OR09-02 Chemogenetic Manipulation Of Brainstem Noradrenergic Neurons Modulates The Activity Of The Kisspeptin GnRH Pulse Generator In Mice

Disclosure: S. Vas: None. M. Ruiz-Cruz: None. S. Han: None. S. Hwa-Yeo: None. A.E. Herbison: None. The kisspeptin neurons in the arcuate nucleus (ARN(KISS)) represent the GnRH pulse generator that drives pulsatile luteinizing hormone secretion. These neurons serve as a hub to integrate multiple cues, such as the negative feedback control from steroid hormones, as well as metabolic, and stress-related inputs. Brainstem noradrenergic (NA) neurons have long been implicated in the control of GnRH pulse generator frequency and fertility but the precise mechanisms through which they operate, and their roles remain unclear. Here we used intersectional Cre-lox and FLP-FRT recombination approaches to couple ARN(KISS) neuron GCaMP6 fiber photometry with the brainstem NA DREADD (Designer Receptor Exclusively Activated by Designer Drug) modulation to investigate the role that NA may play in controlling ARN(KISS) pulse generator activity. Kiss1-Cre,GCaMP6s mice were crossed with a mouse line in which FLP recombinase is expressed selectively in dopamine β-hydroxylase (NA) neurons. Adult female mice were injected bilaterally with a FLP-dependent retrograde viral vector (AAVrg-hSyn-fDIO-hM3D(Gq)-mCherry-WPREpA) into the mid-caudal ARN to express excitatory (hM3Dq) DREADD receptors selectively in brainstem NA neurons that project to the ARN. An optical fiber was then implanted to detect the calcium-dependent population activity of KISS(ARN) neurons. Histology revealed m-Cherry/DREADD expression in small sub-populations of tyrosine-hydroxylase neurons located in the brainstem A1, A2 and A6, confirming direct innervation from these regions to the ARN. Selective activation of these NA neurons with 1.5 and 3 mg/kg CNO (s.c.) in diestrous-stage mice, dose-dependently inhibited the frequency of the pulse generator synchronization episodes by 48-76% over 4 hours. These observations demonstrate that, when activated, brainstem NA neurons exert an inhibitory influence on the kisspeptin GnRH pulse generator in intact female mice. The new data may help to dissect how key components of the stress-responsive circuitry impact the central regulation of fertility. Presentation: Friday, June 16, 2023