Species and sex differences in brain distribution of corticotropin‐releasing factor receptor subtypes 1 and 2 in monogamous and promiscuous vole species

Abstract

Corticotropin-releasing factor (CRF) receptor subtypes 1 and 2 have been implicated in rodent models of anxiety, but much less is known about the CRF system and social behavior. Both corticosterone and central CRF receptors modulate pair bonding in the monogamous prairie vole. Using receptor autoradiography, we mapped CRFR(1) and CRFR(2) in the brains of two monogamous vole species, the prairie vole and pine vole, and two promiscuous vole species, the meadow vole and montane vole. We found markedly different patterns of brain CRFR(1) and CRFR(2) binding among the four species, including species differences in the olfactory bulb, nucleus accumbens, lateral septum, hippocampus, laterodorsal thalamus, cingulate cortex, superior colliculus, and dorsal raphe. Interestingly, we also observed striking sex differences in voles: CRFR(2) binding was higher in the encapsulated bed nucleus of the stria terminalis in males than females for all four vole species. These results suggest possible sites of action for CRF-induced facilitation of pair bond formation in prairie voles, as well as potential sex differences in the CRF modulation of pair bonding. Further examination of CRF receptors in vole species may reveal a novel role for CRF in social behavior. Ultimately, our results identify several brain regions with conserved CRF receptor patterns across rodent and primate species, in contrast to several brain regions with phylogenetically plastic CRF receptor patterns, and have interesting implications for the evolution of CRF receptor patterns and behavior.

Social isolation induces behavioral and neuroendocrine disturbances relevant to depression in female and male prairie voles

“…Consistent with this hypothesis are data from rats showing a more pronounced habituation of corticosterone responses to chronic restraint stress in males versus females (Galea et al, 1997). Sex differences in the central synthesis or effects of other neuropeptides, including vasopressin (DeVries & Simerly, 2002;DeVries & Panzica, 2006) or CRF (Lim et al, 2005;Lim et al, 2006), may also mediate the neuroendocrine responses described here.…”

Neuropeptide binding reflects convergent and divergent evolution in species-typical group sizes

“…The present findings for 125 I-SG demonstrate that putative CRF receptors in songbirds are distributed in a pattern very similar to mammals (Primus et al, 1997;Sanchez et al, 1999;Van Pett et al, 2000;Lim et al, 2005), with 125 I-SG binding sites being found throughout the pallium, striatum, extended amygdala, and various regions of the hypothalamus. However, in contrast to mammals, binding in the septal nuclei was largely restricted to the posterior septum (commissural septal nucleus and nucleus of the pallial commissure).…”

“…Interestingly, these studies have also shown that species-specific densities of V 1a receptors in brain areas other than the ventral pallidum do not correlate with mating system, suggesting that adaptive receptor functions remain to be elucidated that are independent of mating system (review: Goodson and Bass, 2001). A similar observation is made for CRF receptors in voles (Lim et al, 2005). We hypothesize that these other adaptive functions include the regulation of sociality, thus the present studies focus on the evolution of species-typical group size and its relationship to neuropeptide receptor densities.…”

“…Finally, as with V 1a receptor densities, numerous species differences have been observed for CRF receptor densities in voles (Lim et al, 2005), but these differences do not show clear correspondence to an identified dimension of behavior. We found that in songbirds, numerous species differences in 125 I-SG binding reflect sociality, although these areas do not include areas that exhibit species differences in voles.…”

“…Rodents also exhibit significant species differences in V 1a receptor density within the LS, but to date, it has not been possible to link these differences to a particular dimension of behavior (for a discussion, see Goodson and Bass, 2001). However, the rodent species employed (which were selected based largely on their mating systems and patterns of parental care) do not show reliable and/or strong differences along the dimension of species-typical group size.Finally, as with V 1a receptor densities, numerous species differences have been observed for CRF receptor densities in voles (Lim et al, 2005), but these differences do not show clear correspondence to an identified dimension of behavior. We found that in songbirds, numerous species differences in 125 I-SG binding reflect sociality, although these areas do not include areas that exhibit species differences in voles.…”