Effects of maternal mild zinc deficiency and different ways of zinc supplementation for offspring on learning and memory

Figures & data

Fig. 1 Trial profile demonstrating number of dams and pups in each group that were fed with Zn-deficient diet (Zinc 2 µg/g) or control diet (Zinc 25 µg/g). CO=control; PF=pair fed; ZD=zinc deprived; OZS=oral zinc supplementation; IZS=injection zinc supplementation; ICO=injection control.

Table 1 Experiment zinc supplementation design of six groups

Group	Pregnancy Zn	Lactation Zn (till day 21)	Weaning Zn (days 21–35)
CO (controls)	25 µg Zn/g feed	25 µg Zn/g feed	25 µg Zn/g feed
PF (pair fed)	25 µg Zn/g feed, but the amount of food is the same as in the ZD group	25 µg Zn/g feed, but the amount of food is same as in the ZD group	25 µg Zn/g feed, but the amount of food is same as in the ZD group
ZD (Zn deficient)	2 µg Zn/g feed	2 µg Zn/g feed	2 µg Zn/g feed
OZS (Oral Zn)	2 µg Zn/g feed	2 µg Zn/g feed	25 µg Zn/g feed
IZS (intravenous Zn)	2 µg Zn/g feed	2 µg Zn/g feed	Zn-deficient diet, 2.5 mg ZnSO4 intravenously
ICO (intravenous control)	2 µg Zn/g feed	2 µg Zn/g feed	Zn-deficient diet Injection without Zn

Table 2 The effect of zinc supplementation on serum zinc and gain of body weight in rats

Rats	Group	Serum zinc (µg/l)	Gain of body weight (g)
Maternal	CO (6)	1038.50±68.87	70.50±5.96
	PF (6)	998.67±75.34	61.67±9.09^∇
	ZD (6)	657.83±60.83*	12.26±1.45 *
	OZS (6) IZS (6) ICO (6) F values p values	661.00±61.88* 684.33±21.12* 659.50±59.94* 54.80 <0.001	10.83±1.94 * 12.05±2.44 * 11.83±2.34 * 211.37 <0.001
Pups	CO (12)	1427.50±155.38	55.50±9.29
	PF (12)	1376.83±156.67	46.35±8.64^∇
	ZD (12) OZS (12) IZS (12) ICO (12) F values p values	568.86±57.93* 1508.75±157.13 1843.75±341.33*^▼ 559.14±67.71 101.96 <0.001	10.33±2.35* 59.42±9.27 17.83±6.27*^▼ 10.30±1.68 129.09 <0.001

Maternal rats’ serum zinc was measured at postnatal day 21, while pups’ serum zinc was measured at postnatal day 35. Data are expressed as the mean±standard deviation. CO=control; PF=pair fed; ZD=zinc deprived; OZS=oral zinc supplementation; IZS=injection zinc supplementation; ICO=injection control; ()=number of rats.

Comparison between two groups: (*) compared with CO and PF, p<0.05; (^∇) compared with CO, p<0.05; (^▼) compared with ICO, p<0.05.

Fig. 2 Box plots showing median Escape Latency (a) and Path Length (b) for each group for 4 days in Morris water maze test. Boxes show interquartile ranges, and I bars represent highest and lowest values. The horizontal lines indicate significant comparisons at post-hoc analysis. CO=control; PF=pair fed; ZD=zinc deprived; OZS=oral zinc supplementation; IZS=injection zinc supplementation; ICO=injection control.

Fig. 3 The escape latency (a) and Path length (b) for each animal during each training day. Data are means for 12 pups/group. From the second training day, the changes in the ZD, IZS, and ICO groups were not as obvious as those in the PF, CO, and OZS groups (p<0.05). CO=control; PF=pair fed; ZD=zinc deprived; OZS=oral zinc supplementation; IZS=injection zinc supplementation; ICO=injection control.