice weekly to monitor health and cleus is a crucial component of the serotonin (5-HT) pregnancies. When births were due, home cages were checked system and consists mainly of forebrain-projecting se- every day for pups. On postnatal day 1, 2, or 3, females and pups rotonergin neurons (Lowry, 2002; Michelsen et al., were removed from their home cage between 08.00 h and 09.30 2007). Because an intact serotonin system has recently h and either placed in a separate cage, leaving the male alone in been shown to be required for normal expression of ma- the home cage (“isolated”), or immediately placed back with the ternal care in mice (Lerch-Haner et al., 2008), we hypoth- male (“with family”). Isolated males were divided into three groups, esized that paternal experience and/or pup exposure might receiving either no stimulus (nϭ7), a pebble (nϭ7), or a pup activate the serotonin system as reflected by increased (nϭ8). Family-housed males were divided into two groups, receiv- ϭ ϭ Fos expression within serotonergic neurons. ing either no stimulus (n 6) or a pebble (n 7). There was no experimental group of males that remained with their family and The present experiment was performed to characterize received a pup stimulus, since the presence of an actively mater- patterns of neural activation in paternally experienced nal female mate would likely have changed the males’ paternal adult male California mice in response to exposure to their behavior and neuronal activation too much to make it a valid own pup versus a control stimulus (a glass pebble with the control group. All males were semi-randomly spread over the five approximate size and oblong shape of a newborn pup) or experimental groups, with emphasis on the equal distribution of no stimulus at all.