Morphine-like drugs inhibit the stimulation by E prostaglandins of cyclic AMP formation by rat brain homogenate

Bimodal regulation of adenylate cyclase

“…Evidence had also been accumulating that cyclic AMP production could be decreased by a number of agents, such as adenosine and PGE1 in adipocytes [8], or norepinephrine in platelets [9]. Isolated reports demonstrated that adenylate cyclase activity could be inhibited in various broken cell preparations by, for instance, musearinic eholinergic drugs [10], norepinephrine [9] and opiates [11]. These observations were drawn together when it was shown that inclusion of GTP in concentrations exceeding those required for the stimulation of adenylate cyclase by hormones, permitted inhibition of the enzyme by various putative neurotransmitters, for instance, epinephrine in platelets [12] and in neuroblastoma × glioma hybrids [13] and adenosine in fat cells [14].…”

A possible role for prostaglandins in the expression of morphine dependence in guinea‐pig isolated ileum

“…compare Figure 2 with Table 1). Collier & Roy (1974) balance shifts in favour of inhibition so that when naloxone is added the excitability of the tissue is not sufficient to result in a withdrawal contracture.…”

“…There is evidence that prostaglandins can interact with the acute action of opiates in both guinea-pig ileum (Ehrenpries et al, 1973) and brain (Collier & Roy, 1974). It was therefore of interest to examine whether prostaglandins were also involved in the chronic effects of opiates.…”

A Study of the Role of Cyclic Adenosine 3′,5′‐monophosphate in the Depression by Opiates and Opioid Peptides of Excitatory Junction Potentials in the Mouse Vas Deferens

“…First, morphine antinociception in rodents is reduced by prior administration of adenosine-3',5'-cyclic monophosphoric acid (cyclic AMP), its dibutyryl derivative (db cyclic AMP) or the phosphodiesterase inhibitor theophylline (Ho, Loh & Way, 1973). Second, opiates inhibit the prostaglandin-induced rise in cyclic AMP levels in rat brain homogenates (Collier & Roy, 1974). Third, opiates directly inhibit adenylate cyclase activity in neuroblastoma x glioma hybrid cells (Sharma, Klee & Nirenberg, 1975;Traber, Fischer, Latzin & Hamprecht, 1975 Opiates inhibit the release of neurotransmitters at several peripheral and central sites and, although the mechanism of this action is not yet fully understood, there is a good correlation between this effect of opiates and their activity as analgesics in man (interalia Kosterlitz & Waterfield, 1975;Henderson, Hughes & Kosterlitz, 1978).…”