Residual effects of abomasal 5-hydroxytryptophan administration on serotonin metabolism in cattle.

Studies of serotonin in animal husbandry has received growing interest. However, there is limited information about serotonin manipulation using 5-HTP administered postruminally and its residual effects in cattle. The objective of this study was to evaluate the effectiveness of 5-HTP infused into the abomasum for enhancing circulating serotonin in cattle. Four Holstein steers (487 ± 7.6 kg) fitted with ruminal cannulas were used in a 4 × 4 Latin Square design experiment. The treatments were intra-abomasal infusion of 5-HTP at 0, 0.25, 0.5, and 1 mg/kg BW. Blood was collected from the jugular vein of each steer at -60, -30, 0, 30, 60, 120, 240, and 480 min from 5-HTP infusion for basal and short term evaluation and, at 1, 2, 4, and 7 d after 5-HTP infusion for long term evaluation. Dry matter intake was not affected (P > 0.05) by intra-abomasal infusions. The half-life of 5-HTP was dose-independent (128 min). The serum 5-HTP, serotonin, and 5-hydroxyindoleacetic acid area under the curve increased (P < 0.05) linearly with an increased dose of 5-HTP. Serum 5-HTP reached peak concentration in approximately 30 min after dosing while serum and plasma serotonin peaked after 240 min postinfusion. Serotonin was greater than control for all 5-HTP doses 1 d and 2 d after infusion in serum and plasma, respectively. Intra-abomasal infusion of 5-HTP at doses up to 1 mg/ kg BW increases circulating serotonin for up 2 days.

Evaluation of the effects of hyperbaric oxygen therapy for spinal cord lesion in correlation with the moment of intervention.

STUDY DESIGN: Experimental, controlled, animal study. OBJECTIVES: To evaluate the functional effect of hyperbaric oxygen therapy administered shortly, one day after, and no intervention (control) in standardized experimental spinal cord lesions in Wistar rats. SETTING: São Paulo, Brazil. METHODS: In all, 30 Wistar rats with spinal cord lesions were divided into three groups: one group was submitted to hyperbaric oxygen therapy beginning half an hour after the lesion and with a total of 10 one-hour sessions, one session per day, at 2 atm; the second received the same treatment, but beginning on the day after the lesion; and the third received no treatment (control). The Basso, Beattie and Bresnahan scales were used for functional evaluation on the second day after the lesion and then weekly, until being killed 1 month later. RESULTS: There were no significant differences between the groups in the functional analysis on the second day after the lesion. There was no functional difference comparing Groups 1 and 2 (treated shortly after or one day after) in any evaluation moment. On the 7th day, as well as on the 21st and 28th postoperative days, the evaluation showed that groups 1 and 2 performed significantly better than the control group (receiving no therapy). CONCLUSION: Hyperbaric chamber therapy is beneficial in the functional recovery of spinal cord lesions in rats, if it is first administered just after spinal cord injury or within 24 h.