<i>Kiss1</i> neurons in the medial amygdala of mice are sexually dimorphic and unique from hypothalamic anteroventral periventricular <i>Kiss1</i> neurons in their action potential firing properties
Kiss1 neurons in the medial amygdala show some sexual dimorphism in number and excitability, but their overall firing properties appear similar across sexes and estrous cycles.
Where it sits
this study against the rest of the kisspeptin (kp-10) corpusSummary and findings
This study examined the action potential firing properties of Kiss1 neurons in the medial amygdala of adult male and female mice. Whole-cell patch-clamp recordings were performed to assess excitability and firing characteristics. The findings indicate sexual dimorphism in neuron numbers and excitability between sexes.
Abstract
The importance of hypothalamic kisspeptin ( Kiss1 ) neurons in controlling the reproductive axis is well established, while a population of extra-hypothalamic Kiss1 neurons is found in the medial amygdala (MeA) of both males and females in rodents and is less well understood. The MeA is connected with the olfactory bulbs, the hypothalamus and cortical areas. MeA Kiss1 neurons have been implicated in sexual behaviour and modulation of the reproductive axis; however, little is known about their action potential firing properties, which would influence kisspeptin release in target brain regions, nor whether their physiological properties are sex- or estrous cycle-dependent. In this study, whole-cell patch-clamp recordings were made from Kiss1 neurons in brain slices containing the MeA of adult female (estrous and diestrous) and male mice. MeA Kiss1 ( Kiss1 MeA ) neurons were sexually dimorphic, with greater numbers in male compared to female mice and a slower change in excitability in estrous females compared with males. However, combining a range of electrophysiological parameters using principal component analysis did not reveal a distinct sex- or estrous cycle-linked phenotype, suggesting that the properties of Kiss1 MeA neurons- and therefore kisspeptin release- are broadly similar. Interestingly, Kiss1 MeA neurons had unique electrophysiological properties compared with anteroventral periventricular (AVPV) hypothalamic Kiss1 ( Kiss1 AVPV ) neurons in female mice; with their reduced excitability, achieving action potential firing frequencies greater than 10Hz required a larger current input, indicating that Kiss1 MeA neurons require stronger synaptic input to achieve firing frequencies that drive kisspeptin release. These findings provide new information about the physiological properties of Kiss1 MeA neurons, showing subtle sex differences and profound regional differences between the MeA and AVPV.
Background
Not reported in abstract.
Methods
Not reported in abstract.
Results
Not reported in abstract.
Interpretation
Not reported in abstract.
Limitations
Not reported in abstract.