In situ staining of the primo vascular system in the ventricles and subarachnoid space of the brain by trypan blue injection into the lateral ventricle

We examined a new method for visualization of the primo vascular system in the rat brain involving lateral ventricle injection of trypan blue. Results showed that the primo vascular system in the lateral ventricles and arachnoid mater of the brain were preferentially stained relative to blood vessels and fascia. The primo-vessels along blood vessels in the brain were clearly exhibited. In addition, the primo vascular system was evident between the fourth ventricle and the quadrigeminal cistern. Our experimental findings indicate that this new technique of lateral ventricle injection of trypan blue can visualize the primo vascular system in lateral ventricles and arachnoid mater of rats in situ.

Intracerebroventricular leptin injection affects neuroendocrine reproductive axis in ovariectomized rats

BACKGROUND：Leptin regulates neuroendocrine function of the hypothalamus-pituitary-ovary axis in humans. OBJECTIVE： To verify effects of intracerebroventricular leptin injection on neuroendocrine function of the hypothalamus-pituitary-ovary axis in ovariectomized rats. DESIGN, TIME AND SETTING： A randomized, controlled experiment was performed at the Basic Medical Institute, Chengde Medical College between June and October 2007. MATERIALS： Thirty healthy, female, Wistar rats were included in this study. The following compounds were used： leptin; gonadotropin-releasing hormone （GnRH） and luteinizing hormone （LH） enzyme-linked immunosorbent assay kits. METHODS： Rats were randomly divided into 3 groups at 1, 2, and 4 hours after injection. Each group was subdivided into control and experimental groups （n = 5 animals per group and time point）. All rats were subjected to bilateral ovariectomy and, beginning on day 7 after surgery, animals received daily subcutaneous injections of estradiol benzoate （2 μg） for 7 consecutive days. The experimental groups were injected with 5 μL leptin （1 g/L） into the lateral cerebral ventricle, and control groups received an equal volume of physiological saline. MAIN OUTCOME MEASURES： GnRH and LH secretion were examined 1, 2, and 4 hours after injection using GnRH and LH ELISA kits, respectively. RESULTS： In the experimental groups, GnRH secretion significantly increased （P 〈 0.01）, followed by LH secretion （P 〈 0.01）, compared with the control groups. GnRH secretion significantly increased 1 hour after leptin injection （P 〈 0.01）. The LH increase was less pronounced, but still significant （P 〈 0.01）; however, the most prominent LH increase occurred between 1 and 2 hours. Both GnRH and LH secretion reached peak levels at 2 hours after leptin injection. Thereafter, both GnRH and LH secretion decreased, but still maintained very high levels, compared with the control group （P 〈 0.01）. CONCLUSION： Intracerebroventricular leptin injection produced similar effects on GnRH and LH secretion in ovariectomized rats, indicating regulatory effects of leptin on GnRH and LH secretion.