Aloisi A M, Sacerdote P, Albonetti M E, Carli G
Istituto Fisiologis Umana, Siena, Italy.
Brain Res. 1995 Nov 20;699(2):242-9. doi: 10.1016/0006-8993(95)00912-a.
The effects of two intensities of formalin pain on behaviour and beta-Endorphin (beta-EP) concentration in the brain and pituitary were studied in male and female rats. The animals were familiarized with the Hole-Board apparatus for 3 days, and then, after a subcutaneous injection of formalin (50 microliter, 0.1 or 10%) or Sham-injection (Control) in the hindpaw, they were tested in the Hole-Board for 60 min. Licking, Flexing and Paw-Jerk of the injected limb were recorded. beta-EP concentration was determined in the hypothalamus (HYP), the periaqueductal gray matter (PAG), the anterior pituitary (AP) and the neurointermediate lobe (NIL). Licking and Flexing durations were greater in females than males only with formalin 10%. Sex differences in beta-EP concentration between the Control groups were found in all tissues except the HYP; beta-EP levels were higher in females in the PAG and NIL, but greater in the AP in males. beta-EP concentration increased in males in the HYP and NIL with formalin 10%; in females, a decrease was found in the HYP with formalin 0.1%. The present results suggest that: (a) there are differences between males and females in the responses to formalin pain, and the nature (pattern and duration) of the sex differences varies according to the pain intensity; (b) there are differences in beta-EP concentration between the two sexes in control animals, and male and female rats also exhibit differences in the modifications of beta-EP in response to formalin-induced pain.
研究了两种强度的福尔马林疼痛对雄性和雌性大鼠行为以及大脑和垂体中β-内啡肽（β-EP）浓度的影响。动物先在洞板装置中熟悉3天，然后在后爪皮下注射福尔马林（50微升，0.1%或10%）或假注射（对照），之后在洞板中测试60分钟。记录注射肢体的舔舐、弯曲和爪抖情况。测定下丘脑（HYP）、导水管周围灰质（PAG）、垂体前叶（AP）和神经中间叶（NIL）中的β-EP浓度。仅在注射10%福尔马林时，雌性的舔舐和弯曲持续时间比雄性长。除HYP外，对照组所有组织中β-EP浓度均存在性别差异；PAG和NIL中雌性的β-EP水平较高，而AP中雄性的β-EP水平较高。10%福尔马林使雄性HYP和NIL中的β-EP浓度升高；0.1%福尔马林使雌性HYP中的β-EP浓度降低。目前的结果表明：（a）雄性和雌性对福尔马林疼痛的反应存在差异，且性别差异的性质（模式和持续时间）因疼痛强度而异；（b）对照动物中两性的β-EP浓度存在差异，雄性和雌性大鼠对福尔马林诱导疼痛的β-EP变化也存在差异。
