Di-substituted amides for enhancing glutamatergic synaptic responses

#This invention relates to compounds, pharmaceutical compositions and methods for use in the prevention and treatment of cerebral insufficiency, including enhancement of receptor functioning in synapses in brain networks responsible for various behaviors. These brain networks are involved in basic functions such as breathing, to more complex functions such as memory and cognition. Imbalances in neuronal activities between different brain regions may lead to a number of disorders, including psychiatric and neurological disorders, including memory impairment, Parkinson's disease, schizophrenia, attention deficit and affective or mood disorders, respiratory depression and in disorders wherein a deficiency in neurotrophic factors is implicated. In a particular aspect, the invention relates to compounds useful for treatment of such conditions, and methods of using these compounds for such treatment.

#The release of glutamate at synapses at many sites in mammalian forebrain stimulates two classes of postsynaptic ionotropic glutamate receptors. These classes are usually referred to as AMPA and N-methyl-D-aspartic acid (NMDA) receptors. AMPA receptors mediate a voltage independent fast excitatory post-synaptic current (the fast EPSC), whereas NMDA receptors generate a voltage-dependent, slow excitatory current. Studies carried out in slices of hippocampus or cortex, indicate that the AMPA receptor mediated fast EPSC is generally the dominant component by far at most glutamatergic synapses, and activation of AMPA receptors is usually a prerequisite for NMDA receptors activation. AMPA receptors are expressed throughout the central nervous system. These receptors are found in high concentrations in the superficial layers of neocortex, in each of the major synaptic zones of hippocampus, and in the striatal complex, as reported by Monaghan et al., in Brain Research 324:160-164 (1984). Studies in animals and humans indicate that these structures organize complex perceptual-motor processes and provide the substrates for higher-order behaviors. Thus, AMPA receptors mediate transmission in those brain networks responsible for a host of cognitive activities. In addition, AMPA receptors are expressed in brain regions that regulate the inspiratory drive responsible for control of breathing (Paarmann et al, Journal of Neurochemistry, 74: 1335-1345 (2000).

#For the reasons set forth above, drugs that modulate and thereby enhance the functioning of AMPA receptors could have significant benefits for intellectual performance as well as reversal of respiratory depression induced by pharmacological agents such as opioids and opiates, or other means. Such drugs should also facilitate memory encoding. Experimental studies, such as those reported by Arai and Lynch, Brain Research 598:173-184 (1992), indicate that increasing the size of AMPA receptor-mediated synaptic response(s) enhances the induction of long-term potentiation (LTP). LTP is a stable increase in the strength of synaptic contacts that follows repetitive physiological activity of a type known to occur in the brain during learning.

#The terms below have the following meanings unless indicated otherwise. Other terms not specifically defined herein which are used to describe the present invention have the same meaning given to those terms within the context of their use by those skilled in the art.

#The term “alkyl” is used herein to refer to a fully saturated monovalent radical containing carbon and hydrogen, and which may be a straight chain, branched or cyclic. Examples of alkyl groups are methyl, ethyl, n-butyl, n-heptyl, isopropyl, 2-methylpropyl.

#The symbol