Dopaminergic projections to the medial preoptic area of postpartum rats

Abstract

Dopamine receptor activity in the rodent medial preoptic area (mPOA) is crucial for the display of maternal behaviors, as well as numerous other physiological and behavioral functions. However, the origin of dopaminergic input to the mPOA has not been identified through neuroanatomical tracing. To accomplish this, the retrograde tracer Fluorogold was iontophoretically applied to the mPOA of postpartum laboratory rats, and dual-label immunocytochemistry for Fluorogold and tyrosine hydroxylase later performed to identify dopaminergic cells of the forebrain and midbrain projecting to the mPOA. Results indicate that the number of dopaminergic cells projecting to the mPOA is moderate (~90 cells to one hemisphere), and that these cells have an unexpectedly wide distribution. Even so, more than half of the dual-labeled cells were found in what has been considered extensions of the A10 dopamine group (particularly the ventrocaudal posterior hypothalamus and adjacent medial supramammillary nucleus), or in the A10 cells of the ventral tegmental area. The rostral hypothalamus and surrounding region also contained numerous dual-labeled cells, with the greatest number found within the mPOA itself (including in the AVPV and PVpo). Notably, dual-labeled cells were rare in the zona incerta (A13), a site previously suggested to provide dopaminergic input to the mPOA. This study is the first to use anatomical tracing to detail the dopaminergic projections to the mPOA in the laboratory rat, and indicates that much of this projection originates more caudally than previously suggested. Keywordscatecholamine; dopamine; female; maternal behavior; postpartumThe medial preoptic area (mPOA) of the basal forebrain is necessary for a wide range of physiological and behavioral functions in mammals, including thermoregulation (Bicego et al., 2007;Kumar et al., 2007), arousal (Kumar et al., 2007;Szymusiak et al., 2007), sodium and fluid balance (Bourque et al., 1994), gonadotropin release (Funibashi et al., 2002;Mahesh and Brann, 2005), feeding (Patterson et al., 2006;Leibowitz et al., 2007), and sexual responses (Xiao et al., 2005;Hull and Dominguez, 2006;Balthazart and Ball, 2007). The mPOA has also long been implicated in the control of maternal motivation and behavior in mammals (Numan, 1974;Numan and Insel, 2003;Lonstein and Morrell, 2006). With its high concentration of ovarian steroid receptors (Pfaff and Keiner, 1973;Parsons et al., 1982), receipt of multisensory inputs (Kevetter and Winans, 1981;Rizvi et al., 1992;Chadha and Hubscher, 2008), and connections with regions mediating motor activity and reward Sinnamon, 1992), the mPOA is well-equipped to organize parental responses toward offspring.* To whom correspondence should be addressed, lonstein@msu.edu, Phone: 517-353-8675, FAX: 517-432-2744. NIH Public Access Indeed, postpartum rats with lesions of the mPOA display impaired retrieval and licking of pups, and poor nest construction (Numan and Insel, 2003). Conversely, hormonal or electrical stimulation of the mPOA acti...

Dopaminergic inhibition of gonadotropin-releasing hormone neurons in the cichlid fish,Astatotilapia burtoni

“…1, lower row, arrowhead). These cell bodies imply a local source of THpositive processes, although external sources, as reported in mammals (Miller and Lonstein, 2009), may contribute. Our findings agree with previous reports of direct contact between dopaminergic terminals and GnRH1 cells in mammals (Jennes et al, 1983;Lehman et al, 1988;Leranth et al, 1988;Pompolo et al, 2003;Tillet et al, 1989).…”

Neuroanatomical Projections of the Species-Specific Tyrosine Hydroxylase-Immunoreactive Cells of the Male Prairie Vole Bed Nucleus of the Stria Terminalis and Medial Amygdala

“…FG and TH immunohistochemistry was performed on every other section throughout the brain using methods similar to previous work from our laboratory [Miller and Lonstein, 2009]. Sections were rinsed with TBS between incubations.…”

“…In all sites, TH-ir cells were examined in every other section through the brain. Previous work in our laboratory demonstrated that confocal analysis of fluorescing secondary antisera was unfeasible because these brain sites are spread throughout the forebrain and midbrain, and the majority of fluorescence was lost before thorough scanning could be completed [Miller and Lonstein, 2009]. To estimate the total number of double-labeled cells in each site, the number of double-labeled cells counted was multiplied by two for each subject, and an Abercrombie correction factor of 0.78 was applied [Abercrombie, 1946].…”

Heat Shock Factor 1 Deficiency Affects Systemic Body Temperature Regulation

“…Thus, the presence of HSF1 in dopamine-containing hypothalamic regions was analysed by co-labelling with TH, the rate-limiting enzyme in dopamine synthesis. The POA receives dopaminergic input from other brain regions including the POA/MPA itself [39]. In the POA, HSF1 is co-localised with TH, suggesting a potential role of HSF1 in autoregulatory dopaminergic temperature regulation.…”