Poster Abstracts POSTER 1 Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III Sensitization of the rewarding effects of morphine: Effects of (FIS), Redes temáticas de investigación Cooperativa (G03/005). AMPA glutamate receptor blockade Aguilar, Maria A. POSTER 2 Departamento De Psicobiologia, Facultad De Psicologia, The role of dopamine in the innate attraction towards male Universidad De Valencia pheromones displayed by female mice Manzanedo C*, Ribeiro Do Couto B, Rodríguez-Arias M and Minarro J Agustin, M. Carmen * Departamento de Anatomía Humana y Psicobiología, Área de Dept. Cell Biology, Fac. Biology, Universitat de Valencia Psicobiología, Universidad de Murcia, Campus de Espinardo, Martinez-Ricos , J(2), Martinez-Garcia, F(2), Lanuza, E(1) 30100 Murcia, Espana (1) Dept. Cell Biology, (2) Dept. Functional Biology, Fac. Biology, Departamento de Psicobiología, Universidad de Valencia, Avda. Universitat de Valencia Blasco Ibanez, 21, 46010 Valencia, Espana. Female mice raised in absence of male-derived chemicals intense- Drug addiction must be considered as a form of neural plasticity ly explore male-soiled bedding and prefer it to female-soiled bed- and the neuroadaptations leading to addiction and other forms of ding in a two-choice test. Recently, we demonstrated rewarding experience-dependent plasticity, such as learning and memory, properties of male pheromones to female mice using the condi- share the same glutamate-dependent cellular mechanisms. tioned place preference paradigm (Martinez-Ricos et al, 2004, Repeated administration of addictive drugs can produce an increase FENS Abstr., vol.2, A152.19). in some of their effects, i.e., sensitisation. In this work, we attempt The neural basis of the rewarding properties of sexual pheromones to determine the role of AMPA glutamatergic neurotransmission in is unknown. Since dopamine is thought to be involved in reward- the development of sensitisation to the rewarding effects of mor- related processes, we have investigated the effects of intraperi- phine measured with the place preference conditioning procedure toneal injections of antagonists of D1 (SCH 23390, 0.02 mg/kg) in mice. With this objective, we studied the effects of CNQX, an and D2 receptors (Sulpiride, 20 mg/kg) and of an indirect AMPA receptor antagonist, on the acquisition of sensitisation to dopamine agonist (D-amphetamine, 0.5-2 mg/kg), on the attraction place preference induced by morphine. To induce sensitisation, of female mice towards male pheromones. Surprisingly, preference mice were pre-treated daily for 5 days with an injection of physio- for male-soiled bedding is enhanced by sulpiride but not by SCH logical saline (group S+S), 20 mg/kg of morphine plus physiologi- 23390. On the other hand, the preference for male pheromones was cal saline or CNQX 5 or 10 mg/kg (groups M+S, M+CNQX5 and abolished by both amphetamine doses. Given that amphetamine M+CNQX10) and physiological saline plus CNQX 10 mg/kg administration has been shown to affect the olfactory sensitivity, (group S+CNQX10). After an interval of 3 days without any treat- we performed an habituation-dishabituation test for olfactory func- ment, all groups were conditioned following an unbiased procedure tion that showed impaired olfactory discrimination in high- but not after the administration of 2 mg/kg of morphine. The results in low-dose amphetamine-treated animals. Histological data sug- obtained show that the group S+S which was pre-treated with gest that these effects of amphetamine might occur in the olfactory saline and conditioned with 2 mg/kg of morphine did not present bulbs. place preference, suggesting that this dose of morphine is ineffec- Therefore, activation of D1 dopamine receptor is not necessary to tive to induce by morphine. To induce sensitisation, mice were pre- recognize pheromones as rewarding stimuli, whereas activation of treated daily for 5 days with an injection of physiological saline D2 receptor seems to decrease the rewarding properties of sexual (group S+S), 20 mg/kg of morphine plus physiological saline or pheromones. Moreover, increased dopamine levels induced by CNQX 5 or 10 mg/kg (groups M+S, M+CNQX5 and amphetamine might activate D2 receptors thus decreasing the M+CNQX10) and physiological saline plus CNQX 10 mg/kg pheromone-induced reward. Conversely, high doses of ampheta- (group S+CNQX10). After an interval of 3 days without any treat- mine might decrease sensitivity of vomeronasal system, although ment, all groups were conditioned following an unbiased procedure our histological data do not support this view. This work is funded after the administration of 2 mg/kg of morphine. The results by the Spanish MEC and European FEDER (BFU2004-04272/BFI) obtained show that the group S+S which was pre-treated with saline and conditioned with 2 mg/kg of morphine did not present place preference, suggesting that this dose of morphine is ineffec- tive to induce rewarding effects. Conversely, the group M+S, POSTER 3 which was pre-treated with 20 mg/kg of morphine and conditioned Electrical stimulation of the pedunculopontine tegmental with 2 mg/kg of this drug, acquired a clear place preference. Thus, nucleus in freely moving rats: time- and site-specific effects on morphine pre-treatment potentiates the effects of an ineffective two-way active avoidance conditioning dose of morphine, demonstrating the existence of sensitisation to its rewarding effects. Moreover, the higher dose of the AMPA Andero-Galí, R. antagonist CNQX produced a blockade of the effects of pre-treat- Dept Psicobiologia i Metodologia de les Ciencies de la Salut ment with morphine, suggesting the involvement of AMPA gluta- (Institut de Neurociencies), Universitat Autonoma de Barcelona mate neurotransmission in the development of sensitisation to the Quiroz-Padilla MF, Torras-Garcia M, Portell-Cortés I, Coll- rewarding effects of morphine. Andreu M. This work was supported by the following grants: Ministerio de Dept. Psicobiologia i Metodologia de les Ciencies de la Salut Educación y Ciencia y FEDER (ref. BSO2002-00106) (Espana), e (Institut de Neurociencies), Universitat Autonoma de Barcelona ABSTRACTS ARE PUBLISHED AS THEY WERE RECEIVED ONLINE 05/07/2005 23 The pedunculopontine tegmental nucleus (PPTg) is involved in the tems to the measured objects were modeled and then compared. regulation of thalamocortical transmission and of several functions The model predicted that trichromatic phenotypes would have an related to ventral and dorsal striatal circuits. Electrical stimulation advantage over dichromats in fruit and flower segregation. These of the PPTg in anaesthesized animals increases cortical arousal, results suggest that, at least in S. sciureus, heterosis seems to be cortical acetylcholine release, and substantia nigra dopaminergic the mechanism maintaining the observed polymorphism. activity. In turn, integrity of the PPTg is required to acquire sever- Additional studies are necessary, however, to determine if other al learning tasks, such as two-way active avoidance. It was hypoth- important aspects of the primates visual world, such as prey, esized that PPTg stimulation could improve learning by enhancing predator and con-specific detection, favor trichromacy or dichro- cortical arousal and optimizing the activity of striatal circuits. We macy. tested whether electrical stimulation of the PPTg, applied in freely- Key words: visual polymorphism, neotropical primates moving awake rats, would improve the acquisition and/or the reten- Support: CNPq, Capes/DAAD/Probal, Finatec tion of two-way avoidance conditioning, and whether this effect would depend on the specific PPTg region stimulated (central-ros- tral versus caudal) and on the time of stimulation: just before (pre- training) or immediately after (post-training) each of three training POSTER 5 sessions. Electrical stimulation consisted of 1-Hz current trains Are interhemispheric transfer time and hemispheric asymme- composed of 0.2 ms pulses (frequency: 100 Hz), and intensity tries really assessable by Reaction Time analyses ? ranged from 40 to 80 µA. Each treatment session lasted 20 minutes. Results showed that 1) this stimulation did not induce either any Ballanger, Benedicte (1) signs of distress nor abnormal behaviours, apart from some motor (1) INSERM, U534 Espace et Action, Lyon, France stereotyped behaviours that dissapeared when current intensity was Boulinguez Philippe (2), Benraiss Abdelrhani (2) lowered; 2)pretraining stimulation applied at the rostral-central (2) LPMC, EA3814, Université de Poitiers, France PPTg improved the acquisition of two-way active avoidance, 3)neither posttraining stimulation at the rostral-central PPTg, nor Callosal transfer time is generally assessed by reaction time (RT) pretraining and posttraining stimulation at the caudal PPTg had any analyses in target detection tasks using key-press responses (the so- significant effects on learning. The results are discussed in terms of called Poffenberger paradigm). Crossed-uncrossed differences the role of different PPTg regions in striatal functions and thalam- (hands x visual hemifields CUD-) are supposed to reflect inter- ocortical control. hemispheric transfer (IT) time. It has consistently been estimated about 4-5 ms for such simple detection tasks. If several IT may occur during simple interhemispheric visuomotor integration (e.g., POSTER 4 Iacobini & Zaidel, 2004), it is accepted that they all precede motor The importance of color vision for fruit detection by squirrel programming