Comparison of azabicyclic esters and oxadiazoles as ligands for the muscarinic receptor.

The link between the cognitive deficit associated with Alzheimer type dementia and the loss of cholinergic function in the disease provides a basis for examining muscarinic agonists as potential therapeutic agents. This paper describes the design and synthesis of novel azabicyclic methyl esters as ligands for the muscarinic receptor. Replacement of the methyl ester by a 3-methyl-1,2,4-oxadiazole ring produces potent metabolically more stable muscarinic agonists capable of penetrating the central nervous system. These compounds generally show improved affinity relative to the corresponding methyl esters. 3-Methyl-1,2,4-oxadiazole 7b has an affinity 4 times that of acetylcholine. Receptor affinity is discussed in relation to the size and geometry of the azabicyclic ring and the electronic properties of the heteroaromatic ring.

In vitro hepatic insulin resistance in chronic pancreatitis in the rat.

To investigate the effect of chronic pancreatitis (CP) on in vitro hepatic sensitivity to insulin, the suppression of glucagon-stimulated hepatic glucose production (HGP) by insulin was examined during isolated liver perfusion (ILP) in CP and sham-operated rats. CP was induced at laparotomy by infusion of 50 microliters 99% oleic acid into the common bile duct during temporary occlusion of the proximal hepatic duct in 250- to 350-g Sprague-Dawley rats. Eight to sixteen weeks later, single-pass ILP was performed on fed animals. Glucagon (100 pg/ml) was infused for 30 min; the final 20 min of perfusion was performed with (a) no insulin, (b) 25 microU/ml insulin, or (c) 100 microU/ml insulin. CP and sham rats demonstrated comparable HGP responses to glucagon during the 0- to 10-min period (5.2 +/- 0.5 vs 5.9 +/- 0.5 mg/g/min, P = NS). CP rats demonstrated an HGP response to glucagon alone more evanescent than that in sham rats (20-30 min of HGP, 6.6 +/- 0.6 vs 9.5 +/- 0.4 mg/g/min, P less than 0.05). Sham rats showed a dose-dependent inhibition of HGP by insulin, however (percentage 20-30 min of HGP/0-10 min of HGP for 0, 25, and 100 microU/ml insulin: 166 +/- 12, 125 +/- 7, and 101 +/- 5%, P less than 0.01), whereas CP rats showed no effect of insulin (130 +/- 6, 123 +/- 7, 134 +/- 7%, P = NS). Pre- and postperfusion liver glycogen contents revealed comparable decreases in liver glycogen in both groups: insulin inhibition of HGP in sham rats was accompanied by higher postperfusion glycogen content. These data demonstrate a loss of insulin-mediated suppression of hepatic glucose production in livers obtained from pancreatitic rats. We conclude that CP is accompanied by a primary hepatic resistance to insulin; this defect may play a role in the etiology of pancreatogenic diabetes.

Synthesis and pharmacological evaluation of aromatic dihydroxylated spiro[indan-1,3'-pyrrolidine] and spiro[indan-2,2'-pyrrolidine] derivatives.

Aromatic hydroxylated derivatives of the spiro[indan-1,3'-pyrrolidine] and spiro[indan-2,2'-pyrrolidine] ring systems have been synthesized and evaluated for dopaminergic agonist and antagonist activities. None of these conformationally restricted catecholamines possessed any dopaminergic activity, but 5,6-dihydroxy spiro[indan-1,3'-pyrrolidine] hydrobromide exhibited weak dopamine antagonist properties.

Synthesis of spiro[tetralin-2,2'-pyrrolidine] and spiro[indan-2,2'-pyrrolidine] derivatives as potential analgesics.

Spiro[tetralin-2,2'-pyrrolidine] (13) and spiro[6-methoxytetralin-2,2'-pyrrolidine] (17) were prepared by initial Michael condensation of 2-nitrotetralin and 6-methoxy-2-nitrotetralin, respectively, with methyl acrylate to give 7 and 8, both of which could be reductively cyclized to 10 and 11, followed by LiAlH4 reduction. Spiro[indan-2,2'-pyrrolidine] (15) was prepared in an analogous manner form 2-nitroindan, and spiro[6-hydroxytetralin-2,2'-pyrrolidine] (19) was prepared by O-demethylation of 17. Compound 13 and its N-methyl derivative, 14, both showed good analgesic activity. Compounds 13-16 all possessed weak antidepressant properties, but neither 19 nor its N-methyl derivative 20 had any significant CNS activity.