SR 46559A: a novel and potent muscarinic compound with no cholinergic syndrome

Social recognition task in the rat

Among the numerous tasks designed for assessing distinct memory processes, the social recognition task in the rat offers the opportunity to evaluate a form of short-term working memory in the domain of social cognition, and its modification by pharmacological agents or physiopathological states, such as aging. Social cognition in humans is obviously of great importance and its deficits, e.g., during aging and Alzheimer's dementia, often have dramatic consequences for the patient and their environment. Two protocols are described in this unit that permit evaluation of positive and negative drug effects on social recognition memory in adult male rats and beneficial drug effects on age-related social recognition amnesia in aged male rats.

Selective optimization of side activities: the SOSA approach

Selective optimization of side activities of drug molecules (the SOSA approach) is an intelligent and potentially more efficient strategy than HTS for the generation of new biological activities. Only a limited number of highly diverse drug molecules are screened, for which bioavailability and toxicity studies have already been performed and efficacy in humans has been confirmed. Once the screening has generated a hit it will be used as the starting point for a drug discovery program. Using traditional medicinal chemistry as well as parallel synthesis, the initial 'side activity' is transformed into the 'main activity' and, conversely, the initial 'main activity' is significantly reduced or abolished. This strategy has a high probability of yielding safe, bioavailable, original and patentable analogues.

CCK-A and CCK-B receptors enhance olfactory recognition via distinct neuronal pathways

We have previously reported that CCK-A receptor agonists and CCK-B receptor antagonists both enhance memory in an olfactory recognition test. Here, we report that the memory-enhancing effect of the CCK-B receptor antagonist L-365,260 (1 mg/kg i.p.), but not that of the CCK-A receptor agonist caerulein (0.03 mg/kg i.p.), was dramatically decreased following a bilateral transection of the perforant path, a principal source of input to the hippocampal formation. We further confirmed that a significant memory deficit occurred subsequent to this deafferentation of the hippocampus in untreated animals. In contrast, the effect of caerulein, but not that of L-365,260, was abolished following a bilateral subdiaphragmatic vagotomy. These results demonstrate that the hippocampal system plays a role in olfactory recognition and indicate that distinct neuronal pathways underlie the memory-enhancing effects of CCK-A and CCK-B drugs observed in the olfactory recognition test. The former effects (CCK-A) appear to involve a peripheral relay to the brain via the vagus nerve, whereas the latter (CCK-B) are directly central and involve, at least in part, the hippocampal system.