Involvement of the histaminergic system on appetitive learning and its interaction with haloperidol in goldfish

2008

Biol. Res.

Self Cite

This work investigated the effect of the H 1 receptor blockade in the forebrain of ablated Carassius auratus in a simple stimulus-response learning task using a T-maze test with positive reinforcement. The goldfish were submitted to surgery for removal of both telencephalic lobes five days before beginning the experiment. A Tshaped glass aquarium was employed, with two feeders located at the extremities of the long arm. One of the two feeders was blocked. The experimental trials were performed in nine consecutive days. Each fish was individually placed in the short arm and confined there for thirty seconds, then it was allowed to swim through the aquarium to search for food for ten minutes (maximum period). Time to find food was analysed in seconds. Animals were injected intraperitoneally with chlorpheniramine (CPA) at 16 mg/kg of body weight or saline after every trial, ten minutes after being placed back in the home aquarium. The results show that all the training latencies of the A-SAL group were higher than the latencies of the S-SAL group. The S-SAL group had decreased latencies from the second trial on, while the S-CPA group showed decreased latencies after the fourth trial. The A-SAL group showed reduced latencies after the fifth trial, but the A-CPA group mainteined the latencies throughout the experiment. This suggests that CPA impairs the consolidation of learning both on telencephalon ablated animals and in sham-operated ones through its action on mesencephalic structures of the brain and/or on the cerebellum in teleost fish.

Section: Discussioncontrasting

confidence: 74%

Section: Pharmacological Treatmentmentioning

confidence: 99%

Chlorpheniramine impairs spatial choice learning in telencephalon-ablated fish

Romaguera

2008

Biol. Res.

Self Cite

“…Both intracerebroventricular injection of histamine and ip injection of histidine presented proactive effects against memory deficits induced by nucleus basalis lesion in rats (25). In goldfish, L-histidine had a facilitatory effect on appetitive learning (26).…”

Section: Discussionmentioning

confidence: 95%

L-histidine enhances learning in stressed zebrafish

Cofiel

2009

Braz J Med Biol Res

The aim of the present study was to determine the effect of the histaminergic precursor L-histidine and the H 3 receptor antagonist thioperamide on the learning process of zebrafish submitted or not to confinement stress. On each of the 5 consecutive days of experiment (D1, D2, D3, D4, D5), animals had to associate an interruption of the aquarium air supply with food offering. Nonstressed zebrafish received an intraperitoneal injection of 100 mg/kg L-histidine, 10 mg/kg thioperamide or saline after training. Stressed animals received drug treatment and then were submitted to confinement stress for 1 h before the learning procedure. Time to approach the feeder was measured (in seconds) and was considered to be indicative of learning. A decrease in time to approach the feeder was observed in the saline-treated group (D1 = 141.92 ± 13.57; D3 = 55 ± 13.54), indicating learning. A delay in learning of stressed animals treated with saline was observed (D1 = 217.5 ± 25.66). L-histidine facilitated learning in stressed (D1 = 118.68 ± 13.9; D2 = 45.88 ± 8.2) and non-stressed (D1 = 151.11 ± 19.20; D5 = 62 ± 14.68) animals. Thioperamide inhibited learning in non-stressed (D1 = 110.38 ± 9.49; D4 = 58.79 ± 16.83) and stressed animals (D1 = 167.3 ± 26.39; D5 = 172.15 ± 27.35). L-histidine prevented the increase in blood glucose after one session of confinement (L-histidine = 65.88 ± 4.50; control = 53 ± 3.50 mg/dL). These results suggest that the histaminergic system enhances learning and modulates stress responses in zebrafish.

“…The resulting solution was used at a dose of 100 mg/kg body weight, because a previous study indicated that this dose facilitated learning and memory in C. auratus (14). LH was chosen for its ability to quickly cross the blood-brain barrier (15).…”

Section: Pharmacological Treatment and Injection Proceduresmentioning

confidence: 99%

L-histidine reduces inhibitory avoidance in Carassius auratus submitted to cerebellar ablation

Garção

2009

Braz J Med Biol Res

The effect of post-training treatment with L-histidine (LH) on the memory consolidation of inhibitory avoidance was investigated in Carassius auratus submitted to cerebellar ablation. The inhibitory avoidance procedure included 3 days: one habituation day, one training day (5 trials, T1-T5) and one test day. On the training day, each fish was placed individually in a white compartment separated from a black compartment by a sliding door. When the fish crossed into the black compartment, a weight was dropped in front of it (aversive stimulus) and the time to cross was recorded. Saline or LH (100 mg/kg) was injected intraperitoneally 10 min after the trials. Data were log 10 transformed and analyzed by ANOVA and the Student-Newman-Keuls test (P < 0.