OR47-5 Time Course Study of Targeted Ablation of KNDy Neurons, but not Tyrosine-Hydroxylase Neurons, in the Rat Arcuate Nucleus Using a Neurokinin B-Saporin

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: OR47-Hypothalamus-Pituitary Development & Biology
Tuesday, June 18, 2013: 9:15 AM-10:45 AM
Presentation Start Time: 10:15 AM
Room 130 (Moscone Center)
Cleyde Vega Helena1, Bruna Kalil2, Janete A. Anselmo-Franci3 and Richard Bertram*1
1Florida State University, Tallahassee, FL, 2University of Sao Paulo, Ribeirão Preto, Brazil, 3University of Sao Paulo, Ribeirao Preto, Brazil
A subset of hypothalamic arcuate neurons that coexpress kisspeptin, neurokinin B and dynorphin (KNDy neurons) has been postulated to be critical for puberty onset and regulation of gonadotropin secretion. It has been also shown that kisspeptin stimulates prolactin (PRL) release, in an estradiol and time-dependent manner. A method for targeted ablation of KNDy neurons was recently developed using the molecular neurotoxin saporin conjugated to the selective NK3R agonist [MePhe7]Neurokinin B (Nk3-SAP). We describe here a time course study of destruction of KNDy cell bodies and fibers, as well as the integrity of dopaminergic neurons located in the arcuate nucleus. Ovariectomized rats weighting 230-270g were microinjected bilaterally into the arcuate nucleus with Blank-SAP or Nk3-SAP. Rats were transcardiacally perfused 1, 2 or 3 weeks after the injections and an immunocytochemistry for kisspeptin was performed in the arcuate nucleus region containing the KNDy neurons of all rats. The number of KNDy neurons was significantly decreased after 1 week of the toxin injection, however analysis of kisspeptin fiber density demonstrated that maximal fiber ablation was only achieved 3 weeks after the microinjections. Immunocytochemistry was also performed to quantify the expression of tyrosine hydroxylase (TH, the rate-limiting enzyme producing dopamine) in the arcuate nucleus of the same animals injected in our test.  Our results confirmed that the toxin did not modify the number of TH-immunoreactive neurons in the arcuate nucleus. Since KNDy neurons and fibers are ablated after 3 weeks while TH-positive neurons are not, this method can be useful for the study of KNDy neuron actions on prolactin secretion.

Nothing to Disclose: CVH, BK, JAA, RB

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: NIH DA43200