Figure 9: Selective activation of PVN-PACAP neurons mimics the phenotypes displayed by CNO-treated GsD-AgRP mice.

All studies were carried out with mice selectively expressing hM3Dq in PACAP neurons of the PVN of PACAP-ires-Cre mice (hM3Dq-PACAP mice; see ref. 21). (a) PACAP_6–38, a PACAP receptor antagonist, inhibits CNO-induced acute food intake in hM3Dq-PACAP mice. Mice initially received an i.c.v. injection of either saline or PACAP_6–38 (1.2 μg). Thirty minutes later, all mice were injected with CNO (1 mg kg⁻¹ i.p.). (b) Activation of PVN-PACAP neurons promotes hypothalamic AgRP and KLF4 expression. hM3Dq-PACAP mice were injected (i.c.v.) with either saline or PACAP_6–38 (1.2 μg). Thirty minutes later, all mice were treated with CNO (1 mg kg⁻¹ i.p.). Hypothalamic RNA was isolated and processed for quantitative reverse transcription–PCR studies 2 h after CNO treatment. Expression data were normalized relative to the results obtained with CNO-treated GsD-AgRP mice. (c,d) Activation of PVN-PACAP neurons leads to long-lasting increases in food intake and increased body weight (BW). hM3Dq-PACAP mice received a single i.p. injection of either saline or CNO (1 mg kg⁻¹). Changes in BW were expressed relative to pre-injection values (=100%). (e) Scheme summarizing the cellular pathway through which agonist-activated G_s-coupled GPCRs expressed by AgRP neurons are predicted to promote appetite. All experiments were carried out with 10- to 16-week-old male mice. Data are given as means±s.e.m. (n=3–6 mice per group). *P<0.05, **P<0.01, as compared with the corresponding control group (Student’s t-test).