STUDIES ON FUNCTIONAL CONNECTIONS BETWEEN THE HIPPOCAMPUS, B-INSULOCYTES, THYMUS AND EPIPHYSIS

N. V. Grigorova

Zaporizhzhya National University

studies on functional connections between the hippocampus, b-insulocytes, thymus and epiphysis

Abstract

With the aid of elaborated highly sensitive cytochemical reaction zinc was revealed in hippocampus, B-insulocytes, thymus and epiphysis of rats. The intensity of this reaction may serve as indicator of the cell functional state. It was shown that the activation of hypothalamo-pituitary- adrenal axis (HPAA) induced the increase of zinc content in indicated cells. On the contrary the inhibition of HPAA induced the decrease of zinc content in the cells.

Key words: epiphysis, B-insulocytes, hippocampus, thymus, zinc.

I. Introduction

It was shown, that zinc content in the cells may be indicator of it’s functional state [1-4]. High selective cytochemical reaction of 8-(p-toluenesulfonylamino) – quinoline (8-TSQ) was elaborated and used by us for zinc detection in B-insulocytes, hippocampus, thymus and epiphysis [1-6].

It was shown [7-8], that the functional state of hippocampus depends on the state of hypothalamo-pituitary-adrenal axis (HPAA). The HPAA activation with immobilization, fasting and insulin injection induced the inhibition of hippocampus and the decrease of HPAA activity after the injection of leptin, dexamethason, GAMA leads on the contrary to hippocampus activation.

Seto et al. [9] observed the increase of insulin secretion in rabbits after the hippocampus electrical stimulation. We studied the influence of indicated factors on zinc content in hippocampus, B-insulocytes, thymocytes, pinealocytes of the rats.

II. Materials and methods

85 rats were used in experiments. Immobilization of animals made for 8 hours by it’s attachment to the board. Fasting of animals lasted during 1 day. Insulin injections were carried aut in the dose of 1 u/kg, leptin – 10 mg/kg, dexamethason – 0,1 mg/kg, GAMA – 50 mg/kg. The rats were killed in 2 hours after the injections. The pieces of hippocampus, pancreas, epiphysis, thymus and were fixe during 6 hours in cooled (4 °C) 70° alcohol, saturated with H₂S. Then the pieces were conducted through the alcohols of rising concentrations, xylenes, mixture of xylene and paraffin (40 °C), two liquid (56 °C) paraffins and embedded in paraffin.

Paraffin sections of 10 mkm thickness were conducted through xylenes, alcohols and tilled with 0,1 % acetone solution of 8-TSQ (for 1-2 min), washed in water and investigated under luminescent microscope (light filters V-1, Y-18). Zinc was revealed in preparates as yellow-green luminescent granules in the cells. Quantity of this metal were measured in the cells with microfluorimeter. The results were expressed as fluorescence intensity in conditional units (c.u.).

III. Results and discussion

The results of investigations of zinc content in hippocampus and thymocytes were cited at the table 1.

As was shown at table 1 in control animals zinc content in hippocampus formed 100 ± 10,1 c.u., in thymocytes - 100 ± 6,8 c.u. After immobilization concentration of this metal was increased upon 48 % (P < 0,001) in hippocampus and upon 57 % (P < 0,001) - in thymocytes. After fasting the data were obtained accordingly – 44 % (P < 0,001) and 69 % (P < 0,001), after insulin injection – 46 % (P < 0,001), 56 % (P < 0,001). After leptin injection zinc content was decreased on 33 % (P < 0,001) in hippocampus and on 44 % (P < 0,001) - in thymocytes. After dexamethason the data were obtained accordingly 24 % (P < 0,001), 45 % (P < 0,001), GAMA – 25 % (P < 0,001) and 42 % (P < 0,001). In all cases a positive coefficient correlation was noted between changes in hippocampus and thymocytes.

Table 1. Zinc content in hippocampus and thymocytes of rats under the various functional state of HPAA (± m)

Animals group	Zinc content, c.u.		r
Animals group	Hippocampus	Thymocytes	r
Control (n=15)	100±10,1	100±6,8	0,98***
Immobilization (n=12)	148±11,0***	157±15,7^***	0,54*
Fasting (n=12)	144±10,8***	169±10,1^***	0,55*
Insulin (n=11)	146±10,0***	156±16,2***	0,53*
Leptin (n=10)	67±5,3***	56±4,6***	0,64*
Dexamethason (n=11)	76±6,8***	55±5,4***	0,62*
GAMA (n=15)	75±5,9***	58±4,2***	0,65**

Note: * - P < 0,05; ** - P < 0,01; *** - P < 0,001; r – coefficient of correlation.

Thus, the character of zinc content changes in both organs was similar after the influence of the factors, changing functional state of HPAA.

The data of researches of zinc content in B-insulocytes and thymocytes were cited at the table 2.

As was shown at table 2, in control animals zinc content in B-insulocytes formed 33 ± 3,0 c.u. The content of this metal was increased upon 52 % (P < 0,001), after immobilization, fasting – 45 % (P < 0,001), insulin injection – 48 % (P < 0,001). Leptin induced the decrease of zinc content on 21 % (P < 0,01), dexamethason – 30 % (P < 0,01), GAMA – 27 % (P < 0,05).

A positive coefficient correlation of this metal changes was observed in both organs.

Table 2. Zinc content in B-insulocytes and thymocytes of the rats under the various functional state of HPAA (± m)

Animals group	Zinc content, c.u.		r
Animals group	B-insulocytes	Thymocytes	r
Control (n=15)	33±3,0	100±3,8	0,50*
Immobilization (n=12)	50±9,5***	157±13,7^***	0,42*
Fasting (n=12)	48±3,9***	169±12,1^***	0,43*
Insulin (n=10)	43±4,3***	157±13,2***	0,45*
Leptin (n=11)	24±1,6**	56±4,6***	0,54*
Dexamethason (n=11)	23±2,2**	55±5,4***	0,54*
GAMA (n=13)	24±1,8*	58±4,2***	0,62*

Note: * - P < 0,05; ** - P < 0,01; *** - P < 0,001; r – coefficient of correlation.

Thus, activation of HPAA induced the increase of zinc concentration in both organs, but inhibition of HPAA, on the contrary, the decrease of this metal content in organs.

At the table 3 zinc content was compared in B-insulocytes and pinealocytes.

Table 3. Zinc content in B-insulocytes and pinealocytes of the rats after the various functional state of HPAA (± m)

Animals group	Zinc content, c.u.		r
Animals group	B-insulocytes	Pinealocytes	r
Control (n=15)	33±3,0	92±7,5	0,48*
Immobilization (n=12)	50±4,5***	124±10,8^**	0,42*
Fasting (n=12)	48±3,9***	122±14,8^**	0,41*
Insulin (n=11)	49±4,9***	120±11,5**	0,42*
Leptin (n=10)	24±1,6*	53±4,8***	0,55*
Dexamethason (n=11)	23±1,8*	57±4,5***	0,53*
GAMA (n=13)	24±1,8*	59±5,0***	0,54*

Note: * - P < 0,05; ** - P < 0,01; *** - P < 0,001; r – coefficient of correlation.

As was shown at table 3, zinc content in pinealocytes formed 92 ± 7,5 c.u.

After immobilization zinc concentration was increased upon 35 % (P < 0,001), fasting – 39 % (P < 0,01), insulin injection – 30 % (P < 0,01). Leptin induced the decrease of this metal concentration in pinealocytes on 42 % (P < 0,001), dexamethason – 38 % (P < 0,001), GAMA – 36 % (P < 0,001).

A positive coefficient correlation of zinc content changes was observed in both cell types after the changes of HPAA function. The activation of HPAA induced the increase and the inhibition the decrease of zinc content in both cell types.

Comparison of zinc content in B-insulocytes and the cells of hippocampus also indicated positive correlation the changes in these cells.

Thus, activation of HPAA induced the increase and the inhibition of HPAA on the contrary, the decrease of zinc content in B-insulocytes, the cells of hippocampus, pinealocytes, thymocytes. Such date indicate positive functional correlations between all these cell types. Regulation of zinc content in B-insulocytes and accordingly of it’s functional state may be realized through the hippocampus, epiphysis and thymus activities.

These data were supported by the results investigations of Seto and al [9], wich indicated, that electrical stimulation of hippocampus induced increase of insulin secretion by B-insulocytes.

IV. Conclusions

1. Zinc content was revealed in hippocampus, B-insulocytes, thymocytes, pinealocytes.

2. Activation of hypothalamo-pituitary-adrenal axis (HPAA) induced the increase of zinc content in indicated cells.

3. Inhibition of HPAA induced on the contrary the decrease of zinc metal content in the cells.

4. The data obtained indicate positive functional connections between the hippocampus, B-insulocytes, thymus and epiphysis.

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