Mating Increases Neuronal Tyrosine Hydroxylase Expression and Selectively Gates Transmission of Male Chemosensory Information in Female Mice

Abstract

Exposure to chemosensory signals from unfamiliar males can terminate pregnancy in recently mated female mice. The number of tyrosine hydroxylase-positive neurons in the main olfactory bulb has been found to increase following mating and has been implicated in preventing male-induced pregnancy block during the post-implantation period. In contrast, pre-implantation pregnancy block is mediated by the vomeronasal system, and is thought to be prevented by selective inhibition of the mate’s pregnancy blocking chemosignals, at the level of the accessory olfactory bulb. The objectives of this study were firstly to identify the level of the vomeronasal pathway at which selective inhibition of the mate’s pregnancy blocking chemosignals occurs. Secondly, to determine whether a post-mating increase in tyrosine hydroxylase-positive neurons is observed in the vomeronasal system, which could play a role in preventing pre-implantation pregnancy block. Immunohistochemical staining revealed that mating induced an increase in tyrosine-hydroxylase positive neurons in the arcuate hypothalamus of BALB/c females, and suppressed c-Fos expression in these neurons in response to mating male chemosignals. This selective suppression of c-Fos response to mating male chemosignals was not apparent at earlier levels of the pregnancy-blocking neural pathway in the accessory olfactory bulb or corticomedial amygdala. Immunohistochemical staining revealed an increase in the number of tyrosine hydroxylase-positive neurons in the accessory olfactory bulb of BALB/c female mice following mating. However, increased dopamine-mediated inhibition in the accessory olfactory bulb is unlikely to account for the prevention of pregnancy block to the mating male, as tyrosine hydroxylase expression did not increase in females of the C57BL/6 strain, which show normal mate recognition. These findings reveal an association of mating with increased dopaminergic modulation in the pregnancy block pathway and support the hypothesis that mate recognition prevents pregnancy block by suppressing the activation of arcuate dopamine release.

Transient and sustained afterdepolarizations in accessory olfactory bulb mitral cells are mediated by distinct mechanisms that are differentially regulated by neuromodulators

“…To further explore this issue we examined the effects of two neuromodulators, carbachol and dopamine, known to be active in the AOB (Dong et al, 2009 ; Matthews et al, 2013 ) on the sustained firing responses and DAPs in AOB mitral cells.…”

“…M1 activation was shown to enhance persistent firing in both granule and mitral cells of the AOB (Smith and Araneda, 2010 ). Other neuromodulators known to be active in the AOB are noradrenaline and dopamine (Dong et al, 2009 ; Matthews et al, 2013 ), both shown to be associated to the AOB-mediated mate recognition in mice (Brennan, 2009 ). Interestingly, both acetylcholine and dopamine were recently linked to the atypical social behavior of BTBR mice (Karvat and Kimchi, 2014 ; Squillace et al, 2014 ).…”

Cannabinoid modulation of alpha2 adrenergic receptor function in rodent medial prefrontal cortex

“…Western blotting at a concentration of 1–2 μg/mL detects a band of approximately 72 kDa. Immunoperoxidase and immunofluorescence detections of DβH were conducted in sections of mouse brains, and DβH was also expressed in cell cultures (Polanski et al ., ; Matthews et al ., ). The monoclonal antibody against HA‐α2A‐AR was generated in mouse against the 12‐amino‐acid peptide CYPYDVPDYASL.…”

Sexual cues influence cocaine‐induced locomotion, anxiety and the immunoreactivity of oestrogen receptor alpha and tyrosine hydroxylase in both sexes

“…The major sources of DA are the DA‐releasing neurones of the ventral midbrain, mainly originated in the VTA, ZI and substantia nigra pars compacta . Increased levels of TH expression are often used to indicate enhanced DA synthesis and release . Therefore, the TH‐IR neurones observed in the VTA and ZI were likely to have been dopaminergic.…”