Dopamine on D2-like receptors “reboosts” dopamine D1-like receptor-mediated behavioural activation in rats licking for a isotonic NaCl solution

Abstract

These results are consistent with the proposed hypothesis and provide support to the use of the study of licking microstructure as a valid model not only for the investigation of the mechanisms governing ingestive behaviour but also for the investigation of the mechanisms underlying behavioural activation and the related evaluation processes.

Differential effects of dopamine D1‐like and D2‐like receptor agonists on water drinking behaviour under thirsty conditions in mice with reduced dopamine secretion

“…Ropinirole treatment also reduced the number and size of bursts, indicating lower incentive motivation in the mice and a decreased hedonic impact of the water reward. A decrease in burst size after D2‐like receptor antagonist treatment was also reported by previous studies (Canu et al., ; D'Aquila, ; D'Aquila et al., ; Galistu & D'Aquila, ; Genn et al., ; Schneider et al., ). Overall, interfering with DA D2‐like receptor signalling (by either stimulation or blockade) may suppress fluid ingestion, but the underlying cause may not be straightforward and may involve several neural mechanisms.…”

“…Our finding that D1 agonist treatment restored the number of licks but not the number of bursts in DSI mice support this, suggesting that the recovered lick number largely reflects an increase in the hedonic impact. However, previous studies in rats suggested that D1‐like receptor signalling is involved in incentive motivation (D'Aquila, ; D'Aquila et al., ; Galistu & D'Aquila, , ). This discrepancy might reflect differences in species, drugs, or administration routes.…”

“…The DA D1‐like receptor antagonist SCH 23390 agonist reduces the number of licks by rodents for various fluid rewards (water, NaCl solution, or sucrose solution) by decreasing the burst number (D'Aquila, ; D'Aquila et al., ; Galistu & D'Aquila, , ); thus, the D1‐like receptor was suggested to play a role in the activation of reward‐associated responses. By contrast, the DA D2‐like receptor antagonist raclopride reduces the number of licks by decreasing the burst size (Canu, Carta, Murgia, Serra, & D'Aquila, ; D'Aquila, ; D'Aquila et al., ; Galistu & D'Aquila, ; Schneider et al., ); therefore, the D2‐like receptor was suggested to be involved in the evaluation of reward. Moreover, treatment with a D2/D3 receptor agonist, such as 7‐OH‐DPAT or quinpirole, suppresses licking for a sucrose solution by reducing the bout duration (Genn et al., ).…”

“…The mesolimbic dopamine (DA) system is involved in reward‐oriented behaviours (Berridge, ; Flagel & Robinson, ), and DA antagonism in rodents changes their ingestive behaviours (Galistu & D'Aquila, ; Robles & Johnson, ; Salamone, Correa, Yang, Rotolo, & Presby, ). The licking behaviour of rodents is widely used as a means to explore how liking (hedonic impact of reward), wanting (incentive motivation), and learning (reward prediction) modulate animal behaviours (Berridge, ; Berridge, Robinson, & Aldridge, ; D'Aquila & Galistu, ; Dastugue, Merlin, Maquart, Bernard, & Besnard, ; Davies et al., ; Johnson, ; Taha & Fields, ; Uematsu et al., ).…”

“…By contrast, direct administration of flupenthixol, a nonspecific DA receptor antagonist, to the NAc impairs responding for a reward (Danna & Elmer, ; Saunders & Robinson, ). It has been suggested that DA receptors modulate rodent drinking behaviour, but that D1‐like and D2‐like receptors may differentially influence the incentive motivation of mice or the hedonic impact of reward (D'Aquila, Rossi, Rizzi, & Galistu, ; Galistu & D'Aquila, ; Genn, Higgs, & Cooper, ; Robles & Johnson, ; Schneider, Davis, Watson, & Smith, ). To further study the potential differential effects, we analysed drinking behaviour in triple transgenic mice we generated with reduced DA release and treated with a D1‐like or D2‐like DA receptor agonist.…”