Circadian Regulation of Kisspeptin in Female Reproductive Functioning - Kisspeptin Signaling in Reproductive Biology - page 382

Fig. 18.2 ( a ) Representative photomicrographs of Kiss1 mRNA and c-fos mRNA coexpression in
the AVPV of OVX, E 2 -treated female mice housed in constant conditions and killed at different
times throughout the circadian day. Kiss1-containing neurons were visualized with Vector Red
substrate, and c-fos mRNA was marked by the presence of silver grains. White arrows denote
example Kiss1 cells lacking c-fos; yellow arrows denote example Kiss1 cells coexpressing c-fos.
( b ) Mean (±SEM) percentage of Kiss1 mRNA-containing neurons in the AVPV that coexpress
c-fos in OVX, E 2 -treated female mice killed at one of eight times throughout the circadian day.
There was a signifi cant effect of time ( P < 0.01) with increased coexpression of Kiss1 and c-fos in
the late afternoon/early evening. Values with different letters differ signifi cantly from each other.
n = 4-6 animals per group. From Robertson JL, Clifton DK, de la Iglesia HO, Steiner RA, Kauffman
AS. Circadian regulation of Kiss1 neurons: implications for timing the preovulatory gonadotropin-
releasing hormone/luteinizing hormone surge. Endocrinology. 2009;150(8):3664-71. Reprinted
with permission from The Endocrine Society
visualized with mRNA versus protein analyses. To determine whether the SCN
projects to kisspeptin cells to mediate these observed rhythms, we examined
projections from VIPergic and AVPergic SCN cells, given the role of these neuro-
peptides in positively driving the LH surge. We found that AVPergic SCN cells
project directly to a majority of kisspeptin-ir cells, whereas VIPergic SCN cells did
not (Fig. 18.3 ). In mice, AVPergic projections to AVPV kisspeptin cells have also
been identifi ed, with synapses confi rmed at the electron microscopy level, suggesting