Journal: Scientific Reports
Article Title: Raphe glucose-sensing serotonergic neurons stimulate KNDy neurons to enhance LH pulses via 5HT2CR: rat and goat studies
doi: 10.1038/s41598-024-58470-4
Figure Lengend Snippet: Central administration of serotonin (5HT) and serotonin-2C receptor (5HT2CR) agonist stimulated GnRH pulse generator activity, and 5HT2CR antagonism blocked the 5HT-induced stimulation of GnRH pulse generator activity recorded by multiple unit activity (MUA) in the ARC of OVX goats. ( a ) Schematic illustration of the experimental procedure for determining the effects of lateral ventricle (LV) administration of 5HT and 5HT2CR agonist and antagonist on MUA volley in goats. 5HT and MK212, a 5HT2CR agonist, were injected into the LV at a half-time of the mean interval of MUA volleys (Tm/2) determined by the 5-h prerecording of MUA. SB206553 (SB), a 5HT2CR antagonist, was infused into the LV immediately after the second MUA volley until the 5HT injection at Tm/2 after the third MUA volley. ( b ) Profiles of MUA volleys and LH pulses in representative goats treated with 5HT or Veh (arrows). Arrow heads indicate the peaks of LH pulses identified by the PULSAR computer program. ( c ) The mean MUA volley interval of OVX goats after central 5HT (0.5 or 5 µmol) administration was significantly ( p < 0.05) shortened compared with that of Veh-treated control goats. ( d ) Percent change in mean LH levels of OVX goats after central 5HT (5 µmol) administration significantly ( p < 0.05) increased compared with that of Veh-treated controls. ( e ) Profiles of MUA volleys and LH pulses of representative goats treated with LV infusion of SB (green) or Veh (gray) and LV injection of 5HT (arrows). ( f ) The mean MUA volley intervals at the postinfusion period were significantly ( p = 0.0026) shortened by 5HT injection in the Veh-treated group (gray), whereas the interval at the postinfusion period significantly ( p = 0.0026) elongated in the SB-treated group (green). In addition, significant differences were found in the MUA volley interval between the SB + 5HT and Veh + 5HT groups during the postinfusion period ( p = 0.0037). ( g ) The percent change in mean LH levels in OVX goats treated with LV infusion of SB (green) or Veh (gray). ( h ) Profiles of MUA volleys and LH pulse of representative OVX goats treated with LV administration of MK212 (0.5 or 5 µmol) or Veh (arrows). ( i ) The mean MUA volley interval of OVX goats treated with central administration of MK212 (5 µmol) was significantly shorter than that of Veh-treated controls ( p = 0.0022). ( j ) The percent change in mean LH levels in OVX goats treated with LV administration of MK212 (0.5 or 5 µmol) or Veh. Values are means ± SEMs. The numbers in each column indicate the number of animals used. Arrowheads indicate the peaks of LH pulses identified by the PULSAR computer program.
Article Snippet: An 18-G stainless steel guide cannula was implanted in the LV for intracerebroventricular administration of serotonin hydrochloride (Sigma‒Aldrich), MK212 hydrochloride (a selective 5HT2CR agonist; R&D Systems), or SB206553 hydrochloride (5HT2B/2CR antagonist; Santa Cruz Biotechnology) as described previously .
Techniques: Activity Assay, Injection, Control
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