Time-course of changes in hypothalamic NTPDase3-levels after a single subcutaneous injection of 17β-estradiol (E
). Optical density measurements of the 82–85 kDa immunoreactive bands were analyzed in ovx animals and ovx plus E2-treated animals 2–26 hours after a single subcutaneous injection of E2. Samples were taken in two-hours intervals after E2-priming. A: Estrogen-treatment induced a sharp rise in NTPDase3-expression in lateral hypothalamic samples, reaching significantly elevated peak levels by four hrs. After the peak, a gradual decrease in NTPDase3-expression was observed reaching nearly control ovx levels by 26 hrs. B: In medial hypothalamic samples, E2-treatment induced a gradual increase in NTPDase3-levels with highest values observed at 10 hrs after E2-priming. This was followed by falling of NTPDase3-level that reached a nadir at 18 hrs, followed by a second rise by 24–26 hrs. The difference in the time-course of changes in NTPDase3-levels between the medial and lateral part of the hypothalamus suggests that NTPDase3 may serve region-specific functions in the neuroendocrine hypothalamus. C: Mean E2 blood plasma concentrations measured after a single subcutaneous injection of E2 (water soluble, 23 μg/100 g body weight).