Ontogeny of the gut motility control system in zebrafish Danio rerio embryos and larvae.
Using digital motion analysis, the ontogeny of the cholinergic, tachykinin and pituitary adenylate cyclase-activating polypeptide (PACAP) control systems was studied in zebrafish Danio rerio larvae, in vivo. For the first time we show that the regular propagating anterograde waves that occur in the zebrafish larval gut before and around the onset [at 5-6 days post fertilization (d.p.f.)] of feeding are modulated by acetylcholine or atropine, PACAP and NKA (neurokinin A). At 3 d.p.f., when no spontaneous motility has developed, application of acetylcholine did not affect the gut. However, at 4 d.p.f., acetylcholine increased and atropine reduced the frequency of propagating anterograde waves. At 5 d.p.f., NKA increased and PACAP reduced the wave frequency. This suggests that both excitatory and inhibitory pathways develop at an early stage in the gut, independent of exogenous feeding. Immunohistochemistry established the presence of gut neurons expressing PACAP and NKA in the proximal part of the developing gut from the first stage investigated (2 d.p.f.) and before regular motility was observed. 1 d.p.f. (PACAP) or 2 d.p.f. (NKA) stages later the whole gut was innervated. This supports physiological results that gut motility is under neuronal control during the period when regular motility patterns develop.
Holmberg
Anna
A
Department of Zoophysiology, Göteborg University, Box 463, SE 405 30 Göteborg, Sweden.
Schwerte
Thorsten
T
Pelster
Bernd
B
Holmgren
Susanne
S
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004625:Embryo, Nonmammalian / Q000502:physiology; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology; D007150:Immunohistochemistry; D007814:Larva / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D009414:Nerve Growth Factors / Q000494:pharmacology; D015288:Neurokinin A / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018005:Receptors, Vasoactive Intestinal Peptide; D015027:Zebrafish / Q000254:growth & development / Q000502:physiology*; D029961:Zebrafish Proteins
D009414:Nerve Growth Factors; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018005:Receptors, Vasoactive Intestinal Peptide; D029961:Zebrafish Proteins; C495405:vipr2 protein, zebrafish; D001285:Atropine; D015288:Neurokinin A; D000109:Acetylcholine