Mast cells with gonadotropin-releasing hormone-like immunoreactivity in the brain of doves.

Abstract

Using an antiserum (LR-1) raised against mammalian gonadotropin-releasing hormone (GnRH), we previously identified a nonneuronal cell that was more numerous in the medial habenula (MB) of courting ring doves than in individuals housed in visual isolation. The current studies suggest that they are mast cells. Both acidic toluidine blue and toluidine blue dissolved in water/butanediol revealed metachromatic cells with a distribution and morphology similar to that obtained by immunostaining with the GnRH antiserum in the MH. Some cells had granules reactive to safranin in the presence of alcian blue, indicative of a highly sulfated proteoglycan of the heparin family. Immunocytochemical studies demonstrated that all MB cells containing GnRH-like immunoreactivity contained histamine, another mast cell marker.The GnRH-immunoreactive cells had a unilobular, ovoid nucleus. Secretory granules within the cells were electron dense and displayed a variety of internal structures. Fine filamentous processes appeared evenly distributed on the cell surface whether cells were located on the pial surface or within the brain parenchyma. All of these features are characteristic of mast cells. To test whether the epitope recognized by the GnRH antiserum was produced by the mast cells or endocytosed from the cerebrospinal fluid, an iodinated GnRH analog was infected intracerebroventricularly at the initiation of courtship. Radioautography revealed no radioactive cells in the brain, indicating that the GnRH antibody recognized a molecule synthesized by the nonneuronal cells rather than internalized by a receptormediated mechanism. These observations suggest an interaction between a component of the immune network and specific regions of the central nervous system.

Brain mast cells are influenced by chemosensory cues associated with estrus induction in female prairie voles (Microtus ochrogaster)

“…The present results are reminiscent of the reports that mast cells increase in the medial habenula of male ring doves following 2 h of courtship (Silver et al, 1992Silverman et al, 1994;Zhuang et al, 1993). This finding indicates that the medial habenula may be an important brain region in which mast cells congregate and possibly secrete their contents .…”

“…The evidence for mast cells in the brains of birds and rodents is vast, although the precise function of these immune cells in the brain remains unknown (e.g., Silver et al, 1992Silver et al, , 1993Silverman et al, 1994Silverman et al, , 1995Wilhelm et al, 2000;Zhuang et al, 1993;Dimitriadou et al, 1990;Johnson et al, 1991;Johnson and Krenger 1992). In the present study, two independent markers revealed the presence of mast cells in the brains of female prairie voles.…”

“…Brains were cut on a cryostat at 60 μm in the coronal plane. Localization of histamine immunoreactivity was accomplished as previously described (Silverman et al, 1994). Briefly, sections were incubated in 0.5% hydrogen peroxide to remove endogenous peroxidase activity.…”

“…In the medial habenula of ring doves (Streptopelia risoria), mast cells exhibit a marked increase in number and activation in response to sex behavior or sex steroids Silver et al, 1993;Wilhelm et al, 2000). Mast cells are almost completely absent in the brains of longterm castrated males .…”

Changes in Brain Gonadotropin-Releasing Hormone- and Vasoactive Intestinal Polypeptide-like Immunoreactivity Accompanying Reestablishment of Photosensitivity in Male Dark-Eyed Juncos (Junco hyemalis)

“…Blocks were allowed to harden at 4°C for 2-4 h and then immersed in 4% et al, 1994). Studies using avian species other than juncos found that the LR-1 anti-GnRH antibody recognizes brain GnRH-I, but not GnRH-II (Silver et al, 1992;Silverman et al, 1994). Specifically, preoptic area GnRH neurons did not stain following preabsorption with GnRH-I, but were unaffected by preabsorption with GnRH-II.…”