Purinergic receptor activation attenuates pilocarpine-induced water intake

Abstract

Intraperitoneal (ip) injection of pilocarpine (PILO, muscarinic cholinergic agonist) induces salivation, water intake and changes in body temperature. These effects are due to a direct action on the salivary glands and central nervous system (CNS). ATP (adenosine 5'-triphosphate) is a neurotransmitter in the peripheral and CNS and is responsible for activating purinergic receptors located in various regions including the salivary glands. Preliminary results from our laboratory showed that ATP injected intraperitoneally (ip) reduced PILO-induced salivation, suggesting the participation of peripheral purinergic receptors in salivary secretion. The aim of the present study was to investigate the effects of ip injection of ATP (a natural agonist of purinergic receptors) on water intake and changes in body temperature induced by PILO also administered ip. Male Holtzman rats (300-350 g, n=18) were used. The experimental protocols were approved by the Ethical Committee for Animal Care and Use – CEUA from the Dentistry School of Araraquara, UNESP (Proc. CEUA nº 11/2019). A group of 10 rats received ip injection of PILO (1 mg/kg of body weight) to induce water intake. Ten minutes before, half of the group received an ip injection of ATP (200 mg/kg of body weight) and the other half received saline. Then water was offered in graduated burettes fitted with metal drinking spouts. The results showed that ip injections of ATP (200 mg/kg of body weight) reduced PILO-induced water intake (0.2 ± 0.1 ml/15 min, vs. saline + pilocarpine: 2.2 ± 0.6 ml/15 min, p<0.05). Another group of 8 rats was submitted to a median laparotomy for the placement of body temperature sensors in the abdominal cavity. The results showed that ip injection of PILO did not alter body temperature (0.3 ± 0.1 °C, vs. saline: 0.3 ± 0.1 °C) and the combination of ATP + PILO also did not change body temperature (0.2 ± 0.1 °C). Thus, the results suggest that ip injection of ATP reduced PILO-induced water intake, but PILO alone or combined with ATP did not change body temperature in rats CNPq, PROPE UNESP, FAPESP This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.