Due to the interesting anti-proliferative properties of gallium-thiosemicarbazone complexes, the production of [67Ga]labeled 2-acetylpyridine 4,4-dimethyl thiosemicarbazone (APTSM2) was investigated. The freshly prepared [67Ga]GaCl3 was mixed with 2-acetylpyridine 4,4-dimethyl thiosemicarbazone for 60 minutes at 90 °C to yield [67Ga]APTSM2 with a radiochemical yield of more than 98%. Radio-thin-layer-chromatography (RTLC) showed a radiochemical purity of more
than 99%. A specific activity of about 370–740 MBq/mmol (10–20 Ci/mmol) was obtained. The stability of the final product was
checked in the absence and presence of human serum at 37 °C. The partition coefficient of the final complex was also determined.
The biodistribution of the labeled compound in normal rats was compared with that of free Ga3+ cation up to 22 hours.
The effects of an intraperitoneal (i.p.) injection of different doses of sildenafil, a cyclic guanosin monophosphate (cGMP) specific phosphodiesterase type 5 (PDE 5) inhibitor, on memory retention of young (2-month-old) and middle aged (12-month-old) male Wistar rats were investigated. Passive avoidance behaviour was studied in a one trial learning, step - through type, passive avoidance task utilizing the natural preference of rats for a dark environment. In each category (young or middle-aged) different groups of rats received vehicle or sildenafil (1, 3, 10, 20 mg*kg-1, i.p.) immediately after training and one group remained uninjected serwing as control. Retention latencies were measured 48 h later. To asses a possible non-specific proactive effect of sildenafil, the response latencies in a group of rats not receiving foot shock were also tested. The results showed that the post-training i.p. administration of sildenafil did not facilitate retention performance of a passive avoidance response in both young and middle aged rats compared to control or vehicle groups. Also, sildenafil did not affect response latencies in rats not having received the footshock on the training trial, indicating that sildenafil does not show a non-specific proactive affect on retention performance. The comparison of retention time between young and middle aged rats showed that the memory of the latter had been significantly reduced. In conclusion, this study suggests that sildenafil has no effects on memory retention in Wistar rats.
The role of ovarian hormones, nitric oxide, and their interaction on learning and memory has been widely investigated. The present study was carried out to evaluate the effect of Acute (A) and Chronic (C) L-Arginine (L-Arg) administration on learning and memory in ovariectomized (OVx) rats. Forty-five rats were divided into six groups: 1) sham, 2) OVx, 3) sham-L-Arg-A, 4) OVx-L-Arg-A, 5) sham-L-Arg-C, 6) OVx-L-Arg-C. The animals of sham-L-Arg-A and OVx-L-Arg-A were acutely treated with 500 mg/kg of L-Arg during 5 test days. Sham-L-Arg-C and OVx-L-Arg-C chronically received 500 mg/kg/day of L-Arg during 8 weeks before 5 test days. The animals in sham and OVx groups received 1 ml/kg saline instead of L-Arg. At the end of the experiment, the animals were tested in Morris water maze and the escape latency and traveled path to reach the platform were compared between groups. Results showed that the escape latency and traveled path in OVx group were significantly higher than in sham group (
<0.05). The animals in OVx-L-Arg-A group had significantly lower traveled path length and escape latency compared to OVx group (
<0.001). Chronic treatment by L-Arg had no significant effect on learning and memory in OVx and sham-operated animals. It seems that L-Arg has a role in Morris water maze tasks disturbances in OVx rats but it needs to be further investigated.