The role of norepiinephrine in mediating luteinizing hormone release in response to blockade of κ-opioid receptors in the medial preoptic area

The Role of Neurokinin B Signalling in Reproductive Neuroendocrinology

“…However, it is evident that the authors of these reports have been unable to provide adequate morphological evidence of KOR expression within mPOA GnRH neurones, since the only reference to such literature is a review article that mentions KOR expression in the POA without distinguishing between substructures or neuronal populations found therein [90]. Moreover, Zhen and Gallo [87,91] make reference to previous efforts from their laboratory that showed that disinhibition of GnRH secretion following KOR blockade is a noradrenaline-dependent phenomenon, which contradicts their claims of direct action of Dyn on GnRH neurones. The authors cite a poster abstract as the basis of these experiments, which implies that intra-mPOA administration of Dyn suppresses the local noradrenaline tone [92].…”

“…The authors cite a poster abstract as the basis of these experiments, which implies that intra-mPOA administration of Dyn suppresses the local noradrenaline tone [92]. The credibility of claims that GnRH neurones possess inherent (and direct) sensitivity to Dyn, arising solely from the laboratory of Gallo [87,88,89,91], is compromised by the observation that μ- and Δ-opioid receptor agonists, but not KOR agonists, were able to suppress the noradrenaline tone within rat mPOA slices [93]. Collectively, these data do not dispel the controversy over the mechanisms of GnRH pulse generator modulation by KNDy neuropeptide systems.…”