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Acute administration of angiotensin II improves long-term habituation in the crab Chasmagnathus
ELSEVIER
Neurosciencc Letters 196 (1995) 193 196
NEUROSCIEHC[ IEIT[RS
Acute administration of angiotensin II improves long-term habituation in the crab Chasmagnathus Alejandro Delorenzi b.*, M. Eugenia Pedreira ~, Arturo Romano a, Carlos J. Pirola b, Victor E. N a h m o d b, Hector Maldonado a al.~lboratorio de Fisiolo~,,fa del Comportamiento Anitmd, Facultad de Ciencias Exactas y Naturales, Depto Biologfa, Universidad de Buenos Aires (1428), Buenos Aires, Argentina bLaboratorio de Sustancias Vasoactivas, Instituto de lnvestigaciones Mddicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
Received 10 May 1995; revised version received 5 July 1995; accepted 26 July 1995
Abstract
A shadow moving overhead acts as a danger stimulus and elicits an escape response in the crab Chasmagnathus granulatus that habituates after 15 trials and for a long period. A shorter training of ten trials fails to induce long-term habituation; however, a good retention of the habituated response is manifest after a 24-h interval when angiotensin il (AII) (10 -6 M, 3 ng/g) is injected post-training. By contrast, no amnestic effect of AII was found even though high doses were administered. The facilitatory effect of AII is suppressed by saralasin (10 7 M, 0.3 ng/g), a specific angiotensin lI receptor antagonist. Results are considered as suggesting that angiotensin on memory processes might have emerged early in evolution. Keywords: Angiotensin !1; Learning; Memory; Chasmagnathus; Crab; Saralasin; Receptors; Invertebrates.
The peptide angiotensin II (AII) has long been recognized as exerting a wide range of physiological actions in the cardio-vascular, renal and endocrine systems [ 18]. On the other hand, AII was shown to have central effects [ 12] and to be present in brain tissue with the features of a neurotransmitter [4]. Manipulation of brain angiotensin levels appears to influence acquisition and recall of newly learned tasks. Centrally administered A l l was initially attributed a disrupting effect on memory [8] but more recent reports have indicated a facilitatory effect [2] mainly by angiotensin fragments such as angiotensin 3-8 [19]. Research on the role of angiotensins in processes involving learning has been confined to the mammalian brain. However, an attempt to study angiotensins in invertebrates would be justified by two reasons at least. First, the interest of testing if angiotensin's mnemonic properties emerged early in evolution and second, the potential advantage of using a simple model for studying the role
* Corresponding author.
of these peptides in a complex process like long-term memory. A shadow moving overhead acts as a danger stimulus and elicits an escape response in the crab C h a s m a g n a t h u s g r a n u l a t u s that habituates promptly and for a long period [3,7]. This habituation process proved to be a good model to study mechanistic and theoretical aspects of long-term memory. Studies have been performed on the context and stimulus specificity of this process [7,17]; on its adaptive value [17]; on its relation to age and circadian cycle [9]; on its dependence on P K A activity [11]; and on its modulation by opioids [5,10,16]. The purpose of the present work was to use such an experimental model to test the effect of AII on a memory process. The apparatus is described in detail elsewhere [10]. Briefly, the experimental unit was the actometer, a bowl-shaped plastic container suspended by strings from an upper wooden framework and illuminated from above. A crab was housed in the container and an opaque rectangular screen was moved across the upper border of the framework by a motor, thus provoking a crab's running response and consequent container oscillations that in-
0304-3940/95/$09.50 © 1995 Elsevier Science Ireland Ltd. All rights reserved SSDI 0304-3940(95)11876-U
194
A. Delorenzi et al. /Neuroscience Letters 196 (1995) 193 196
3000
tu
2000
z
o
Z tu
1000
0
10
V
-10
[]
10
-8
All
•
10
-6
DOSES(M)
Fig. I. Effect of diverse doses of All at 24 h after a ten-trial training session. Ordinate: mean of escape response score at testing (sixqrial block). Abscissa: doses of All per group. Dunnet-test: *P < 0.05, comparison between saline group and an All-injected group. The height of each bar is the mean _+SEM. duced electrical signals, through a piezoelectric transducer. These signals were amplified, integrated during the recording time (9 s), translated into numerical units ranging from 0 to 1530 and processed by computer. The experimental room had 40 actometers, isolated from each other by partitions. Groups of 20 crabs which underwent 15 9-s trials separated by a 3-rain interval showed retention of the habituated response when tested 24 h after training (a t-test invariably disclosed a significant difference between trained and control groups). However, when ten or fewer training trials were given, no retention was manifest. Thus, by using one or other amount of training the putative amnestic or facilitatory (hyperamnestic) effect of a drug could be tested. Animals were adult male crabs weighing 17 + 0.2 g, collected from water less than 1 m deep in the rias (narrow coastal inlets) of San Clemente del Tuyfi, Argentina. Fifty millilitres of vehicle (saline solution for crustacean [1]) or drug solution were injected in the pericardial sac. Such a volume represents approximately 1% of total haemolymph. In a first experiment, six groups of crabs were injected after ten training trials with vehicle (n = 80) or different solutions of human AII (10 -I°, 10 -s and 1 0 - 6 M; n = 40) and given six testing trials after a 24-h time interval. Mean response level of the AII groups at testing (six-trial blocks) was in any case lower than that of the saline group but a significant difference was only shown with 10 -6 M solution (3 ng/g) (Fig. I; Dunnet test, P < 0.05). By contrast, no between-group differences were disclosed when groups received the same doses than above but underwent 15 instead of ten training trials (data not shown), thus suggesting that AII has no amnestic effect on the crab's long-term habituation, but a facilitatory one.
The possibility that the foregoing result could be accounted for in terms of an unspecific depressing effect of the drug was addressed in a second experiment. One group of animals was trained as above (ten trials) (TR) and another one remained in the actometers during the time corresponding to the training session but without being stimulated by the passing shadow (CT). Half of the crabs in each group were injected immediately after the last training trial with vehicle (V) and the other half with 10 -6 M of AII. Thus, four groups were formed named VCT, V-TR, A I I - C T and AII-TR. Twenty-four hours after training, crabs were tested with six trials separated by a 3min interval. Results were analysed considering accumulated scores from the six testing trials. A t-test performed on these data showed a significant difference for A I I - C T versus AII-TR ( t = 3 . 1 5 , P < 0 . 0 0 5 ) but not for V-CT versus V-TR (Fig. 2). When a Duncan test was performed, the only significant differences were found between AII-TR and any other group (P < 0.05). Similar results were obtained in three further replications. A third experiment was aimed at testing the specificity of the putative facilitatory effect of AII. Six groups of 20 crabs each were formed. Three groups were trained as above (TR) and three other groups were corresponding controls (CT). One pair of groups was injected post-training with saline (V); a second pair, with 10 -6 M of AII (AII); a third pair, with 104 M of AII and 10 -7 M (0.3 rig/ g) of saralasin, a specific angiotensin receptor antagonist (23) ( A I I + SA). Results were analysed considering accumulated scores from the six testing trials. When a t-test was performed on data corresponding to each pair of groups (CT versus TR), a significant difference was dis3200-
2400Ix.I Z
o ,~ 1600,,m
o
/
Z
I
800-
TR
CT
V
[Z
CT All
TR
•
Fig. 2. The facilitatory effect of AII could not be explained by an unspecific attenuating effect on the response. White bars, groups injected with the vehicle (V-CT, control; V-TR, trained); black bars, groups injected with All (AII-CT, control; AII-TR, trained). A Duncan test only showed a significant difference for AII-TR versus any other group (*P < 0.05). Other symbols as in Fig 1.
A. Delorenzi et al. / Neurosctence Letters 190 (1995) 193-196 4000-
3200W Z 0
2400-
O
1600W
800-
CT
I--I
TR v
CT
i TR
A,,
CT
TR
p'~ SAn+All
Fig. 3. The facilitatory effect of All is receptor specific. While and black bars as in Fig 2. Striped bars. groups injected with All (10 -6 M) plus saralasin (10 -7 M) (All + SA-CT, control; All + SA-TR, trained) A Duncan test only showed a significant difference for AII-TR group versus any of the other groups (*P < 0.05). Other symbols as in Fig 1. closed only for the pair injected with AII ( t = 3.4, P < 0.001). W h e n a Duncan test was performed, the only significant differences were found between A I I - T R and any other group ( P < 0 . 0 5 ) (Fig. 3). Thus, saralasin blocked the AII effect. A further e x p e r i m e n t was aimed at testing the eflect of saralasin itself on the response level of either trained or control group. A design including four groups as in the second e x p e r i m e n t (Fig. 2) was used but injecting saralasin ( J 0 .7 M) instead of AII. R e s p o n s e level was statistically similar for all four groups (data not shown). Therefore, a b o v e results with the cocktail AI] plus saralasin (Fig. 3) could hardly be accounted for by an enhancing effect o f saralasin itself on the reactivity of trained or control groups at testing. T o sum up, A l l seems to facilitate the acquisition and/or consolidation of the habituated response since crabs injected with this drug show a robust long-term retention in spite of the fact that they had been given an insufficient n u m b e r o f training trials. The specificity of this facilitatory effect appears to be justified in one aspect. Saline and AII control groups display similar levels of r e s p o n s i v e n e s s at testing, thus ruling out an explanation in terms of response d e c r e m e n t due to a far-lasting. A I I - i n d u c e d sensorial or m o t o r impairment. H o w e v e r . further research is necessary to test specificity from other angles. N a m e l y , to d e t e r m i n e whether the action of AII is selective in the sense that it acts on m e m o r y by inducing 'all or n o n e ' type effects, or if it acts by modulating the activity of any other transmitter i n v o l v e d in m n e m o n i c processes [6]. Besides, it is worth exploring whether AII is selectively i n v o l v e d in c r a b ' s m e m o r y or if it has, like almost all neuropeptides in m a m m a l s , widespread endocrine activities. T h e fact that saralasin abates the action of AII on m e m o r y does not p r o v i d e direct e v i d e n c e of the crab's
195
receptor being the s a m e as that of m a m m a l s . H o w e v e r , this result along with previous reports describing the presence of A I I - l i k e substance in C N S of annelids [13] and a n g i o t e n s i n - c o n v e r t i n g e n z y m e - l i k e activity in a crab J14], are in keeping with the assumption that a peptide like m a m m a l ' s angiotensin is present in invertebrates. In this context, it is noteworthy that s y s t e m i c administration of AII or saralasin in doses as small as 5 0 / z l o f 10 4 10 -7 M are effective on the c r a b ' s m e m o r y , thus suggesting a high affinity by the receptor. Therefore, it m i g h t be c o n c l u d e d that the angiotensin action on m e m o r y processes would not be a collateral one, o b s e r v e d only in m a m m a l s , but a direct action that could perhaps h a v e e m e r g e d early in evolution. Ill Bnnd-Buckup, G., Fen-eira Fontura, N., Possa Marroni, N. and Kucharski, L., O Carangeuejo, Porto Alegre, Editora da Universidad, 1991.64 pp. [2J Braszko, J.J. and Wisniewski, K., Effective angiotensin It and saralasin on motor activity in the passive avoidance behavior of rats, Peptides, 9 (1988) 475~-79. [3] Brunner, D. and Maldonado, H., Habituation in the crab Chasma;,nathus granulatus: effect of morphine and naloxone., i. Comp. Physiol.. 162A (1988) 687-694. [4] Fischer-Ferraro, C., Nahmod, V.E, Goldstcin, D.J. and Finkielman, S., Angiotensin and renin in rat and dog brain, J. Exp. Med., 133 (1971) 353-361. [5] Godoy, A. and Maldonado, H., Modulation of the escape response by D(Ala2)Mebenkephalin in the crab Chasmagnathus, Pharmacol. Biochem. Behav., 50 (1995) 445~:~51. [6] Kovacs, GL. and De Wied, D., Peptidergic modulation of learning and memory processes, Pharmacol. Rev., 46 (1994) 269-291. [71 Lozada, M, Romano, A. and Matdonado, H., Long term habituation to a danger stimulus in the crab Chasmagnathus granulatus, Physiol. Behav., 47 (1990) 35~1-1. [81 Morgan, T.M. and Routtenberg, A., Angiotensin injected into the ncostriatum after learning disrupts retention performance, Science, 196 (1977) 87 89. [91 Pereyra, P., de la Iglcsia, H. and Maldonado, H., Training to testmg intervals different from 24 h impair habituation in the crab Chasma,q,nathus, Physiol. Bchav., (1995) in press. [101 Ronmno, A., Lozada, M. and Maldonado, H., Effect of naloxone prctreatmcnt on habituation in the crab Chasmagnathus granulatus. Behav. Neural Biol., 53 (1990) 113-122. [1 I J Romano, A., Delorenzi, A., Pedreira, M.E, Tomsic, D. and Maldonado, H., Acute administration of a permeant analog of cAMP and a phosphodicsterase inhibitor improve long-term habituation in the crab Chasmagnathus, Behav. Brain Res, (1995) in press. [12] Severs, W.B. and Daniels-Severs, A.E., Effects of angiotensin on the central nervous system, Pharmacol. Rev., 25 (1973) 415M-49. [131 Salzet, M., Verger-Bocquet, M., Waner, C. and Malecha, 1., Evidcncc for angiotcnsin-like molecules in the central nervous system of the leech Theromvzon tessulatum (O.F.M.): a possible diuretic effect, Comp. Biochcm. Physiol., 101A (1992) 83-90. [141 Smiley, J.W. and Doig, MT.. Distribution and characterization of angiomnsimconvening enzyme-like activity in tissues of the blue crab ('(d/inectes sapidus. Comp. Biochem. Physiol., 4 (1994) 491 M-96. [15J Timnmrmans, P.B., Wong, P.C., Chui, A.T.. Herblin, W.F., Benfield. P., Carini, D.J., Lee, R.J., Wexler, R.R., Saye, J.A.M. and Snnith. RD.. Angiotensin II receptors and angiotensin 11 receptor antagonists, Pharmacol. Rev., 45(2) (1993) 205-251. [161 Tomsic, D., Maldonado, H. and Rakitin, A., Morphine and GABA: effects on perception, scape response and long-term ha-
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A. Delorenzi et al. / Neuros~'tence Letters 196 (1995) 193-196
bituation to a danger stimulus in the crab Chasmagnathus, Brain Res. Bull., 26 (1991) 699-706. [17] Tomsic, D., Massoni, V. and Maldonado, H., Habituation to a danger stimulus in two semiterrestrial crabs: ontogenic, ecological and opioid modulation correlates, J. Comp. Physiol., 173A (1993) 621-633. [18] Wright, J,W. and Harding, J.W., Regulatory role of brain angio-
tensins in the control of physiological and behavioral responses, Brain Res. Rev., 17 (1992) 227-262. [19] Wright, J.W., Miller-Wing, A.V., Shaffer, M.J., Higginson, C., Wright, D.E., Hanesworth, J.M. and Harding, J.W., Angiotensin 11(3-8) (ANG IV) hippocampal binding: potential role in the facilitation of memory, Brain Res. Bull., 32 (1993) 492-502.
Neurosciencc Letters 196 (1995) 193 196
NEUROSCIEHC[ IEIT[RS
Acute administration of angiotensin II improves long-term habituation in the crab Chasmagnathus Alejandro Delorenzi b.*, M. Eugenia Pedreira ~, Arturo Romano a, Carlos J. Pirola b, Victor E. N a h m o d b, Hector Maldonado a al.~lboratorio de Fisiolo~,,fa del Comportamiento Anitmd, Facultad de Ciencias Exactas y Naturales, Depto Biologfa, Universidad de Buenos Aires (1428), Buenos Aires, Argentina bLaboratorio de Sustancias Vasoactivas, Instituto de lnvestigaciones Mddicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
Received 10 May 1995; revised version received 5 July 1995; accepted 26 July 1995
Abstract
A shadow moving overhead acts as a danger stimulus and elicits an escape response in the crab Chasmagnathus granulatus that habituates after 15 trials and for a long period. A shorter training of ten trials fails to induce long-term habituation; however, a good retention of the habituated response is manifest after a 24-h interval when angiotensin il (AII) (10 -6 M, 3 ng/g) is injected post-training. By contrast, no amnestic effect of AII was found even though high doses were administered. The facilitatory effect of AII is suppressed by saralasin (10 7 M, 0.3 ng/g), a specific angiotensin lI receptor antagonist. Results are considered as suggesting that angiotensin on memory processes might have emerged early in evolution. Keywords: Angiotensin !1; Learning; Memory; Chasmagnathus; Crab; Saralasin; Receptors; Invertebrates.
The peptide angiotensin II (AII) has long been recognized as exerting a wide range of physiological actions in the cardio-vascular, renal and endocrine systems [ 18]. On the other hand, AII was shown to have central effects [ 12] and to be present in brain tissue with the features of a neurotransmitter [4]. Manipulation of brain angiotensin levels appears to influence acquisition and recall of newly learned tasks. Centrally administered A l l was initially attributed a disrupting effect on memory [8] but more recent reports have indicated a facilitatory effect [2] mainly by angiotensin fragments such as angiotensin 3-8 [19]. Research on the role of angiotensins in processes involving learning has been confined to the mammalian brain. However, an attempt to study angiotensins in invertebrates would be justified by two reasons at least. First, the interest of testing if angiotensin's mnemonic properties emerged early in evolution and second, the potential advantage of using a simple model for studying the role
* Corresponding author.
of these peptides in a complex process like long-term memory. A shadow moving overhead acts as a danger stimulus and elicits an escape response in the crab C h a s m a g n a t h u s g r a n u l a t u s that habituates promptly and for a long period [3,7]. This habituation process proved to be a good model to study mechanistic and theoretical aspects of long-term memory. Studies have been performed on the context and stimulus specificity of this process [7,17]; on its adaptive value [17]; on its relation to age and circadian cycle [9]; on its dependence on P K A activity [11]; and on its modulation by opioids [5,10,16]. The purpose of the present work was to use such an experimental model to test the effect of AII on a memory process. The apparatus is described in detail elsewhere [10]. Briefly, the experimental unit was the actometer, a bowl-shaped plastic container suspended by strings from an upper wooden framework and illuminated from above. A crab was housed in the container and an opaque rectangular screen was moved across the upper border of the framework by a motor, thus provoking a crab's running response and consequent container oscillations that in-
0304-3940/95/$09.50 © 1995 Elsevier Science Ireland Ltd. All rights reserved SSDI 0304-3940(95)11876-U
194
A. Delorenzi et al. /Neuroscience Letters 196 (1995) 193 196
3000
tu
2000
z
o
Z tu
1000
0
10
V
-10
[]
10
-8
All
•
10
-6
DOSES(M)
Fig. I. Effect of diverse doses of All at 24 h after a ten-trial training session. Ordinate: mean of escape response score at testing (sixqrial block). Abscissa: doses of All per group. Dunnet-test: *P < 0.05, comparison between saline group and an All-injected group. The height of each bar is the mean _+SEM. duced electrical signals, through a piezoelectric transducer. These signals were amplified, integrated during the recording time (9 s), translated into numerical units ranging from 0 to 1530 and processed by computer. The experimental room had 40 actometers, isolated from each other by partitions. Groups of 20 crabs which underwent 15 9-s trials separated by a 3-rain interval showed retention of the habituated response when tested 24 h after training (a t-test invariably disclosed a significant difference between trained and control groups). However, when ten or fewer training trials were given, no retention was manifest. Thus, by using one or other amount of training the putative amnestic or facilitatory (hyperamnestic) effect of a drug could be tested. Animals were adult male crabs weighing 17 + 0.2 g, collected from water less than 1 m deep in the rias (narrow coastal inlets) of San Clemente del Tuyfi, Argentina. Fifty millilitres of vehicle (saline solution for crustacean [1]) or drug solution were injected in the pericardial sac. Such a volume represents approximately 1% of total haemolymph. In a first experiment, six groups of crabs were injected after ten training trials with vehicle (n = 80) or different solutions of human AII (10 -I°, 10 -s and 1 0 - 6 M; n = 40) and given six testing trials after a 24-h time interval. Mean response level of the AII groups at testing (six-trial blocks) was in any case lower than that of the saline group but a significant difference was only shown with 10 -6 M solution (3 ng/g) (Fig. I; Dunnet test, P < 0.05). By contrast, no between-group differences were disclosed when groups received the same doses than above but underwent 15 instead of ten training trials (data not shown), thus suggesting that AII has no amnestic effect on the crab's long-term habituation, but a facilitatory one.
The possibility that the foregoing result could be accounted for in terms of an unspecific depressing effect of the drug was addressed in a second experiment. One group of animals was trained as above (ten trials) (TR) and another one remained in the actometers during the time corresponding to the training session but without being stimulated by the passing shadow (CT). Half of the crabs in each group were injected immediately after the last training trial with vehicle (V) and the other half with 10 -6 M of AII. Thus, four groups were formed named VCT, V-TR, A I I - C T and AII-TR. Twenty-four hours after training, crabs were tested with six trials separated by a 3min interval. Results were analysed considering accumulated scores from the six testing trials. A t-test performed on these data showed a significant difference for A I I - C T versus AII-TR ( t = 3 . 1 5 , P < 0 . 0 0 5 ) but not for V-CT versus V-TR (Fig. 2). When a Duncan test was performed, the only significant differences were found between AII-TR and any other group (P < 0.05). Similar results were obtained in three further replications. A third experiment was aimed at testing the specificity of the putative facilitatory effect of AII. Six groups of 20 crabs each were formed. Three groups were trained as above (TR) and three other groups were corresponding controls (CT). One pair of groups was injected post-training with saline (V); a second pair, with 10 -6 M of AII (AII); a third pair, with 104 M of AII and 10 -7 M (0.3 rig/ g) of saralasin, a specific angiotensin receptor antagonist (23) ( A I I + SA). Results were analysed considering accumulated scores from the six testing trials. When a t-test was performed on data corresponding to each pair of groups (CT versus TR), a significant difference was dis3200-
2400Ix.I Z
o ,~ 1600,,m
o
/
Z
I
800-
TR
CT
V
[Z
CT All
TR
•
Fig. 2. The facilitatory effect of AII could not be explained by an unspecific attenuating effect on the response. White bars, groups injected with the vehicle (V-CT, control; V-TR, trained); black bars, groups injected with All (AII-CT, control; AII-TR, trained). A Duncan test only showed a significant difference for AII-TR versus any other group (*P < 0.05). Other symbols as in Fig 1.
A. Delorenzi et al. / Neurosctence Letters 190 (1995) 193-196 4000-
3200W Z 0
2400-
O
1600W
800-
CT
I--I
TR v
CT
i TR
A,,
CT
TR
p'~ SAn+All
Fig. 3. The facilitatory effect of All is receptor specific. While and black bars as in Fig 2. Striped bars. groups injected with All (10 -6 M) plus saralasin (10 -7 M) (All + SA-CT, control; All + SA-TR, trained) A Duncan test only showed a significant difference for AII-TR group versus any of the other groups (*P < 0.05). Other symbols as in Fig 1. closed only for the pair injected with AII ( t = 3.4, P < 0.001). W h e n a Duncan test was performed, the only significant differences were found between A I I - T R and any other group ( P < 0 . 0 5 ) (Fig. 3). Thus, saralasin blocked the AII effect. A further e x p e r i m e n t was aimed at testing the eflect of saralasin itself on the response level of either trained or control group. A design including four groups as in the second e x p e r i m e n t (Fig. 2) was used but injecting saralasin ( J 0 .7 M) instead of AII. R e s p o n s e level was statistically similar for all four groups (data not shown). Therefore, a b o v e results with the cocktail AI] plus saralasin (Fig. 3) could hardly be accounted for by an enhancing effect o f saralasin itself on the reactivity of trained or control groups at testing. T o sum up, A l l seems to facilitate the acquisition and/or consolidation of the habituated response since crabs injected with this drug show a robust long-term retention in spite of the fact that they had been given an insufficient n u m b e r o f training trials. The specificity of this facilitatory effect appears to be justified in one aspect. Saline and AII control groups display similar levels of r e s p o n s i v e n e s s at testing, thus ruling out an explanation in terms of response d e c r e m e n t due to a far-lasting. A I I - i n d u c e d sensorial or m o t o r impairment. H o w e v e r . further research is necessary to test specificity from other angles. N a m e l y , to d e t e r m i n e whether the action of AII is selective in the sense that it acts on m e m o r y by inducing 'all or n o n e ' type effects, or if it acts by modulating the activity of any other transmitter i n v o l v e d in m n e m o n i c processes [6]. Besides, it is worth exploring whether AII is selectively i n v o l v e d in c r a b ' s m e m o r y or if it has, like almost all neuropeptides in m a m m a l s , widespread endocrine activities. T h e fact that saralasin abates the action of AII on m e m o r y does not p r o v i d e direct e v i d e n c e of the crab's
195
receptor being the s a m e as that of m a m m a l s . H o w e v e r , this result along with previous reports describing the presence of A I I - l i k e substance in C N S of annelids [13] and a n g i o t e n s i n - c o n v e r t i n g e n z y m e - l i k e activity in a crab J14], are in keeping with the assumption that a peptide like m a m m a l ' s angiotensin is present in invertebrates. In this context, it is noteworthy that s y s t e m i c administration of AII or saralasin in doses as small as 5 0 / z l o f 10 4 10 -7 M are effective on the c r a b ' s m e m o r y , thus suggesting a high affinity by the receptor. Therefore, it m i g h t be c o n c l u d e d that the angiotensin action on m e m o r y processes would not be a collateral one, o b s e r v e d only in m a m m a l s , but a direct action that could perhaps h a v e e m e r g e d early in evolution. Ill Bnnd-Buckup, G., Fen-eira Fontura, N., Possa Marroni, N. and Kucharski, L., O Carangeuejo, Porto Alegre, Editora da Universidad, 1991.64 pp. [2J Braszko, J.J. and Wisniewski, K., Effective angiotensin It and saralasin on motor activity in the passive avoidance behavior of rats, Peptides, 9 (1988) 475~-79. [3] Brunner, D. and Maldonado, H., Habituation in the crab Chasma;,nathus granulatus: effect of morphine and naloxone., i. Comp. Physiol.. 162A (1988) 687-694. [4] Fischer-Ferraro, C., Nahmod, V.E, Goldstcin, D.J. and Finkielman, S., Angiotensin and renin in rat and dog brain, J. Exp. Med., 133 (1971) 353-361. [5] Godoy, A. and Maldonado, H., Modulation of the escape response by D(Ala2)Mebenkephalin in the crab Chasmagnathus, Pharmacol. Biochem. Behav., 50 (1995) 445~:~51. [6] Kovacs, GL. and De Wied, D., Peptidergic modulation of learning and memory processes, Pharmacol. Rev., 46 (1994) 269-291. [71 Lozada, M, Romano, A. and Matdonado, H., Long term habituation to a danger stimulus in the crab Chasmagnathus granulatus, Physiol. Behav., 47 (1990) 35~1-1. [81 Morgan, T.M. and Routtenberg, A., Angiotensin injected into the ncostriatum after learning disrupts retention performance, Science, 196 (1977) 87 89. [91 Pereyra, P., de la Iglcsia, H. and Maldonado, H., Training to testmg intervals different from 24 h impair habituation in the crab Chasma,q,nathus, Physiol. Bchav., (1995) in press. [101 Ronmno, A., Lozada, M. and Maldonado, H., Effect of naloxone prctreatmcnt on habituation in the crab Chasmagnathus granulatus. Behav. Neural Biol., 53 (1990) 113-122. [1 I J Romano, A., Delorenzi, A., Pedreira, M.E, Tomsic, D. and Maldonado, H., Acute administration of a permeant analog of cAMP and a phosphodicsterase inhibitor improve long-term habituation in the crab Chasmagnathus, Behav. Brain Res, (1995) in press. [12] Severs, W.B. and Daniels-Severs, A.E., Effects of angiotensin on the central nervous system, Pharmacol. Rev., 25 (1973) 415M-49. [131 Salzet, M., Verger-Bocquet, M., Waner, C. and Malecha, 1., Evidcncc for angiotcnsin-like molecules in the central nervous system of the leech Theromvzon tessulatum (O.F.M.): a possible diuretic effect, Comp. Biochcm. Physiol., 101A (1992) 83-90. [141 Smiley, J.W. and Doig, MT.. Distribution and characterization of angiomnsimconvening enzyme-like activity in tissues of the blue crab ('(d/inectes sapidus. Comp. Biochem. Physiol., 4 (1994) 491 M-96. [15J Timnmrmans, P.B., Wong, P.C., Chui, A.T.. Herblin, W.F., Benfield. P., Carini, D.J., Lee, R.J., Wexler, R.R., Saye, J.A.M. and Snnith. RD.. Angiotensin II receptors and angiotensin 11 receptor antagonists, Pharmacol. Rev., 45(2) (1993) 205-251. [161 Tomsic, D., Maldonado, H. and Rakitin, A., Morphine and GABA: effects on perception, scape response and long-term ha-
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A. Delorenzi et al. / Neuros~'tence Letters 196 (1995) 193-196
bituation to a danger stimulus in the crab Chasmagnathus, Brain Res. Bull., 26 (1991) 699-706. [17] Tomsic, D., Massoni, V. and Maldonado, H., Habituation to a danger stimulus in two semiterrestrial crabs: ontogenic, ecological and opioid modulation correlates, J. Comp. Physiol., 173A (1993) 621-633. [18] Wright, J,W. and Harding, J.W., Regulatory role of brain angio-
tensins in the control of physiological and behavioral responses, Brain Res. Rev., 17 (1992) 227-262. [19] Wright, J.W., Miller-Wing, A.V., Shaffer, M.J., Higginson, C., Wright, D.E., Hanesworth, J.M. and Harding, J.W., Angiotensin 11(3-8) (ANG IV) hippocampal binding: potential role in the facilitation of memory, Brain Res. Bull., 32 (1993) 492-502.