TY - JOUR
T1 - Ovarian steroids increase spinogenetic proteins in the macaque dorsal raphe
AU - Rivera, H. M.
AU - Bethea, C. L.
N1 - Funding Information:
The authors greatly appreciate the time and effort devoted by Dr. Jessica Henderson for conducting steroid implants and collecting brain tissue, Dr. Luisa Appleman for helping optimize the immunocytochemistry protocol, Dr. John Morrison's laboratory for helping us develop an immunogold silver staining protocol, and Dr. Anda Cornea for teaching the operation of Marianas Stereological workstation/Image J software and Zeiss microscope/StereoInvestigator software. The authors are deeply grateful to the dedicated staff of the Division of Animal Resources for their outstanding care and attention to the health and well-being of our monkeys. This research was supported by NIH grants MH062677 to C.L.B., T32HD007133 to H.M.R., the Eunice Kennedy Shriver NICHD through cooperative agreement HD018185 as part of the Specialized Cooperative Center Program in Reproduction and Infertility Research , and the core grant RR000163 for the operation of the ONPRC.
PY - 2012/4/19
Y1 - 2012/4/19
N2 - Dendritic spines are the basic structural units of neuronal plasticity. Intracellular signaling cascades that promote spinogenesis have centered on RhoGTPases. We found that ovarian steroids increase gene expression of RhoGTPases [Ras homolog gene family member A (RhoA), cell division control protein 42 homolog (Cdc42), and ras-related C3 botulinum toxin substrate (Rac)] in laser-captured serotonin neurons. We sought to confirm that the increases observed in gene expression translate to the protein level. In addition, a preliminary study was conducted to determine whether an increase in spines occurs via detection of the spine marker protein, postsynaptic density-95 (PSD-95). Adult ovariectomized (Ovx) monkeys were treated with estradiol (E), progesterone (P), or E+P for 1 month. Sections through the dorsal raphe nucleus were immunostained for RhoA and Cdc42 (n=3-4/group). The number and positive pixel area of RhoA-positive cells and the positive pixel area of Cdc42-positive fibers were determined. On combining E- and E+P-treated groups, there was a significant increase in the average and total cell number and positive pixel area of RhoA-positive cells. E, P, and E+P treatments, individually or combined, also increased the average and total positive pixel area of Cdc42-positive fibers. With remaining sections from two animals in each group, we conducted a preliminary examination of the regulation of PSD-95 protein expression. PSD-95, a postsynaptic scaffold protein, was examined with immunogold silver staining (n=2/group), and the total number of PSD-95-positive puncta was determined with stereology across four levels of the dorsal raphe. E, P, and E+P treatment significantly increased the total number of PSD-95-positive puncta. Together, these findings indicate that ovarian steroids act to increase gene and protein expression of two pivotal RhoGTPases involved in spinogenesis and preliminarily indicate that an increased number of spines and/or synapses result from this action. Increased spinogenesis on serotonin dendrites would facilitate excitatory glutamatergic input and in turn, increase serotonin neuronal activity throughout the brain.
AB - Dendritic spines are the basic structural units of neuronal plasticity. Intracellular signaling cascades that promote spinogenesis have centered on RhoGTPases. We found that ovarian steroids increase gene expression of RhoGTPases [Ras homolog gene family member A (RhoA), cell division control protein 42 homolog (Cdc42), and ras-related C3 botulinum toxin substrate (Rac)] in laser-captured serotonin neurons. We sought to confirm that the increases observed in gene expression translate to the protein level. In addition, a preliminary study was conducted to determine whether an increase in spines occurs via detection of the spine marker protein, postsynaptic density-95 (PSD-95). Adult ovariectomized (Ovx) monkeys were treated with estradiol (E), progesterone (P), or E+P for 1 month. Sections through the dorsal raphe nucleus were immunostained for RhoA and Cdc42 (n=3-4/group). The number and positive pixel area of RhoA-positive cells and the positive pixel area of Cdc42-positive fibers were determined. On combining E- and E+P-treated groups, there was a significant increase in the average and total cell number and positive pixel area of RhoA-positive cells. E, P, and E+P treatments, individually or combined, also increased the average and total positive pixel area of Cdc42-positive fibers. With remaining sections from two animals in each group, we conducted a preliminary examination of the regulation of PSD-95 protein expression. PSD-95, a postsynaptic scaffold protein, was examined with immunogold silver staining (n=2/group), and the total number of PSD-95-positive puncta was determined with stereology across four levels of the dorsal raphe. E, P, and E+P treatment significantly increased the total number of PSD-95-positive puncta. Together, these findings indicate that ovarian steroids act to increase gene and protein expression of two pivotal RhoGTPases involved in spinogenesis and preliminarily indicate that an increased number of spines and/or synapses result from this action. Increased spinogenesis on serotonin dendrites would facilitate excitatory glutamatergic input and in turn, increase serotonin neuronal activity throughout the brain.
KW - Estradiol
KW - Immunocytochemistry
KW - PSD-95
KW - Progesterone
KW - RhoGTPase
KW - Serotonin
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UR - http://www.scopus.com/inward/citedby.url?scp=84858624894&partnerID=8YFLogxK
U2 - 10.1016/j.neuroscience.2012.02.002
DO - 10.1016/j.neuroscience.2012.02.002
M3 - Article
C2 - 22342969
AN - SCOPUS:84858624894
SN - 0306-4522
VL - 208
SP - 27
EP - 40
JO - Neuroscience
JF - Neuroscience
ER -